This document provides a summary of revisions made to the Water and Sewerage Authority (WASA) of Trinidad and Tobago Water and Wastewater Design Guideline Manual. Key changes include: adding minimum flood level requirements; changing the minimum fire duration criteria; revising PVC pipe specifications; adding a new section on polyurethane coating; revising fence height requirements; adding new sections on impoundment reservoirs and trenchless technologies; and adding criteria for as-built drawings and standards. The document contains a table of contents outlining the various sections and topics covered in the design guideline manual.

1. Water And Sewerage Authority (WASA)
Of Trinidad and Tobago
Water and Wastewater Design Guideline Manual
Revision 1 – October 2008

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Water and Wastewater Design Guideline Manual Table of Contents
i October 2008
R1
Major elements of revision no 1 – October 2008 :
In section 3.1, a minimum flood level requirement has been added.
In section 5.2.5.3, the minimum duration criteria for fire has been changed to one hour.
In section 5.6.2, the required specification for PVC pipe was changed.
In section 5.7.2, a new polyurethane coating section was added.
In section 6.6; 7.11; 12.16; 14.10, the height of fences have been reviewed to 2.1 m.
In a new section 6.2, requirements for impoundment reservoirs were added
In section 5.1 and 10.1, requirements for trenchless technologies were added
In a new section XX, criteria for As build and drawing standards were added.

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Table of Contents
Table of Contents
List of Abbreviations
Section 1 General Information .......................................................................... 1-1
Section 2 Design Approach & Approvals......................................................... 2-1
2.1 Introduction ...................................................................................................................... 2-1
2.1.1 Multi barrier approach ........................................................................................................ 2-1
2.1.2 Sustainable development .................................................................................................... 2-1
2.2 Design Guidelines............................................................................................................. 2-2
2.3 Review process of the guidelines ..................................................................................... 2-2
2.4 Approvals.......................................................................................................................... 2-2
Section 3 Design Standards................................................................................ 3-1
3.1 Design requirements......................................................................................................... 3-1
3.2 Acts, Codes and Standards ............................................................................................... 3-1
3.3 Other Design & Construction Standards .......................................................................... 3-2
3.4 Industry Standards ............................................................................................................ 3-2
Section 4 Process and Equipment Redundancy............................................... 4-1
4.1 General.............................................................................................................................. 4-1
4.2 Minimum redundancy – Wastewater systems .................................................................. 4-1
4.3 Minimum redundancy – Drinking Water systems............................................................ 4-1
4.4 Standby Power.................................................................................................................. 4-2
4.5 Standardization of Equipment .......................................................................................... 4-2
Section 5 Design of Water Distribution System............................................... 5-2
5.2.1 Design Water Demand........................................................................................................ 5-2
5.2.2 Average Water Demand (light industrial and commercial)............................................... 5-3
5.2.3 Residential Per capita demand............................................................................................ 5-4
5.2.4 Equivalent Population......................................................................................................... 5-5
5.2.5 Fire Flow Requirements...................................................................................................... 5-5
5.3.1 Pipe Design Flow................................................................................................................ 5-6
5.3.2 Hazen Williams roughness coefficient............................................................................... 5-6
5.3.3 Standard Pipe Sizes............................................................................................................. 5-7
5.3.4 Minimum Pipe Sizes........................................................................................................... 5-7
5.3.5 Pressure ............................................................................................................................... 5-7
5.4.1 Velocity ............................................................................................................................... 5-7
5.4.2 Pipe redundancy.................................................................................................................. 5-7
5.4.3 Pumping capacity................................................................................................................ 5-8
5.5.1 Grid System......................................................................................................................... 5-8
5.5.2 Location............................................................................................................................... 5-8
5.5.3 Separation from Stormwater and Wastewater Mains......................................................... 5-8
5.5.4 Pipe Depth........................................................................................................................... 5-9
5.5.5 Valves.................................................................................................................................. 5-9
5.5.6 Hydrants .............................................................................................................................. 5-9

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5.5.7 Blow Off............................................................................................................................ 5-10
5.6.1 Pipe Material ..................................................................................................................... 5-10
5.6.2 Pipe specification.............................................................................................................. 5-10
5.6.3 Structural Requirements.................................................................................................... 5-11
5.6.4 Tracer Wire ....................................................................................................................... 5-12
5.6.5 Water Service Connections............................................................................................... 5-12
5.7.1 Polyethylene Encasement ................................................................................................. 5-13
5.7.2 Polyurethane coating......................................................................................................... 5-13
5.7.3 Cathodic Protection........................................................................................................... 5-13
Section 6 Drinking Water Reservoirs ............................................................... 6-1
6.1 General.............................................................................................................................. 6-1
6.2 Impoundment design ........................................................................................................ 6-1
6.3 Reservoir (tank) Design.................................................................................................... 6-1
6.4 Reservoir Capacity............................................................................................................ 6-2
6.5 Re-chlorination System Requirements ............................................................................. 6-2
6.6 Emergency Eye-wash ....................................................................................................... 6-2
6.7 Site Access Road and Security ......................................................................................... 6-2
6.8 Architectural ..................................................................................................................... 6-3
6.9 Structural .......................................................................................................................... 6-3
6.10 Mechanical........................................................................................................................ 6-4
6.11 Ventilation ........................................................................................................................ 6-4
6.12 Instrumentation and Control............................................................................................. 6-4
6.13 Alarms .............................................................................................................................. 6-5
6.14 Control System ................................................................................................................. 6-5
6.15 Equipment Redundancy.................................................................................................... 6-5
Section 7 Potable Water Pumping Stations...................................................... 7-1
7.1 General.............................................................................................................................. 7-1
7.2 Pump design ..................................................................................................................... 7-1
7.3 Layout of Pumping Station............................................................................................... 7-1
7.4 Equipment Redundancy.................................................................................................... 7-2
7.5 Pumping Station Requirements ........................................................................................ 7-2
7.6 Control System ................................................................................................................. 7-2
7.7 Instrumentation................................................................................................................. 7-3
7.8 Alarms .............................................................................................................................. 7-3
7.9 Ventilation ........................................................................................................................ 7-4
7.10 Architectural ..................................................................................................................... 7-4
7.11 Site Access Road and Security ......................................................................................... 7-4
Section 8 Well Pumping Station Design............................................................ 8-1
8.1 General.............................................................................................................................. 8-1
8.2 Well Construction............................................................................................................. 8-1
8.3 Well Instrumentation & Control....................................................................................... 8-2
8.4 Alarms .............................................................................................................................. 8-2
8.5 Preferred Layout............................................................................................................... 8-3
8.6 SCADA System................................................................................................................ 8-3
8.7 Equipment Redundancy.................................................................................................... 8-4

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Section 9 Water Treatment Plants .................................................................... 9-1
9.1 General.............................................................................................................................. 9-1
9.2 Drinking water standards.................................................................................................. 9-1
9.2.1 Microbiological................................................................................................................... 9-2
9.2.2 Naturally occurring chemicals............................................................................................ 9-2
9.2.3 Chemical contaminants....................................................................................................... 9-3
9.2.4 Aesthetic guidelines............................................................................................................ 9-6
9.3 Performance targets and treatment objectives .................................................................. 9-6
9.3.1 General ................................................................................................................................ 9-6
9.3.2 Minimum treatment objectives........................................................................................... 9-7
9.3.3 Additional treatment objectives for Class I water supplies................................................ 9-9
9.4 Calculations of the water treatment performance........................................................... 9-10
9.4.1 General .............................................................................................................................. 9-10
9.4.2 Evaluation of the water treatment efficiency ................................................................... 9-11
9.4.3 Treatment based on physical removal of parasites and virus .......................................... 9-12
9.4.4 Treatment based on chemical inactivation of parasites and virus ................................... 9-14
9.4.5 Treatment based on physical inactivation of parasites and virus..................................... 9-14
9.5 Treatment plant general design....................................................................................... 9-15
9.5.1 Water intake ...................................................................................................................... 9-15
9.5.2 Monitoring......................................................................................................................... 9-15
9.5.3 General design elements ................................................................................................... 9-15
9.6 Disinfection design guidelines........................................................................................ 9-16
9.6.1 Chlorination System.......................................................................................................... 9-16
9.6.2 Ultraviolet Radiation (UV)............................................................................................... 9-18
Section 10 Design of Wastewater Collection System....................................... 10-1
10.2.1 Design Wastewater Flow.................................................................................................. 10-1
10.2.2 Average Dry Weather Flow.............................................................................................. 10-1
10.2.3 Peak Wastewater Flow Factor .......................................................................................... 10-3
10.2.4 Infiltration Allowance....................................................................................................... 10-4
10.3.1 Manning’s Formula........................................................................................................... 10-4
10.3.2 Coefficient of Roughness.................................................................................................. 10-4
10.3.3 Minimum Pipe Size........................................................................................................... 10-4
10.7.1 Location of Wastewater Main .......................................................................................... 10-6
10.7.2 Pipe Depth......................................................................................................................... 10-6
10.7.3 Grid Design ....................................................................................................................... 10-6
10.8.1 Concrete Pipe .................................................................................................................... 10-6
10.8.2 Polyvinyl Chloride Pipe.................................................................................................... 10-6
10.8.3 Polyethylene Pipe.............................................................................................................. 10-7
10.8.4 Glass Reinforced Plastics (GRP) Pipes and Fittings........................................................ 10-7
10.8.5 Ductile iron........................................................................................................................ 10-7
10.9.1 Maintenance Chamber Design.......................................................................................... 10-7
10.9.2 Manhole Hydraulics.......................................................................................................... 10-8
10.10.1 Street Line Connection ..................................................................................................... 10-8
10.10.2 Connection Size and Grade For Multi Family Sites ........................................................ 10-8
10.10.3 Pipe Material ..................................................................................................................... 10-9
10.11.1 System Design................................................................................................................... 10-9
10.11.2 Pipe Size............................................................................................................................ 10-9
10.11.3 Pipe Depth....................................................................................................................... 10-10
10.11.4 Tracer Wire ..................................................................................................................... 10-10
10.11.5 Thrust restraint ................................................................................................................ 10-10

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Section 11 Wastewater Treatment Plants......................................................... 11-1
11.1 General............................................................................................................................ 11-1
11.2 Wastewater Effluent treatment objectives...................................................................... 11-2
11.3 Wastewater Loads........................................................................................................... 11-2
11.4 Plant Layout.................................................................................................................... 11-2
11.5 Plant Design Capacity..................................................................................................... 11-3
11.6 Equalization tank ............................................................................................................ 11-3
11.7 Pre treatment – Inlet Works............................................................................................ 11-3
11.8 Secondary and tertiary treatments .................................................................................. 11-4
11.9 Disinfection System........................................................................................................ 11-4
11.9.1 Chlorination System.......................................................................................................... 11-5
11.9.2 Ultra-Violet (UV )............................................................................................................. 11-6
11.9.3 Sulphur Dioxide System................................................................................................... 11-7
11.10 Sampling and monitoring ............................................................................................... 11-7
11.11 Odor Control................................................................................................................... 11-7
11.12 Structural consideration.................................................................................................. 11-8
11.13 Water reuse for irrigation................................................................................................ 11-8
11.14 Control System ............................................................................................................... 11-8
11.15 SCADA System.............................................................................................................. 11-9
11.16 Equipment Redundancy.................................................................................................. 11-9
11.17 Stormwater management ................................................................................................ 11-9
11.17.1 Combined Sewer System vs. Separate Sanitary Sewer.................................................... 11-9
11.17.2 Runoff impact.................................................................................................................... 11-9
11.17.3 Requirements................................................................................................................... 11-10
Section 12 Wastewater Pumping Stations........................................................ 12-1
12.1 General............................................................................................................................ 12-1
12.2 Wastewater Pumping Station General Design................................................................ 12-1
12.3 Wastewater Pumping Station Layout ............................................................................. 12-1
12.4 Configuration of Pumping System ................................................................................. 12-2
12.5 Wastewater Pumping Station Sizing Design .................................................................. 12-1
12.6 Wastewater Pumping Station (Inflow less than 20 l/s)................................................... 12-1
12.7 Wastewater Pumping Station (20 l/s<Inflow < 200 l/s) ................................................. 12-1
12.8 Wastewater Pumping Station (Inflow > 200 l/s) ............................................................ 12-1
12.9 Pump Design................................................................................................................... 12-2
12.10 Piping & Valve Design................................................................................................... 12-2
12.11 Corrosion resistance........................................................................................................ 12-3
12.12 Pump Controls ................................................................................................................ 12-3
12.13 Odour Control................................................................................................................. 12-4
12.14 Ventilation ...................................................................................................................... 12-4
12.15 Equipment and Material Specifications.......................................................................... 12-4
12.16 Site Access Road and Security ....................................................................................... 12-5
12.17 Instrumentation & Control Alarms................................................................................. 12-5
12.18 SCADA System.............................................................................................................. 12-6
12.19 Equipment Redundancy.................................................................................................. 12-6
Section 13 Septage & Biosolids Management .................................................. 13-1
13.1 Septage Management – General ..................................................................................... 13-1
13.1.1 Stabilisation pond.............................................................................................................. 13-1
13.1.2 Wastewater Treatment Plant............................................................................................. 13-1

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13.1.3 Alkali treatment................................................................................................................ 13-2
13.2 Biosolids Management - General ................................................................................... 13-2
13.3 Sludge stabilization......................................................................................................... 13-3
13.3.1 Aerobic digesters............................................................................................................... 13-3
13.3.2 Anaerobic digesters........................................................................................................... 13-3
13.4 Incineration and heat treatment ...................................................................................... 13-4
13.5 Dewatering...................................................................................................................... 13-4
13.5.1 Sludge drying beds............................................................................................................ 13-5
13.5.2 Vacuum filters, belt filters, belt filter presses, and other mechanical dewatering filters 13-5
Section 14 Architectural Standards .................................................................. 14-1
14.1 General............................................................................................................................ 14-1
14.2 Laboratory control .......................................................................................................... 14-1
14.3 Roofing Design............................................................................................................... 14-1
14.4 Windows......................................................................................................................... 14-2
14.5 Doors .............................................................................................................................. 14-2
14.6 Ceiling ............................................................................................................................ 14-2
14.7 Wall Finishes .................................................................................................................. 14-2
14.8 Floor Finishes ................................................................................................................. 14-2
14.9 Light Fixtures ................................................................................................................. 14-3
14.10 Landscaping.................................................................................................................... 14-3
Section 15 Structural Standards........................................................................ 15-1
15.1 General............................................................................................................................ 15-1
15.2 Design of Water Retaining Structure.............................................................................. 15-1
15.3 Construction Requirements ............................................................................................ 15-1
15.4 Structural requirements................................................................................................... 15-1
15.4.1 Concrete ............................................................................................................................ 15-1
15.4.2 Steel Reinforcement.......................................................................................................... 15-2
15.4.3 Precast Structural Concrete............................................................................................... 15-2
15.4.4 Structural Steel.................................................................................................................. 15-3
15.4.5 Steel protection.................................................................................................................. 15-4
15.4.6 Concrete Block Masonry (C.B.M.) .................................................................................. 15-4
Section 16 Electrical Standards......................................................................... 16-1
16.1 General............................................................................................................................ 16-1
16.2 Equipment Identification Nameplates Requirements ..................................................... 16-1
16.3 Wiring Identification ...................................................................................................... 16-2
16.4 Panel Boards................................................................................................................... 16-2
16.5 Seismic braces ................................................................................................................ 16-2
16.6 High Efficiency Electrical Motor ................................................................................... 16-2
16.7 Motor Control Centre ..................................................................................................... 16-2
16.8 Transformers................................................................................................................... 16-3
16.8.1 High Efficiency Transformers .......................................................................................... 16-3
16.8.2 Distribution Transformers................................................................................................. 16-3
16.9 Co-ordination Studies of Protective Devices.................................................................. 16-3
16.9.1 Co-ordination Studies of Protective Devices Report ....................................................... 16-3
16.9.2 Short Circuit and Protective Device Evaluation and Co-ordination Study ..................... 16-4
16.9.3 Protective Device Co-ordination Study............................................................................ 16-4
16.9.4 Power System Study Report ............................................................................................. 16-5
16.9.5 Insulation Resistance Tests............................................................................................... 16-5
16.9.6 Lamps................................................................................................................................ 16-5

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Section 17 Instrumentation & Control ............................................................. 17-1
17.4.1 Design Criteria .................................................................................................................. 17-2
17.4.2 Interlocks........................................................................................................................... 17-2
17.4.3 Field Instrument................................................................................................................ 17-3
17.4.4 Indicators........................................................................................................................... 17-4
17.4.5 Instrumentation Loops (Analogue)................................................................................... 17-4
17.4.6 Control Circuits................................................................................................................. 17-4
17.4.7 Automation of Treatment Process .................................................................................... 17-5
17.4.8 Variable Frequency Drive (VFD) Control ....................................................................... 17-6
17.4.9 Pump Control Systems for Wastewater Pumping Stations.............................................. 17-7
17.4.10 PLC/RPU Interface ........................................................................................................... 17-7
17.4.11 Services ............................................................................................................................. 17-7
17.4.12 Documentation.................................................................................................................. 17-7
17.4.13 Preventive Maintenance Program..................................................................................... 17-8
17.4.14 Testing and Commissioning ............................................................................................. 17-9
Section 18 SCADA System................................................................................. 18-1
18.2 SCADA Operating Characteristics................................................................................. 18-1
18.3 SCADA System Requirements....................................................................................... 18-2
18.4 SCADA System Control Levels ..................................................................................... 18-2
18.4.1 Field (Local)...................................................................................................................... 18-2
18.4.2 Level 1 – Programmable Logic Controller (PLC) ........................................................... 18-3
18.4.3 Level 2 – PLANT.............................................................................................................. 18-3
18.8.1 Screen................................................................................................................................ 18-7
18.8.2 Button Bars........................................................................................................................ 18-7
18.8.3 Overview Screens ............................................................................................................. 18-8
18.8.4 Pop-Up Screen .................................................................................................................. 18-8
18.8.5 Control Pop-Ups Screens.................................................................................................. 18-8
18.8.6 Information Pop-Ups Screens........................................................................................... 18-9
18.8.7 Setpoint Pop-Up Screens .................................................................................................. 18-9
18.10.1 Raw Water Monitoring Parameters (Water) .................................................................. 18-12
18.10.2 Treated Water Monitoring Program (Water).................................................................. 18-13
18.10.3 Distribution System Monitoring Program (Water) ........................................................ 18-14
18.10.4 Raw Water Monitoring Program (Wastewater) ............................................................. 18-15
18.10.5 Treated Water Monitoring Program (Wastewater) ........................................................ 18-15
18.10.6 Process Parameters Monitoring Program (Wastewater) ................................................ 18-15
18.11.1 Trend Display Requirements .......................................................................................... 18-16
18.11.2 Water Treatment Plant Operating Statistics ................................................................... 18-16
18.11.3 Wastewater Treatment Plant Operating Statistics.......................................................... 18-19
18.13.1 Process Control Display.................................................................................................. 18-20
18.13.2 Standard Colour Convention – Process Stream ............................................................. 18-20
18.13.3 Standard Colour Convention – Pump/Motor/Valve....................................................... 18-21
18.14 Symbols ........................................................................................................................ 18-21
18.17.1 General ............................................................................................................................ 18-22
18.17.2 SCADA System Operation Manual Requirements........................................................ 18-23
18.18 System Architecture...................................................................................................... 18-26
18.24.1 PLC Program Structure................................................................................................... 18-28
18.24.2 PLC Programming Protocol............................................................................................ 18-29
Section 19 Mechanical Standards...................................................................... 19-1
19.1 General............................................................................................................................ 19-1
19.2 Valves............................................................................................................................. 19-1
19.3 Fittings............................................................................................................................ 19-1

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19.4 Pumps ............................................................................................................................. 19-2
19.5 Piping & Equipment Identification................................................................................. 19-3
19.5.1 General .............................................................................................................................. 19-3
19.5.2 Security equipment ........................................................................................................... 19-3
19.5.3 Piping Identification Labels.............................................................................................. 19-4
19.5.4 Colour Legend................................................................................................................... 19-4
19.5.5 Method of Application...................................................................................................... 19-6
19.5.6 Sizes of Characters............................................................................................................ 19-7
19.5.7 Location of Labels ............................................................................................................ 19-7
19.5.8 Pumps & Valves Colour Schedule ................................................................................... 19-8
19.5.9 Nameplates........................................................................................................................ 19-9
19.5.10 Equipment Name Tags.................................................................................................... 19-10
19.6 Equipment..................................................................................................................... 19-10
19.6.1 Bearings........................................................................................................................... 19-10
19.6.2 Pump Shaft Seals ............................................................................................................ 19-10
19.6.3 Couplings ........................................................................................................................ 19-10
19.6.4 Equipment Guard ............................................................................................................ 19-10
19.6.5 Gauge Taps and Test Plugs............................................................................................. 19-10
19.6.6 Alignment........................................................................................................................ 19-11
19.7 Equipment Maintenance Requirements........................................................................ 19-11
Section 20 Ventilating & Air Conditioning Standards.................................... 20-1
20.1 General............................................................................................................................ 20-1
20.2 VAC System................................................................................................................... 20-1
20.3 Minimum Air standard ................................................................................................... 20-2
20.4 System Redundancy........................................................................................................ 20-2
20.5 VAC Control System...................................................................................................... 20-2
20.5.1 VAC Master Control......................................................................................................... 20-2
20.6 Verification of VAC System .......................................................................................... 20-2
20.7 Location of air intakes .................................................................................................... 20-2
Section 21 Diesel Generator Standard.............................................................. 21-1
21.1 General............................................................................................................................ 21-1
21.2 Power Supply.................................................................................................................. 21-1
21.3 Approvals........................................................................................................................ 21-1
21.4 Noise Attenuation........................................................................................................... 21-1
21.5 Diesel Generator Power Requirements........................................................................... 21-2
21.5.1 Water Supply System........................................................................................................ 21-2
21.5.2 Wastewater Pumping Station............................................................................................ 21-2
21.5.3 Ancillary Electrical and Mechanical Equipment ............................................................. 21-2
21.6 Diesel Generator System Operation ............................................................................... 21-2
21.7 Diesel Engine Requirements........................................................................................... 21-3
21.7.1 General .............................................................................................................................. 21-3
21.7.2 Flame Detection System................................................................................................... 21-3
21.7.3 Fuel System....................................................................................................................... 21-3
21.7.4 Speed Governor................................................................................................................. 21-3
21.7.5 Fuel Tank........................................................................................................................... 21-4
21.7.6 Oil Lubricating System..................................................................................................... 21-4
21.7.7 Intake and Exhaust System............................................................................................... 21-4
21.7.8 Cooling System................................................................................................................. 21-4
21.7.9 Ventilation System............................................................................................................ 21-4
21.7.10 Gauges............................................................................................................................... 21-5
21.7.11 Battery Start System ......................................................................................................... 21-5

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21.7.12 Failure Annunciator .......................................................................................................... 21-5
21.8 Generator Requirements ................................................................................................. 21-5
21.8.1 General .............................................................................................................................. 21-5
21.8.2 Voltage Regulator ............................................................................................................. 21-6
21.9 Control System ............................................................................................................... 21-6
Section 22 Treatment Plant Operation Manual............................................... 22-1
22.1 General............................................................................................................................ 22-1
22.2 Operation Manual Requirements.................................................................................... 22-1
22.3 Format of Operation Manual .......................................................................................... 22-1
22.4 Water Treatment Plant Operation Manual...................................................................... 22-2
22.5 Wastewater Treatment Plant Operation Manual............................................................. 22-4
22.6 Training on the Use of the Operation Manual................................................................ 22-8
22.7 Training of WASA Staff................................................................................................. 22-9
22.7.1 Training Provided by the Contractor................................................................................ 22-9

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List of Abbreviations
AI Analogue Input
AO Analogue Output
ANSI American National Standard Institute
ARI Air-Conditioning and Refrigeration Institute
ASHRAE American Society of Heating, Refrigerating and Air-conditioning
Engineers
AWWA American Waterworks Association
CAD Computer Aided Design
CIBS The Chartered Institution of Building Services
CPM Critical Path Method
CV Curriculum vitae
CVS Certified Value Specialist
DI Digital Input
DO Digital Output
DTC Direct Torque Control
EA Environnemental Analysis
EIA Environmental Impact Assessment
EPA Environmental Protection Act
FAT Factory Acceptance Test
FIDIC Federation Internationale Des Ingenieurs – Conseils
(International Federation of Consulting Engineers)
HAZOP Hazard and Operability Study
HFS Hydrofluosilicic Acid
HLPS High Lift Pumping Station
I&C Instrumentation and Control System (I&C)
I/O Input / Output
LOH Loss of Head
MCC Motor Control Centre
MoWT Ministry of Works and Transport
MoALMR Ministry of Agriculture, Land and Marine Resources
EMA Environmental Management Agency
MoH Ministry of Health
MoPD Ministry of Planning and Development

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Project Design and Technical Specifications Manual List of Abbreviations
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MoPUE Ministry of Public Utilities and the Environment
NSF National Sanitation Foundation
NTU Nephelometric Turbidity Units
P&ID Proportional and Integral Derivative
PDR Pre-Design Report
PID Proportional Integral Derivative
PLC Programmable Logic Controller
QA Quality Assurance
QC Quality Control
RFP Request for Proposal
RIC Regulated Industries Commission
RPU Remote Processing Unit
SAT Site Acceptance Test
SCADA Supervisory, Control and Data Acquisition
SMACNA Sheet Metal and Air Conditioning Contractors' National Association
SPMDD Standard Proctor Maximum Dry Density
THD Total Harmonic Distortion
TKN Total Kjeldahl Nitrogen
TTBS Trinidad & Tobago bureau of Standards
UV Ultra Violet
VAC Ventilation and Air Conditioning
WASA Water And Sewerage Authority of Trinidad & Tobago
WTP Water Treatment Plant
WWTP Wastewater Treatment Plant
WHO World Health Organisation

13. Water And Sewerage Authority (WASA)
Water and Wastewater Design Guideline Manual General Information
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Section 1 General Information
As Trinidad & Tobago moves toward a 2020 vision of a modern and developed country, new and
refurbished water and wastewater infrastructures are needed all around the islands. The Water
And Sewerage Authority (WASA) of Trinidad and Tobago has put together this document in
order to guide the engineering design and establish the recommended standards for all new water
and wastewater infrastructure.
WASA has the responsibility for the provision of water supply and sewerage services in Trinidad
and Tobago, under Water and Sewerage Act, chapter 54:40. Increasing the levels of service
provided to the population has been a continuous concern for WASA. The present guidelines are
adapted to Trinidad and Tobago’s context and are compatible with WASA’s long term
operational policies. They present a comprehensive document for the construction and
rehabilitation of new and existing water and wastewater infrastructures.
The 2020 vision requires capital works from the government of Trinidad & Tobago in order to
meet the goals set. The implementation of water, wastewater and linear services projects requires
the services of Consultants to provide the required engineering expertise in accordance with the
requirements as specified herein. Consultants should therefore familiarize themselves with these
guidelines and provide their services accordingly to meet WASA’s expectation.
These guidelines are primarily intended to outline acceptable levels of servicing and minimum
criteria for future infrastructure in Trinidad & Tobago. They will assist consulting engineers,
engineering staff and other designers in the preparation of water and wastewater system
infrastructure design. Some of the design standards, detailed herein this manual, are not currently
used by WASA in the implementation of water and wastewater projects. These include the
Supervisory, Control and Data Acquisition system. However the information contained herein
will serve as a preliminary basis for consideration by WASA and should be followed if no other
directives have been stated.
This Water and Wastewater Design Criteria Manual is the property the Water And Sewerage
Authority (WASA) of Trinidad and Tobago. The design guidelines as detailed herein are for the
implementation of water and wastewater projects, including linear services and treatment plants.
The stipulated design guidelines must be complied with unless dispensation has been obtained in
writing from WASA or specified in the Request for Proposal,
Other References
This manual shall be used in conjunction with:
1. All rules, laws and regulations of the Republic of Trinidad and Tobago
2. Project’s Tender documents
3. WASA requirements and standards
4. Policies and Guidelines from stakeholders

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Water and Wastewater Design Guideline Manual Design Approach & Approvals
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Section 2 Design Approach & Approvals
2.1 Introduction
These guidelines do not supersede nor replace any legislation governing the design of such
treatment plants. Options and design optimisation are still to be conducted and investigated at the
prefeasibility level. The Consultants must be fully familiar with Trinidad & Tobago legislations
with respect to the design of water and wastewater infrastructure.
The guidelines and standards, as provided herein, were set by WASA in order to guide and frame
the engineering and consultancy works and assure a standardised and adequate design level in
the implementation of such systems. Approvals by WASA of infrastructures will require
compliance to these guidelines in conformity with WASA’s Water and Wastewater Policies.
Since standards, technology and priorities evolve, this manual is aimed to be reviewed frequently
and consultants are to assure that they are using the latest revision.
2.1.1 Multi barrier approach
In conformity with WASA’s policies, in order to ensure clean, safe and reliable drinking water, a
multi barrier approach is to be implemented from the source all the way to the consumer's tap.
This requires an understanding of the general characteristics of the water, the watershed or land
surrounding the water source, as well as mapping all the potential threats to the water quality.
The approach of the required design is to provide for barriers to either eliminate the threats or
minimize their impact. It includes protecting the available source from contamination, using
effective water treatment, and preventing water quality deterioration in the distribution system.
Together the barriers work to provide greater assurance that the water will be safe to drink.
2.1.2 Sustainable development
An integrated water resources perspective ensures that social, economic, environmental and
technical dimensions are taken into account in the management of water resources. WASA
wishes to promote practices that encourage sustainable development so there won’t be any
compromising of future generations’ ability to meet their needs.
As examples, protection of well’s head, installation of domestic water meters, and setting
wastewater effluent standards are part of the sustainable approach provided in this manual.
These are some of the good practices needed to assure long term sustainable and valuable water
for Trinidad & Tobago.
The water treatment standards and guidelines are established to ensure production of safe
drinking water. The amount and minimum scale of treatment processes are based on type and
quality of raw water, including their variability.

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2.2 Design Guidelines
This manual provides details on the design of water and wastewater related infrastructure so that
a standard of quality, reliability and uniformity will be achieved for WASA services to the
population of Trinidad & Tobago. It covers a wide range of applicable standards and
characteristics that need to be considered in order to assure the minimal quality requested. Items
covered by this manual include the following:
1. Equipment redundancy
2. Architectural standard
3. Structural standard
4. Underground pipelines
5. Electrical standard
6. Mechanical standard
7. Instrumentation & control standard
8. Emergency standby diesel generator standard
9. Equipment coding system standard
10. Operation & maintenance manual standard
11. Water quality and treatment standard
12. Wastewater effluent and treatment standards
13. SCADA
2.3 Review process of the guidelines
As technology, exigencies and standards evolve; these guidelines will have to be submitted for a
regular review by WASA in order to reflect the latest findings and comments. It is recommended
that this document be revised at minimum every five (5) years to comply with the best interest of
the population of Trinidad & Tobago.
2.4 Approvals
The Consultants shall comply with, and shall conduct all work with cognisance given to all
relevant statutory regulations and requirements, and where required, shall apply for all relevant
approvals or certificates.
In all cases, the Water and Sewerage Authority (WASA) should have granted approvals on the
outline and details of all projects prior to the installation of any facility. The WASA’s
administrative procedures are part of another document that must be consulted.

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In addition, all projects must meet Environmental Management Authority (EMA) approvals by
obtaining a Certificate of Environmental Clearance (CEC). Depending on the type of project, an
Environmental Impact assessment (EIA) may be required as established by EMA.
The Consultants shall comply with other stakeholders’ Policies and Rules, or tender documents.
They shall prepare all required documents for submission and review with WASA.
The Consultants must deliver to WASA a status report of all the applications for approvals
required for the project. Where there are outstanding approvals, the Consultants shall indicate the
time frame within which these approvals are expected to be in place.
Consultants are responsible for ensuring that plants designed by them comply with Acts, Codes,
Standards and Guidelines. The Standards and Guidelines provided in this manual are intended to
set the minimum acceptable standard and not to relieve them of their responsibilities to comply
with their legal and contractual requirements and obligations.
For detailed information about WASA’s administrative procedures for review, including costs,
type and number of copies of documents to submit for approval, consult WASA’s approval
process documentations.

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Water and Wastewater Design Guideline Manual Design Standards
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Section 3 Design Standards
3.1 Design requirements
It is the Consultant’s responsibility to ensure that they have fully understood the requirements of
the project as detailed in the Request for Proposal as they will be required to fulfil the specified
scope of work.
The infrastructure work includes both water and wastewater projects. WASA retains the services
of Consultants to provide the required engineering expertise to implement these projects in an
integrated manner with all building, safety and quality requirements. WASA requires and
expects that the Consultant will comply with the requirements as specified herein and therefore
provide their services accordingly to meet this expectation.
All materials and equipment supplied shall be suitable for being delivered, store and operated
under tropical conditions of high temperature, high humidity, heavy rainfall, mildew and fungus
conductive environment.
All WASA buildings or structures shall be flood proof. The site for the new facility shall be
appropriately selected or designed to be above the 20 years recurrence interval flood line.
When standards are provided, they are minimum requirements to be met by the system. When
specified, these standards are mandatory unless otherwise specified in writing by WASA.
Mandatory standards include drinking water quality standards and wastewater treatment plant
effluent standards.
3.2 Acts, Codes and Standards
The design of infrastructure shall comply with the following regulations, Acts, Codes, Standards,
Guidelines for all projects undertaken by Consultants on behalf of WASA:
1. Environmental Management Authority (EMA) of T&T
2. Water And Sewerage Authority (WASA) of Trinidad and Tobago
3. Ministry of Public Utilities and Environment (MoPUE)
4. National Building Code
5. National Fire Code
6. OSHA
The standards specifications for materials should be consistent with the requirements of the
following:
1. Trinidad and Tobago Standards (TTBS)
2. International Standards (ISO)
3. North American Standards (ANSI/AWWA)

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4. British Standards (BS)
3.3 Other Design & Construction Standards
Consultants shall comply with all Trinidad & Tobago technical rules and regulations related to
the design and construction of treatment plants as well as linear services.
Stakeholders if applicable should be included in the design. The T&T water and wastewater
stakeholders include but are not limited to:
- Ministry of Public Utilities
- Town and Country Planning Division
- Environmental Management Authority (EMA)
- Ministry of Local Government
- Ministry of Works and Transport
- Ministry of Finance
- Ministry of Health
- Regulated Industries Commission
- Ministry of Agriculture, Land and Marine Resources
- Office of the Ombudsman (Ministry of Legal Affairs)
- Consumer Affairs Division (Ministry of Legal Affairs)
- Water Recourses Agency and Forestry Division
- Trinidad & Tobago Fire Services
3.4 Industry Standards
All materials for potable water and sewers shall meet the ASTM, AWWA or other approved
equivalent standards. The Standards also provide literature on Workmanship. The following
standards are listed for guidance and are not final or exclusive to other standards.

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Water and Wastewater Design Guideline Manual Design Standards
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Storage Tanks
Welded Steel Tank
Painting for Welded Steel Tanks
Factory Coated Tanks
Disinfection
Concrete Structures for Retaining Liquids
ANSI/AWWA D100-84
ANSI/AWWA D102-78
ANSI/AWWA D103-80
ANSI/AWWA D652-86
AS 3735 1991
Pipelines
Polybutylene (PB)
Polyethylene (PET)
Poly Vinyl Chloride (PVC)
Fabricated Steel Pipe and Fittings
Steel Pipe Flanges Class D
Coal tar protection coatings and linings for steel water
pipelines
Flanged Ductile Iron Pipelines
Rubber Gasket
Disinfection
Pressure Test
Grey Iron Casting
GRP
Elastometrix Joint Rings for pipework and pipelines
Flanges and bolting for pipes valves and fittings metric
series
(copper alley and composite flanges)
Metal Washers for General Engineering Purposes
Metric Series
Specifications for Poly Vinyl Chloride (PVC) Solvent
Cement for use with unplasticized PVC Pipes and
fittings for cold water applications
Cast Iron Non-pressure pipes and pipe fittings metric
units
AWWA C-902-78
AWWA C-901-78
AWWA C-900-75
AWWA C-208-83
AWWA C-207-86
AWWA C-203-86
AWWA C-115/A21
AWWA C-111/A21
AWWA C-651-86
AWWA C-600-82
BS 1452:1977
AWWA C 950 - ASTM D 3754
BS 2494:1986
BS 4504: Part 2 1974
BS 4320:1968
TTS 413-1992
AS 1631-1974

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Water and Wastewater Design Guideline Manual Design Standards
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Valves
Ball Valves
Rubber Sealed Butterfly Valves
Sluice Valves
Predominantly key Operated Cast Iron Valves for
Waterworks purposes
Butterfly Valves
Copper Alloy Gate Valve and Non-Return Valves for
use in water supply and hot water services
Float Operated Valves
Specifications for Piston Type Float Operated valves
(Copper Ally Body) (Excluding Floats)
Specifications for Diaphragm type float operated valve
(copper Alloy Body) (Excluding Floats)
Specifications for Diaphragm type operated valves
plastic bodies, for cold water services only excluding
floats
Draw off taps and stop valves for water services (screw
down pattern)
AWWA C-507-85
ANSI/AWWA C-50
AWWA C-501-86
BS1 5163:1986
BS 5155:1984
AS 1628:1977
BS 1212
PT 1 1990
PT 2 1990
PT 3 1990
BS 1010 PT 2 1973
Safety Valves
Safety Valves
Specification for safety valves for steam and hot water
BS 6759
PT 1 1984
Mixing Valves
Mixing Valves
Non-Thermostatic, Non-Compensating mixing valves
Specification for Thermostatic mixing valves
BS 1415
PT 1 1976
PT 2 1986

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Water and Wastewater Design Guideline Manual Design Standards
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Various standards
Glass Filament reinforced thermosetting plastics (GRP)
Pipes Polyester Based-Water Supply. Sewerage and
Drainage Applications
Water Supply Metal Bodied Taps – Specified by
performance
Water Well Casing
Specification for steel tubes for casing
Specification for thermoplastics tubes for casing and
slotted casing
Stationary circulation pumps for heating and hot water
service system
Specification for Cold Water Storage and combined
feed and expansion cisterns (polyolefin or olefin
copolymer) up to 500L capacity used for domestic
purposes
Multi Standard
Measurement of flow of cold potable water in closed
conduits
Safety and control Devices for use in hot water systems
Code of Practice for test pumping of Water Well
Storage Cisterns up to 500L Actual Capacity for water
supply for domestic purposes
Bitumen – based coatings for cold application, suitable
for use in contact with potable water
Bitumen based hot applied coating materials for
protecting iron and steel including suitable primers were
required
Water Quality (Multi Standards) Physical, Chemical and
Biochemical methods
AS 3571 1989
AS 3718 – 1990
BS 879
PT 1 – 1985
PT Z – 1988
BS 1394
BS 4213 – 1991
BS 5728
BS 6283
BS 6316 – 1992
BS 7181 – 1989
BS 3416 – 1980
BS1 4147 – 1980
BS 6008
PT 2

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Water Meters
Cold – Water Meters – Multi – Jet Type ANSI/AWWA C 708-82
Cold – Water Meters – Displacement Type
Cold – Waters – Turbine type for customer service
Filtering material
Meters for cold potable water
ANSI/AWWA C 700-7
ANSI/AWWA C 701-78
ANSI/AWWA B 100
AS 3565 - 1988
Water Sampling
Water Quality – Sampling Pt 1 Guidance on
Design of Sampling Programmes 13 p
PT 2 Guidance on sampling technique
PT 3 Guidance on the Preservation and
handling of samples
PT 6 Guidance on sampling of rivers and
streams
PT 8 Guidance on sampling of Wet
depositions
PT 9 Guidance on sampling from marine
waters
PT 10 Guidance on sampling of waste waters
PT 11 Guidance on sampling of Ground waters
ISO 5667 – 1980
ISO 5667 – 1991
ISO 5667 – 1987
ISO 5667 – 1990
ISO 5667 – 1993
ISO 5667 – 1992
ISO 5667 – 1992
ISO 5667 – 1993
Water Testing of Pipes
Methods of test for unplasticized polyvinyl chloride
(PVC) Pipes. PT4 - Effects of Sulphuric Acid –
Requirements and Test method
Method of test for unplasticized PVC pipes and fittings
PT 3 - Determining the fracture toughness of UPVC
Pipes
Methods of test for unplasticized PVC pipes
PT8 - Method for Hydrostatic pressure testing of UPVC
short term test
Methods of test for unplasticized PVC Pipes PT 9 -
Methods of test for hydrostatic pressure testing of
UPVC pipes long term test
Methods of test for unplasticized polyvinyl chloride
TTS 16 80 30
PT 4 - 1991
TTS 16 80 30
PT3 - 1991
TTS 16 80 30
PT8 - 1991
TTS 16 80 30
PT9 - 1991
TTS 16 80 30
PT7 1991

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(PVC) Pipes PT 7 - resistance to external blows
Wastewater systems
Cement
Aggregate
Steel (Reinforcer)
Structural Steel
Manhole Bricks
Precast Sections
Manhole Frames Cones
Reinforced Concrete Pipes
Non reinforced Concrete Pipes
Welded Steel Pipe
Steel Fitting Couplings
Gate Valves
Sluice Valves
Drain Pipes and Fittings
Sewer
Grey iron
Ductile Iron
Thermoplastic Pipe for Sewers
Thermoplastics waste pipes and fittings
Polypropylene Waste pipe and fittings
(external Diameter 34.6 mm 41.0 mm 54.1mm)
Unplasticized PVC (UPVC) Pipes and Fittings for storm
and surface water applications
Unplasticized PVC (UPVC) Pipes and Fittings for soil
waste and vent (SWV) applications
Design charts for water supply and sewerage
Water supply – Mechanical backflow prevention devices
Plastics Waste Fittings
Specifications for compact type float operated valves for
WC Flushing Cisterns (including floats)
Specification for Galvanized low Carbon Steel, Cisterns,
lid tanks and Cylinders
Specification for unplasticized PVC Drain, Waste and
vent pipes
Technical Drawing Installation, Graphical symbols for
supply water and drainage systems
ASTM C-150 -60
ASTM C-33-59
ASTM A-15-58T
ASA-ASA A57 1-1952
ASTM C-32-58 Grade MA
ASTM C-478-61T usina
Type II cement
ASTM A48-60T
ASTM C76-60T
ASTM C14-59, l
AWWA C 202-59
AWWA (Same as Water)
ASA B16 10-1957
AWWA C 501-41T
BS 4660
BS 4660, BS 5481 or Class
B, BS 3505
BS 4622
BS 4772
ASTM D 2321, F-894
BS 5255 – 1989
BS 5254 – 1976
AS 1254
AS 1415 PT 1-4
AS 2200-1978
AS 2845-1986
AS 2887 – 1986
PT 4 -1991
BS 417
TTS 414-1992
TTS 31 85 006
PT 6 – 1998
Recommendations for the Design of buildings,
plumbing and drainage systems
TTS 16 90 400
PT 4 - 1985

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Water and Wastewater Design Guideline Manual Process and Equipment Redundancy
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Section 4 Process and Equipment Redundancy
4.1 General
The provision for process and equipment redundancy depends on the process and/or the
functionality of the associated process equipment. In the design of Water and Wastewater
facilities, Consultants must ensure that the level of redundancy for process and/or equipment is
provided such that the treated wastewater effluent or quality of the drinking water will be in
compliance with the Design guidelines & Environmental Management Authority (EMA)
Certificate of Environmental Clearance Rules or objectives at all times.
The current standard for provision of process and equipment redundancy level in water and
wastewater treatment plants is minimal. As existing plants are upgraded or expanded in the
future, key process equipments are to be provided with the redundancy level to safeguard the
supply of potable water or the discharge of treated wastewater to the environment.
4.2 Minimum redundancy – Wastewater systems
To ensure that the plant’s treated wastewater effluent will be in compliance with WASA’s
criteria or objectives at all times, the following minimum level of redundancy for equipment and
treatment processes shall be provided:
1. To ensure that the process train is available to meet the wastewater plant’s treatment capacity
requirements, the minimum redundancy of unit processes such as aeration tankages,
clarifiers, screens, etc. shall be equal to 50% of the total design capacity with the largest unit
processes out of service.
2. Similarly, to ensure that the wastewater flow will be handled to meet the required hydraulic
throughput, pumping stations shall be generally sized and installed with a 100% redundancy
with the largest equipment unit out of service. See section 12 for more details.
3. Pipe lines and forced mains do not require redundancy.
4.3 Minimum redundancy – Drinking Water systems
To ensure that the drinking water quality will be in compliance with WASA’s criteria or
objectives at all times, the following minimum level of redundancy for equipment and treatment
processes shall be provided:
1. To ensure that the process train is available to meet the drinking water treatment plant’s
capacity requirements, the minimum redundancy of unit processes such as clarifiers,
chemical dosers, filtration unit, etc. shall be equal to 100% of the total design capacity
with the largest unit processes out of service.
2. Similarly, to ensure that the water flow will be handled to meet the required hydraulic
throughput, pumping stations shall be sized and installed with a 100% redundancy with
the largest equipment unit out of service. Other distribution equipment such as piping,

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Water and Wastewater Design Guideline Manual Process and Equipment Redundancy
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valves, pressure reducing valves and water tanks do not require redundancy. See section
7 for more details.
3. Main water trunk systems should allow for some level of redundancy by aiming for
smaller double parallel pipe layout with adequate valving rather than one large pipe
diameter.
4.4 Standby Power
Whenever feasible, power supply to WASA’s plants shall be provided with dual feed from the
power supply grid network. Where this is not possible, standby power shall be provided in the
following key process system:
1. Wastewater treatment plant
.1 SCADA System
.2 Plant VAC System
.3 Plant disinfection system
.4 All equipment required to enable effective treatment for plants discharging in
environmentally sensitive areas.
2. Water intake pumps and equipment
3. Water Treatment Plant
.1 All equipment that is required to be operational to enable the water treatment plant to
meet average day demand is to be provided with standby power or an alternate source of
power.
3. Potable Water Pumping Station on main trunk systems. Other pumping stations shall be
assessed to establish criticality based on network configuration, gravity feed reservoirs, type
of supplied customers etc.
4. Wastewater Pumping Station
Power ratings for standby power are defined by ISO 8528-1 as the power available in the event
of a main power network failure up to a maximum of 500 hours per year of which up to 300
hours may be run continuously. Load factor may be up to 100% of standby power. No overload
is permitted.
4.5 Standardization of Equipment
Consultants shall ensure that the selection of equipment for use in the plants shall be
standardized as much as possible. In all cases, consultants must first refer to WASA’s available
list of approved suppliers and manufacturers for each application. For each process, the variety
of major equipment manufacturers should be limited to a maximum of three. The advantages of
keeping the selection of equipment to a maximum of three are:

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1. Reduction of time required to review design information
2. Minimize the inventory of spare parts
3. Reduction of time for staff to become fully familiarized with new equipment and facility
In general, consideration shall be given for new equipment to be from the same manufacturer as
those that are already installed in the same unit process train. This requirement will be reviewed
at the detailed design stage and alternate equipment or technology will be considered at that time.
Approved and alternate equipment shall be specified in the tender document such that WASA
has the right to accept or reject any equipment that the Contractor proposes to supply under the
contract.

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Water and Wastewater Design Guideline Manual Design of Water Distribution System
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Section 5 Design of Water Distribution System
5.1 General Requirement
This section outlines the requirements for the design of water supply systems. However, the
Consultants shall apply sound engineering judgement and approach to the design of such
systems. All designs shall comply with Trinidad & Tobago National Plumbing Code, AWWA
Standards of Practice and Specifications, relevant codes or design guidelines. The designs must
as much as it’s applicable, include mechanism for water conservation, including but not limited
to pressure control devices, low flush toilets, low volume faucets, etc.
Notwithstanding the above, the Consultants shall be familiar with the policy and standards
related to fire protection services requirements in Trinidad & Tobago.
In all projects, assessment of trenchless construction techniques and rehabilitation methods for
existing pipes shall be thoroughly prepared. The assessment shall as a minimum cover the
geotechnical conditions, traffic disruptions, survey the existing utilities and sub surface
structures, obtain right-of-way and property line information, take account of possible
improvements to street or utilities, risk and safety, and include technology aspects on
construction and costs etc.
For all new communities, the Consultants shall establish the geodetic invert elevations and ties of
all water service connections at the street line. All of this information shall be incorporated on
the “As-built” plans. To avoid proliferation of booster stations and reservoirs within each
development, each project should be assessed through modelling of regional network and
optimum development scheme. WASA’s Master Plan for Trinidad & Tobago should be reviewed
to grasp the bigger communities and regional planning priorities.
5.2 Water Demand
In the past years, many studies have been undertaken to assess the water demand for the different
types of consumers in Trinidad & Tobago. The available information is usually scarce and
significant variations exist between the different studies. The following design criteria for water
demands is based on different sources, notably the 1994 “Project Memoranda on Existing and
Future Demands” by William Halcrow & Partners Ltd., the 2006 “Analysis and Estimation of
Water Demand Forecasts” by Gordon Wyke, and various international figures including British
and North American standards.
5.2.1 Design Water Demand
The system shall be designed to meet the greater of either of the following demands:
1. Maximum Daily Demand Plus Fire Flow
2. Maximum Hourly Demand

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Where applicable, individual studies shall be conducted for the following:
1. Special commercial establishments and major commercial areas
2. Special industries and major industrial areas
3. Institutional development
4. High density residential areas
5.2.2 Average Water Demand (light industrial and commercial)
If individual data is not available, the following typical numbers should be used in order to
establish the daily average flow demand for light commercial and industrial facilities (sources :
WASA, Metcalf & Eddy) :
Facilities - Consummation per usage [L/(capita·d) or L/(unit·d)]
Airport (per passenger) 15
Shopping malls
Per parking spot 8
Per employee 40
Vacation center
Vacation colony ; central bathroom (per person) 160 – 200
Workers
Work camp with bath facilities (per worker) 140 – 200
Theatre
Per seat 10
Outdoor (per car) 15
School (per student)
With cafeteria 50 – 60
With cafeteria, shower and gymnasium 80 – 100
Boarding school or University Dormitory 285
Offices (per employee) 60
Health care facilities
General hospital (per bed) 1000
General hospital (per employee) 40
Other institution (per bed) 400
Hotels and hostels
Hotel room (per client) 200 - 300
Room and pension (per person) 200
Motel with kitchen 400 – 600
Laundry self service (per customer) 190

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Conference center (per person) 30
Stores
Per customer 8
Per employee 40
Restaurants
Medium size restaurant (per seat) 150
Medium size restaurant; open 24 h (per seat) 200
Bar (per place) 80
Gas station
Per car served 30
Per employee 50
Industrial facility (small to medium size)
Without cafeteria or shower (per employee) 70
With cafeteria and shower (per employee) 140
5.2.3 Residential Per capita demand
Residential Water demands have been historically high in Trinidad & Tobago. As water meters
are installed throughout the country, it is expected that residential water consumption will
linearly be lessened by 10% by 2020. When possible, per capita consumption and peaking
factors should be determined from historical data for the area. The following design factors,
based on the “Water Consumption & Demand Study” GENIVAR (2008), are to be used for the
design of residential water distribution systems in the absence of actual flow data:
Water demand 2007 2020
Residential per capita demand
Trinidad
330 litres/cap.d 280 litres/cap.d
Residential per capita demand
Tobago
315 litres/cap.d 280 litres/cap.d
Note : The demand per capita does not include any unaccounted for water (UFW) which is
historically very significant in Trinidad & Tobago. Depending on the region, the project and the
state of the distribution system, a case by case analysis is required for each project to include the
UFW and leakages of the system.
Maximum Daily and Maximum Hourly Demand Factors as noted in the table below:

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Peak Demands: Peak Day Peak Hour
Population 0 - 1,000 3 x Avg. Day 1.5 x Peak Day
Population 1,000 - 5,000 2.5 x Avg. Day 1.5 x Peak Day
Population 5,000 – 25 000 2.0 x Avg. Day 1.5 x Peak Day
Population > 25 000 1.5 x Avg. Day 1.5 x Peak Day
5.2.4 Equivalent Population
The design population is to be the ultimate for the area under consideration, the design life
threshold or local recommendation. The following equivalent population densities shall be used
to estimate the water service demand for the different types of developments in the design of
water distribution systems.
The average daily demand shall take into account water distribution system leakages, water
conservation as well as night time usage. The daily minimum flow is set as 35% of the average
daily flow.
3. Recommended flows to be used are (area is development area excluding major public streets,
freeways and railroad areas):
Single Family Residential 13 litres/min/ha
Multi-Family Residential 20 litres/min/ha
Walk-up Apartments 26 litres/min/ha
Community Services 10 litres/min/ha
Light Commercial 22 litres/min/ha
Light Industrial 40 litres/min/ha
5.2.5 Fire Flow Requirements
5.2.5.1 Policy and Standards related to Fire Protection
The 2020 vision aims to provide an adequate water supply for fire fighting for every building. In
general, fire flow requirements are established in close collaboration with insurance companies
and must involve capacity assessment of the Trinidad and Tobago Fire Services (TTFS). Since
insurance risk assessments or fire protection technical guidelines are yet to be established, the
following guidelines are to be used, derived from different sources including Fire Underwriters
Survey (FUS) and NFPA.
5.2.5.2 Reservoir Storage Capacity Requirements
Total reservoir storage capacity requirements shall be designed to be equal to the sum of the fire
storage requirements, 18 hours of average daily demand, plus emergency storage, which is 25%
of the sum of fire storage capacity and annual average daily demand. See section 6 for more
details.

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The required fire storage capacity may be equal to:
Vrc = Vfs + 0,75 Vad + 0.25(Vfs +Vad)
Where Vrc = Total reservoir water storage capacity requirement
Vfs = Fire storage capacity required
Vad = Annual average daily demand
Pressure zones with reservoirs should allow local pressure zone area of 40 to 80 psi (28 m to 56
m). In all cases, the pressure shall not be over 100 psi (70 m) and below 20 psi (14 m) for all
sectors supplied by the reservoir as recommended by the Regulated Industries Commission.
5.2.5.3 Fire Flow
For residential areas, the minimum acceptable fire flow shall be as stated in the following table
for a duration of minimum 1 hour with a residual pressure of 140 kPa (20 psi). For other types of
consumers, the fire flow shall be calculated on a case-by-case basis, but shall always exceed the
minimum residential fire flow requirements. Unless specified, major industrial sites are not to be
protected by the public water network. The required fire flow demand shall be supplied from at
least two fire hydrants.
Development Type Fire Demand (usgpm) Fire Demand (lpm)
Residential 1 000 3 800
5.3 Hydraulic Design
5.3.1 Pipe Design Flow
The Consultants may use the following Hazen Williams equation or the Darcy-Weisbach
equation in the design of watermains:
f = 0.2083 (100/c)1.852
q1.852
/ dh
4.8655
where
f = friction head loss in feet of water per 100 feet of pipe (fth20/100 ft pipe)
c = Hazen-Williams roughness constant
q = volume flow (gal/min)
dh = inside hydraulic diameter (inches)
5.3.2 Hazen Williams roughness coefficient
The Hazen-William’s coefficients for water pipelines equal to or less than 300 mm diameter
shall be set at 120 with no regard to pipe material. For pipe larger than 300 mm, use the
following table :

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Pipe Material Hazen William’s “c” Coefficients
Ductile Iron 130
HDPE 140
PVC or FRP 140
Steel 130
5.3.3 Standard Pipe Sizes
The Consultants shall use the following standard pipe sizes for the design of water distribution
systems:
150, 200, 300, 400, 450, 500, 600, 750, 900, 1050, 1200 mm diameter. No larger or other
diameter pipes shall be used prior to a written approval by WASA. In all cases, Consultants
must first refer to the WASA approved supplier and manufacturer list for approved supplier
and available diameters.
5.3.4 Minimum Pipe Sizes
The minimum pipe size for residential areas shall be 150 mm diameter. The velocity of water
flow should be between 0.9 and 1.55 m/s.
For dead end mains and mains exceeding minimum size, proper analysis shall be carried out to
ensure that the required pipe size is adequate to deliver the required water demand.
5.3.5 Pressure
The maximum working pressure at the point of connection shall not be more than 550 kPa (80
psi) and the minimum shall not be less than 140 kPa (20 psi) under fire flow conditions or not
less than 275 kPa (40psi) under normal operating conditions.
Any localized area which has a working pressure in excess of 550 kPa (80 psi), shall be provided
with a pressure-reducing valve on the distribution main or on individual services as required.
5.4 Trunk systems
Transmission pipelines are defined as larger diameter pipelines (typically 400 mm and higher)
which serves to transport large flows of water in the Trinidad & Tobago national grid system.
5.4.1 Velocity
The trunk system must be designed so the velocity shall not exceed 2.4 m/s in the peak hour flow
condition.
5.4.2 Pipe redundancy
Main water trunk systems should allow for some level of redundancy by aiming for smaller double
parallel pipe layouts with adequate valving rather than one hefty pipe diameter.

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5.4.3 Pumping capacity
Booster stations on the Trunk system must be designed in order to allow bidirectional (up flow or
down stream) pumping capacity so as to offer redundancy to the national grid system. The
valving configuration shall allow pumping in both directions and be controlled by the SCADA
systems to accommodate emergency situations.
5.5 System Layout
5.5.1 Grid System
Grid systems shall be designed to ensure flexibility of operation and to minimize the area of the
community required to be shutdown for the repair of the water distribution network. Wherever
possible, the Consultants shall consider the following in the design of the water distribution
system grid:
1. Dead ends shall be minimized by looping all watermains.
2. The use of easements to loop watermains shall be minimized.
3. At the dead end of all watermains, provide a fire hydrant or purge system for washout.
4. Maximum allowable pipe joint deflection shall be 70% of the manufacturer’s specifications.
Pipe barrel bending/deflection will not be permitted.
5. System should facilitate regular flushing of the network.
6. No flushing device is permitted to be directly connected to any stormwater, non potable
water or wastewater main.
5.5.2 Location
In general, the location of watermains shall be off-set 1.5 m from edge of the Right-of-Way
boundary.
5.5.3 Separation from Stormwater and Wastewater Mains
Lateral separation of watermains from stormwater and wastewater mains shall be a minimum of
2.5 m.
Under normal conditions, watermains shall cross above the stormwater and wastewater mains
with a minimum vertical separation of 450 mm to allow for proper bedding and structural
support of the watermain, stormwater and/or wastewater mains. As an alternative, the watermain
may be located under the stormwater and/or wastewater mains with the required minimum
vertical separation.
Where the watermain is located under the stormwater or wastewater main, the required vertical
clearance between the stormwater or wastewater main and the watermain shall be a minimum of
0.6 m. The watermain pipe shall be centred over the crossing so that the joints of the pipe are
equidistant from the stormwater or wastewater main.

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Where the specified vertical separation cannot be achieved, the stormwater and/or wastewater
main shall be constructed of material and with joints that will comply with watermain
construction standards and shall be pressure tested to assure water tightness.
5.5.4 Pipe Depth
Consultants shall allow a minimum of 0.9 m of cover for the watermain.
On open ditch or unimproved roads, a minimum cover shall be provided to allow for future road
improvements or lowering of the road profile. In areas where minimum cover cannot be
achieved, special provision shall be considered to protect pipe from live loading.
5.5.5 Valves
On distribution mains, gate valves shall be provided at every watermain junction but not greater
than 500 m apart and shall be arranged and placed so that no more than 75 units (residential or
commercial/institutional) and 2 hydrants are shut off at any time. On transmission mains over
250 mm diameter, location of the valves should be determined by the Consultants in conjunction
with WASA, but shall not be greater than 1000m. Under normal circumstances on distribution
mains, 3 valves shall be provided on a tee intersection and 4 valves shall be provided on a cross
intersection. Line valves shall be the same size as the watermain up to and including 600 mm
diameter. On 750 mm diameter and larger watermains, one size smaller valve is permissible.
Single line valves up to and including 300 mm shall be buried. Valves and washouts larger than
400 mm shall be installed in adequately designed shallow valve boxes..
Pressure reducing or pressure sustaining valves and chambers are permitted. However, special
designs shall be incorporated to meet the requirements of the water system and of pressure zones.
Resilient seat gate valves are to conform to AWWA C509, up to 300 mm (12 inch) size, with a non-
rising spindle, to be opened by turning in a counter-clockwise direction. All bolts and nuts shall be
304 or 316 stainless steel.
Butterfly valves could be provided on watermains larger than 300 mm diameter and valve
selection must be done in consultation with senior design engineer and utility owner.
5.5.6 Hydrants
Hydrants for fire fighting shall be of a type familiar to and approved by the Trinidad and Tobago
Fire Service (TTFS). The connections are to meet BS336 as 2 x 63.5 mm diameter nozzles and
be installed as per fire service recommendation on all distribution watermains with the following
maximum allowable spacing:
Maximum Allowable Hydrant Spacing
Development Area Maximum Spacing
Residential 250 m
Commercial, Industrial, & High Density Residential 100 m

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All hydrants shall be conform with TTS 622:20XX (in process by TTFS) and AWWA practices.
Laterals shall have a secondary valve, valve box and anchor tee. Spacing of hydrants on all
distribution watermains shall be adjusted to allow for the installation of hydrants at high points
along the watermains and at all dead ends. Hydrants shall be located outside of the ditch line.
Maximum horizontal distance between any point on the building perimeter facing the street and
the hydrant shall be 90 m.
An isolating valve shall be provided on each hydrant lead. This valve shall exist completely in the
sidewalk or entirely out of the sidewalk and conform to the grade of the surrounding area.
5.5.7 Blow Off
A blow-off is not permitted for permanent installations but may be used during the construction
stage for flushing of new watermains. Dead ends on mains 150 mm in diameter or larger shall be
provided with a standard fire hydrant or a two-inch blow-off at the terminal end.
5.6 Pipe Requirements
5.6.1 Pipe Material
All pipes shall have a minimum designed pressure rating of 10 bar and calculation of the strength
and thickness of the pipe shall be made in accordance with AWWA practice or procedures.
Pipes shall be one of the following unless otherwise approved in writing by the Local
Authorities:
Pipe material passing through structural walls should generally be steel.
5.6.2 Pipe specification
See table below for the preferred watermain design range, joint type, service connections and
specifications. The proper selection of water pipe material shall take into consideration the
following:
Working and Surge Pressure Rating;
Internal and External Corrosion Resistance;
Negative Pressure Capacity;
Ease of Installation & Repair;
Availability;
Material Composition e.g. pipes and shall be lead free;
Pipe Rigidity with regards to trench conditions; and
Preferred Design Range for Watermains
Material Main Size Joint Type Services Specification

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Material Main Size Joint Type Services Specification
Ductile Iron (cement
lined)
≤ 1600 mm Tyton > 50 mm
AWWA C151, EN 545 or ISO
2531
Polyvinyl Chloride
(PVC)
< 300 mm
Gasketed Bell &
Spigot
> 100 mm
AWWA C900, AWWA C905,
EN 1452 parts 1 to 5
ISO 4422
Steel Pipe
> 750 mm
Or when pipe
exposed above
surface.
Gasketed Bell &
Spigot or flanged
AWWA C200, EN 10244 or
BS 534
Glass reinforced plastic
(GRP)
450 mm to
3000 mm
Gasketed Bell &
Spigot
AWWA C 950 - ASTM D 3754
5.6.3 Structural Requirements
5.6.3.1 Thrust Restraints
All watermains and thrust restraints shall be designed to withstand the cycling operation of water
mains in T&T in addition to the maximum operating pressure plus the transient pressure to
which it will be subjected. The value of the transient pressure will not be less than the pressure
surge that would be created by immediate stoppage of a water column moving at 0.6 m/s. The
design pressure shall not be less than 10 bar in any case.
All plugs, caps, tees and bends will have approved mechanical thrust restraints based on
applicable AWWA standards. Concrete thrust blocks shall be used with WASA’s approval.
Mechanical thrust restraint devices shall have third party testing certification for water systems.
5.6.3.2 Bedding and Backfill
All buried pipes and conduits entering or exiting a structure shall be fully supported in backfilled
zones by means of a structural bridge or other suitable system to protect against settlement. Bedding
requirements shall be determined by the depth of bury of the pipe, soil type and trench
conditions. As a minimum requirement, watermain shall be laid on 100 mm of sand bedding
conforming with AASHTO M-43 requirement.
5.6.3.3 Above surface Pipe Support
Pipes shall always be supported adequately in accordance with applicable ANSI B31.1, ANSI
B31.9 or other building service pipe codes. If unsupported span is required (for a river crossing per
example), Consultants should address the requirements based on manufacturers recommendations,
considering bending stresses and deflection. Also, the design must address the presence of
concentrated loads (valves, strainers, etc) and changes in direction.

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5.6.4 Tracer Wire
Tracer wire shall be installed on all new installations of PVC and Polyethylene watermain pipes
for locating purposes. A solid 1.5 mm diameter TWU copper wire shall be installed along the top
of the pipe and strapped to the pipe at 6 m intervals. All wires shall be jacketed with a minimum
of 0.76 mm Polyethylene.
The wire shall be installed between each valve and/or at the end of the new PVC watermain.
Joints in the wire between valves are not permitted. At each valve, a loop of wire is to be brought
up inside the valve box to the top of the box.
5.6.5 Water Service Connections
In designing service connections, the Consultants shall comply with the following requirements:
1. All underground water service connections up to and including two-inch sizes shall be extra
Polyethlene PE pipe conforming to ANSI/AWWA C901-96. Connections shall be secure,
durable and watertight.
2. All water services shall be installed at right angles to the watermain.
3. All underground services larger than 50 mm in size shall be ductile iron pipe or PVC pipe.
4. No electrical grounding shall be connected to the water service.
5. Water service connections to any transmission main shall be provided only if no distribution
main is available. A pressure reducing valve shall be installed on the connection if required.
6. All water services shall be provided with a main stop, curb stop and service box at the
property line. Valve box stem extension rods are to be used on water services up to and
including 32 mm.
7. Double service connection is not permitted.
8. The size of water service connections shall be provided as follows:
Minimum Service Connection Size
Type of Development Service Connection Size
Single Family 19 mm diameter
Commercial and Industrial 25 mm diameter or higher
9. Every water service shall be metered in compliance with WASA policies. Design
calculations shall be done in accordance with AWWA M22. No soldered joints or fittings
shall be allowed before the meter or on the bypass valve. The volume of water delivered to
consumers must be measured by meters installed on all direct service connections. Meters
must conform to WASA’s specification and must be installed, operated, calibrated, and
maintained following generally accepted industry standards and information from the
manufacturer. The meter setting shall be as close as possible to the property line at the point
of entrance of the water service connection.

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10. Major water services 100 mm and larger shall be valved at the main. If the service crosses the
road, it shall be valved at the main and at the property line.
11. Pipe manufacturer’s recommendations shall be followed on the use of saddles when tapping
services to mains.
12. Services longer than 30 m to the meter in a single family dwelling shall be 25 mm in
diameter. No service shall be longer than 60 m without WASA’s approval.
13. On high rise buildings or high buildings, where a booster pump is required, an approved
check valve must be incorporated before the pump.
14. Fire lines connected to any private fire system using chemicals are to be equipped with an
approved check valve and back flow fixture.
15. Minimum depth for water service line is 450 mm.
5.7 Corrosion Prevention
The Consultants shall ensure that all metallic components in the water distribution system are
protected from corrosion with appropriate protection measures. Soil condition reports and
geotechnical recommendations should be applied where applicable.
5.7.1 Polyethylene Encasement
Polyethylene encasement can be used on metallic watermain pipes, fittings, restrainers and
hydrants to top of lower barrel, and shall be manufactured of virgin polyethylene material
conforming to the requirements of ANSI/ASTM Standard Specification D1248. The specified
minimum nominal thickness is 200 microns. Material and installation methods shall be in
accordance with the requirements of AWWA C105.
5.7.15.7.2 Polyurethane coating
Where soil corrosiveness is significant, 100% solid polyurethane coating shall be used on ductile
iron pipe, fittings and specials. Coating should meet ASTM D4541, G14 and 2240 for their
performance and material be conform to the latest AWWA standard or ASTM D-16.
5.7.25.7.3 Cathodic Protection
5.7.2.15.7.3.1 New Pipes
For new pipes, comply with the following requirements unless otherwise recommended by a
geotechnical survey:
1. All sacrificial anodes shall be made of high grade electrolytic zinc, 99.99% pure conforming
to ASTM standards.
2. All metallic watermains, fittings, hydrants and restrainers must be coated and catholically
protected to have one zinc anode per length of pipe in sizes according to the table below.
3. Anode installation is not required within valve chambers, drain chambers or air release
chambers.
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4. All weld connections are to be coated.
5. For all anodes connected to new pipes, fittings, hydrants, restrainers or to existing metallic
watermains, a Cadwelder and CA-15 or equivalent cartridge shall be used. Anode installation
shall be performed in accordance with the manufacturer’s instructions and ASTM
requirements.
6. Where new pipe is to be connected to existing ductile iron or cast iron pipe, a 14.5 kg
magnesium anode is to be connected to the first length of existing pipe.
Anode Requirement for Pipes and Fittings
Pipe / Fitting Size (mm) Zinc Anode Size (kg)
150 and 100 2.7
200 5.5
250 5.5
300 11
400 11
450 11
Hydrant 11
5.7.2.25.7.3.2 Existing Pipe
For existing cast iron or ductile iron watermains, the Consultants shall consider cathodic
protection requirements as follows:
1. Anodes may be used to cathodically protect existing cast iron or ductile iron watermains if
the number of breaks is less than 5 break/km/yr for non-critical residential mains and 1
break/km/year for more critical mains. For watermains with a higher break frequency (based
on structural failures), the watermain is to be replaced.
2. Soils investigation shall be undertaken to identify the aggressiveness of the existing soil
conditions, including resistivity, pH value and chloride ion concentration. Based on the
results of the soil investigation, the appropriate cathodic protection measure will be
determined.
3. Anodes used for protecting existing pipe shall be packaged 14.5 kg magnesium anodes at a
spacing to be specified by the Consultants.
4. All metallic pipe extension and services should be electrically isolated from the metallic
main.
5.8 Pipe commissioning
Once pipes are completely installed, leakage test shall be driven and be conform to AWWA
standards C600 and C605. All new, cleaned or repaired water mains, tanks and equipment, which
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convey potable water or stored potable water, shall be flushed, and disinfected in accordance
with the latest AWWA Standard C651, and a satisfactory bacteriological report obtained.

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Section 6 Drinking Water Reservoirs
6.1 General
The design guidelines as provided herein are for the design of new or rehabilitation of existing
drinking water distribution reservoirs and shall be read in conjunction with the guidelines and
codes applicable to Trinidad & Tobago including those mentioned in section 3 Design Standards.
Where the higher standards have been specified or required, comply with such requirements.
6.2 Impoundment design
For new impoundment reservoirs, a complete assessment of the project including as a minimum
siting, hydrology, nutrient loading, stratification, water quality, sediment accumulation,
operation and maintenance should be established and reviewed by WASA. A separate report
covering the safety, security and failure impact of a dam must be done by competent dam
specialists. A source water protection plan enacted for continued protection of the watershed
from potential sources of contamination shall be also provided.
New reservoirs site should be prepared by removing bushes and trees to the high level elevation.
Several intakes with different elevations should be provided to assure good water quality down
to the lowest level of the reservoir.
6.26.3 Reservoir (tank) Design
Where land and topography allows, it is considered advantageous to provide gravity storage for
potable water distribution. This will account for daily fluctuations in demand and will balance
the network.
Finished-water storage facilities should have sufficient capacity to control the operation of
pumps, balance the fluctuation in domestic demands, and provide emergency and fire protection
reserves. This storage should be reliably available, preferably by gravity. If site conditions
preclude elevated storage, pumping from ground level storage may be considered, in which case
auxiliary power should be provided. The pressure zones are to be defined according to prevailing
topographic conditions.
The reservoir shall be designed to meet the following criteria:
1. Locate inlet and outlet pipe separately to promote circulation of fresh water and minimize
dead spots. To promote water circulation, interior walls (baffles) should be used.
2. Ensure that the full depth of the reservoir is available for operation. Preferred pressure zones
are between 275 kpa (40 psi) and 550 kpa (80 psi). As a primary goal, reservoirs shall be
sited at elevations which will ensure these pressures are maintained.
3. The reservoir should be divided in a minimum of two cells for maintenance and access. Each
compartment should have human access and adequate ventilation. Provide isolation valve(s)
and piping to permit the isolation of reservoir cell(s) for maintenance or construction work
without having to shut the entire reservoir down.
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4. Prevent entry by birds, animals, insects, excessive dust, and other potential sources of
external contamination
5. The design shall include provisions for a lockable weathertight roof, a screened roof vent, an
overflow pipe with atmospheric discharge and sample collection capability.
6. Allow for future expansion of reservoir capacity to its ultimate capacity in an orderly
manner.
7. Reservoirs floors should have adequate slope and finish to allow draining and cleaning.
8. Connection for pumps and washdown pump shall be made to the reservoir’s fill line.
Overflow from the reservoir is not generally permitted at any time unless emergency conditions
arise. A separate instrumentation and control system shall be provided exclusively to prevent
overflow. When the water level reaches the high high level (HHL) condition, the instrumentation
and control system shall initiate the valve to shut off to prevent further water supply into the
reservoir and at the same time activate the reservoir high high level (HHL) overflow alarm
condition to the operator through the SCADA system.
Design reservoir to drain by gravity to the adjacent property drainage area. In the absence of
municipal storm drain, consider controlled discharge such as pumps and holding ponds. In all
cases, include adequate measures to control erosion of earthen channels or scouring of paved
sections.
6.36.4 Reservoir Capacity
The capacity of the required reservoir will be dictated by the water supply system need study.
Operational, standby, and fire suppression storage volumes must be considered, as applicable, for
all pressure zones to meet both normal as well as abnormal demands of the system. Refer to
section 5.2.4.2 for calculation of recommended minimum storage.
6.46.5 Re-chlorination System Requirements
Where specified, design and provide the required chlorination system at the reservoir with
respect to Section 9.6 on chlorination systems. The re-chlorination system shall be sized to
provide an increase to the total chlorine residual at the maximum inflow of water.
6.56.6 Emergency Eye-wash
Provide an emergency eye-wash station in the vicinity of the chlorination system and also close
to the analyzer location.
6.66.7 Site Access Road and Security
Unless otherwise specified by WASA, or local approval agencies, the reservoir or tank access
road shall be fenced off with 2100 mm high galvanized steel chain link fence and razor wire.
Access gate(s) to the property shall be 7000 mm wide and 2100 mm high. The location of the
gate(s) may be required to comply with the requirements of the approval agencies and or area
municipality.
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Water and Wastewater Design Guideline Manual Drinking Water Reservoirs
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Design reservoir exterior exposed surfaces such as access hatches, doors etc are to be vandal
resistant. Ensure that all ventilation louvers to the reservoir are properly secured to prevent entry
of foreign material. All hatches are to be lockable and keyed to WASA’s master lock system.
The exterior of reservoir shall be provided with high pressure sodium vapour light fixtures
(vandal and tamper resistant) with high power factor ballast and lamps suitable for horizontal,
base up or base down operation. The need for surveillance camera and alarms shall be assessed
for each site.
All exterior access such as the valve house doors and reservoir roof access shall be provided with
locking devices.
6.76.8 Architectural
Comply with Section 14 – Architectural Standards.
Design reservoir with valve chamber in front with access door and retaining walls.
The reservoir shall be architecturally designed to ensure that the exterior complements with its
surrounding environment. The exterior material and or finishes shall be designed to be
completely maintenance-free wherever possible. It shall be provided with two entrances and to
be without any windows. All openings in the exterior walls shall be equipped with insect screens
and vandal-proof louvers.
All roof drains shall have a dome protection. Drains inside the valve house shall have easily
accessible traps.
Roof access hatches shall be fabricated of aluminium frame with insulated cover and watertight.
It shall be provided with a snap lock with a removable handle for topside hardware, and recess
padlock complete with cover.
Floor layout shall allow for an easy access to all equipment inside the Valve House. Floor areas
shall be sealed with a waterproofing membrane and shall have a slip resistant finish. Interior
finish shall require minimum maintenance. Walls shall be treated with a waterproofing
membrane. Unless it is absolutely necessary, do not paint interior surface of Valve House.
All electrical equipment including control panel shall be located on the main floor. Interior
lighting shall be wall mounted fluorescent light fixtures, and readily accessible for replacement/
maintenance purposes (but protected against vandalism).
Landscaping within the property limits shall comply with the regional authority Site Plan
Approval requirements. It shall complement with the surrounding environment and require
minimum maintenance or watering. Select plant species that are native to Trinidad & Tobago.
6.86.9 Structural
Comply with Section 15 – Structural Standards.
For new reservoirs, glass lined steel tanks should be prioritised. Reservoirs should have a
minimum of two (2) cells with isolation valves between the cells.
Reservoirs shall be designed to withstand all force imposed on them and be watertight.
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Interior of the tank shall be protected from corrosion by glass lining or other approved
protection. Stainless steel will not be acceptable because of chlorine attack.
For expansion of existing reservoirs, design new cell(s) capable of being isolated from existing
cell(s) for repair and or cleaning or to float independently on the water supply distribution
system.
Reservoir to be designed with the structure half in and half out of the ground with the roof cover
sloped to promote drainage, including granular zone at base of cover material.
Provide reservoir with an overflow piping capable of discharging the designed maximum inflow
of water to the reservoir. Design overflow capacity from each cell to meet maximum pumped
input and combine discharge with reservoir drain. Design drain to permit discharge of water in a
controlled manner to the site drainage system. Provide perimeter drainage system and prevent
erosion.
Provide access and ventilation shafts, two for each cell.
6.96.10 Mechanical
Comply with Section 19 – Mechanical Standards.
Provide valve box as required to allow easy operation. Valve box shall be cast in place concrete
with a lockable stainless steel cover. Ensure that the stainless steel cover is designed to prevent
water from entering into the reservoir from the valve box.
Altitude valves with closing speed control are the preferred mode of control for inflow in the
reservoirs.
The overflow pipe shall be secured with a non-corrodible mesh screen (size 25 mm) installed
within the pipe at a location least susceptible to damage by vandalism.
Hardware inside the reservoir, ladders, handrails, safety chains and rails, equipment hatches,
gratings etc., shall be corrosion and chlorine resistant.
Internal manway from valve chamber to the reservoir, if provided, shall be chlorine resistant
material or Fibreglass.
6.106.11 Ventilation
Comply with Section 20 – Ventilation and Air Conditioning Standards.
Provide dehumidification equipment in Valve House to reduce humidity below dew point.
6.116.12 Instrumentation and Control
Provide one ultrasonic level sensor in each reservoir cell. Control of the inlet valve and
monitoring of the reservoir water level should be made possible through ultrasonic level sensor.
Provide a backup float system which will detect the reservoir water level. At the overflow water
level condition, system must initiate the valve to shut off further water supply into the reservoir
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and at the same time activate the reservoir high high level (HHL) overflow alarm condition at the
Water Treatment Plant SCADA Control Room.
Reservoir PLC operation:
1. Reservoir Cell duty selection
2. Reservoir High Level
3. Reservoir High High Level
4. Reservoir Fire Zone Level
5. Reservoir Low Level
6. Chlorine metering pumps duty selection, manual or automatic mode (where required)
7. Chlorine residual set point, manually set by operator
8. Reservoir inlet/outlet control valve
6.126.13 Alarms
The following alarm points shall be monitored at the reservoir by the SCADA System:
1. Fire Alarms
2. Levels sensor indications in each cell
3. Chemical metering pumps uncommanded stop
4. Chemical metering pumps uncommanded start
5. High/low chlorine residual level
6. Low chemical liquid level in the tank
7. Low reservoir level, normally set at the fire zone
8. High, High water level
9. Chlorine gas alarm
6.136.14 Control System
For additional information on I&C and SCADA systems requirements, refer to Section 17 –
Instrumentation & Control and Section 18 – SCADA System for control system requirements.
6.146.15 Equipment Redundancy
Comply with Section 4 – Process and Equipment Redundancy.
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46. Water And Sewerage Authority (WASA)
Water and Wastewater Design Guideline Manual Potable Water Pumping Stations
7-1 October 2008
R1
Section 7 Potable Water Pumping Stations
7.1 General
The design guidelines as provided herein are for the design of new or rehabilitation of existing
potable water pumping stations and shall be read in conjunction with the guidelines and codes
noted in section 3.0 Design Standards. Where the higher standards have been specified or
required, comply with such requirements.
7.2 Pump design
For any particular project there is likely to be more than one acceptable booster pump station
design concept. Pumps should be selected in order to have high efficiency under normal
operating conditions. Firm pumping capacity for a water pumping station is based on the total
pumping capacity with the largest pump out of service. Design should always consider the
hydraulics in order to avoid cavitation, excessive vibration and noise. The pump’s parts and
components should be chlorine resistant, weather proof and rated for continuous operation in
tropical countries.
In addition to the selection of the appropriate pump type and size, there is also a need to select
the suitable resistant material or coatings, which can guarantee an extended lifetime. Usually,
where clean water is pumped, pump material to be employed is cast steel (with surface
protection), with the impeller usually made from chromium steel. If there are solids suspended or
dissolved in the water, the speed of the pump should be limited to avoid abrasion.
Booster stations on the Trunk system must be designed in order to allow bidirectional (up flow or
down stream) pumping capacity so as to offer redundancy to the national grid system. The
valving configuration shall allow pumping in both directions and be controlled by the SCADA
systems to accommodate emergency situations.
7.3 Layout of Pumping Station
Below are recommended requirements for the expansion or upgrading of pumping station:
1. Provide adequate space (min 1.0 m) to allow removal of pump, valve etc. between existing
and new equipment for operation and maintenance requirements.
2. As much as possible, maintain similar types of existing equipment.
3. Provide flexibility for incorporating modification to facility to meet more stringent water
quality requirements.
4. Ensure that the facility is designed to allow for future expansion works.
5. Lifting devices shall be provided for removing pumps or motors.

47. Water And Sewerage Authority (WASA)
Water and Wastewater Design Guideline Manual Potable Water Pumping Stations
7-2 October 2008
R1
7.4 Equipment Redundancy
See Section 4 – Process and Equipment Redundancy. As per common practice the maximum
number of pumps shall be limited to 5 or less in order to keep the complexity and lifetime costs
at reasonable levels.
7.5 Pumping Station Requirements
Usually there are two types of pumping stations. Low lift pumping stations are generally used to
bring water from the intake to the treatment plant. High lift pumping stations are generally used
for water distribution. Design the pumping station in accordance with the following guidelines.
Where there is a more stringent design standard, comply with the higher standard.
Equipment Comment
1 Design Standard Hydraulic Institute Standards
2 Number of Pumps Minimum – 2
3 Capacity of Pumps Maximum Daily Demand
4 Preferred Type Horizontal Split Case Centrifugal Pump & Vertical turbine pumps in
canisters (canned)
5 Pump’s Standard EN 733 DIN 24255
6 Variable Frequency Drive To be considered but not a standard requirement, and not to be provided for
Standby Pump
7 Number of Standby Pump Minimum – 1
8 Capacity of Standby
Pump
Equal to capacity of largest pump
9 Drive Unit Starter Solid State Reduced Voltage Starter or Variable Frequency Drive
10 Equipment Monitoring
Requirement
1. RTD connections for windings, minimum one per phase
2. RTD for motor inboard and outboard bearings
3. RTD connections for pump inboard and outboard bearings.
4. Drive speed
11 Instrumentation & Control Programmable Logic Controller c/w all required field instrumentation
hardware.
12 Emergency Standby
Diesel Generator
Generator output shall be sized to meet pumps power demand for average
day water supply demand as well as for SCADA and ventilation systems.
,
7.6 Control System
The need for installing a Variable Frequency Drive (VFD) pump must be assessed with
considerations to economical, operational and maintenance aspects of such equipment.
Pumps should be adequately valved to permit satisfactory operation, maintenance and repair of
the equipment. For pipe diameter over 450 mm, isolating butterfly valves should be preferred.
Check valves and surge valves (if applicable) on the discharge side of each booster pump are to
be provided.

48. Water And Sewerage Authority (WASA)
Water and Wastewater Design Guideline Manual Potable Water Pumping Stations
7-3 October 2008
R1
Control systems shall include automatic and manual Start/stop control for each system.
7.7 Instrumentation
Provision shall be made for the visual indication of the suction and discharge pressure at each
pump and the common discharge line pressure. Provision shall also be made for the
measurement of flow using a flow meter or other reputable flow measuring device at each pump
station.
Pressure switches shall be installed at the suction line of each pump at water pump stations. A
common discharge pressure switch shall be installed at water pump stations. The pressure
switches shall be set as to trip pumps at low suction and high discharge pressures and to start
pumps at the required pressure.
All pump stations shall be designed with due consideration for the effects of water hammer.
Adequate protection for adverse effects should be included in the design.
Instrumentation should include ammeters and voltmeter for each station and include motor
protection fixtures like thermal overloads and phase imbalance or loss protection. Disposition
should be taken to control moisture and condensation. Permanent pressure and flow monitoring
and recorder should be provided.
For additional information on I&C and SCADA systems requirements, refer to Section 17 –
Instrumentation & Control and Section 18 – SCADA System for control system requirements.
7.8 Alarms
The following equipment or logic-defined alarms shall be generated for the following:
1. Building
.1 Access Security Authorized and unauthorized entry
.2 Building – Smoke Smoke in building
.3 Building – Flood Flooding
2. Pump(s)
.1 Overload trip
.2 Thermistor trip
.3 Bearing temperature
.4 Fail to start
.5 Fail to stop
.6 High pressure
.7 Low pressure
.8 Uncommanded stop
.9 Phase unbalance

49. Water And Sewerage Authority (WASA)
Water and Wastewater Design Guideline Manual Potable Water Pumping Stations
7-4 October 2008
R1
7.9 Ventilation
Comply with Section 20 – Ventilation and Air Conditioning Standards.
Provide dehumidification equipment in pumping rooms to reduce humidity below dew point.
7.10 Architectural
Comply with Section 14 – Architectural Standards.
The building shall be architecturally designed to ensure that the exterior complements with its
surrounding environment. The exterior material and or finishes shall be designed to be
completely maintenance-free wherever possible. It shall be provided with two entrances and to
be without any windows. All openings in the exterior walls shall be equipped with insect screens
and vandal-proof louvers.
All roof drains shall have a dome protection. Drains inside the valve house shall have easily
accessible traps.
Floor layout shall allow for an easy access to all equipment inside the pumping station. Floor
areas shall be sealed with a waterproofing membrane and shall have a slip resistant finish.
Interior finish shall require minimum maintenance. Walls shall be treated with a waterproofing
membrane.
All electrical equipment including control panels shall be located on the main floor. Interior
lighting shall be wall mounted fluorescent light fixtures, and readily accessible for replacement/
maintenance purposes (but protected against vandalism).
Landscaping within the property limits shall comply with the regional authority Site Plan
Approval requirements. It shall complement with the surrounding environment and require
minimum maintenance or watering. Select plant species that are native to Trinidad & Tobago.
7.11 Site Access Road and Security
Unless otherwise specified by WASA, or local approval agencies, the building access road shall
be fenced off with 2100 mm high galvanized steel chain link fence and razor wire.
Access gate(s) to the property shall be 7000 mm wide and 2100 mm high. The location of the
gate(s) may be required to comply with the requirements of the approval agencies and or area
municipality.
Design building exterior exposed surfaces such as access hatches, doors etc are to be vandal
resistant. Ensure that all ventilation louvers to the reservoir are properly secured to prevent entry
of foreign material. All hatches to be lockable and keyed to WASA’s master lock system.
The exterior of the building shall be provided with high pressure sodium vapour light fixtures
(vandal and tamper resistant) with high power factor ballast and lamps suitable for horizontal,
base up or base down operation. The need for surveillance camera and alarms shall be assessed
for each site.

50. Water And Sewerage Authority (WASA)
Water and Wastewater Design Guideline Manual Well Pumping Station Design
8-1 October 2008
R1
Section 8 Well Pumping Station Design
8.1 General
The design guidelines as provided herein are for the design of new or rehabilitation of existing
wells and shall be read in conjunction with AWWA Standard for Water Wells. Drilling and
construction of wells shall be supervised by a hydro-geological specialist and be tested for yield
and drawdown. A report of at least a 24-hour pumping test to determine yield shall be submitted.
Wells shall be located so that the drawdown of any well will not interfere with the required yield
of another well. The immediate 30 m radius surrounding of a well shall be protected from any
source of contamination (minimum well head protection).
It is important that wells and underground water supplies be always assessed through a Source
Water Protection program with regional coverage to assure sustainability and health protection
for users. The issue of redundancy must be captured in the number of wells within the area so to
allow operation on a rotational basis.
Water quality must be defined prior to the construction of the well. The water quality shall
respect WASA water quality standard as defined in Section and if required, adequate treatments
are to be provided to comply with the water quality standards. Treatment for all secondary
aesthetic standards should be included after confirmation by WASA. All chemicals, substances,
and materials added to or brought in contact with water in a public water system well shall have
either standard ANSI/NSF 60 or 61 certification.
8.2 Well Construction
Consultants shall make sure to protect the aquifer by avoiding the introduction of any
contamination. All underground material shall be made of new material.
The well casing shall neither terminate below ground nor in a pit. Well casing shall be made of
steel conform to ASTM A53/A53M-01 or ASTM A589-96 or plastic conform to ASTM F480-
00. Tubing must be equipped with a drive shoe when driven. All casing and screen must be
supplied with threaded flush joints or threaded couplers, PVC casing and screen must not have
glue joints. The well casing should extend 0.9 meter above the ground surface when the well is
completed and always above flood line. Screen shall be installed such that corrosion caused by
contact with dissimilar steel casing is minimized. Thermoplastic screen may be attached to steel
casing with the use of an appropriate coupler. The screen shall provide sufficient column and
collapse strength to withstand installation and borehole pressures. Screen joints between screen
sections and blank casing shall be welded, or threaded and coupled
The upper terminal of the well casing shall be equipped with a well cap and be watertight with
the exception of a vent pipe or vent tube having a downward-directed, screened opening.
All underground connections with the casing shall be sealed and waterproof. Measures shall be
taken to avoid infiltration on the side of casing. Adequate provisions for washout must be
included.

51. Water And Sewerage Authority (WASA)
Water and Wastewater Design Guideline Manual Well Pumping Station Design
8-2 October 2008
R1
Every water supply well shall have a continuous bond concrete slab or well house concrete floor
extending at least 1 meter horizontally around the outside of the well casing. Minimum thickness
for the concrete slab or floor shall be 100 mm. For line shafts pumps, a pedestal shall be
provided to support the pumps and the shaft.
The annular space remaining above the seal must be grouted. The grout mixture should be
composed of Portland cement and powdered bentonite. The well must not be disturbed for at
least 48 hours after grouting to allow the grout time to set up.
Plumbing and alignment shall be in accordance with the pump manufacturer’ requirements.
Demonstration of well alignment shall be made by passing a 12 m long dummy through the inner
casing.
All pipes will have to be anchored to prevent movement and damages. The discharge pipe must
have a check valve and if applicable, an air release vacuum valve.
A water supply well shall be secured against unauthorized access (see section 14.10). All new
wells, and wells that have been repaired or reconditioned shall be cleaned of foreign substances
such as soil, grease, and oil, and then shall be disinfected.
8.3 Well Instrumentation & Control
The well pumping station shall be equipped with the following equipments:
1. Turbidity meter
2. A totalizing meter shall be installed in the piping system from each well.
3. Pressure monitoring gages
4. Automatic chlorination equipment
5. Chlorine residual analyser
6. Level sensors inside the well
7. Mechanical Flow or pressure control device
8. Emergency standby diesel generator (if dual feed not available)
9. Chlorine gas detector
10. A sampling point
Comply with Section 16 – Electrical Standards for electrical protection requirements for the
wells.
8.4 Alarms
The following alarm points shall be monitored (if applicable) at the reservoir by the SCADA
System:
1. Level sensor low level alarm
2. Chemical metering pumps uncommanded stop

52. Water And Sewerage Authority (WASA)
Water and Wastewater Design Guideline Manual Well Pumping Station Design
8-3 October 2008
R1
3. Chemical metering pumps uncommanded start
4. High/low chlorine residual level
5. Low chemical liquid level in the tank
6. Chlorine gas detector alarm
8.5 Preferred Layout
Buildings must comply with Section 14 – Architectural Standards, Section 15 – Structural
Standards and Section 20 – Ventilation and Air Conditioning Standards.
A preliminary assessment of type of well pump must be done for review to WASA.
If a building is required, install a skylight immediately over the centre of the pump to facilitate
removal of pumping unit.
All electrical control panels and MCC panels shall be located in a separate room.
All chemical systems shall be located in a separate room.
All equipment shall be accessible for repair and or replacement and shall have a minimum
clearance of one meter from the nearest obstruction.
Design of the well pumping station must allow for the removal of all equipment at all times
when the work has been constructed. Adequate provision for wash out must be included.
Provide an emergency eye-wash station in the vicinity of the chlorination system and close to the
analyzer location.
Hardware for the wells and inside the building shall be corrosion and chlorine resistant.
Landscape must be designed to allow drainage and aquifer protection.
8.6 SCADA System
Tie the pumping station PLC/RPU to the SCADA system.
Provide all field instrumentation for local and remote control and monitoring of all equipment in
the pumping station.
Provide fully automated chemical feed system with the capability of plant manual control
through the SCADA HMI software.
Provide a remote processing unit RPU for local and remote control and monitoring of all
equipment through the SCADA MMI software.
Comply with Section 17 – Instrumentation & Control and Section 18 – SCADA System design
standard requirements.

53. Water And Sewerage Authority (WASA)
Water and Wastewater Design Guideline Manual Well Pumping Station Design
8-4 October 2008
R1
8.7 Equipment Redundancy
No redundancy in process or equipment is required.

54. Water And Sewerage Authority (WASA)
Water and Wastewater Design Guideline Manual Water Treatment Plants
9-1 October 2008
R1
Section 9 Water Treatment Plants
9.1 General
The following sections are the design standards and guidelines for water treatment plants, should
any new plants be constructed or existent plants be expanded or upgraded in the future to current
water treatment process standards.
The drinking water quality standards are a public health issue and have to be carefully set. The
following standards are based on the 2006 World Health Organisation (WHO) addendum 1 to
volume 3 maximum allowable concentration. Treatment systems or devices shall be piloted and
designed to ensure finished water quality conforms to the latest World Health Organization
(WHO) water quality standards
The water supply strategy shall adopt the multi barrier approach which will ensure safe drinking
water based on four barriers:
• Source water protection
• Water treatment
• Distribution system integrity
• Public information and legislation
Protection of well’s recharge area (Source Water Protection) allied with concerted public
involvement and watershed management are recommendations that should be implemented as
part of a sustainable approach for drinking water. The aim is to frame the good practices needed
for assuring acceptable raw water quality at the intake of treatment plants. These
recommendations are specifically designed to ensure an adequate design, construction, sampling,
maintenance, and operation practices; and a provision of safe and high quality drinking water in
a reliable manner and in a quantity suitable for intended use.
All materials in substantial contact with potable water supplies shall conform to the ANSI/NSF
Standard 60 or 61. Examples of water system components that would be considered to be in
"substantial contact" with drinking water are filter media, storage tank interiors or liners,
distribution piping, membranes, exchange or adsorption media, or other similar components that
would have high potential for contacting the water. Materials associated with components such
as valves, pipe fittings, debris screens, gaskets, or similar appurtenances would not be considered
to be in substantial contact.
9.2 Drinking water standards
The WHO has established guideline values for 94 parameters divided in three (3) different
groups: microbiological contaminants, natural and chemical contaminants. These guidelines are
to be used as the WASA`s Water Quality Standards and are presented in the following tables.

55. Water And Sewerage Authority (WASA)
Water and Wastewater Design Guideline Manual Water Treatment Plants
9-2 October 2008
R1
Notes on standards :
P=provisional guideline value as there is evidence of a hazard, but the available information on
health effects is limited; T=provisional guideline value because calculated guideline value is
below the level that can be achieved through practical treatment methods, source protection, etc;
A= provisional guideline value because calculated guideline value is below the practical
quantification level; C=concentrations of the substance at or below the health-based guideline
value may affect the appearance, taste or odor of the water, resulting in consumer complaints.
D=provisional guideline value because disinfection is likely to result in the guideline value being
exceeded;
9.2.1 Microbiological
Values for verification of microbial quality
Organisms value
All water directly intended for drinking
E. coli or thermotolerant coliform bacteria Must not be detectable in any 100-ml
sample
Treated water entering the distribution system
E.coli or thermotolerant coliform bacteria Must not be detectable in any 100-ml
sample
Treated water in the distribution system
E.coli or thermotolerant coliform bacteria Must not be detectable in any 100-ml
sample
Treated water in the distribution system
Total coliform bacteria Must not be detectable in any 100-ml
sample
9.2.2 Naturally occurring chemicals
Values for naturally occurring chemicals that are of health significance in drinking-water
value
Chemical (mg/litre) Remarks
Arsenic 0.01 (P)
Barium 0.7
Boron 0.5 (T)
Chromium 0.05 (P) For total chromium
Fluoride 1.5 Volume of water consumed and intake from
other sources should be considered when
setting national standards.
Manganese 0.4 (C)
Molybdenum 0.07
Selenium 0.01
Uranium 0.015 (P,T) Only chemical aspects of uranium
addressed

56. Water And Sewerage Authority (WASA)
Water and Wastewater Design Guideline Manual Water Treatment Plants
9-3 October 2008
R1
9.2.3 Chemical contaminants
Values for chemicals from industrial sources and human dwellings that are of health
significance in drinking-water.
Inorganics value (mg/litre) Remarks
Cadmium 0.003
Cyanide 0.07
Mercury 0.006 For inorganic mercury
Organics value (µg/litre) Remarks
Benzene 10
Carbon tetrachloride 4
Di(2-ethylhexyl)phthalate 8
Dichlorobenzene, 1, 2- 1000 (C)
Dichlorobenzene, 1, 4- 300 (C)
Dichloroethane, 1, 2- 30
Dichloroethane, 1, 2- 50
Dichloromethane 20
Dioxane, 1, 4- 50
Edetic acid (EDTA) 600 Applies to the free acid
Ethylbenzene 300 (C)
Hexachlorobutadiene 0.6
Nitrilotriacetic acid (NTA) 200
Pentachlorophenol 9 (P)
Styrene 20 (C)
Tetrachloroethene 40
Toluene 700 (C)
Trichloroethene 20 (P)
Xylenes 500 (C)

57. Water And Sewerage Authority (WASA)
Water and Wastewater Design Guideline Manual Water Treatment Plants
9-4 October 2008
R1
Values for chemicals from agricultural activities that are of health significance in drinking
water.
Non-pesticides value (mg/litre) Remarks
Nitrate (as NO3
-
) 50 Short-term exposure
Nitrate (as NO2
-
) 3 Short-term exposure
0.2 (P) Long-term exposure
Pesticides used in agriculture value (µg/litre)
Remarks
Alachlor 20
Aldicarb 10 Applies to aldicarb
Sulfoxide and
aldicarb
Sulfone.
Aldrin and dieldrin 0.03 For combined aldrin
plus dieldrin
Atrazine 2
Carbofuran 7
Chlordane 0.2
Chlorotoluron 30
Cyanazine 0.6
2,4-D (2,4-dichlorophenoxyacetic acid) 30 Applies to free acid
2,4-DB 90
1,2-Dibromo-3-chloropropane 1
1,2-Dibromoethane 0.4 (P)
1,2-Dichloropropane (1,2-DCP) 40 (P)
1,3-Dichloropropene 20
Dichlorprop 100
Dimethoate 6
Endrin 0.6
Fenoprop 9
Isoproturon 9
Lindane 2
MCPA 2
Mecoprop 10
Methoxychlor 20
Metolachlor 10
Molinate 6
Pendimethalin 20
Simazine 2
2,4,5-T 9
Terbuthylazine 7
Trifluralin 20

58. Water And Sewerage Authority (WASA)
Water and Wastewater Design Guideline Manual Water Treatment Plants
9-5 October 2008
R1
Values for chemicals used in water treatment or materials in contact with drinking water
that are of health significance in drinking-water.
Disinfectants value (mg/litre) Remarks
Monochloramine 3
Disinfection by-products value (µg/litre) Remarks
Bromate 10 (A,T)
Bromodichloromethane 60
Bromoform 100
Chlorate 700 (D)
Chlorite 700 (D)
Chloroform 300
Cyanogen chloride 70 For cyanide as total cyanogenic
compounds
Dibromoacetonitrile 70
Dibromochloromethane 100
Dichloroacetate 50 (T,D)
Dichloroacetonitrile 20 (P)
Monochloroacetate 20
Trichloroacetate 200
Trichlorophenol, 2,4,6- 200 (C)
Trihalomethanes The sum of the ratio of the
concentration of each to its
respective guideline value should
not exceed 1
Contaminants from Value (µg/litre) Remarks
Treatment Chemicals
Acrylamide 0.5
Epichlorohydrin 0.4 (P)
Contaminants from pipes
And fittings Values (µg/litre) Remarks
Antimony 20
Benzo [a]pyrene 0.7
Copper 2000 staining of laundry and sanitary
ware may occur below guideline
value
Lead 10
Nickel 70
Vinyl chloride 0.3

59. Water And Sewerage Authority (WASA)
Water and Wastewater Design Guideline Manual Water Treatment Plants
9-6 October 2008
R1
Values for pesticides used in water for public health purposes that are of health
significance in drinking-water.
Value (µg/litre)
Pyriproxyfen 300
Values for cyanotoxins that are of health significance in drinking-water
Value (µg/litre) Remarks
Microcystin –LR 1 (P) For total microcystin-LR (free plus cell-bound)
9.2.4 Aesthetic guidelines
The following guidelines called secondary drinking water guidelines are adopted by WASA.
Some parameters are considered aesthetic objectives and others are considered operational
objectives.
Acceptability aspects
Parameter Aesthetic objective
(mg/litre)
Operational
objective (mg/litre)
Aluminium 0,2
Chloride 250
Colour 15 TCU
Hardness 150
Iron 0,3
Manganese 0,05
Silver 0,10
pH 6,5-8,5
Sodium 200
Sulfate 250
Sulfide 0,05
Total Dissolved Solids 500
Turbidity < 5 NTU <1 NTU
Zinc 5
9.3 Performance targets and treatment objectives
9.3.1 General
In order to evaluate disinfection performance at a water treatment facility, three (3) different
pathogens micro-organisms be targeted: enteric virus, Giardia cysts and Cryptosporidium
oocysts. The selection of those organisms is founded on the following facts:
• The targeted organisms are frequently detected in surface water supplies of lakes, rivers and
occasionally in groundwater sources.

60. Water And Sewerage Authority (WASA)
Water and Wastewater Design Guideline Manual Water Treatment Plants
9-7 October 2008
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• The targeted organisms have been known to have caused epidemics, some causing illness to
thousand of people;
• The targeted organisms are resistant to disinfection. Thus, by eliminating the targeted
organisms, it is very probable that other less resisting organisms will also be eliminated.
Giardia cysts and Cryptosporidium oocysts are considered among the most common intestinal
parasites found in the world.
The removal and inactivation of viruses, Giardia and Cryptosporidium to evaluate the
disinfection effectiveness of a water treatment facility is the preferred approach in most
jurisdictions having drinking water legislation.
Water is disinfected but never completely sterilized in the water treatment process. This
disinfection is a two (2) part process that includes:
1. Removal of particulate matter by filtration. A rule of thumb is that high
turbidity in the effluent is a potential health risk, because viruses and bacteria can hide within
the rough texture of particulates. Therefore, removal of the particulates reduces the chance of
pathogenic microorganisms in the effluent.
2. Inactivation of pathogenic microorganisms by chlorine, chlorine dioxide, ozone or UV
radiation.
9.3.2 Minimum treatment objectives
Water sources are to be classified and the minimum treatment objectives for the removal of the
targeted objectives be as per the ones included in Table 1.0.
Log decimal is usually used as the method to evaluate organism elimination in a process train.
One log decimal corresponds to a 90% reduction of the original concentration, 2 log decimal
corresponds to 99% reduction and 3 log decimal corresponds to 99,9% reduction and so on.
The log removal for the reduction of the virus and parasites can be obtained either by a
combination of:
• Physical removal such as coagulation/flocculation/sedimentation and filtration and/or
membranes;
• Chemical inactivation such as chlorination or physical inactivation such as ultra-violet
radiation.
For a specific water treatment facility, the sum of the total log removal obtained by physical
removal and the total log removal obtained by inactivation must be greater than the treatment
objectives established in Table 1.0.
Table 1.0 – Minimum treatment objectives for various raw water supplies

61. Water And Sewerage Authority (WASA)
Water and Wastewater Design Guideline Manual Water Treatment Plants
9-8 October 2008
R1
Class Raw water source Mandatory minimum treatment objectives
Cryptosporidium Giardia Virus
I Surface water 2 log (99%) 3 log
(99,9%)
4 log
(99,99%)
II Groundwater under the direct
influence of surface water
2 log (99%) 3 log
(99,9%)
4 log
(99,99%)
III Groundwater not under the
direct influence of surface
water
0 0 2log
(99%)
Class I water:
Class I water means surface water bodies (lakes, wetlands, ponds - including dug-outs), water
courses (rivers, streams, water-filled drainage ditches), infiltration trenches, and areas of
seasonal wetlands.
The minimum treatment objectives for raw water of Class I must necessarily be obtained with a
filtration system (conventional filtration, direct filtration, slow sand filtration or membrane
filtration). At least 0,5 log removal or inactivation of Giardia cysts and 2 log removal or
inactivation of viruses must be provided through the disinfection portion of the overall water
treatment process.
Note: Systems that rely on Sea water and brackish sources are considered surface water and must
also conform to these minimum requirements.
Class II water:
Ground water under the direct influence of surface water means ground water having incomplete
or undependable subsurface filtration. The following drinking-water systems are deemed to be
drinking-water systems that obtain water from a raw water supply that is ground water under the
direct influence of surface water:
• A drinking-water system that obtains water from a well that is not a drilled well or that does
not have a watertight casing that extends to a depth of at least 6 meters below ground level.
• A drinking-water system that obtains water from an infiltration gallery.
• A drinking-water system that obtains water from an overburden well, any part of which is
within 100 meters of surface water.

62. Water And Sewerage Authority (WASA)
Water and Wastewater Design Guideline Manual Water Treatment Plants
9-9 October 2008
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• A drinking-water system that obtains water from a bedrock well, any part of which is within
500 meters of surface water.
• A drinking-water system that exhibits evidence of contamination by surface water.
• A drinking-water system in respect of which a written report has been prepared by a
professional engineer or professional hydro-geologist that concludes that the system’s raw
water supply is ground water under the direct influence of surface water and that includes a
statement of his or her reasons for reaching that conclusion.
For drinking-water systems that rely on a raw water supply which is considered ground water
under the direct influence of surface water, filtration should always be incorporated prior to
disinfection. The filtration requirement could be waived if it can be demonstrated that raw water
average monthly turbidity is always below 1 NTU. In that case, the filtration could be replaced
by a double disinfection system consisting of UV radiation and chemical disinfection.
Class III water:
This class is for raw water which is considered groundwater meaning water located in subsurface
aquifer(s) protected by overlay aquitards which act as an effective filter to removes micro-
organisms and other particles by straining and antagonistic effect, to a level where the water
supply may already be potable. In all cases water turbidity must be below 5 NTU. Disinfection
is required as an additional heath risk barrier.
9.3.3 Additional treatment objectives for Class I water supplies
For surface water supplies, treatment objectives shall be adjusted to take into account the level of
pollution in the source. The minimum water treatment objectives are for raw water supplies of
good quality. For polluted sources, the level of treatment must be adjusted to the values included
in Table 2.0.
Table 2.0 – Treatment objectives for Giardia, Cryptosporidium and virus versus fecal
coliforms contamination in the raw water supply
Fecal coliforms
concentration in the
raw water (UFC/100
ml)
Treatment objective
for Giardia
Treatment objective
for Cryptosporidium
Treatment objective
for virus
< 20 3 log 2 log 4 log
20 - 200 4 log 2 log 5 log
200 – 2 000 5 log 2 log 6 log
2 000 – 20 000 6 log 2 log 7 log
> 20 000 Must consider a change in the raw water supply
The fecal coliforms values shown in the Table are annual arithmetic average values for fecal
coliforms measured at the raw water source.

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9.4 Calculations of the water treatment performance
9.4.1 General
Once the treatment objectives have been determined, consultants must verify that the process
train selected or in place will provide sufficient treatment to attain the treatment objectives.
The treatment objectives must be achieved at all times including the critical seasons.
Table 3.0 presents a series of water treatment technologies which are generally known to achieve
log removal for virus and parasites.
Water treatment technologies can be combined to achieve the total log removal requires.
Table 3.0 – Water treatment processes and capabilities for the removal of Giardia,
Cryptosporidium and virus
Process Targeted micro-organisms
Virus Giardia Cryptosporidium
Physical removal
Conventional
treatment (1)
Yes Yes Yes
Direct filtration (2) Yes Yes Yes
Slow sand filtration Yes Yes Yes
Microfiltration (3) No Yes Yes
Ultra and
nanofiltration and
reverse osmosis
Yes Yes Yes
Chemical
inactivation
Chlorination Yes Yes No
Ozonation Yes Yes No
Chlorine dioxide Yes Yes No
Chloramines (4) No No No
Physical
inactivation
UV radiation Yes Yes Yes
(1) Includes coagulation, flocculation, settling and filtration
(2) Includes a coagulation with or without flocculation
(3) Excludes a coagulation
(4) If use as secondary disinfection

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9.4.2 Evaluation of the water treatment efficiency
The evaluation of the water treatment process efficiency is done based on the physical removal
of the targeted micro-organisms and on the chemical and physical inactivation of the targeted
micro-organisms.
For a particular process train, the log removal of each process must be added to obtain the total
log removal for the water treatment facility.
Log removal = Sum of the log removal obtained from physical removal + sum of the log removal
obtained from chemical inactivation + sum of the log removal obtained from physical
inactivation

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9.4.3 Treatment based on physical removal of parasites and virus
Performance credits for log removal can be allowed to various water treatment processes and for
various targeted micro-organisms.
Table 4.0 presents the log removal that can be obtained from various water filtration processes.
Table 4.0 – Log removal credits for targeted micro-organisms for water filtration processes
Treatment technology Log removal credit
Giardia Cryptosporidium Virus
Direct filtration 2,0 2,0 1,0
Conventional filtration 2,5 2,0 2,0
Slow sand filtration 2,0 2,0 2,0
Membrane filtration 3,0 + 2,0 (4) 0 to 2,0 +
Conventional filtration
In order to be considered conventional filtration and meet the 2,5 log removal credit for Giardia
cyst, the 2,0 log removal credit for Cryptosporidium oocyst and the 2,0 log removal credit for
virus, the filtration process must meet the following criteria:
• Use a chemical coagulant at all times when the treatment plant is in operation;
• Monitor and adjust chemical dosages in response to variations in raw water quality;
• Maintain effective backwash procedures, including filter-to-waste or an equivalent procedure
during filter ripening to ensure that the effluent turbidity requirements are met at all times;
• Continuously monitor filtrate turbidity from each filter; and,
• Meet the performance criterion for filtered water turbidity of less than or equal to 0,30 NTU
in 95% of the measurements each month.

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Direct filtration
In order to meet the 2,0 log removal credit for Giardia cyst, the 2,0 log removal credit for
Cryptosporidium and the 1,0 log removal credit for virus, the direct filtration process must meet
the conventional filtration criteria above.
Slow sand filtration
In order to meet the 2,0 log removal credit for Giardia cyst, the 2,0 log removal credit for
Cryptosporidium oocyst and the 2,0 log removal credit for virus, the slow sand filtration process
must meet the following criteria:
• Maintain an active biological layer;
• Regularly carry out effective filter cleaning procedures;
• Use filter-to-waste or an equivalent procedure during filter ripening periods;
• Continuously monitor filtrate turbidity from each filter or take a daily grab sample; and,
• Meet the performance criterion for filtered water turbidity of less than or equal to 1,0 NTU in
95% of the measurements each month.
Because of the selective mechanisms of slow sand filtration, filtrate turbidity levels exceeding
1,0 NTU can occur as a result of passage of inorganic particles through the filter without
influencing the effective removal of harmful organisms. Temporary filtrate turbidity levels of
over 1,0 NTU therefore should not be interpreted as indicating an adverse water condition in the
absence of additional supporting evidence.
Membrane filtration
In order to meet the 3,0 + log removal credit for Giardia, the 2,0 + log removal credit for
Cryptosporidium oocyst and the 0 to 2,0 + log removal credit for virus, the membrane filtration
process must meet the following criteria:
• Maintain effective backwash procedures, including filter-to-waste or an equivalent
procedure, to ensure that the effluent turbidity requirements are met at all times;
• Monitor integrity of the membrane by continuously particle counting or equivalently
effective means (e.g., intermittent pressure decay measurements);
• Continuously monitor filtrate turbidity; and,
• Meet the performance criterion for filtered water turbidity of less or equal to 0,1 NTU in 99%
of the measurements each month.

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9.4.4 Treatment based on chemical inactivation of parasites and virus
The efficiency of chemical inactivation or disinfection is founded on the CT concept.
The CT disinfection concept uses the combination of a disinfectant residual concentration (in
mg/L) and the effective disinfectant contact time (in minutes), to quantify the capability of a
chemical disinfection system to provide effective pathogen inactivation to the required level.
The use of this concept involves determining the CT values required at the actual, often variable,
operating conditions (flow, temperature and pH) and ensuring that the employed disinfection
process achieves these values at all times.
Chemical disinfection CT values are calculated by multiplying the disinfectant residual
concentration (in mg/L) by the disinfectant contact time (in minutes).
CT = Concentration (mg/L) x Time (minutes)
Varying degrees of disinfection can be attained by altering the type and concentration of
disinfectant, as well as the time water is in contact with the disinfectant. The decision to use one
type of disinfectant versus another will set the precedence for the remainder of the values needed
to attain the proper disinfection.
The log of inactivation obtained for a particular treatment step using chemical disinfection can be
determines as follows:
Log of inactivation = CT available = C residual x T10
CT required CT required
where T10 must be calculated for the maximum flow exiting the water treatment facility.
Refer to EPA’s “Technical Guidances for Implementation of the Microbial and Disinfection
Byproducts Rules” for details.
9.4.5 Treatment based on physical inactivation of parasites and virus
Water treatment based on physical inactivation of parasites and virus is achieved by ultra-violets
(UV) radiation. UV disinfection technology is developing rapidly across the world. Contrary to
most of the other disinfectants, UV radiation does not inactive parasites and virus by chemical
action.
Ultraviolet (UV) disinfection systems are used in many water treatment facilities to control
pathogens micro-organisms. UV units can be effective water treatment tools, but it is important
to recognize what UV can do, what its limitations are, and what maintenance is required.
Table 8.0 presents the required doses to inactive targeted micro-organisms.

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Table 8.0 – Design doses for UV radiation disinfection
Supply source
Dose (mJ/cm2)
Parasites: 3 log
Virus: 2 log
Parasites: 3 log
Virus: 4 log
Surface water (1) (2) 40 80
Groundwater (3) Not required 40
(1) Surface water with chemically assisted filtration, direct filtration, slow sand filtration or
membrane filtration
(2) Surface water sources also include groundwater under the direct influence of surface water
(3) For groundwater sources non under the direct influence of surface water
Refer to EPA’s “Technical Guidances for Implementation of the Microbial and Disinfection
Byproducts Rules” for details.
9.5 Treatment plant general design
9.5.1 Water intake
The location of the intake should be set at such a depth that the quantity of suspended solids,
colloidal matter, and plankton is as low as possible throughout the year. The river intakes are to
be located in a reasonably accessible and stable reach of the channel, where erosion or deposition
will not endanger the intake. The intake shall be buried and graded to prevent accumulation of
grasses. Speed in the intake should be calculated with future peak demand and be low enough to
limit impact on fish and sediments.
Screening of the water may be done with a coarse bar screen followed by a medium bar screen.
Finer screening and grit removal may be necessary when the water has to be conveyed through a
long pipeline or when it has to be pumped. Grit removal necessity is to be analysed in each
project to eliminate gravel, sand or mineral particles larger than 200 microns from the water. All
screening must be provided with automatic and reliable cleaning systems to avoid maintenance
and operation works.
9.5.2 Monitoring
Water monitoring should be facilitated to allow monitoring of treatment efficiency at each unit
process.
9.6.29.5.3 General design elements
It is not the intent of this manual to replace professional expertise and innovation from the hand
of water treatment design engineers. It is therefore mandatory that a complete preliminary report
be provided for review to WASA giving the rationale for the recommended processes and their
Formatted: Bullets and Numbering

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design elements. This document must assess all the requirements of this manual and the
following :
- Water need and design flows
- Characterisation of water
- Supply and treatment options
- Treatment processes
- Disinfection processes and by-products
- Taste and odour treatment
- Corrosion and stabilisation methods
- Sludge management
- Instrumentation and system control
9.6 Disinfection design guidelines
All design must comply with WASA "Chlorine Policy and Procedures General Guidelines".
As a general rule WHO recommends that there should be a residual concentration of free
chlorine of >0.5 mg/litre after at least 30min contact time at pH <8.0. Refer to section 9.4.4 for
more details on method for proving effective disinfection. Free residual chlorination may be
achieved through the use of chlorine gas, sodium hypochlorite, calcium hypochlorite or free
chlorine producing electrochemical process.
9.6.1 Chlorination System
Chlorination pre and/or post-chlorination must be provided with gas-type chlorinator or
electrically operated, positive displacement hypochlorite solution chlorinator. If necessary,
alternative technologies such as ozone, UV etc. should be considered in accordance with
associated design guidelines.
For distribution system, the system shall maintain a detectable residual disinfectant concentration
measured as free chlorine, of at least 0.5 mg/L at all times (for 95% of the samples taken each
calendar month).
In a reservoir, the re-chlorination system shall be sized to provide an increase to the total
chlorine residual at the maximum inflow of water.
9.6.1.1 Gas Chlorination System
Depending on the plant process treatment capacity requirements, one chlorinator shall be
provided for each chlorine application point. A minimum of two (2) standby chlorinators, sized
to meet maximum day demand shall be provided. The chlorine piping and controls shall allow
the use of the standby chlorinators for all possible application points.

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1. For gas chlorination system, provide one chlorinator for each chlorine application point. A
minimum of one (1) standby chlorinator, sized to meet maximum day demand shall be
provided. The chlorine piping and controls shall be configured to allow the use of the standby
chlorinator.
2. Two (2) chlorinators shall be provided for Post-Chlorination
Where plants have SCADA system, the chlorinators shall have the capability of being controlled:
1. Locally at the equipment
2. At the PLC/Manual
3. At the PLANT/Manual through the SCADA Human Machine Interface (HMI) using the
Graphics User Interface (GUI) main screen
The chlorinators shall be provided with the required switches to enable control of the feed rate
through the SCADA system.
Chlorination room:
If gas chlorination is used, the following safety steps must be taken:
1. Consult WASA "Chlorine Policy and Procedures General Guidelines" for the requirements
of the room and the preferred layout in the standard drawings.
1.2.The room dimension must allow for working staff to be able to work properly with no risk or
hazard to their safety. Allow for at least 1.5 m free corridor for passage and operation around
equipments.
2.3.The chlorinator and chlorine supply must be located in a separate, special room. The sealed
chlorine dioxide tank(s) shall be vented to the exterior of the building, with door opening to
out-of-doors and sign on door.
3.4.The ventilation start switch must be remote or door activated. The room must be properly
vented with minimum one air change per minute. The exhaust shall be near floor and the
fresh air intake near ceiling.
4.5.Scales must be provided with automatic switchover.
5.6.An observation window must be provided.
6.7.A gas mask must be provided and stored outside the chlorination room.
7.8.Chlorine gas detector shall be installed at each critical location.
The gas chlorination equipment room shall be provided with ventilation system that meets the
requirement set by regulatory standards.
9.6.1.2 Hypochlorite Chlorination System
The raw water quality and chlorine demand should always be assessed prior of using sodium or
calcium hypochlorite systems and results should evaluate impact on disinfection by-products’
impact. Unless specified, the following guidelines apply both to sodium or calcium hypochlorite
disinfection systems.
Formatted: Bullets and Numbering

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The hypochlorite chlorination system shall be positive displacement metering pumps with
capacity located in the Hypochlorite Storage Room. In general, the application points for the
hypochlorite chlorination system shall be located similarly to the gas chlorination system but the
system should be reviewed to ensure the needs of the treatment process has been complied.
• Sodium and calcium hypochlorite facilities should include a cool, dark, dry, clean, above
ground and vented area for the storage and use of the hypochlorite disinfectant. For
hypochlorite facilities include covered make-up and feed solution tanks.
• Where hypochlorite is used, provide a minimum of two metering pumps sized for
maximum day demand.
• When calcium hypochlorite is used for disinfection, the tablets or granules shall be
completely dissolved in water prior to injection.
• The liquid hypochlorite shall be injected into the common inlet/outlet pipe by a metering
pump and shall be controlled by the chlorine residual analyser or magnetic flowmeter.
Isolation valves shall be provided so that the analyser can sample water from the
reservoir inlet pipe only. The chlorination system shall only operate when the water is
flowing into the reservoir and the reservoir inlet valve is in the open position. Provide
strainer on the chlorine output to dosing pumps.
• Isolate hypochlorite tank(s) in a separate containment area. Volume of containment area
to be equal to110% of volume of hypochlorite tank(s).
• The level of the hypochlorite in tank shall be monitored by the field instrumentation,
which shall be connected to the SCADA System for the monitoring and alarm.
• Provide air vent to chlorine reservoirs and assure sufficient ventilation of room to avoid
corrosion.
• Hypochlorite solution in tank should not be diluted unless dilution water treated for
hardness.
9.6.2 Ultraviolet Radiation (UV)
UV water treatment devices must comply with Class A criteria under ANSI/NSF Standard 55 -
Ultraviolet Microbiological Water Treatment Systems. UV water treatment device shall meet the
following standards:
• Raw water quality shall be evaluated and pre-treatment equipment shall be designed to
handle water quality changes and performance specs.
• The UV device shall be fitted with a light sensor to safely verify that UV light is being
delivered into the reactor.
• The UV unit should be installed on a designated electrical circuit and equipped with a
solenoid operated automatic emergency water shut-off valve that will shut off the water
supply to the UV unit in the event of a loss of power supply to the UV unit or a drop in
dosage below the minimum required level of 40 mJ/cm2
. When power is not being
supplied to the UV unit, the valve should be in a closed (fail-safe) position.

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• UV units installed vertically should have the water outlet located at the top to allow the
chamber to completely fill with water and maximize water exposure to the UV lamp.
Similarly, UV units installed horizontally should have the water outlet directed upward.
• The UV assemblies shall be accessible for visual observation, cleaning and replacement
of the lamp, lamp jackets and sensor window/lens.
• A sufficient number (required number plus one) of parallel UV treatment systems shall
be provided to assure a continuous water supply when one unit is out of service.
• Provide and have available on site at least one replacement lamp per unit and a 5 micron
replacement filter where applicable.
• Provide with a mean of recording the water quality test data, dates of lamp replacement
and cleaning, a record of when the device was shutdown and the reason for shutdown,
and the dates of pre-filter replacement.

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Section 10 Design of Wastewater Collection System
10.1 General Requirements
This section outlines the minimum requirements for the design of wastewater collection systems.
However, the Consultants shall apply sound engineering judgement and approach in the design
of such systems.
All wastewater mains and appurtenances shall be designed in compliance with all relevant codes,
design guidelines or standards as well as in accordance with current Trinidad & Tobago National
Plumbing Code,
For new communities, the Consultants shall establish the geodetic invert elevations and ties of all
wastewater lateral connections at street line. The information shall be incorporated on the “As-
built” drawings. To avoid proliferation of lift stations and package treatment plants within
developments, each project should be assessed through modelling of regional network and
optimum development scheme. WASA’s Master plan for Trinidad & Tobago should be reviewed
to grasp the bigger communities and regional planning priorities.
In all projects, assessment of trenchless construction techniques and rehabilitation methods for
existing pipes shall be thoroughly prepared. The assessment shall as a minimum cover the
geotechnical conditions, traffic disruptions, survey the existing utilities and sub surface
structures, obtain right-of-way and property line information, take account of possible
improvements to street or utilities, risk and safety, and include technology aspects on
construction and costs etc.
10.2 Design Flow
10.2.1 Design Wastewater Flow
All wastewater flow should be calculated to convey the maximum flow, including inflow &
infiltration in wet weather flow. The following formula shall be used unless a more rigorous
analysis is carried out:
Fd = Fadw x Kap + Ia
Where Fd = Design flow
Fadw = Average Dry Weather Flow
Kap = Average Peak Wastewater Flow factor
Ia = Infiltration Allowance
10.2.2 Average Dry Weather Flow
The average dry weather flow (ADWF) includes all flow components from residential,
commercial, institutional and industrial usages. Detailed flow monitoring done in the Greater
Port of Spain Region (Reid Crowther, nov 1998) & in the Eastwest corridor (Safege, april 2005)
have established local reliable ADWF. Since 1998, a 10% increase of the residential flow is

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expected in order to contain the grey water inclusion in new developments. It is assumed that
because of the planned metering of all supplied water, the domestic consummation should
gradually linearly lessen by 10% for 2020.
The Consultants shall perform the wastewater design flow calculations based on the following
tables. Individual studies are to be made for special commercial establishments, major
commercial areas, special industrial areas, and major industrial areas.
General per capita flows for all types of development
2005 2020
Total ADWF without infiltration 280 (litres/ capita/ day) 252 (litres/ capita/ day)
Occupancy rate per unit house * 3.7 (person/unit) 3.5 (person/unit)
* From T&T Central Statistical Office census 2000
Residential Dry Weather Flow
Type of Development
Equivalent Population
Density
(persons/hectare)
Unit Wastewater Flow
lpcd l/ha/s
Single Family (new) 55 280 0.178
Single Family (existing) 45 280 0.146
High density single family 85 280 0.276
Semi-detached, duplex and 4-plex 100 280 0.324
Townhouse, Maisonette
(6 storey apt. or less)
135 280 0.438
Notes: i) lpcd = litres per capita per day
ii) l/ha/s = litres per hectare per second
Commercial, Industrial, and Community Dry Weather Flow
Type of Development
Equivalent Population
Density
(persons/hectare)
Unit Wastewater Flow
m
3
/ha/day l/ha/s
Light Commercial Areas 90 25.2 0.156
Community Services 40 11.2 0.123
Light Industrial Areas 150 42 0.462
Notes: i) l/ha/s = litres per hectare per second
ii) m3
/ha/day = metres3
per hectare per day

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10.2.3 Peak Wastewater Flow Factor
Detailed assessment of peak flows, based on existing data and local conditions are required for
each project. Design flows are to be set with consideration for daily average and hourly peak
flows, inflow and infiltration, illegal connections, and rainy season wet weather peak flow.
10.2.3.1 Residential and Community Services Land Use
For residential and community services land use, the peak wastewater flow shall be derived by
assessing existing available data based on local catchment basins. If these are not available,
apply the ratio established by the Harmon Formula to the average wastewater flow for residential
and community services areas as follow:
P+
+=
4
14
1Kap
where, Kap = ratio of peak flow to average flow
P = tributary population in thousands
Note: For small populations, do not use a peak factor higher than 4.
10.2.3.2 Commercial and Industrial Land Uses
For commercial and industrial land uses, the peaking factor shall be determined from a modified
Harmon Formula as follow:
)
4
14
1(80.0Kap
eP+
+⋅=
where, Kap = ratio of peak flow to average flow
Pe = equivalent tributary population in thousands
10.2.3.3 Combined Land Use
When a tributary area consists of residential, industrial and commercial land uses, the peaking
factor for the combined land use shall be calculated using the modified Harmon Formula as
follow:
)
4
14
1(Kap
e
av
PP
K
++
+⋅=
where,
CIR
CIR
av
AAA
AAA
K
++
+⋅+
=
)(80.0
and AR = residential area
AI = industrial area
AC = commercial area

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10.2.4 Infiltration Allowance
Except under individual assessment or suspected poor condition collection system, infiltration
allowance shall be determined at 5 000 l/ha/day for all types of land use. The Infiltration rate
should be substantially higher in old existing areas of Trinidad & Tobago and/or with high water
tables and care should be taken to include wet weather inflow problems. In those areas,
infiltration rate up to 15 000 l/ha/day could be required with justification data to support.
Any manholes located in depressions are subject to an additional 0.4 l/s per manhole. Minimum
flow is estimated between 0.3 to 0.5 the average daily flow. The value 0.4 should be used as
general for Trinidad & Tobago.
10.3 Gravity Pipe Size
10.3.1 Manning’s Formula
To determine the pipe size and its capacity, the Manning’s Formula may be used. Manning’s
Formula is expressed as:
ASR
n
Q ⋅⋅= 2/13/21
where, Q = design flow (m3
/sec)
n = coefficient of roughness (dimensionless)
R = hydraulic radius (m)
S = slope (m/m)
A = section area of flow (m2
)
10.3.2 Coefficient of Roughness
For all pipe materials, the coefficient of roughness should be set as 0.013.
10.3.3 Minimum Pipe Size
For residential areas, the minimum pipe shall be 200 mm diameter.
For commercial and industrial areas, the minimum pipe size shall be 250 mm diameter.
10.4 Flow Velocities
The flow velocity shall be determined from the following:
A
Q
V =

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where, V = flow velocity (m/sec)
Q = design flow (m3
/sec)
A = cross section area of flow (m2
)
The maximum velocity shall not be greater than 3.0 m/sec with the pipe flowing full and the
minimum velocity shall not be less than 0.60 m/sec with actual flow on a daily basis. The depth
of flow should never exceed 75% of the internal diameter of the sewer.
10.5 Pipe Slopes & Manhole distances
The minimum slopes shown are those required for “self-cleansing velocity set as 0.7 meter per
second, The maximum length between manholes and the absolute minimum slopes for different
sewer sizes shall conform the following:
Sewer size
(mm)
Maximum length
(m) between Man hole
Minimum slope
(m/100m)
200 90 0.40
250 110 0.28
300 110 0.20
350 110 0.17
375 110 0.15
400 120 0.14
450 120 0.12
525 120 0.10
600 150 0.08
900 150 0.046
1200 assess 0.031
1800 assess 0.020
10.6 Structural Layout
In determining the suitable pipe class to be used, live load, dead load, soil type and trench
conditions shall be considered in the calculation. The pipe manufacturer’s recommendations
shall be incorporated into the design. All pipes are to be provided with minimum 150 mm
compacted granular bedding and backfill up to 300 mm above the pipe. In cases where
geotechnical recommendations are not available, granular materials shall meet AASHTO M-43
requirement for the following pipe sizes:
Pipe size AASTHO M-43 size
Less than 375 mm 67, 7, or 8
375 mm to 750 mm 6 or 67
Greater Than 750 mm 57 or 67

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10.7 System Layout
10.7.1 Location of Wastewater Main
All new wastewater mains shall be located within the road allowance.
Location of replacement wastewater mains shall be determined specifically based on the location
of existing utilities and other site conditions and will be dealt with as situation arises. Preferably,
sewers are to be 1.5 m offset from roadway centreline. System arrangement shall include
redundancy and overflows to propose alternate routes in case of blockage. Overflow shall be
rerouted in the sewer system. Sewer easements are required if sewer located out of roadway.
Gas pipelines need a minimum separation of 0.9 m at crossings. See section 5.5.3 for distances
from drinking water lines & pipes.
10.7.2 Pipe Depth
The depth for wastewater main pipe cover shall be determined in consideration of economic
factor, the strength of the pipe and external loads due to trench backfill and wheel loads.
Minimum cover shall be of 1.2 m for roadways and 0.9 m for open areas.
10.7.3 Grid Design
Wastewater mains changing in alignment shall have man holes at the point of the alignment
change.
10.8 Pipe Material
10.8.1 Concrete Pipe
Reinforced concrete pipes may be used for pipe size greater than or equal to 300 mm in diameter.
Portland Cement shall comply with ASTM C150.
All concrete pipes, fittings and joints shall conform to ASTM standards C-76 or EN 641. All
concrete pipe to be manufactured to give Type V Sulfate Resisting Cement for all sub-structures.
Sulphate resistant cement or concrete shall be used for on site concrete pouring.
For flat curves, straight pipe with joint deflections is permissible. Maximum joint deflection shall
be 13 mm.
10.8.2 Polyvinyl Chloride Pipe
PVC pipe sizes from 150 mm to 375 mm in diameter are acceptable.
No curve radius or joint deflection shall be allowed on pipe layouts. Saddle type connections are
not permitted. Tangent length of tee connections must be taken into considerations when
calculating the minimum radius that can be achieved.
PVC pipes and gaskets shall conform to the requirements of ASTM D-3034-77 & ISO 4435.

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10.8.3 Polyethylene Pipe
High density polyethylene profile pipe sizes from 150 mm to 600 mm diameter shall conform to
ASTM and ISO 4437 and fittings to ISO 8085. Joints shall be bell and spigot or butt fused. The
pipe shall only be used with manufactured tees.
10.8.4 Glass Reinforced Plastics (GRP) Pipes and Fittings
Glass reinforced plastics (GRP) pipes and fittings for diameter over 200mm and shall comply
with the relevant provisions of ASTM F1092-04, or BS 5480, and ISO 10639.
10.8.5 Ductile iron
Ductile iron pipe, fittings, accessories and their joints shall be conform to ISO 7186:1996
requirements and test methods applicable.
10.9 Maintenance Chamber (Manhole)
10.9.1 Maintenance Chamber Design
All maintenance chambers shall be designed based on the following criteria:
1. See section 10.5 for distances between manholes depending on pipe diameter.
2. At maintenance chambers where pipe sizes change from smaller pipe size to a larger
downstream pipe size, match the pipes obvert elevations. It is not permissible to design
downstream pipe size smaller than the upstream pipe size.
3. Drop maintenance chambers shall be provided where the difference in elevation is greater
than 0.60 metres. The drop pipe shall be one size smaller than the wastewater main. The
economic feasibility of providing deeper wastewater mains versus excessive invert drops,
drop maintenance chambers, or excessively steep benching shall be ascertained prior to
finalizing the design. Prefabricated drops internal to the maintenance chamber are not
permitted on 1200 mm diameter maintenance chambers. Where the maintenance chamber
depth exceeds 10 m, provide safety grating.
4. Watertight and locking covers shall be provided on maintenance chambers located on all
easements and in areas where maintenance chambers are susceptible to flooding. Where
significant sections of wastewater mains are provided with watertight covers, extended vents
may be required which shall be determined by the Consultants on a case-by-case basis.
Frames and covers to be a floating style (NF80 or 90) capable of withstanding H-20 loading.
5. Tee maintenance chambers may be used for wastewater mains 1200 mm or larger in
diameter.
6. Sanitary sewer service connection to a maintenance chamber should be avoided. However, it
may be permissible should the proposed sanitary sewer service falls within the same obvert
elevation of the sanitary sewer entering the maintenance chamber.

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7. For commercial and industrial establishments, an inspection maintenance chamber must be
placed at a location immediately behind the property line to service the lateral connection.
8. All enclosures and rails should be corrosion resistant.
10.9.2 Manhole Hydraulics
1. On runs with horizontal alignment changes from 0° to 15°, invert drops from 0.015 m to
0.030 m shall be provided.
2. Where the alignment change exceeds 15°, drops shall be provided in accordance with the
following table.
Alignment Change and Required Drop
Alignment Change Required Drop
15
o
– 45
o
min. 0.030 m
45
o
– 90
o
min. 0.050 m
10.10 Connection from Main to Street Line
10.10.1 Street Line Connection
Single family and semi-detached dwellings in residential areas shall have a minimum of 150 mm
diameter street line connection.
Dual connections or two separate lines in a common trench are acceptable in residential areas
where the difference in basement elevation does not exceed 0.60 m. Two or more units serviced
on a common line with wye branches are acceptable.
Where the diameter of the lateral connection is greater than or equal to half the diameter of the
wastewater main, the connection shall be made with a tee-wye or wye connection.
The minimum and maximum cover at property line shall be 1.2 m and 1.8 m, respectively. A 2%
minimum grade for lateral connections shall be maintained. Pipe size change must be made
through similar quality eccentric pipe reducers.
10.10.2 Connection Size and Grade For Multi Family Sites
In multiple family blocks in residential areas, the lateral connections shall meet the following
requirements:

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Connection Size and Grade
Diameter of Drain
(mm)
Slope of Drain
2.0 % 4.0 %
Maximum No. of Fixture Units Per Connection
150 840 1000
200 1920 2300
250 3500 4200
300 5600 6700
375 10000 12000
10.10.3 Pipe Material
PVC pipe may be used for residential lateral connections. Service connections to the main line
sewer shall be at a maximum of 45o
from the horizontal.
10.11 Forcemains
10.11.1 System Design
All forcemains and thrust restraints shall be designed to withstand the maximum operating
pressure plus the number and timing of the pump cycles to which they will be subjected. If the
forcemains are subject to vaccum conditions, avoid plastic and HDPE pipes.
To allow pumping stations to be by-passed during emergencies or major modifications, all
forcemains shall be equipped with suitable valve connections to permit connection of discharge
piping from a portable pump.
Air release valves suitable for use with wastewater shall be positioned at all forcemain high
points. The valve shall be set horizontally and an insulated coupling, ball valve, and pipe union
shall be provided on each assembly to allow maintenance and removal of the air valve.
All plugs, tees and bends shall have approved design mechanical thrust restraints.
The bedding requirements for the forcemains will depend upon the type and the class of pipe
used. As a minimum requirement, the forcemains shall be laid on 100 mm of sand bedding
material conforming to AASHTO type 7 or as indicated by the geotechnical study.
The type of backfill material will usually be determined from the location of the forcemain
within the right-of-way (ROW). Under the pavement, an approved granular backfill shall be used
with conformity to road structural support and design.
10.11.2 Pipe Size
Forcemains shall be sized to have a flow velocity in the range of 0.7 to 3.0 m/s, with the lower
limit being preferred for the initial phase. The minimum size of the forcemain shall be 100 mm
in diameter.

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10.11.3 Pipe Depth
Consultants shall allow a minimum of 1.2 m of cover for forcemains.
10.11.4 Tracer Wire
Tracer wire shall be installed on all new installations of forcemain pipes for locating purposes.
Handwell spacing is not to be greater than 150 m apart. The wire shall be installed between each
valve or handwell and/or the end of the new pipe. Joints in the wire between valves or handwells
are not permitted. At each valve a loop of wire shall be brought up inside the valve box or
handwell to the top of the box.
10.11.5 Thrust restraint
Mechanical thrust restraints shall be designed to withstand the maximum operating pressure plus
the number and timing of the pump cycles to which they will be subjected. Concrete thrust
blocks shall only be permitted for use in special circumstances subject to the approval of WASA.

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Water and Wastewater Design Guideline Manual Wastewater Treatment Plants
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Section 11 Wastewater Treatment Plants
11.1 General
These design criteria are minimum guidelines to be used for the comprehensive consideration of
domestic sewage treatment, or disposal systems and to establish the minimum design criteria
pursuant to existing state statutes pertaining to effluent quality necessary to meet state water
quality standards. These criteria are intended to promote the design of facilities in accordance
with good public health and water quality engineering practices.
This section deals with community collected sewage and does not cover the design of septic
tanks and associated secondary treatment and disposal systems. The design requirements for that
type of system can be found in TTS 16 80 400.
All inflow into the sewerage is assumed to meet the normal domestic water charges and quality.
All collected users are required to meet WASA TES 101-2004 Trade Effluent Standards for
Discharges into Sewers. These design standards supplements do not supersede the requirements
of the EMA and or any legislation relating to the design and operation of wastewater treatment
plants.
Whenever possible, existing data of flows and raw waste strength from the same plant or nearby
plants with similar service areas should be used in design of treatment facilities. When using
such data for design purposes, the variability of data should be considered and the design based
on the highest flows and strengths encountered during normal operating periods taking into
consideration possible infiltration/inflow. More information on wastewater design flows are
found in section 10.
There shall be no water connection from any public drinking water supply system to a
wastewater treatment plant facility unless made through an air gap or a backflow prevention
device, in accordance with AWWA Standard C506 (latest revision) and AWWA Manual M14.
All washdown hoses using potable water must be equipped with atmospheric vacuum breakers
located above the overflow level of the washdown area.
The subject of effluent reuse should be assessed in the preliminary design stage since there is a
considerable potential for the reuse of wastewater in irrigation of parks and gardens, agriculture
and horticulture, aquaculture and some industrial processes.

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11.2 Wastewater Effluent treatment objectives
The sets of standards for effluent quality are based on the T&T Water Pollution Rule 2004.
Wastewater treatment plants shall be designed to consistently (95% average) meet the effluent
concentration and loading requirements of the following criteria:
Discharge Point BOD
mg/l
Suspended
Solids
mg/l
pH
Fecal
Coliform
MPN/100ml
Total
Residual
Chlorine
mg/l
Amm
Nitrogen
(NH3-H)
mg/l
Total
Phosphorus
as P
mg/l
Inland Surface Waters 20 * 20 * 6-9 400 1 10 5
Inshore Sea Waters 50 150 6-9 400 1 10 5
Offshore Sea Waters 100 200 6-9 400 2 10 5
Environmentally
Sensitive Areas 10 15 6-9 100 0.2 0.1 0.1
* These criteria have been modified from the EMA 2006 objectives to impose a stricter environmental criteria and
allow for design security,
11.3 Wastewater Loads
There is limited data available in Trinidad & Tobago upon which to make an accurate estimate of
the unit loading rate expected. Whenever possible, Consultants should assess the loadings in
individual assessment reports, especially for areas with significant industrial development. Based
on values measured in the Greater Port of Spain (Reid Crowther, Nov. 1998), the Eastwest
Corridor (Safege, April 2005) and experience in the remainder of the world, loads contribution
shall be based on the following table for T&T.:
Maximum Dwelling Units Densities
Type of charges Unit Loads (g/c/d)
BOD5 65
TSS 90
NTK 10
Total Phosphorus (Pt) 2
11.4 Plant Layout
In designing the layout of wastewater treatment plants, consideration shall be given for future
expansions of the plant to its ultimate site capacity in order to maximize the utilization of the
available space of the property. Future expansion requirements are as a rule, identified in studies
or in master servicing plan. The staging of each expansion phase is tied to the servicing of new
development areas as well as growth in the existing urban designated areas.

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In this regard, consideration should be given at the design stage, to the requirements for future
expansion as well as the economical and practical sizing of plant process requirements.
The Consultants should in all cases maximize the site’s ultimate capacity in planning the plant
layout, which may be much higher than the capacity requirement. Designing of the expansion
works should be carried out to permit the orderly construction of the facility economically with
minimal disruption of the existing facility.
The piping within all plants shall be arranged so that when one unit is out of service for repairs,
plant operation will continue and emergency treatment can be accomplished. Valves and piping
shall be provided and sized to allow dewatering of any unit, in order for repairs of the unit to be
completed in as short a period of time as possible. Removed wastes must be stored for
retreatment or delivered to another treatment facility for processing. Consideration shall be given
in design for means to clean piping, especially piping carrying raw wastewater, sludges, scum,
and grit. H2S gas detectors shall be supplied with visual and audible alarms in order to protect
staff working at wastewater treatment plants.
11.5 Plant Design Capacity
The design for various components of the wastewater collection system (collector sewers,
interceptor sewers, pumping stations) will be based on peak hourly flow. Force mains from
pumping stations will be sized to handle the pumping capacity of the station.
The design for various components of the treatment plant will be based upon either peak design
flow or peak hourly flow. Generally, the organic loading of a wastewater treatment unit is based
on the design average flow and the hydraulic loading of a unit is based on the peak design flow.
Peak design flow is generally set between 2 to 2.5 times the average dry daily flow. Where
recirculation is provided, the recirculation rate shall be added as required.
The engineering report shall list the design influent flow, peak factors and concentration of
BOD5, TSS, N, P, or other parameters.
11.6 Equalization tank
The wastewater treatment facility, in general, shall consist of a minimum of two trains.
Equalization units should be provided after screening and grit removal. Generally, an
equalization facility requires a volume equivalent to 10% to 20% of the anticipated dry weather
flow. Tankage should be divided into separate compartments to allow for operational flexibility,
repair, and cleaning.
If a filter is present, backwash water is discharged into the two equalization tanks where it is then
pumped to the clarifiers. Settled sludge from clarifiers is pumped to the thickeners. Normally, the
sludge would flow from the clarifiers to the thickeners by gravity.
11.7 Pre treatment – Inlet Works
Bar screens, screens, or shredders through which all wastewater will pass should be provided at
all plants with the exception of plants in which septic tanks, Imhoff tanks, facultative, aerated, or
partially mixed lagoons represent the initial treatment unit. In the event bar screens, screens, or

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Project Design and Technical Specifications Manual Wastewater Treatment Plants
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shredders are located 1.2 meters or more below ground level, appropriate equipment shall be
provided to lift the screenings to ground elevation. Where mechanically cleaned bar screens or
shredders are utilized, a backup unit or manually cleaned bar screen shall be provided. A means
of diverting flow to the backup screen shall be included in the design.
Inlet Works shall be sized to handle hourly peak flow into the facility. Peak flow is defined as
the average dry weather flow multiplied by the peak flow factor plus the allowance for
infiltration in the wastewater collection system (see section 10.2).
The Inlet Works shall be housed in a building and designed for ease of operation for the removal
of grit bin(s), screen, and cleanup of the facility so as to promote a positive working environment
for the Operators.
1. Provide screening compactor for the compaction of screening waste material.
2. Provide grit removal equipment sized to meet service requirements. Grit removal facilities
should be considered for all wastewater treatment plants.
3. All screenings and grit shall be disposed of in an approved manner. All wastewater
originating from the grit cyclone and classifier, automatic bar screen waste material bin,
compactor and grit bins shall be piped for return to the plant process stream.
4. Design the Inlet Work’s ventilation system, including all necessary interlocks, for proper
operation of the system. Control and instrumentation for the heating and ventilation system
shall be explosion-proof for all electrical equipment and system.
5. Provide instrumentation for monitoring of the operation of the grit cyclone and classifier,
automatic bar screens and compactor equipment in the Inlet Works. All monitoring and
alarming methods shall be fail-safe.
6. Provide metering of wastewater entering the Inlet Works or Outlet, depending on the
hydraulics of the headworks.
7. The ventilation systems shall be designed to maintain acceptable working and living
environments for personnel and non- destructive conditions for equipment. H2S gas detectors
shall be installed when such risks are present to working staff.
11.8 Secondary and tertiary treatments
Secondary treatment is mandatory in all processes in order to attain the effluent objectives.
Depending on type of environment or on the projects’ terms of reference, tertiary polishing
treatments should be also assessed. Consultants shall assess the options for secondary and
tertiary treatments as part of the prefeasiblity study and take into consideration all required
information, including the site, economical and social constraints and treatment objectives.
11.9 Disinfection System
Facilities for disinfection shall be provided in all cases to protect the public health and as an aid
to plant operation. Adequate disinfection is to be provided for the Treatment Plant’s effluent in
keeping with TT4417.1993 prior to its discharge into a receiving stream.

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Project Design and Technical Specifications Manual Wastewater Treatment Plants
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Ultraviolet disinfection is the preferred mode of disinfection. Disinfection techniques not in
widespread use, such as ozonation, bromine chloride, and chlorine dioxide, have to be submitted
for approval on a case-by-case basis.
11.9.1 Chlorination System
Depending on the plant process treatment capacity requirements, one chlorinator shall be
provided for each chlorine application point. Equipment shall be selected and installed which is
capable of applying desired amounts of chlorine continuously to the effluent. Chlorination
equipment may also be installed to control odors, remove nutrients and generally assist
treatment. To accomplish these objectives, points of chlorine application may be established at
the head of the plant for prechlorination, in the effluent chlorine contact chamber, or other
suitable locations.
Chlorination equipment shall have a capacity greater than the highest expected dosage to be
applied. Chlorination systems shall be capable of operating under all design hydraulic conditions.
Duplicate equipment with automatic switchover should be considered for standby service, so that
continuous chlorination can be provided. A minimum of two (2) standby chlorinators, sized to
meet maximum day demand shall be provided. The chlorine piping and controls shall allow the
use of the standby chlorinators for all possible application points.
1. Two (2) chlorinators shall be provided for Post-Chlorination
2. One Standby Chlorinator shall be provided and sized for maximum day demand
3. A scale for determining the amount of chlorine used daily, as well as the amount of chlorine
remaining in the container, shall be provided.
Where plants have SCADA systems, the chlorinators shall have the capability of being
controlled:
1. Locally at the equipment
2. At the PLC/Manual
3. At the PLANT/Manual through the SCADA Human Machine Interface (HMI) using the
Graphics User Interface (GUI) main screen
The chlorinators shall be provided with the required switches to enable control of the feed rate
through the SCADA system.
For each chlorinator, provide a GUI pop-up menu box to indicate the feed rate. In the
CPU/Manual control mode, provide a GUI pop-up menu box for the respective chlorinator to
permit changes of feed rate set point from zero to 100%.
For chlorination system, the feed rate will be based on a closed feedback loop.
Rapid initial mixing of the chlorine solution and wastewater is essential for effective
disinfection. Contact chambers shall be designed to provide a minimum average hydraulic
residence time (chamber volume divided by flow) of 20 minutes at the design peak hydraulic
flow. Chemical disinfection is not normally required when the total residence time in the
wastewater treatment system (based on design flow) is at least 21 days.

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11.9.2 Ultra-Violet (UV )
Ultraviolet disinfection systems are considered applicable to treated wastewaters with daily
average BOD 5 and TSS concentrations consistently less than 20 mg/liter. Disinfection units will
be designed in accordance with methodologies presented in the United States Environmental
Protection Agency Design Manual, Municipal Disinfection, EPA/625/1-86/021. Turbulent flow
is necessary due to non-uniform intensity fields in an ultraviolet reactor. Disinfection systems
shall consist of a minimum of two ultraviolet banks in series and shall be capable of providing
disinfection to the effluent fecal coliform requirements (See section 11.3) at the design daily
average flow with the largest bank out of service.
Ultra-Violet (UV) is the preferred choice for the disinfection system and design system as
follows:
1. Provide a minimum of two banks of UV lamps with 100% redundancy. The two banks are to
be operated in-series, each with a capacity to meet average day flow.
2. The ultraviolet unit shall be configured so that there is adequate space for the removal and
maintenance of lamps. One person should be able to replace lamps without the aid of
mechanical lifting devices, special tools, or equipment. Drains shall be provided to
completely drain the ultraviolet reactor unless the equipment can be easily removed from the
effluent channel, but lamps shall be replaceable without draining the unit. The materials used
to construct the reactor shall be resistant to ultraviolet light. Ballasts and other electrical
components shall be consistent with the ultraviolet lamp manufacturer's recommendations.
Temporary screens shall be installed to protect the lamps and other fragile components from
construction debris.
3. For wastewater treatment with tertiary treatment, provide low intensity UV lamps.
4. Where possible, the horizontal lamp arrangement is preferred over the vertical arrangements.
5. Provide a cleaning solution tank for the UV lamps adjacent to the UV channels and pump the
spent cleaning fluid to the head of the plant.
6. Each individual ultraviolet lamp shall be provided with a remote operation indicator. Lamp
failure alarms shall also be provided for a predetermined number of lamp failures.
Techniques that result in nonirradiated flow pathways are prohibited. Each ultraviolet bank
shall be equipped with at least one ultraviolet intensity meter or some means to monitor
changes in ultraviolet dosage; however, intensity meters shall not be relied upon to
automatically control system operation. A flow control device, such as an automatic level
control, shall be provided to ensure that the lamps are submerged in the effluent at all times
regardless of flow rate. The automatic level control shall be arranged so that it will allow
suspended solids, which may settle, to be washed out of the area of UV disinfection. Proper
ventilation is critical to the ultraviolet system operation. Cabinets containing ballasts and or
transformers shall be provided with positive filtered air ventilation and automatic shutdown
alarms at high temperatures. Provisions shall also be made to maintain the ultraviolet lamps
at or near their optimum operating temperature and to filter ventilating air so as to limit
ultraviolet light absorbance by dust accumulations. Elapsed operation time meters shall be
provided for each bank of ultraviolet lamps.

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7. Provisions for routine cleaning such as mechanical wipers, high pressure sprayers, ultrasonic
transducers, or chemical cleaning agents are required. Quartz sleeve ultraviolet systems shall
have a chemical cleaning capability in addition to any ultrasonic and/or mechanical wiper
systems. Operators shall be protected from exposure to ultraviolet light during normal
operations.
11.9.3 Sulphur Dioxide System
Where the final effluent water must be dechlorinated as required by EMA or WASA, the
dechlorination process shall be achieved by the use of sulphur dioxide or sodium metabisulphite.
Sulphur dioxide system shall be sized for maximum day demand and a minimum of two (2)
sulphonators shall be provided.
Provide one additional standby sulphonator sized for maximum day demand.
All sulphonators shall have the capability of being controlled:
1. Locally at the equipment
2. PLC/Manual
3. PLANT/Manual at the Plant through the SCADA HMI at the GUI main screen
The metering pump shall be provided with the required switches to enable control of the
sulphonators through the SCADA system.
For each sulphonator, provide a GUI pop-up menu box to indicate the feed rate. In the
CPU/Manual control mode, provide a GUI pop-up menu box for the respective sulphonator to
permit changes of feed rate set point from zero to 100%.
11.10 Sampling and monitoring
Monitoring stations shall be provided at influent, effluent and after each unit treatment during the
process to allow for control and assessment of treatment.
Automatic sampling stations are required to perform discrete or composite, flow proportional
and time proportional sampling at the inlet and the outlet of treatment plants. Sampling sequence
is to begin with high pressure air purge of intake assembly to clear obstructions. Sampler
enclosure is to be weatherproof, corrosion resistant, insulated and c/w forced air heater and
thermostat, locking door and bolt down base. Provide with refrigerated sample compartment.
Controller to be programmable with LCD display and include battery to maintain program
settings and stored information in the event of power failure.
11.11 Odor Control
Provide odour control with appropriate ventilation system designed to minimize the odour level
in the Inlet Works working area. To protect working staff from gas inhalation risks, H2S gas
detector shall be supplied with visual and audible alarms.

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Project Design and Technical Specifications Manual Wastewater Treatment Plants
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Odour control may be achieved by isolation of the areas having odour problems and ventilating it
separately or by providing direct ventilating capability at the source of odour. Alternatively, the
air blower(s) air intake can be connected to the Inlet Works ventilation system for the removal of
the odour and the air is used in a separate coarse air bubble aeration system in the aeration tank.
Where odour control is not feasible, provide odour treatment in the alternate with gas scrubbing
system, which may be chemical or biological unit.
The need for odour control facilities shall be evaluated for each plant. Factors to be considered
are the dissolved oxygen level of the incoming sewage and the type of treatment process
proposed. When required, air supply must be sufficient to maintain 1.0 mg/litre of dissolved
oxygen in the wastewater.
At the outlet of the odour treatment system, the concentration of pollutants must be lower than
the following values:
Pollutant Concentration (mg/Nm3
)
Hydrogen sulphide <0.1
Amines <0.07 (in methyl sulphur)
Ammonia <1
Mercaptans <0.7 (in methyl sulphur)
11.12 Structural consideration
The structural design of treatment plants shall be sufficient to accommodate anticipated ground
movement including any active geologic faults and allow for independent dewatering of all
treatment units.
Basins having vertical walls terminating 1.2 meters or more above or below ground level shall
provide a stairway to the walkway. Guard rails on walkways shall have adequate clearance space
for maintenance operations. All enclosures and rails should be corrosion resistant.
Refer to Section 15 – Structural Standards.
11.13 Water reuse for irrigation
If the wastewater treatment plants include a tertiary treatment, the design should allow for
pumping and using some of the effluent flow for irrigation purposes of plants in the
neighbourhood of the treatment plant.
11.14 Control System
Where SCADA control is implemented at the facility, refer to Section 17 – Instrumentation &
Control and Section 18 – SCADA System for control system requirements.

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A means for measuring effluent flow shall be provided at all plants. Consideration should be
given to providing a means to monitor influent flow. Where average influent and effluent flows
are significantly different, e.g., plants with large water surfaces located in areas of high rainfall
or evaporation or plants using a portion of effluent for irrigation, both influent and effluent must
be measured.
11.15 SCADA System
Comply with SCADA design standards as noted in Section 18 – SCADA System.
11.16 Equipment Redundancy
See Section 4 – Process and Equipment Redundancy
Auxiliary power facilities are required for all plants, unless dual power supply arrangements can
be made or unless it can be demonstrated that the plant is located in an area where electric power
reliability is such that power failure for a period to cause deterioration of effluent quality is
unlikely. Acceptable alternatives to auxiliary power include the ability to store influent flow or
partially treated wastewater during power outage. Auxiliary power is required for plants
discharging near drinking water reservoirs, shellfish waters, areas used for contact recreation,
and for plants discharging into environmentally sensitive areas.
Multiple units may be required based on the uses of the receiving waters and the significance of
the treatment units to the treatment processes
11.17 Stormwater management
11.17.1 Combined Sewer System vs. Separate Sanitary Sewer
The philosophy for combined or separate sewer systems is assessed in the long term on its
impact on the operation of the wastewater treatment plants capacity. The positive aspect of
separate sewer systems will result in a reduced peaking factor at the plant. This has the
advantage that the design capacity of the plant can be reduced to meet actual wastewater
treatment capacity requirement only. Therefore the designed capacity of the plant can be
reduced; size or capacity of process equipment can be reduced and it will also result in the
reduction of chemicals and energy consumption. A combined sewer on the other hand has the
opposite effects but it has the advantage that all wastewater is treated prior to the effluent being
discharged into the environment.
The preferred design approach to be implemented in T&T is for separate sanitary and storm
water sewer systems.
11.17.2 Runoff impact
Environmental impacts from stormwater runoff are not to be underestimated, particularly in
areas with a high population density. A proactive approach should be implemented.
Implementation of mitigation strategies on receiving environments are preferred rather than

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restorative efforts, which are more expensive and time consuming before a positive effect is
noticed on the benthic communities and the fish species.
A stormwater program must be designed to:
• reduce pollution to the maximum extent practicable;
• protect water quality; and
• meet environmental effluent standard requirements (EMA 2004).
To achieve these goals one aspect of the management program is to prevent pollution and install
measures to control runoff water quality. Experience in North America has shown that a key
component to a proactive approach is a clear and consultative environmental planning procedure
and the use of biological monitoring, particularly benthic community analysis. Possible strategies
to be implemented are:
• Public education to prevent litter, pet wastes, and debris from street gutters and storm
drains
• Provision of public disposal sites for used oil, antifreeze, paints, and other household
chemicals
• Control of soil erosion on land, public parks and construction sites
• Implementation of agricultural best practices to avoid nutrient and pesticide pollution
• In new development areas, efforts should be made to attempt to maintain the volume of
runoff at predevelopment levels by using structural controls and pollution prevention
strategies.
Treatment processes may be necessary to diminish pollution. Storm drains and catch basins
could include some form of treatment technology to help minimize impact on local eco-systems.
Urban surface runoff quality control installations (detention ponds etc.) are often very effective
for suspended solids and oxygen-demanding matter controls.
11.17.3 Requirements
Unless otherwise directed by WASA, for all water and wastewater treatment facilities,
Consultants are to provide for means of reducing development site runoff during and after
construction. Minimizing these development impacts include simple techniques such as green
areas, erosion controls, maximizing infiltration, rooftop gardens, vegetated swales, buffers, and
preservation of trees.

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Water and Wastewater Design Guideline Manual Wastewater Pumping Stations
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Section 12 Wastewater Pumping Stations
12.1 General
Consultants shall design wastewater pumping stations in accordance with WASA’s requirements
and all other codes, guidelines, design standards etc. to ensure compliance. Studies shall assess
future growth so the facility design will provide sufficient space for future expansion work.
These guidelines are intended to establish the basic design parameters to be used in the
development of wastewater pumping stations. As each pumping station is inherently different,
the specific design for each pump station will be unique and sound judgment and acceptable
engineering practices are to be provided.
12.2 Wastewater Pumping Station General Design
Different types of pumping stations are possible and should be based on the incoming flow of
wastewater, the peak flow and the total head required. The space requirements of pumps, piping,
and equipment, along with the storage volume required in the wet well, will be carefully
determined so that the proper size, shape, and configuration of the pumping station can be
selected. The size and shape of the station will often be dictated by equipment other than pumps,
such as bar racks or screens.
Toilet/bath facilities are to be provided for wastewater pumping stations except for small
submersible stations.
12.3 Wastewater Pumping Station Layout
Design wastewater pumping station configuration based on most efficient layout of pumps and
equipment for safe and cost effective operation and maintenance of the facility. Select specific
pumps based on the optimal combination of pump efficiency, capital, operating and maintenance
costs.
Influent pipe for in-ground pumping stations shall be designed with a minimum distance of two-
volute diameter away from the pump centre line. Benching in the wet well shall be steep and
close to the pump inlet to prevent sediment build-up on the wet well floor.
Access opening for the pump shall be located and sized for the efficient installation or removal
of the pump. It must also be sized to permit the entry of Operators or Maintenance staff wearing
retrieval equipment harness without having to disconnect the safety line. The minimum
dimensions of the access hatch shall be 900 mm by 750 mm. The access hatch cover shall be
fabricated with light non corrosive material and be hinged and lockable by a padlock.
Lock port shall be recessed and provided with drainage pipe. The cover shall be provided with
the necessary hold open arm to keep the cover in the vertical position once it is opened. Vertical
access ladder shall be a non-slip, non corrosive material. An overflow pipe will be required in all
cases unless the location prohibits its installation. In such cases, standby power will be required.
Overflow pipes (minimum 200 mm) shall be installed in the wet well as high as possible without

94. Water And Sewerage Authority (WASA)
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causing a sewer backup or basement flooding, and shall be equipped with a dedicated overflow
alarm. A pressure gauge shall be provided at each pump discharge pipe above the flood line.
All fixtures, enclosures and rails shall be made of certified corrosion resistant material.
Provide required equipment for the safe retrieval of personnel in confined space. Provide lifting
devices for the removal and installation of equipment.
Provide a minimum of one (1) meter clear space around equipment for servicing.
12.4 Configuration of Pumping System
Wet wells shall be designed to suit the pump capacity, which should in turn, be matched to the
design flow for the station. The size of the wet well in relation to the suction pipe(s) shall be in
accordance with the Hydraulic Institute to prevent hydraulic interference. The depth of the wet
well shall be sufficient to ensure adequate control bands for each pump. Where the continuity of
the pumping station operation is critical, consideration should be given to dividing the wet well
into two sections, properly interconnected, to facilitate repairs and cleaning.
Coarse (50 mm and finer) screening systems must be provided upstream in the collection system
to avoid damages to lifting pumps. The system must include a means of collecting and disposing
of screen wastes. As a general rule, for each pumping station, the screening requirements must be
analysed and assessed to define the need for type and size of screens.
In no case shall the wet well be designed which will result in the pump(s) cycling more than six
(6) times per hour for a station with a motor of less than 30 kW. In no case shall this exceed that
as recommended by the manufacturer but in all cases, the more stringent criteria shall apply.
All wet wells shall be provided with water service to enable flushing or cleaning of the wet well.
Wet wells shall be designed to prevent deposition of solids. In all cases, provide piping from the
pump discharge header to the bottom of the wet well for flushing when the pump starts for a
short period of time. Duration of the flushing of the wet well shall be adjustable from the control
panel or PLC. Water service shall be provided with backflow preventer, sized not smaller then
40 mm and shall be metered.
All electrical equipment in the wet well shall be explosion-proof in accordance with applicable
codes and/or standards. Lights shall be explosion-proof and equipped with a switch located in the
electrical utility box. All hardware inside the station shall be stainless steel.
Laser or Ultrasonic equipments are to be preferred in the pump control system, and their
installations are to comply with the following:
1. Above the highest top water level, usually above the top of the overflow pipe.
2. Within easy reach of the operator for maintenance or repair purposes.
3. Away from all possible interference arising from the wastewater flowing into the wet well
through the inlet pipe.
4. Away from all possible interference arising from water surface turbulence.
5. Provide floats controls as a backup to the ultrasonic pumps control system. Ensure that the
floats are installed complete with anti-sway hardware.

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12.5 Wastewater Pumping Station Sizing Design
Station Size Building Type Number Of Pumps Standby Pump
Requirement
Type of
Drives
Gen Set
1 Inflow less than 20 L/s. Typically small in-ground
prefabricated submersible
pumping stations.
One (1) rated at peak flow.
Locate pumps in wet well.
One (1) rated at
peak flow.
Direct Drive
with float
control
Provide for
connection to
mobile
Generator
2 Inflow greater than
20 L/s but less than
200 L/s.
Submersible pumping station
with wet well and
superstructure for housing
controls, MCC, standby
generator etc.
Two (2) pump
configuration, each rated at
peak flow or
Three (3) equally sized
pumps with two (2) in
parallel at peak flow.
Locate pumps in wet well.
For three pumps
configuration, one
(1) standby pump
rated at the same
capacity of the
largest.
Direct Drive
with ultrasonic
level control
complete with
backup float
control
Provide Gen
Set sized for
peak flow.
3 Inflow greater than 200
l/s.
Pumping station with
superstructure in a dry well
configuration.
Pumps could be of
submersible type.
Two (2) pump
configuration, each rated at
peak flow or
Multiple pump
configuration. Design
pumping system for most
efficient configuration for
peak flow.
Locate pumps in dry well.
For multiple pumps
configuration, one
(1) standby pump
rated at the same
capacity of the
largest unit
Direct and
VFD with
ultrasonic
level control.
(VFD with
bypass for
Direct Drive)
Provide Gen
Set sized for
peak flow.

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12.6 Wastewater Pumping Station (Inflow less than 20 l/s)
Provide storage for a two-hour retention capacity on peak flow in the wet well. Provide a vandal-
proof, lockable, electrical hardware connector and switch gear for hook-up on the exterior wall,
designed to provide electrical power to the station by a portable electric generator under a local
power supply grid network failure. Type and model of lock will be provided by WASA.
A visual and audible alarm system should be installed for reporting to WASA. The electrical
utility box shall be compact and low profile to complement the aesthetics of the location. Cabinet
shall be located so as to permit the removal of the pump without undue difficulties.
A positive forced air ventilator shall be provided with a switch in the electrical panel to permit
operation of the ventilator on a required basis.
12.7 Wastewater Pumping Station (20 l/s<Inflow < 200 l/s)
Design pumping station with two constant speed submersible pumps in a single wet well
configuration; with each pump sized for peak flow. Additional on-site wet well storage capacity
is not required. Control, MCC, generator and electrical equipment are to be situated in a dry well.
Dry wells, including their superstructure, shall be completely separated from the wet well.
Design pump control system to alternate pumping sequence. Provide a separate union box for
pump power supply and to enable the removal and installation of the pumps.
A bypass hook-up for the forcemain with the necessary isolation valves shall be located outside
the wet well. The bypass, regardless of the forcemain size, shall be 200 mm in diameter, flanged
and provided with a quick connector extending 450 mm above the finished grade. Bypass
fittings, pipe and isolating gate valves shall be 200 mm in diameter.
Provide an emergency standby diesel generator to provide power supply to the largest pumping
unit in the station and other essential electrical equipment such as louvers, fans, instrumentation,
controls, etc.
12.8 Wastewater Pumping Station (Inflow > 200 l/s)
Use pumps in a dry pit configuration. Common walls must be gas tight.
For a station with two fixed speed pump operating systems, size each pump to handle 50% of
peak flow. Provide one standby pump sized for peak flow. Submersible pumps should be
installed if there is a flooding risk.
For stations with a multiple-pump operating system, determine the most efficient pumping
configuration for the station based on:
1. Equally sized pumps,
2. One small pump with several equally sized pumps,
3. Combination of the above, or
4. Combination of 3 with variable frequency speed pump(s)

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In all cases, provide at least one standby pump with equal capacity to the biggest operating
pump.
Provide variable frequency drive pump(s) where there is a need for continual flow from one
pumping station to the next pumping station or wastewater treatment plant. The final design
decision shall be based on good engineering practices. In no case shall the minimum design
discharge velocity be less than 0.8 m/s.
Where required, as dictated by the characteristics of the wastewater flowing into the pumping
station, provide an automatic screen complete with compactor and grit bin and/or comminutor.
Provide an emergency standby diesel generator.
12.9 Pump Design
Pumps shall be non-clog and able to pump a 3 inch diameter solid. Convert to a "Vortex" pump
volute any time pumping liquid contains lots of solids. Provide a back up seal for each seal.
Provide pipe flushing connections to facilitate the cleaning of plugged lines or pumps.
Provide an air vent pipe from high point on pump volute continuously discharging to wet well
above overflow level to facilitate priming after wet well pump down.
For a dry pit with wet well configuration, provide piping and valves to allow re-circulation of
pumped wastewater into wet well to prevent solids built-up at bottom of wet well.
12.10 Piping & Valve Design
In the design of wastewater pumping station piping, the Consultants shall comply with the
following criteria:
1. Only ductile iron pipe shall be used for the forcemain.
2. Stainless steel piping is not permitted for use in the forcemain.
3. Butterfly valves shall not be used in the forcemain.
4. Depending on the size of the forcemain, isolation valves shall be resilient seated full port gate
valve or knife gate. Knife gate valves shall only be allowed on the suction piping from the
wet well to the pump when space is limited and the hydraulic head is less than 6 meters.
5. Sluice gates shall be fabricated from stainless steel. Operators shall be located at ground
level. Sluice gates shall only be allowed for isolation of the trunk sewer from the wet well or
to isolate two wet well compartments.
6. The piping from the pump to the forcemain shall be designed for horizontal connection and
not vertical.
7. Design piping layout with “Y” configuration and not “T”.
8. All valves shall be located in the horizontal position. Valves are not permitted to be installed
in the vertical position.

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9. Air relief, air-vacuum release, or combination air release and vacuum valves shall be of a
type and brand manufactured for the specific purpose in sewage service, and shall be
provided at critical locations in the pump station and force main.. For each air-valve
assembly, the pipe-nipple connection to the manifold and all other piping in the assembly
shall be copper. An insulated coupling, ball valve, and pipe union shall be provided on each
assembly to allow maintenance and removal of the air valve.
10. Provide flushing connections to facilitate cleaning of the pipe.
11. Provide isolation valve on the discharge header prior to it leaving the pumping station.
12. Provide horizontally placed anti-slam check valves on all pump discharge headers.
13. Provide for surge protection by installing soft start/stop electrical control equipment or surge
control on pumps main discharge header and recycle wastewater to the wet well above top
water level (TWL).
14. Properly located and sized pipe supports shall be provided. No loads shall be transmitted to
pump flanges. All pipe restraints shall be designed to resist maximum expected surge and
earthquake forces. Pipe restraints shall be adequately anchored for vertical and lateral
support.
12.11 Corrosion resistance
The wet well interior and exterior concrete surfaces shall be corrosion resistant and receive as a
minimum two coats of a coal tar epoxy coating to protect the concrete from the corrosion due to
hydrogen sulfide in the influent sewage. HDPE lining is also an adequate means to ensure
protection of concrete.
Type 316 stainless steel should be specified for guide rails, brackets, bolts, nuts, structural steel,
supports, and stairs. Fiberglass grating and ladders are recommended. The exterior of ductile iron
piping shall be epoxy coated. Corrosion resistant materials should also be specified for electrical
components.
12.12 Pump Controls
For each pump include the following indicator lights: pump electrical supply (white); pump
running (green); pump off (red); and pump failure (flashing red), unless otherwise approved by
WASA. All indicating lights shall be connected to a push-to-test button to test for proper
functioning of the bulbs. Indicator lamps shall be either transformer or diode-type device.
Provide an externally non-resettable elapsed time meter for each pump in service.
The configuration of the pumping system shall be set by level sensor or float devices and will
generally be as follows:
1. Low Water Level (LWL) Pumps off
2. P1 Pump No.1 start
3. P2 Pump No.2 start
4. High Water Level (HWL) Standby pump starts

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Status reported by PLC to Central Control
5. High High Water Level Overflow condition
Status reported by PLC to Central Control
Where the operation of the pumps is controlled by ultrasonic level control tied to the station
Programmable Logic Controller (PLC) or remote programmable unit (RPU), provide float
switches hardwired to the pump motor starter for starting the pump(s) on High High Level in the
event that the ultrasonic level control and/or PLC control fails.
The PLC/RPU for the pumping station shall be designed for integration with WASA’s
Supervisory Control and Data Acquisition (SCADA) system for the operation of the wastewater
collection systems and treatment plants.
12.13 Odour Control
For pumping stations located in residential areas, provide odour control within 100 meters of
residential dwellings.. The wet well air shall be treated by a replaceable activated carbon filter or
an equivalent system.
12.14 Ventilation
Stations with pumps in a dry well shall be designed with ventilation systems for the dry well to
be a Class 1 Division 2 classification per NFPA 820. At a minimum, separate ventilation systems
shall be provided for the wet well and dry well. Interconnections between the dry well and wet
well ventilation systems are not allowed.
Ventilation of a wet well under normal operating conditions is not required.
For entry for maintenance and/or operation functions, provide intermittent positive ventilation in
the well with 30 air changes per hour. The ventilation system in the well shall be started
manually by a switch, which will also turn on the lights in the wet well.
If continuous positive ventilation is provided, then it shall have six (6) air changes per hour
under normal operating conditions.
Ventilation ducts shall be maintenance free and shall preferably be fibreglass or plastic with an
unpainted finished surface. All ventilation equipment such as dampers, fans or motors shall be
readily accessible for maintenance and servicing.
Provide dehumidification equipment in dry wells to reduce humidity below dew point.
12.15 Equipment and Material Specifications
The primary drive system for all new sanitary pump stations shall be electric motors. Motors
shall be explosion proof, solid shaft squirrel-cage induction type. The enclosure shall be totally
enclosed, fan cooled and the insulation shall conform to NEMA Class F, or H. Electric motors
greater than 7.5 kW shall be of the high efficiency type and for motors greater than 90 kW, the
efficiency shall be better than 94% when ever possible.
Bearings for all rotating equipment shall be rated for 100,000 hours as a minimum.

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If a residential area is nearby, noise reducing features should be provided to avoid noise level
disturbances.
WASA’s list of preferred suppliers must be consulted in order to select the pump’s manufacturer.
12.16 Site Access Road and Security
Unless otherwise specified by WASA, or local approval agencies, the building access road shall
be fenced off with 2100 mm high galvanized steel chain link fence and razor wire.
Access gate(s) to the property shall be 7000 mm wide and 2100 mm high. The location of the
gate(s) may be required to comply with the requirements of the approval agencies and or area
municipality.
Design building exterior exposed surfaces such as access hatches, doors etc to be vandal
resistant. Ensure that all ventilation louvers to the reservoir are properly secured to prevent entry
of foreign material. All hatches are to be lockable and keyed to WASA’s master lock system.
The exterior of the building shall be provided with high pressure sodium vapour light fixtures
(vandal and tamper resistant) with high power factor ballast and lamps suitable for horizontal,
base up or base down operation. The need for surveillance camera and alarms shall be assessed
for each site.
12.17 Instrumentation & Control Alarms
All new sanitary pump stations shall be equipped with a flow measurement device which will
continuously measure the total flow being pumped by the station. Parshall flumes, Magnetic,
Doppler, or ultrasonic meters are acceptable and the selection will depend on the anticipated
grease and solid content of the wastewater. A pressure gauge shall be installed on the suction and
discharge side of each pump that is installed in a dry well, and in the valve vault on the discharge
side of each submersible pump.
The following equipment or logic defined alarms shall be generated by the PLC/RPU at the
pumping station and transmitted to the SCADA system:
1. Building:
.1 Access Security – Authorized and unauthorized entry
.2 Building – Smoke in building
.3 Building – Flooding in basement
2. Wet Well / Dry Well :
.1 Pump(s)
.2 Overload trip
.3 Thermistor trip
.4 Fail to start
.5 Fail to stop

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.6 Uncommanded stop
.7 Low pressure
.8 Overflow
3. Diesel Generator:
.1 Fail to start
.2 Fail to stop
.3 Overload
12.18 SCADA System
Comply with Section 17 – Instrumentation & Control and Section 18 – SCADA System design
standard requirements.
12.19 Equipment Redundancy
See Section 4 – Process and Equipment Redundancy.

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Section 13 Septage & Biosolids Management
13.1 Septage Management – General
These design criteria deals with management of septage, which is classified as all matter (liquids
and solids) that is pumped out of septic tanks and holding tanks. These guidelines aim to provide
guidance for the treatment of septage if indicated by WASA for a particular project. Septage
pumped from individual septic tanks is not adequately stabilized and should not to be applied
directly on land so as to protect the public health and the environment. Once stabilized, septage
solids are usually less metal contaminated than sewage solids, which allows them to be often
used for land application.
13.1.1 Stabilisation pond
Stabilisation lagoons should be designed to treat septage solids based on organic and nutrient
loading rates and also hydraulic loading rates. Solids retained in the lagoon are stabilized by
anaerobic decomposition while the supernatant is treated in a second polishing lagoon or treated
in a wastewater treatment plant. Solids must be periodically removed from the lagoon for use or
disposal as indicated by WASA.
Siting of the lagoon must be established with careful consideration to soil, hydrogeological
characteristics, surrounding land uses, and protection of public health and water quality. Wind
direction shall be assessed in order to prevent public nuisance.
Multi celled basins with two parallel lagoons are the minimum configuration in order to allow
capacity for maintenance of the lagoons. The lagoons should be capable of operating as a single
or two-step unit. Retention time must be calculated based on end objective of disposal indicated
by WASA. Slopes should be seeded and runoff prevented from entering the lagoons. The liner
must be installed in order to protect from infiltration with monitoring wells included for control.
Lime addition should be included if odor becomes be nuisance.
Stabilisation ponds must be designed to allow easy access for loading and unloading septage.
Site must be fenced and signage should indicate the hazard.
13.1.2 Wastewater Treatment Plant
If indicated by WASA, the design of the wastewater treatment plants should allow discharge and
treatment of septage. The treatment plant must allow separation of solid and liquid streams.
Design of treatment plants should be capable of treating these streams with careful knowledge of
loadings in order to not adversely affect unit processes. The process usually involves screening,
dewatering, and treatment of the separated liquid and of the solid fraction. The solid fraction
should be stabilized (See section 13.3) based on end objective of disposal indicated by WASA.
The facility must be designed in order to allow capacity and capability of treating the
supernatant/liquid effluent with consideration to possible high BOD and grease contents.
Assessment should be done on a case by case basis to properly design and keep the right mixture
of septage to sewer water.

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13.1.3 Alkali treatment
If indicated by WASA, an alkali treatment site should allow for stabilization of septage. At the
maximum design volume, the process must be able to maintain a pH of over 12 for at least 30
minutes, and shall include a minimum 150% over capacity for lime addition. Lime addition and
replenishment should be mechanized with total control over rate of addition. Alkali facilities
must be designed to allow easy access for loading and unloading septage and also screening of
septage from hauled trucks. Screening should be mechanically compacted and disposed.
The stabilization basin must allow for separation of liquid and stabilized solids. Sludge pumps
must allow transfer of all the volume to a hauling truck for land application. If indicated by
WASA, the facility should allow for dewatering (See section 13.5) of the stabilized solids and
pumping of the liquid part into a sewer.
13.2 Biosolids Management - General
These design criteria are minimum guidelines to be used for the comprehensive consideration of
biosolid management and establish the bases of WASA’s requirements. Sludge processing and
treatment shall be in agreement with the requirements of the ultimate form of disposal. The
activated sludge can be thickened followed by disposal in the following manner:
1. The waste activated sludge can be used as an agricultural source of nutrient.
2. The waste activated sludge can be dewatered and the solids disposed off on land-filled site.
3. It can be dewatered and turned into pellets as a source of nutrient for farmers or gardener.
4. The dewatered cake can be dried and incinerated to provide energy at the plant.
The choice as to which method to proceed with depends on many factors. These alternatives
should be reviewed at the pre-design stage to ensure that the most economic and viable option is
selected for the plant handling of its bio-solids.
Provisions shall be made to insure that waste sludge will be discharged to the sludge digester in
such a manner so as to minimize the volume of digester supernatant liquor. Provisions shall be
made for the return of supernatant from sludge thickeners and digesters to the head of the
treatment works or to the aeration system accounting for the impact on the treatment units.
All piping from clarifiers to thickeners, digesters, or other sludge processing facilities shall be
arranged for ease of maintenance, with hose gates and cleanouts, and with sufficient hydraulic
gradient to insure the flow of sludge. Maximum flow velocity is 1.8 m/s. Piping under stationary
structures shall be arranged so that stoppages can be readily eliminated by rodding or with sewer
cleaning devices. The sludge piping within the digester, including the sludge drain line, shall be a
minimum of 150 mm in diameter. Appropriate facilities for transfer of supernatant liquor shall be
provided. Piping shall include a means to observe the quality of the supernatant from each of the
withdrawal outlets provided. All units shall be capable of being drained independently of one
another.

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13.3 Sludge stabilization
Sludge stabilization is recommended for all biological treatment processes with the exception of
extended aeration processes (with a solids retention time of 20 days or more) in which case the
sludge may be drawn directly to a sludge dewatering facility.
Considerations should be given to sludge treatment at centralized facilities at key plants. Consult
with WASA with regards to examination of social, financial and technical issues.
Sizing requirements must be determined using the BOD5 and design flow of the raw sewage
influent to the plant. Alternative stabilization techniques like composting, wet oxidation and
other processes shall include the demonstrated level of stabilization achieved by the process to be
employed.
13.3.1 Aerobic digesters
Aerobic digesters should be provided with sludge thickening capability. If a separate system of
air compressors or blowers will supply air to the digester, then the compressor or blower system
shall be designed so that the air requirements can be met with the largest single unit out of
service. Adequate mixing of the sludge shall be provided to keep the solids in suspension and to
bring the deoxygenated liquid continuously to the aeration device. The amount of mixing shall
be based upon the sludge characteristics, the tank geometry, and type of aeration mixing device.
A digester shall provide a minimum sludge retention time of 15 days. This volume should be
provided in two cells capable of operating as a single or two-step unit. Provisions shall be made
to include an effective means of removing solids from the digester.
13.3.2 Anaerobic digesters
The digester volume shall be designed with a minimum solid retention time (SRT) of 30 days for
unheated digesters and a minimum SRT of 15 days for heated digesters. Heating of the digester
means that adequate facilities shall be provided for heating and mixing the sludge and
maintaining a year-round temperature of at least 35 degrees Celcius. Heating coils inside the
digester is not recommended. All heated digesters shall include a thermometer with not less than
a four-inch dial to indicate the temperature of digester contents.
The calculations for the required sludge digestion volume shall be based on the minimum percent
solids in the sludge expected to be encountered.
Adequate mixing of digester contents is required for all first-stage and all single-stage digesters.
Mixing may be performed by mechanical equipment, including external pumps, or by gas
recirculation. The rate of mixing shall be such that the flow created in the digester is sufficient to
completely mix the incoming sludge with the digester contents and prevent the formation of a
scum layer.
Anaerobic digesters are to be in a covered facility. Digester covers shall be equipped with an air
vent which includes a flame trap, a vacuum breaker, and a pressure relief valve. The sludge and
supernatant withdrawal piping for all single-stage and first-stage digesters with fixed covers shall

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be arranged in such a manner so as to minimize the possibility of air being drawn into the gas
chamber above the liquid in the digester. All digester covers shall include a gas chamber
adequate for the gas production anticipated. Digester covers shall be gas tight and the
specifications shall require a test of every digester cover for gas leakage.
The gas piping shall be adequate for the volume of gas to be handled and shall be pressure tested
for leakage before the digester is placed into operation. The main gas line from the digester shall
have a sediment trap equipped with a drip trap. Drip traps shall be provided at all other low
points in gas piping. A natural or bottled gas source shall be utilized for the burner pilot. Flame
traps with fusible shutoffs shall be included in all main gas lines. The gas line to the waste gas
burner shall include a suitable pressure, vacuum, relief valve, flame checks or flame traps. The
main gas line shall be provided with a manometer or other acceptable devices which measure the
gas pressure in inches of water. Manometers may be used to measure the gas pressure in other
gas lines. All manometers shall be vented to the atmosphere outside digester buildings. A gas
meter to measure the rate of gas production is desirable. All rooms in digester buildings with
floor level below grade shall be adequately ventilated.
The discharge end of sludge inlet piping shall be separated from the overflow of the supernatant
liquor withdrawal point by a minimum distance equal to the radius of the digester tank. Every
digester shall be provided with an overflow. A means shall be provided by which the level can be
varied from which supernatant liquor is withdrawn either automatically or by the operator. If this
means is by withdrawal of pipes at different levels in the digester, at least three different levels
of supernatant liquor withdrawal shall be provided. All supernatant liquor withdrawal systems
shall be provided with sampling cocks or other means of inspecting and testing the supernatant
liquor from each level. Piping for hot water heating systems may be of any size adequate for the
flow. The fresh water supply to hot water heating systems shall be from a tank with an air gap
between the top of the tank and the fresh water supply pipe to prevent a cross connection
between the digester hot water system and the fresh water supply system.
Supernatant liquor from anaerobic digesters may be treated by chemical means or other
acceptable methods before being returned to the plant.
13.4 Incineration and heat treatment
The equipment shall be housed in a fireproof building. Adequate facilities shall be provided for
storage of sludge during the longest period that drying and or incineration units might normally
be out of service for repairs or maintenance. Plans for control of odors, insects, fly ash, and for
adequate facilities for the disposal of dried sludge or ash shall be provided.
13.5 Dewatering
Sludge shall be dewatered sufficiently to meet the requirements of the ultimate form of disposal.
As part of the biosolids handling and disposal process, the dewatering facility will also require
the construction of a cake receiving and transfer facility to enable the hauling of the cake to
landfill site or to the incinerator.

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13.5.1 Sludge drying beds
The area of sludge drying beds to be provided will vary in accordance with the average rainfall,
average humidity, and type of treatment process used. The required area for aerobic sludge
dewatering shall be determined from using a waste load based on sewage strength and the daily
average flow of the raw sewage. Because of the rainy season, provisions shall be made in the
design of beds for covering the beds, means of accelerated dewatering, or extra storage capacity
and alternate dewatering methods to effectively dewater the sludge during inclement weather.
At least two sludge drying beds shall be provided and they shall be constructed at elevations
above groundwater level. Construction shall be such as to exclude surface water runoff from the
beds and seepage from the beds into the ground. Channels shall be of sufficient grade and size to
facilitate the flow of the sludge to the various beds. Runners should be provided to facilitate
sludge handling.
The filtrate (or drainage) from the sludge drying beds shall be returned to the head of the
treatment works or to the aeration system.
A splash block or slab shall be provided at the point where digested sludge is discharged onto
each of the beds. Appropriate means shall be provided to facilitate the removal of the dried
sludge from the beds for disposal without bed damage resulting. Every sludge drying bed should
include a removal gate or stop planks on one end to provide access for machinery and trucks to
remove and haul away the dried sludge. A minimum depth of 300 mm of filtering material, of
which 100 to 150 mm is coarse sand, is required. To exclude surface water and eroded earth, the
bed shall be protected by a permanent wall which shall extend at least 300 mm but not more than
600 mm above the finished surface of the beds.
13.5.2 Vacuum filters, belt filters, belt filter presses, and other mechanical
dewatering filters
Where dewatering of sludge is proposed, the design engineer shall provide data to document
sufficient capacity, alternate disposal means, or storage facilities capable of maintaining normal
daily operations during breakdowns, upsets, etc.
The filtrate from the filters shall be returned to the head of the treatment works or to the aeration
system. Consideration shall be given to the impact of the returned filtrate on the treatment units
and to provide odor and insect control facilities.
If sludge is to be treated using portable mechanical dewatering units, provisions shall be made in
the facility plan or preliminary engineering report for the location and connection of the portable
dewatering unit(s) during facility operation.

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Section 14 Architectural Standards
14.1 General
These design criteria are minimum guidelines and establish the recommend WASA’s design
standards. Architectural design criteria are to allow Water and Wastewater infrastructure
facilities to be:
1. Energy efficient;
2. Have minimal maintenance requirements; and
3. To withstand vandalism
4. Is conforming to requirements specified in the Occupation Safety and Health Act (OSHA).
5. Allocate sufficient space for hygiene and safety, and provision for fire
6. Be able to withstand hurricane/earthquake for the region.
In all cases, designs must comply with the architectural code of practice and Trinidad & Tobago
Small Building Code.
14.2 Laboratory control
Laboratory capability for operational control and testing shall be provided. The laboratory should
be located on ground level and easily accessible to the treatment plant and sampling points. The
laboratory should be located away from vibrating machinery or equipment which could have an
adverse effect on the performance of the operation of laboratory instruments. The extent of the
equipment to be provided and the specific tests to be performed will vary according to the
capacity and type of plant.
The needs of male and female employees, the handicapped, and visitors to the plant, should be
considered in the design of sanitary facilities. Hand washing facilities should be provided for the
protection of operating personnel.
Appropriate facilities should be provided for the storage of tools and spare parts, and a workshop
should be provided to allow repairs and maintenance.
Upon completion of the treatment plant, the grounds should be properly graded for surface
drainage. Asphalt, concrete, gravel, or shell walkways should be provided for access to all
treatment units and to the final sampling point.
14.3 Roofing Design
Roofs are to be designed to complement the surrounding environment.
Consultants shall design the roofing architectural treatment and where the choice of roofing
material is clay roofing tiles, pre-painted aluminium or steel roofing tiles, these shall be included

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as part of the conventional roofing construction works to be installed by experienced roofing
contractors.
The installation of the engineered roofing system shall be performed by applicators approved by
WASA and the Consultants and are to be specified in the tender Specifications.
14.4 Windows
Where possible, design plants with a minimal number of windows on the ground floor level
unless they are located on a secured site. For pumping stations or other such facilities, minimize
the number of windows and where possible, avoid windows altogether. As much as possible,
consider aluminium windows with anodic (clear or colored) or epoxy finishes.
14.5 Doors
All exterior doors shall be insulated metal doors complete with touch-bar devices and concealed
vertical rod devices.
The minimum width of all doors shall be equal to or greater than 900 mm and shall be provided
with a minimum of four hinges.
All exterior doors shall be provided with extra heavy-duty closer mechanism.
All exterior doors shall be keyed to WASA’s master key lock system, where applicable.
14.6 Ceiling
Where ceilings are specified, provide drop-in ceiling tiles having high sound-transmission
resistance characteristics selected for the use intended.
Ceiling tiles shall be washable matte white finish with light reflectance of LR-1 (over 75%).
14.7 Wall Finishes
Interior and exterior walls shall be provided with the following finishes:
1. All exterior exposed concrete walls shall be given a sack rub finish and comply with the
required wall finish schedule.
2. All interior walls shall be architecturally co-ordinated to provide a level of finish for the use
or service intended.
3. For bathrooms and washrooms, provide ceramic tile finishes on the wall not exceeding 1,800
mm in height.
14.8 Floor Finishes
Floors are to be finished in accordance with the following usage criteria:
1. Office floor finishes shall be finished with industrial grade carpet material.

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2. Laboratories, computer control rooms, lunchrooms and others for general use shall be
provided with ceramic tile floor finishes.
3. Concrete floors that are subjected to a continuous flow of dirty water shall be given an epoxy
finish with anti-slip additive. All other concrete floors shall be provided with non-coloured
floor concrete hardener complete with floor sealer.
4. Exposed formed concrete walls shall be provided with a “sack rub”.
5. All other formed concrete finishes shall be at the discretion of the Consultants.
14.9 Light Fixtures
Mercury vapour light fixtures shall not be specified unless the lighting requirement makes it
absolutely necessary. In all lighting requirements, florescence light fixtures are preferable.
Locate ceiling light fixtures in readily accessible locations for maintenance, but of a model that
sustains vandalism. Do not locate fixtures directly over tall equipment such as a chemical tank or
in the middle of open tank’s ceiling such as a water filtration basin. Location shall be selected to
provide (a) the required illumination intensity level in accordance with current legislation and (b)
easy accessibility for changing of light fixtures. Fixtures may be located on walls to provide the
required illumination intensity level and for maintenance accessibility.
For light fixtures that must be located in very high ceilings, provide access for servicing by crane
or other practical alternate means of accessibility.
Provide with several sodium vapour dusk external lights to avoid vandalism.
14.10 Landscaping
Design landscape requiring minimal maintenance work to meet the regional Site Plan Approval
requirements. Specify only native plant or tree species in Trinidad & Tobago for landscaping
design, which requires minimal watering.
Sod shall be provided only to areas, which are required immediately for the proper functioning of
the plant. All other areas shall be seeded and mulched.
Landscaping shall be designed with minimum maintenance requirements such as watering or
mowing of grass.
Exterior of building is to be fenced with 2.1 m high steel wire wall with razor wire. Double
swing gates are to be installed with an adequate locking device.
Vehicular access to pump stations shall have a minimum five meter wide paved road at a 15
percent maximum slope, unless otherwise approved by WASA. Site layout of the pump station
shall take into consideration vehicle access. Provisions shall be made for adequate turning radius
and room for outriggers for WASA’s equipment, such as dump trucks, backhoes, and crane
trucks required for the removal of equipment.The need for surveillance camera and alarms shall
be assessed for each site.

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Section 15 Structural Standards
15.1 General
Comply with applicable Acts, Codes or Design Guidelines as detailed in Section 3.0 – Design
Standards.
For all non-water retaining structures, design structures in accordance with Ultimate Strength
Design (USD). For water retaining structures, design structures in accordance with Working
Stress Design.
Designs must assure that the structures are to sustain regional earthquakes and hurricane events.
15.2 Design of Water Retaining Structure
Water retaining structure shall be designed with consideration for crack control design. A
reference is ACI-350R-89, “Concrete Sanitary Engineering Structures”.
Design walls as propped cantilevers, permitting any combination of internal and external load
(such as reservoir full, without backfill and vice-versa), thus transferring loading to roof slab and
reducing wall thickness and the need for internal wall support struts. Design reservoir perimeter
wall with reduced water depth.
Design an efficient structure to minimize the number of internal columns. For cast in place
reservoir’s roof, design capital integral with column.
Ground storage reservoirs shall be designed with a minimum of two or more cells. Each cell
must be capable of being isolated for inspection and maintenance purposes without affecting the
operation of the other cell(s). Where possible, design entry into reservoir cells through submarine
hatches. Each cell shall be provided with a minimum of two entry/exit points.
15.3 Construction Requirements
Interior surfaces of new concrete structures shall be smooth and Consultants shall specify the
application of the available formwork liner manufactured or available in Trinidad & Tobago.
Consultants shall specify wet curing period requirements for a minimum of 7 days.
The seismic design of civil structures will be based on an earthquake zone 3 as defined in UBC-
1997. Should it be required by the Client, seismic calculations may be based on another
earthquake zone.
15.4 Structural requirements
15.4.1 Concrete
Portland Cement shall comply with ASTM C150. The following types of Portland cement shall
be used:

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- Type I Ordinary Portland Cement for all superstructures (above grade works).
- Type V Sulfate Resisting Cement for all sub-structures (below grade works).
The minimum strength requirements, based on 28 days compressive strength as determined by
tests on concrete cylinders according to ASTM, are as follows:
Minimum Strength Requirements for Concrete
Type of Construction
Concrete
Strength
(N/mm2
)
PSI
Unreinforced Concrete, Lean Concrete 10 1,450
Encasement, Duct Banks, Cast in Place
Concrete Curbs
25
3,600
Superstructures 35 5,000
Sub-structures 35 5,000
Waterproofing shall be applied to all concrete surfaces in contact with soil or liquids.
For hot weather concreting, Consultants must ensure that specifications include provisions for
procedures in conformance with American Concrete Institute (ACI) Recommended Practice 305,
Hot-Weather Concreting.
Do not use brackish water or seawater in any connection with masonry construction.
15.4.2 Steel Reinforcement
Materials for structural steel shall comply with International Standards
a) Reinforcement bars shall be deformed, new steel bars complying with the
“Specifications for Billet Steel Bars for Concrete Reinforcement”: ASTM A615
Grade 60 or approved equal, with a minimum yield strength of fy = 400 MPa (60ksi).
b) Sizes shall be as shown on the drawings. Bars shall be free of flaking rust, scale,
grease or coatings of any character that would tend to reduce or destroy their bond
with concrete.
c) Welded plain wire reinforcement shall comply with “Specifications for Steel Welded
Wire Reinforcement, Plain, for Concrete” (ASTM A185) or approved equal with wire
mesh sizes as shown on the drawings.
15.4.3 Precast Structural Concrete
1) Comply with the following codes, specifications and standards.

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1. American Concrete Institute (ACI) – 318 - Code requirements for reinforced
concrete
ACI - 301 - Specifications for standard concrete for buildings
2. Precast/Prestressed Concrete Institute (PCI) MNL 120 – Design Handbook
PCI MNL 122 – Architectural Precast Concrete
3. ASTM Specifications
C33 – Concrete Aggregates
C150 – Portland Cement
A615 – Deformed and Plain Steel Bars for Reinforcement
2) Fabricate all precast units in a precasting plant designated by WASA and certified by
the P.C.I.
3) Erect units without damage to shape or finish, level, plant and within design tolerances.
15.4.4 Structural Steel
The use of structural steel in a tropical environment requires painting exposed structural steel for
interior uses. For exterior uses, consider high-strength, low-alloy steel with epoxy paint or
elastomeric systems. As much as possible, avoid exterior bolted connections.
Where fasteners are exposed to the weather, specify galvanized or other corrosion resistant
metals.
1) Structural Steel shall conform with international standards and with the following ASTM
standards:
1. ASTM A369 A36M – Specifications for Structural Steel
2. ASTM – A193A & 193M – Specifications for Alloy-Steel and Stainless Steel
for Bolting Material for High temperature Service
3. ASTM – A307, A325 & A490 – Specifications for Structural Steel Bolts and
Bolted Joints.
2) Steel Structures shall be designed in accordance with ASTM A36 to resist forces,
moments and shears.
3) Steel structures shall be fabricated in accordance with ASTM A36 and reviewed shop
drawings. Welding must be done by a shop certified for both shop and field structural
welding.
4) Quality control: - Inspection and testing of materials and workmanship will be carried out
by a testing company designated by the WASA.

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15.4.5 Steel protection
All materials mentioned below shall be hot dip galvanized as follows:
a) Grating: Galvanized ASTM A569 or equivalent.
b) Checkered Plate: ASTM A36 or equivalent.
c) Handrail: ASTM A53 or equivalent.
d) Kick Plates: ASTM A36 or equivalent.
e) Stairs and Ladders: ASTM A36 or equivalent.
If surface is to be exposed to direct saline weather, reinforced steel shall be covered by a
minimum of 75 mm of concrete.
Reinforcing steel may be epoxy coated for tropical construction to reduce corrosion damage
in land based concrete construction.
15.4.6 Concrete Block Masonry (C.B.M.)
1) Block masonry shall conform with international standards and with the following
standards:
1. ASTM – American Standard for Testing Materials
1. ASTM C90 – Specifications for Load Bearing Concrete Masonry Units
2. ASTM C129 – Specifications for Non-Load Bearing Concrete Masonry Units
3. ASTM C270 – Specifications for Mortar for Unit Masonry
4. ASTM C476 – Specifications for Grout for Masonry
2) Masonry construction shall conform to ASTM standards for load and non load bearing
masonry units and for mortar and grout.
3) Reinforcing steel used in masonry construction should conform to the same specifications
as for concrete work – (see 1.4.2). Use grout to ASTM C476 where reinforcing steel is
grouted in the cavities in the block walls.
4) Quality control: - Inspection and testing of materials and workmanship shall be carried
out by a testing company designated by WASA.

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Section 16 Electrical Standards
16.1 General
All designs must comply with the electrical code of practice TTS 171: Parts 1 & 2: 2002 of
Trinidad & Tobago and the National Electrical Code of USA. Comply with applicable Acts,
Codes or Design Guidelines as detailed in Section 3.0, Design Standards.
All materials and equipment supplied shall be suitable for being delivered, stored and operated
under tropical conditions of high temperature, high humidity, heavy rainfall, mildew and fungus
conductive environments.
16.2 Equipment Identification Nameplates Requirements
Identify electrical equipment with lamicoid nameplates, 3 mm thick plastic engraving sheet,
white face, black core, and mechanically attached to the equipment with self tapping screws. Self
adhesive nameplates are not permitted. Use rivets and/or nut & bolts to fasten nameplates to the
equipment where access is not available.
The general requirements and characteristics of nameplate shall be as follows:
1. Size of nameplate shall be as follows:
NAMEPLATE SIZES
Size 1 10 x 50 mm 1 line 3 mm high letters
Size 2 12 x 70 mm 1 line 5 mm high letters
Size 3 12 x 70 mm 2 lines 3 mm high letters
Size 4 20 x 90 mm 1 line 8 mm high letters
Size 5 20 x 90 mm 2 lines 5 mm high letters
Size 6 25 x 100 mm 1 line 12 mm high letters
Size 7 25 x 100 mm 2 lines 6 mm high letters
2. In general, the Consultants shall allow for an average of twenty-five (25) letters per
nameplate.
3. Nameplates for terminal cabinets and junction boxes are to indicate system and/or voltage
characteristics.
4. Nameplates for disconnected switches, starters and contactors shall indicate the equipment
being controlled and the operating voltage and shall be mounted externally on switch box
cover. Typical identification – “Pump No. 1, 400 V, 3 phase”. Plates shall be installed and
secured with self-tapping screws except on the inside of panel doors where gluing will be
permitted.
5. Nameplates for terminal cabinets and pull boxes shall indicate system and operating voltage.

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6. Nameplates for transformers shall indicate capacity, primary and secondary voltages, tap
range and steps, % impedance and vector group.
16.3 Wiring Identification
Identify all wiring with permanent indelible identifying markings, either numbered or coloured
plastic tapes, on both ends of phase conductors of feeders and branch circuit wiring. Maintain
phase sequenceing and colour coding throughout.
Control wiring to have identical tags at both ends.
16.4 Panel Boards
For all new or replacement panel boards, all pertinent information including the voltage,
amperage, and minimum system short circuit rating shall be specified on a one-line diagram.
New panel boards shall contain minimum 20% spare circuit breakers. Provide 20% future
branch circuit breaker bussed spaces and choose the standard size manufactured panel board.
Main circuit breakers shall be provided for all panel boards which are not located in the same
room as their feeder, disconnect or breaker. Adequate ventilation/cooling shall be provided for
closets to avoid heat and corrosion. Avoid ferrous metal enclosures and boxes when exposed to
salt-laden air.
16.5 Seismic braces
Seismic braces shall be installed on all electric service cabinets and other freestanding equipment
per Code requirements. Details of the seismic braces shall be included in the design drawings.
16.6 High Efficiency Electrical Motor
All electric motors greater than 7.5 kW shall be high efficiency motors. For motors greater than
90 kW, the minimum efficiency shall not be less than 94% at the specified operating point.
However, the final determination shall be made based on life cycle costing analysis
16.7 Motor Control Centre
The Motor Control Centres (MCC) and all components shall be designed, manufactured and
tested in accordance with the latest applicable standards of EN 60439 as well as applicable
NEMA, NEC & UL Standards. The panels shall have individual lines and control leads brought
to terminal boards suitably located in each starter. The complete panels shall have adequate
ventilation to limit the internal temperature rise to 55°C. There shall be a continuous ground bus
with accessible external connection for bonding to the station ground. All necessary control
transformers, switches, indicating lights, wiring, fuses, interlocks, terminal boards, etc. shall be
provided to suit the power and control requirements. All indicating light lamps shall be long life
LED type. The MCC shall be complete with a neutral assembly to receive the grounded wye
secondary conductor from the transformer. All compartmentalized vertical sections shall be
provided with common power bus-bars. Each vertical section of the MCC to be designed to
permit ready removal or addition of motor starters and control units as required. MCC shall be

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floor mounting, freestanding, dead front, completely enclosed control assembly and
accommodating front mounting combination starters and circuit breakers.
All motor starters shall be equipped to provide under-voltage release and overload protection on
all three phases. Motor starter coil and contacts shall be easily replaceable without removing the
motor starter from its mounted position or without the removal of the phase conductors. Fuses
shall be provided on the primary and secondary sides of the control power transformers and
separate power control transformers for each motor starter.
It is recommended that all switchboards and motor control centers be installed in enclosed
buildings.
16.8 Transformers
Consultant to review the project load profile and select transformers to obtain peak loading
between 60-80%. Adequate ventilation/cooling shall be provided for transformers enclosed in
closets.
16.8.1 High Efficiency Transformers
High efficiency transformers shall be investigated; there is a potential benefit under the energy
conservation programs. In order to qualify, each transformer bid must be evaluated based on the
total life cycle cost.
16.8.2 Distribution Transformers
Distribution transformers for lighting and convenience loads shall be 3-phase, 115/230 V
secondary. Distribution transformers shall be suitable for installation in the selected location.
16.9 Co-ordination Studies of Protective Devices
16.9.1 Co-ordination Studies of Protective Devices Report
The study report shall be presented in tables and on composite charts and shall include but not be
limited to the following:
1. Maximum available short circuit current of systems.
2. Maximum available ground fault current of systems.
3. Feeder cables thermal short circuit damage curve.
4. Primary fuse to power the transformer.
5. Power transformer thermal short circuit damage curve, 3 phase, phase to ground.
6. Main secondary 400 volt system circuit breakers.
7. Largest 400 volt moulded case distribution breaker and characteristics.
8. Largest distribution transformer thermal short circuit damage curve.
9. Maximum available fault current, 3 phase and phase to ground for the 400 volt system.

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10. Main 230 volt breaker and characteristics.
11. Largest 230 volt distribution breaker and characteristics.
12. Maximum available fault currents, 3 phase and phase-to-ground for the 230 volt system.
13. Maximum available fault current RMS symmetrical at each panel.
14. Establish the required settings for all ground fault relays.
16.9.2 Short Circuit and Protective Device Evaluation and Co-ordination Study
In the short circuit study, provide:
1. Calculation methods and assumptions, the base per unit quantities selected, single line
diagrams, source impedance data including power company system characteristics, typical
calculations, tabulations of calculation quantities and results, conclusions, and
recommendations.
2. Calculate short circuit interrupting and momentary (when applicable) duties for an assumed
3-phase bolted fault at each supply switchgear line up, unit substation primary and secondary
terminals, low-voltage switchgear line up, switchboard, motor control centre, distribution
panel board, pertinent branch circuit panel board, and other significant locations throughout
the system.
3. Provide a ground fault current study for the same system areas, including the associated zero
sequence impedance data. Include in tabulations fault impedance, X to R ratios, asymmetry
factors, motor contribution, short circuit kVA, and symmetrical and asymmetrical fault
currents.
4. The short circuit study shall be performed with the aid of a digital computer program and
shall be in accordance with the latest applicable IEEE and ANSI standards.
16.9.3 Protective Device Co-ordination Study
In the protective device co-ordination study, provide:
1. Time-current curves graphically indicating the co-ordination proposed for the system,
centred on conventional, full-size, log-log forms. Include with each curve sheet a complete
title and one-line diagram with legend identifying the specific portion of the system covered
by that particular curve sheet.
2. Include a detailed description of each protective device identifying its type, function,
manufacturer, and time-current characteristics.
3. Tabulate recommended device tap, time dial, pickup, instantaneous, and time delay settings.
4. Include on the curve sheets power company relay and fuse characteristics, system medium
voltage equipment relay and fuse characteristics, low voltage equipment circuit breaker trip
device characteristics, pertinent transformer characteristics, pertinent motor and generator
characteristics, and characteristics of other system load protective devices.
5. Include at least all devices down to largest branch circuit and largest feeder circuit breaker in
each motor control centre, and main breaker in branch panel boards.

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6. Include all adjustable settings for ground fault protective devices.
7. Include manufacturing tolerance and damage bands in plotted fuse characteristics.
8. Separate medium voltage relay characteristic curves from curves for other devices by a least
0.4 second time margin.
9. When emergency generator is provided, include phase and ground co-ordination of the
generator protective devices. Show the generator decrement curve and damage curve along
with the operating characteristic of the protective devices. Obtain the information from the
generator manufacturer and include the generator actual impedance value, time constants and
current boost data in the study. Do not use typical values for the generator.
10. For motor control circuits, show the MCC full load current plus symmetrical and
asymmetrical of the largest motor starting current and time to ensure protective devices will
not trip during major or group start operation.
16.9.4 Power System Study Report
The results of the power system study shall be summarized in a final report and shall include the
following sections:
1. Description, purpose, basis and scope of the study.
2. Tabulations of circuit breaker, fuse and other protective devices ratings versus calculated
short circuit duties, and commentary, and commentary regarding same.
3. Tabulations of all protection and configuration settings for each microprocessor based
protection relays including multifunction protection relays for branch feeders and motor
protection relays.
4. Protective device time versus current co-ordination curves, tabulations of relay and circuit
breaker trip settings, fuse selection, and commentary regarding same.
5. Fault current calculations including a definition of terms and guide for interpretation of
computer printout.
16.9.5 Insulation Resistance Tests
Insulation resistance tests shall be performed for all wiring and equipment installed. Insulation
resistance tests shall be performed with a 500V megger instrument for equipment up to 350V
and with 1000V megger for 350-600V circuits and recorded in log book for reference. Lighting
and power circuit feeders shall be meggered and the insulation resistance between live parts and
ground shall not be less than that specified in the Trinidad & Tobago regulations.
16.9.6 Lamps
16.9.6.1 Fluorescent lamps
Fluorescent lamps shall be T-8 4100°K, 2900 (initial) lumens 75 CRI and unless otherwise
specified, shall be rapid start and life rated at 20,000 hours (average).

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Lamps shall be provided with single or multi-lamp ballasts, approved for the type, voltage and
rating of lamp, also for the operating and starting temperature of the ballasts. Unless otherwise
indicated, ballasts shall be integrally mounted with the fixture housing and thus approved for the
enclosure and ventilation. Ballasts separately mounted shall be accessible, spaced and located to
enclosure proper temperature conditions. Ballasts capacitors shall not contain PCB’s.
Fluorescent ballasts shall be rapid start electronic energy conserving, high power factor, low
harmonic distortion and shall be approved for use with T8 fluorescent lamps.
16.9.6.2 Emergency Lighting
Emergency lighting shall be battery operated units and heads.
Each battery unit shall be a sealed lead acid type, long life cells in plastic cases and ten (10) year
design life. They shall be 24 volt with indicated capacity for one (1) hour (to 91% voltage)
operation and shall be in a standard shelf mounted cabinet, and have integrally mounted 24 volt
sealed beam or quality halogen lamps, as indicated on drawings.
Each battery unit shall have an integral charger which shall be fully automatic, solid state,
high/low rate with indicating and pilot light, load transfer, meters, test switch, overload and low
voltage protection and A.C. 230 volt line cord and plug. A D.C. fused block shall be provided for
load circuits together with conduit entry.

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Section 17 Instrumentation & Control
17.1 General
Conform to the design standard as stipulated herein to ensure that the design of all
instrumentation and control systems are uniform and consistent for seamless integration to
existing system.
The main instrumentation and control components shall be interconnected to establish a
complete control hierarchy.
All materials and equipment supplied shall be suitable for being delivered, stored and operated
under tropical conditions of high temperature, high humidity, heavy rainfall, mildew and fungus
conductive environment.
17.2 Local Control Switch
All equipment shall be provided with a local control switch with LOCAL-REMOTE positions.
The LOCAL position overrides all other control modes including PLANT. When in the LOCAL
position, the equipment is activated based on START/STOP pushbuttons. When in the REMOTE
position, the equipment is controlled in either MANUAL or AUTO mode from the PLANT level.
When in the AUTO mode - PLANT, the equipment is controlled by the programmable logic
controller/remote processing unit (PLC/RPU) or is connected directly (hardwired) to the circuit
of another piece of equipment. If controlled through the PLC/RPU, the equipment can be
controlled in MANUAL mode through the Human Machine Interface (HMI), or it can be
operated in AUTO mode using the control program in the PLC/RPU. As a general rule, the
closer the control switch is to the equipment, the higher its precedence to control the equipment.
17.3 Instrumentation & Control General Information
The main components of the Instrumentation & Control systems are listed below:
1. Local Control Panels (for equipment control and monitoring).
2. Junction boxes and interface cabinets as required.
3. All field instruments, and the installation, testing and commissioning of these instruments.
4. Fire Alarm System.
5. Security System.
6. Connection of common alarms and status signals from VAC and other process area to the
Local Control Panel for connections into the PLC/RPU, and the SCADA system.
A detailed engineering specification of all major components, and all associated instrumentation
for each process area shall be included as part of the engineering assignment.

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The engineering will include detailed drawings showing connection of the instruments and
equipment status signals into a Local Control Panel, which will also act as a termination cabinet
for all input and output signals to and from the PLC/RPU dedicated to the process area. The
signals will connect to the SCADA system through the PLC/RPU.
Control actions and the philosophy for control of the process will be defined by means of Process
& Instrument Diagrams (P&IDs) and control narratives. These will be reviewed for conformity
with the guidelines and will form as a part of the documentation package.
A review of the SCADA system and the software implementation of the process design
requirements will be undertaken and include as a minimum, the following items:
1. Drawing/Specifications review
2. Factory or office simulation acceptance tests (FAT)
3. On-site functional acceptance tests (SAT)
17.4 Design of I&C System
17.4.1 Design Criteria
The PLC/RPU shall only control equipment associated with the local area of the process, but
may provide limited status monitoring of other associated areas. This device will connect all
field devices, i.e. pumps, valves, flow meters, switches, etc. to the SCADA system. It shall be
provided with a display and keyboard, which provides all recorder, indicator, totalizer,
annunciator, controller, and manual switches, required for full monitoring and controlling of the
process area. The display may be an HMI workstation, depending on the system architecture
design.
All automatic control shall be achieved by auto-programs in the PLC/RPU. The control hierarchy
shall define how the field equipment, PLC/RPU and SCADA workstations are interrelated to
provide a complete process control system. Process control systems shall include varying levels
of hardwired and software interlocks to ensure safety of the personnel as well as the automatic
control systems and its interlocks inputs into the PLC/RPU. Normal operation shall be in AUTO
mode, and the PLC/RPU programming will ensure fail-safe conditions result, as defined during
the design stage, in the event of equipment or instrumentation failure. In MANUAL modes of
control, the same equipment and safety interlocks will still apply (when hardwired), but operator
action will be required to initiate equipment control.
17.4.2 Interlocks
In LOCAL control from the Local Control Panel, the PLC/RPU software interlocks shall no
longer be functional. Any personnel or equipment safety interlocks must be protected by means
of hardwired interlocks, which will interrupt operation of the equipment until the condition is
reset in the field. The following interlocks are possible hardwired protective interlocks and
several of these are intrinsic to the design of motor control systems and each system must be
evaluated on an individual basis. In several instances, software interlocks are sufficient to
provide adequate protection.

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Hardwired protective interlocks shall be provided in accordance with the following table:
Interlock Application
Pressure Protection of piping, valves, pumps from high pressures (pipe
blockages, closed valves, etc.); and
Low pressure protection for run out conditions
Temperature High temperature protection against overheating (motors, pumps,
etc.).
Level Low level cutouts of pumps; and,
High level overflow protection (chemical tanks, reservoirs, etc.).
Flow No flow conditions - running pumps dry.
Vibration/Motion Damage to motor/pump/piping from excessive vibration.
Torque Valves - end of travel protection; and,
Pump shafts.
Current Motor overcurrent protection.
Voltage Motor over/undervoltage protection.
Prime/Seal Pump protection.
Limit Pump/valve operation in combination (pump discharge valves).
Gas Detection Personnel protection against hazardous and/or explosive gases and
lack of oxygen.
17.4.3 Field Instrument
The PLC/RPU panel shall be located as required by the system architecture design, and the
configuration of the facility.
Field instruments shall be standardized to a minimal acceptable number of different vendor’s
equipment to minimize the stocking of different spare parts for water and wastewater treatment
plants. During preliminary and detailed design, the PIU will review the tender documents of the
specified instruments and models.
Field instrument enclosures shall be rated in accordance with the hazardous area classification
assigned to the area.
All instruments mounted outdoors shall be in weather tight enclosures and should be suitable for
operating temperatures from 0 to +50 deg. C.
All instruments mounted outdoors shall be provided with hoods formed by three sides and a
sloping roof, to provide protection against sun, and rain. Those with viewing dials, or that require
access for routine calibration, shall be provided with tip-up type hoods.
All instruments shall be provided with isolation devices.
Valves must be installed on all instrument lines to allow for its removal without disruption to the
process. Electrical switches must be located near the equipment to allow for isolation while
servicing or installing instruments.

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Local indicators shall be provided for all transmitters. Where manual operation of valves or other
equipment is required, based on a transmitter signal value, the indicator shall be located adjacent
to the valve or equipment local control panel.
17.4.4 Indicators
Indicators shall be provided with the following characteristics:
1. Local indicators shall read as follows:
.1 Temperature – direct reading in °C
.2 Level – 0-100 uniform as % of calibrated range
.3 Flow – direct reading in m3
/hr
.4 Pressure – direct reading in bars or metres
2. Unless specified otherwise, or required due to process conditions, calibrated instrument
ranges shall be selected such that the normal operating value will be between 50 and 75
percent of scale, taking into account both minimum and maximum values.
3. Dedicated or conventional analogue panel instruments such as chart recorders or indicators
are not required unless specifically stipulated.
4. Nameplates carrying instrument/equipment numbers and services shall be provided for all
equipment requiring manual operation (located locally at the equipment controls). Field
mounted instruments generally require an identification number only.
17.4.5 Instrumentation Loops (Analogue)
All instrumentation loops shall be designed to conform to the following requirements:
1. All analogue instrumentation loops shall be 4-20 mA current loops (and 2 wire wherever
possible). There shall be no dedicated or conventional analogue panel instruments such as
chart recorders or indicators unless specifically stipulated. In cases where existing 0-10Vdc
or other signals exist, incorporate these instruments into the PLC/RPU.
2. DC power supplies within the Local Control Panel shall be provided with power to the
transmitters via fused terminal blocks or mini-circuit breakers.
3. The signal cables should be shielded twisted pairs and should run through metal conduit,
which is not located in close proximity to high voltage power cables. The shields should be
terminated and grounded to a dedicated instrument ground bar at the Local Control Panel end
only.
4. Where field instruments such as analyzers require a 230V AC power supply, this must be run
in separate conduit from the signal cables. The output of the transmitter should be 4-20 mA,
and must be electrically isolated from the power supply.
17.4.6 Control Circuits
All control circuits shall be designed to conform to the following requirements:

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1. Control circuits shall use normally open push-buttons and avoid the use of switches to
simplify the interface to the PLC/RPU. The PLC/RPU shall use momentary contacts instead
of maintained ones in order to provide smooth bump less transfers without using tracking
software.
2. Where maintained contacts must be used, provide tracking software in the PLC/RPU to allow
bump less transfers from local to computer control. The use of mercury switches for such
purposes, or for any other purposes, is not permissible in the water and wastewater treatment
plants.
3. All equipment controlled by the PLC/RPU must be evaluated as to whether it is required to
stop, or to continue running in the event of a PLC/RPU failure.
4. The PLC/RPU tracking software shall provide smooth transfers by ensuring that the output of
the PLC/RPU reflects the condition of the field equipment status. Regardless of the mode of
control, the PLC/RPU must be programmed to track all operator-initiated actions and adjust
its output accordingly.
5. For PLC/RPU outputs that have electronic devices rather than mechanical relays, the output
shall be in the “normally closed” status when the PLC/RPU is energised. Provide an
interposing relay to maintain contact. These interposing relays shall be provided and installed
in the Local Control Panel.
6. Status inputs from equipment, Local Control Panel LED’s and in general, all digital inputs to
the PLC/RPU will be DC (nominal 24V DC) sourced from a power supply in the Local
Control Panel or PLC/RPU cabinet.
7. Start, stop commands and in general, all digital output signals from the PLC/RPU will be
230V AC. This 230V AC shall be “sourced” from the equipment starter (MCC).
17.4.7 Automation of Treatment Process
In determining which process should be automated, the following factors should be taken into
account. It is not necessary for all processes to be automated as this increases capital cost
considerably without any real benefit.
1. Automation, when the process is under PLANT control, refers to the use of events, timing
intervals or other trigger actions to affect control output to field devices in response to
process changes.
2. Complete hardwired automatic control systems shall be implemented where it is deemed that
the process is critical to the facility operation, and where the manual operation of such a
process is not feasible for prolonged periods of time.
3. When LOCAL (at the equipment) control is required (maintenance, or operational mode
changes due to equipment failure) automation in this context refers to provision of
electrically powered actuators instead of hand wheels, push-button operation of multiple
solenoid routing valves instead of numerous levers, etc.
4. Provide automatic control for equipment that is operated on a frequent basis. (Initial plant
start-up and commissioning modes should be considered here.)

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5. Equipment used infrequently should not be automated but shall be provided with full manual
control unless stipulated otherwise.
6. Where the increased downtime required by a manual changeover is not important, and the
level of the manual operation required is not significant, do not implement automation.
7. For manually operated valves whose position is required to be known by the SCADA system,
position indications via limit switches shall be provided.
8. Where motorized valves are installed, the valve position (limit switches) and its service status
(local/remote) is required. For control of manual valves from the PLC/RPU in future
automatic programs, provide control wiring from the manual valve to the Local Control
Panel or PLC/RPU cabinet at the time of construction.
9. The PLC/RPU shall monitor the number of starts per hour and should the number of starts
exceed the setting of the program an alarm shall be generated. Should the equipment fail to
start after three consecutive attempts, the control system shall inhibit any further attempts to
start the piece of equipment. An alarm shall be generated and indicated at the SCADA
workstations.
10. The PLC/RPU shall monitor all equipment and should the equipment fail to stop, the control
system shall generate an alarm immediately, which will be displayed through the SCADA
system.
11. The PLC/RPU shall also monitor:
.1 Equipment fails to open/start or fail to close/stop.
.2 Power Supply loss of phase.
.3 Process parameters and analytical instruments.
.4 Uncommanded open/start or close/stop.
.5 Equipment status, field alarm conditions, etc.
.6 The control system shall generate an alarm immediately through the SCADA system.
17.4.8 Variable Frequency Drive (VFD) Control
All VFD’s shall be provided with a digital operator control module for control and indication of
the following:
1. Start/Stop.
2. LOCAL-REMOTE.
3. Manual speed adjustment.
4. Speed indicator 0-100%.
5. Load indicator 0-100%.
6. Run indicator.
7. Power-on indicator.

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For a VFD/motor control system, in the event of a shutdown of the variable frequency drive due
to a fault condition, the drive shall stay shut down until the fault is removed and the drive reset
locally at the starter.
17.4.9 Pump Control Systems for Wastewater Pumping Stations
Standard pump control systems and alarm points connected to the PLC/RPU shall include the
following:
1. Electronic level sensor used to monitor wet well level.
2. Automatic program capable of starting/stopping pumps based on wet well level, cycling
pumps based on starts/runtime, duty control, and alarming.
3. Turn second duty pump on if first duty pump fails to start.
4. Hardwired float control to start/stop pump on PLC failure.
5. LOCAL-REMOTE switch and associated pushbuttons to allow for the pumps to operate in
the event of float control failure and/or maintenance.
17.4.10 PLC/RPU Interface
Terminals, as an interface for all signals between the field equipment and the PLC/RPU, shall be
supplied.
4-20 mA current loops from field transmitters shall be provided with 250 ohm termination
resistors at or within the terminal blocks in the Local Control Panel or PLC/RPU cabinet.
17.4.11 Services
Electrical supplies for the PLC/RPU panel shall be provided. A minimum of three 230V AC, 15
A lighting panel supply, from the same phase, shall be allowed for, and conduit and wiring
installed from the panel to the PLC/RPU cabinet location.
Additional dedicated conduit runs shall be provided from the PLC/RPU cabinet location to the
designated building cable tray or cable access point, for the future installation of communication
cables.
17.4.12 Documentation
Documentation and drawings are to be included as part of the complete Instrumentation &
Control/SCADA package.
Process & Instrument Diagrams (P&ID’s) showing tag numbers of all inputs and outputs. ISA
tag numbers shall be used for PI&D’s, loops to be from assigned blocks.
Loop drawings for analog devices showing clearly the relationship between primary and final
elements, all terminals, wire tags, etc.
Provide process/control narratives in the English language.

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Provide all logic flow diagram of control functions and actions to control process including
normal start-up, normal shut-down, emergency shut-down and alarm scenarios.
Interface wiring definition in tabular format, providing the following information with the
following headings:
1. Instrument/signal identification number.
2. Process function or service.
3. Field contact status to achieve function (for DIs) or analog signal type (4-20 mA).
4. Instrument range and engineering units.
5. Calibrated range.
6. Setting (as required for function – alarm, safety, interlock).
7. DI, DO, AI or AO with respect to PLC/RPU.
8. Local control panel terminal block identification.
9. PLC/RPU cabinet termination point.
10. Software function required (alarm, monitor, control, interlock).
The tabular format shall be produced in a MS-Excel/MS-Access file format.
Local control panel(s) wiring diagrams, showing field and interface terminations.
Dimension layout drawings of local panel(s) with full legend plate and bill of material
information for internal and panel mounted equipment.
Record drawings for all modifications within existing panels or cabinets, showing interface
terminations between old and new equipment.
17.4.13 Preventive Maintenance Program
After the start-up and commissioning of equipment, WASA shall commence the implementation
of a preventive maintenance program. In order to ensure that the preventative maintenance
program is properly carried out, the Consultants shall provide the following information at start-
up and commissioning. Submission of the information in both hard copy and CD-ROM is
required.
1. Equipment and instrumentation list for the specific area.
2. Recommended routine maintenance, alternating and calibrating programs for the above
items.
3. A paperwork system based on simple checklist procedure to monitor the ongoing
maintenance.

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17.4.14 Testing and Commissioning
Testing and commissioning of all plants’ instrumentation and control circuits from the field
instrument up to and including manual control from the Local Control Panel and appropriate
status indication shall be provided.
Pre-delivery inspection and testing of instrumentation and controls for “package” equipment, or
fabricated panels should be performed wherever possible, to minimize site work.
“Testing” includes wiring integrity and setting of field adjustable instruments according to
specifications, and verification of equipment performance against manufacturer’s data sheets by
shop calibration over a minimum of five points (0, 25, 50, 75, and 100%).
“Commissioning” includes operation of equipment using initially simulated interlock and alarm
signals where necessary, to check functionality. It also requires completion of loop checks from
field instruments by simulated or quantifiable process inputs to the terminals in the Local Control
Panel, for interface with the PLC/RPU. These checks may require further calibration of field
instruments.
Commissioning of the process area on LOCAL and PLANT-MANUAL control via the
PLC/RPU, and on AUTO control via the PLC/RPU must be completed.

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Section 18 SCADA System
18.1 General
The use of the SCADA system technology in water and wastewater treatment plants in Trinidad
& Tobago has not been systematic. However, consideration should be given for the inclusion of
such a system in new plants or retrofitting to existing plants when they are expanded or upgraded
in the future. The SCADA system offers the following advantages:
1. Reduces plant energy consumption from process equipment
2. Reduces plant consumption of chemical by monitoring and feedback to the chemical
metering system
3. Monitors personnel safety
4. Monitors plant security
5. Monitors plant effluent and water quality
With confirmation from WASA, Consultants shall apply directives from the following
documents in order of preference:
1- The WASA Masterplan SCADA Workplan SSP2 (Technology and Standards) and
SSP3 (SCADA Project Delivery Procedures).
2- 2005 report by Ixanos Ltd., “WASA SCADA Consolidation Assessment and Design”
3- If specifically indicated as not applicable, the following recommendations (following
sections) shall be applied.
18.2 SCADA Operating Characteristics
The Supervisory, Control and Data Acquisition systems (SCADA) shall be designed to have the
following characteristics:
1. Real-time control and monitoring
2. Storage/retrieval of short and long term historical data
3. Easily expandable for future additions of new sites and interconnection of plants
4. Open architecture systems that will permit future applications or existing applications to
migrate to this environment based on industry standards
The SCADA system has a Graphical User Interface (GUI) environment, which will provide a
Human Machine Interface (HMI) to the operators for real-time control and monitoring of the
facility or system.

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18.3 SCADA System Requirements
The system must be fully capable of real-time control and monitoring of all automated process
operations within the water treatment plant and wastewater treatment plant, in the water
distribution system and wastewater collection system on a continuous basis.
Unless specifically instructed in the Request for Proposal that automation in the facility is not
required, all plant processes with analogue control capacities shall be fully automated through
the SCADA system, including that of the water distribution system and wastewater collection
system.
All automatic processes must also be configured to allow fully manual control of all process
equipment from any workstation within the system.
Water distribution systems shall include all associated pumping stations, reservoirs, zone valve
chambers, pressure reducing chambers and flow monitoring sites.
Wastewater collection systems shall include all pumping stations and flow monitoring sites.
All process standby equipment shall be configured such that it can be operated in a fully
automatic control mode under the PLC/RPU or manually controlled and monitored from the
SCADA workstation(s).
All automatic process control programs shall reside in the PLC/RPU.
The system shall be fully capable of archiving historical data and it must be capable of
generating reports based on historical data as required.
The system architecture must be open and easily expandable to permit future additions as well as
allowing future applications or existing applications to migrate to this environment.
All hardware and software (PLC/RPU programming and HMI application) must be standard off-
the-shelf products requiring no customization of any kind.
18.4 SCADA System Control Levels
The SCADA System, except for the FIELD level, has two distinct levels of control, which are as
follows:
1. PLC
2. PLANT
18.4.1 Field (Local)
The FIELD layer is not identified as a control level, because this level will exist for all
equipment, even those devices not connected to the SCADA system.
The field devices consist of the hardwired interlocks and the emergency stop pushbuttons. This
layer also contains the Local/Remote switch that enables the equipment to be controlled locally
at this level through pushbuttons or remotely in the subsequent levels. This also includes all field
mounted instruments and equipment that directly or indirectly controls the process. They include

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devices/equipment such as air flow measurement instrument, D.O. level transmitters, blowers,
modulating valves, chlorinators, limit switches, metering pumps and so forth.
The information gathered at this level may be transferred to Level 1, where PLCs/RPUs provide
an interface between the field devices and the HMI of the SCADA system.
The Local Control Panel is intended to provide back-up control in the case of failure of the
PLC/RPU at Level 1. From this location, it shall control and monitor selected equipment and
parameters. There will be no automatic control available at this level unless, which is determined
on a case-by-case basis, the process is critical to the operation of the facility, and would be
difficult to operate under changing conditions (see instrumentation and control).
18.4.2 Level 1 – Programmable Logic Controller (PLC)
LEVEL 1 includes the PLC/RPU and all automatic programs shall be configured to reside there.
The REMOTE mode selection is made through the SCADA workstations or an operator interface
at LEVEL 2 (PLANT) of the hierarchy.
They also provide the interface between SCADA, field instruments and equipment.
Equipment supervision and alarm generation are tasks that are done at this level and reported to
the SCADA level. All control, monitoring and alarming resides at this level.
Communication links at this level are generally at the plant level, but may involve remote site
links via telephone lines, or other mediums dependent on the available systems at the sites
involved. Communication between PLCs/RPUs will be selected on a site-by-site basis dependent
upon the needs of the system.
18.4.3 Level 2 – PLANT
At the PLANT level, the Graphic User Interface (GUI) shall provide a Human Machine Interface
(HMI) to the operator for total control of the plant through workstation(s) in PLANT mode of
control. This level of control will have access to all monitored points and data in the plant. In
PLANT mode, the operator will select, through a software switch, either PLT-MAN or PLT-
AUTO modes of control. In the plant manual mode, the operator can start/stop equipment from
the SCADA workstation or operator interface. The plant auto mode will transfer control to the
automatic program residing in the PLC.
Through any workstation, given the correct security clearance, the operators shall be capable of
controlling all equipment through the selection of control modes and setting of set points.
At the PLANT Level, through the HMI, it shall provide all the operating information such as
historical trending, real-time trending and alarm prioritizing. At this level the system generates
reports, logs data, and provides a link to other systems, where required.
18.5 Real-Time Control and Monitoring
The configuration of the SCADA system architecture is to be based on the open distributed
control concept.

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The SCADA system shall be provided with integrated support for a secondary server to take over
data collection in the event of a failure of the primary server and must be capable of:
1. Automatic failover to secondary server.
2. Run-time point values, statuses and alarm are synchronised on both servers.
3. There must be no duplication in configuration.
4. Configuration provides for automatic update of secondary computer when the primary
computer is updated.
5. Start/stop both systems from primary server.
6. Merge the two databases on recovery of a failure.
7. Global points are synchronized as are changes to alarm limits and the disabling of alarms.
8. Must automatically alarm when a communication error is detected and the graphic displays
are changed to reflect error.
The Consultants shall provide a two level control hierarchy for all process related equipment.
Regardless of the Terms of Reference, all process related control system shall be of the two
levels of control.
Under LOCAL control, the equipment is controlled by local switches and pushbuttons at the
equipment.
Under PLANT MANUAL control, the equipment is controlled manually through the HMI
system located in the plant/system. All signals from the HMI are transferred to the PLC/RPU
where the appropriate control actions are carried out.
In PLANT AUTO modes of control, the PLC/RPU will be controlling all of the associated
process equipment based on setpoints and process feedback.
All automatic control programs shall be resident in the local PLC/RPU wherever practical for
devices frequently operated.
18.6 Automatic Control
Equipment that is normally frequently operated shall be automated and software interlocks will
be provided in the automatic program to protect equipment and personnel.
Infrequently operated equipment shall be capable of manual operation through the SCADA
System. Safety interlocks shall also be incorporated for all manual operation through the
SCADA system.
For process that is critical to the facility operation and where manual operation of such processes
is not feasible for prolong periods of time, local automatic control system shall be implemented.
This includes both local and compound loop controllers.

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18.7 Minimum Equipment Control Requirements
Pump discharge valves are a function of their respective pumps and do not require on screen
independent control. However, the status of the valve must be shown. If the valve fails to open or
close within the specified time, indicate the valve fail status in a pop up menu.
If the pump discharge valve is in an opened position, the software control logic in the PLC/RPU
must inhibit starting of the motor.
Notwithstanding the above, the motor shall be hard-wired to permit manual start-up at the local
control switch even with the discharged valve in the opened position.
For all equipment that uses a 4-20 ma control system, provide pop-up windows to indicate the
setpoint in AUTO mode. In the MANUAL mode, provide a box on the menu such that a setpoint
can be entered.
Maintain all software protection provided for any equipment in AUTO mode while they are
operated in the MANUAL mode through the HMI. In the event of a transmitter failure, provide
individual override buttons.
All setpoints must be accessible through the HMI.
For processes involving several pieces of equipment, such as a High Lift Pumping Station,
provide a pop up menu to set-up the equipment duty setting.
Provide multiple start protection for all process equipment. Provide software reset for this
protection. This protection shall be provided for all REMOTE modes of operation. In general, all
equipment shall be inhibited from further starting after three (3) failed attempts by the PLC/RPU.
Indicate failure status by a pop-up window.
Provide a separate fault reset button for process equipment’s software interlocks.
18.8 Control Process Narratives
For each process, the following list details the standard required for the process narratives to be
provided by Consultants:
1. Safety of Personnel
2. Security of the Process
3. Software Interlocks
4. Logic Flow Diagrams
5. Virtual Points generated by PLC/RPU and/or HMI
6. Options for Process Control
7. Setpoints for Each Process
8. Emergency Procedures (Shutdowns, etc.)
9. Troubleshooting

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10. Field Adjustable Timers (Equipment, Modes of Operation)
11. Tagging/Description
The format used to describe the required process operation and automatic control sequences to be
implemented in the PLC/RPU shall be as follows.
1. GENERAL
2. BACKGROUND
Presents the terms of reference and purpose of the document.
3. PROCESS OVERVIEW
This Chapter introduces the entire process and briefly describes the major steps involved and
their sequence. It is intended to outline the scope of the work and its general form.
4. CONTROL SYSTEM STANDARDS
This Chapter refers to the standard methods or guidelines that are being conformed to in the
work. These standards and typically defined in other documents. A list of these documents
should be included here.
Also include information that is common to all equipment but not described in other
documents. This avoids repeatedly describing it in the more detailed information that
follows. Any general deviation from the above standards should be elaborated upon in sub-
sections. These could include control modes, I/O interface, alarm horns, alarm
acknowledgement, etc.
5. SYSTEM
.1 Sub Process #1 Title
This title identifies the first portion of the process that uses one or more pieces of
major equipment. This sub-process performs a distinct function that is the first major
“building block” of the entire process.
This section briefly describes the major functions of this sub-process and its scope.
The extent of each of these building blocks is defined in terms of the material going
in and out of each block.
.2 Equipment
A list of equipment including a brief description, equipment code, and location shall
be presented here.
.3 Control Modes
The locations from where each component may be controlled are listed here. If there
are any exceptions to the standards, these are noted here.
.4 List of I/O Points
All instrument signals for this equipment are listed here, grouped by device. For
example, a large pump has 3 digital inputs (status, control mode, general alarm) and 2
digital outputs (start, stop).

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.5 Control Logic
Control logic shall be used for any equipment required to be operated in the AUTO
mode. For AUTO logic which is hard wired, a description of this shall be provided. If
the equipment is PLC/RPU controlled, then all PLC/RPU logic needed for this
equipment shall be defined in detail. If standard methods are used, comply with the
standards as referred to herein, along with any specific setpoints.
This includes definition of all input information required by this logic to operate
correctly. When this information is unavailable, the default operation is defined.
The responses to all possible alarms or failure are listed (if this varies from a standard
that has been referenced). Any time delays involved in these actions must also be
specified.
.6 Sub Process # 2 Title
This is the next major “building block” of the process (if it exists). Sub process # 2 to
be prepared as per Sub Process #1 above. Repeat as needed for all sub-processes.
18.8.1 Screen
Screen display shall be organized to provide various displays in predictable order. The following
shall be the minimum screen display requirements for the SCADA system.
The options button on the Menu bar will provide miscellaneous information as follows and
details will be decided on a per plant/process basis:
1. SCADA Node Status
2. Equipment Runtimes
3. Totalizers
4. Enable/Disable Alarm Horns
18.8.2 Button Bars
Button bar shall be provided at the top of every screen with the following buttons to enable the
operator to navigate between screens:
1. Screens
2. Trends
3. Reports
4. Alarms
5. Map
6. Process
7. Options
8. Setpoints

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9. Process Narratives
18.8.3 Overview Screens
Provide the display hierarchy with the least detailed displays at the top, with increasingly
detailed displays towards the bottom of the hierarchy. There may or may not be display screens
at each level in the hierarchy. However, the structure should be maintained so that future
graphics developments are similar. A flowchart illustrating the display hierarchy is noted below.
Three main divisions in the display hierarchy for overview screens include:
1. System Overview (if applicable)
2. Plant Overview
3. Process Overview
The process overview is further sub-divided into the following:
1. Detailed Views
2. Equipment Specific
The detailed view and the equipment specific screens form the contents of the pop-up screen.
Alarms, trends, reports and event logs are each placed on a different screen. The button bar is
displayed at the top of all screens which allows the operator to navigate from one display screen
to another, view the alarm page summary, trends, reports, and enter setpoints.
18.8.4 Pop-Up Screen
Pop-Ups are generally accessed by clicking on the equipment icon from a process screen.
Generally, three categories of programmable pop-ups exist:
1. Control
2. Information
3. Setpoints
Create appropriate pop-ups for both control and information control layouts that provide non-
confusing layouts and language to the operator, which will allow the operator to interact quickly
with the HMI. The pop-ups shall be accessible either by clicking on the Main Menu or by
clicking at a particular device.
18.8.5 Control Pop-Ups Screens
Although there are several types of control pop-ups, they all permit the operator to interact with
the equipment and its associated device specific setpoints and control outputs. The operator can
operate the device, or change the operating mode from within a control pop-up.
Control pop-ups vary with each type of device or control element. A typical two-state (on/off or
open/close) device pop-up allows an operator to:
1. Change the device’s operating mode from PLT-MAN to PLT-AUTO

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2. Change the mode of operation (depending on the operating philosophy)
3. Control the device (when in PLT-MAN mode)
A three-state device pop-up is similar to a two-state one. A typical three-state device pop-up
allows an operator to:
1. Change the device’s operating mode from PLT-MAN to PLT-AUTO
2. Change the mode of operation (depending on the operating philosophy)
3. Control the device (when in PLT-MAN mode)
4. Manually set the speed (VFD) or a percentage open (modulating valve) in the PLT-MAN
mode
5. Changing the mode or state of a device from the control screen is done by clicking on the
button (Auto/Manual or Start/Stop). If the device is a VFD or a modulating valve, in manual
mode, the operator can enter the desired setpoint by clicking on the user input box and using
the electronic keypad to enter the setpoints.
18.8.6 Information Pop-Ups Screens
Information pop-ups provide information about equipment such as tag #, make, model #, etc. The
information pop-ups do not allow the operator to control the equipment.
Information pop-ups are called by selecting the “Information” button which will reside on the
control pop-up for a device. The information pop-up will include generic information as follows:
1. Tag Number
2. Make
3. Model Number
4. Plant Maintenance Information System Number
5. Location
18.8.7 Setpoint Pop-Up Screens
The setpoint pop-up allows the operator to enter values for parameters that are used to control the
process. Setpoint pop-ups can be classified into 2 types:
1. Plant setpoints
2. Alarm setpoints
An operator will be able to enter plant setpoints by clicking on the “Setpoints” button on the
main button bar. The Alarm setpoints can be accessed by clicking on the analog value display
which will bring the transmitter (alarm setpoint) pop-up. The operators can then choose the
process(s) or transmitter they want to view and change setpoints.
1. Plant setpoints will include the following where required:

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.1 Equipment start/stop times
.2 Duty pump setting
.3 Process setpoints including start/stop flows, pressure, etc.
The alarm setpoint screen, as mentioned above, brings up the transmitter pop-up. This contains a
description of the analog value being scanned, the units and the setpoints associated with the
alarms for that date. The operator can disable or enable the alarms as well as the scan for the
transmitter. The operator can also change the setpoints for the alarms associated with that
transmitter provided he/she has the correct access level to do so.
18.9 Alarm
An alarm is a device or a function that signals the existence of a critical or abnormal condition by
means of an audible and/or visible indication, intended to attract operator attention to a specific
condition. Alarms can be displayed by changing the colour or state of the equipment and/or by
printing an alarm summary on an alarm summary display. The following is the standardized
HMI alarming technique.
1. The alarm page will be accessible through the button bar located at the top of the screen.
2. The alarms will be categorized into critical alarms, non-critical alarms and advisory or
warning alarms.
3. These can be visibly indicated by the usage of colour and/or animation of the associated
device.
4. The critical alarm screen will pop-up regardless of the screen that is being currently being
viewed.
5. The process area associated with an active alarm will flash to indicate the presence of an
alarm.
6. Alarms will be acknowledged through an acknowledge button.
7. The alarm summary page will provide the following information, as a minimum, date and
time of occurrence for each alarm, time it was acknowledged, the type of alarm (hihi, lo,
etc.), the event (ack, alm, rtn), priority, comment, tag name, value and alarm state
(unack_alm, ack_alm, etc.).
Any alarm generated by the SCADA system must be capable of being acknowledged on a global
basis from any workstation.
All unacknowledged alarms shall be displayed in flashing red and acknowledged alarms be
displayed in white.
This status shall be maintained even if the workstation crashes and has to be rebooted ie it must
maintain its alarm status prior to the workstation crash.
Provide a system master reset switch for acknowledging all alarms. This normally occurs when
the workstation handling alarms crashes and has to be rebooted. At that time, all acknowledged

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alarms, if it is still in an alarm condition, will be shown to be in an alarm condition. The master
reset switch will acknowledge all alarms activated at that time.
18.10 Trends/Reports
Provide trends and reports to enable the evaluation of the performance of the system and make
qualitative decisions about the processes. This also includes those that are required by the EMA
and WASA. Configure software to provide required reporting, trending etc and integrate plant
data with event, summary, configuration and production data.
The following pages include parameters for Water Treatment Plants and Wastewater Treatment
Plants.

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18.10.1 Raw Water Monitoring Parameters (Water)
Daily Weekly Quarterly
Flow Rate Total Coliform Alkalinity
pH Fecal Coliform Hardness
Colour pH Calcium
Turbidity Turbidity Sodium
Temperature Colour Iron
Conductivity Copper
Total Chlorine Residual Lead
Zinc
Arsenic
Aluminum
Manganese
Conductivity
Chloride
Sulphate
Ammonia and Ammonium (N)
Total Kjeldahl Nitrogen
Nitrite
Nitrate
Dissolved Organic Carbon
Phenols

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18.10.2 Treated Water Monitoring Program (Water)
Daily Weekly Quarterly
Flow Rate Total Coliform Alkalinity
pH Fecal Coliform Hardness
Colour Standard Plate Count Calcium
Turbidity Turbidity Sodium
Temperature Colour Iron
Free Chlorine Residual pH Copper
Total Chlorine Residual Lead
Zinc
Arsenic
Aluminum
Manganese
Conductivity
Chloride
Sulphate
Ammonia and Ammonium (N)
Total Kjeldahl Nitrogen
Nitrite
Nitrate
Dissolved Organic Carbon
Total Trihalomethanes

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18.10.3 Distribution System Monitoring Program (Water)
Weekly Quarterly
Total Coliform Alkalinity
Fecal Coliform Hardness
Standard Plate Count Calcium
Colour Sodium
Iron
Copper
Lead
Zinc
Arsenic
Aluminum
Manganese
Conductivity
Chloride
Sulphate
Ammonia and Ammonium (N)
Total Kjeldahl Nitrogen
Nitrite
Nitrate
Dissolved Organic Carbon
Total Trihalomethanes

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18.10.4 Raw Water Monitoring Program (Wastewater)
Daily Weekly Monthly
Total Plant Flow Suspended Solids (Twice a week) Total Plant Flow
Plant By-Pass BOD5
Secondary By-Pass Total Phosphorus
Suspended Solids Ammonia
BOD5 TKN Nitrogen
Total Phosphorus
Ammonia
TKN Nitrogen
18.10.5 Treated Water Monitoring Program (Wastewater)
Daily Weekly Monthly
Chlorine Residual Suspended Solids (Twice a week)
BOD5 (Twice a week)
Total Phosphorus (Twice a week)
Ammonia (Twice a week)
TKN Nitrogen (Twice a week)
E-Coli
18.10.6 Process Parameters Monitoring Program (Wastewater)
Daily Weekly Monthly
Dissolved Oxygen Percentage Total Solid in Digester Sludge
(Thrice a week)
Chlorine Used
Mixed Liquor Suspended Solids Percentage Volatile Solids in Digested
Sludge (Thrice a week)
Other Chemicals Used
Sludge Volume Index Grit Removed
Waste Activated Sludge Screening Removed
Return Activated Sludge
Secondary Clarifier Sludge
Blanket Level
Primary Clarifier Sludge Blanket
Level
Chlorine Used
Other Chemicals Used
Primary Sludge to Digesters
Digester Sludge Removed
Digester Gas Total

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Digester Gas Used
Digester Gas Wasted
18.11 Trend Display
18.11.1 Trend Display Requirements
Graphical trending display shall be provided for all processes, equipment run-time, water quality
etc on the following basis:
1. Last 6 hours
2. Last 12 hours
3. Last 24 hours
4. Last 7 days
5. Last one month
6. Last six months
7. Last 12 months
18.11.2 Water Treatment Plant Operating Statistics
The following operating statistics for water treatment plant and water supply system shall be
produced for each 8-hour shift. Each display page shall be configured for a 3-shift period with
sub-total for each shift and the grand-total for each 24-hour period. At the end of each week,
each calendar month and on an annual basis, provide a summary for the year for the following:
1. WATER QUALITY LIMITS
2. WATER QUALITY – DAILY REPORT
3. WATER QUALITY – GENERAL
4. WATER QUALITY – TURBIDITY
.1 Raw water turbidity and individual filter effluent turbidity.
5. PLANT FLOWS SUMMARY – RAW, FINISHED & WASH WATER
6. PLANT FLOW MONTHLY REPORT - RAW WATER FLOW
.1 Include Monthly average, high, low and total.
7. PLANT FLOW ANNUAL REPORT – RAW WATER FLOW
.1 Include Annual average, high, low and total.
8. PLANT FLOW MONTHLY SUMMARY
.1 Include daily average, minimum, maximum for raw and finished water. Include volume
and percent of washwater and number of washes.

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9. PLANT FLOWS - DAILY REPORT
.1 Include maximum and minimum rate for raw and finished water.
.2 Number of filter washes, volume and percent of wash water.
10. WATER QUALITY MONTHLY REPORT
.1 Individual filter water quality reporting average, high and low NTU.
11. FILTER STATUS
.1 Include service, status, flow, LOH, NTU, operating time, volume filtered, total number of
washes and total filtration rate.
12. FILTER LIMITS
.1 Include filtration rate, headloss and turbidity.
13. FILTER MONTHLY REPORT
.1 Include operating time, volume filtered, number of washes, average wash volume and net
production.
14. FILTER ANNUAL REPORT
.1 Include operating time, volume filtered, number of washes, average wash volume and net
production.
15. CHEMICAL CONSUMPTION SUMMARY - DAILY REPORT
.1 Include average dose and total consumed.
16. CHEMICAL TREATMENT – DAILY REPORT
.1 Include current dose, daily average, set point, current residual, daily total consumed and
status. Include total daily raw and finished water produced.
17. CHEMICAL TREATMENT – MONTHLY REPORT
.1 Include total consumed and average dosage rate.
18. CHEMICAL TREATMENT – ANNUAL REPORT
.1 See 9.4.2.17.
19. WATER QUALITY RAW WATER TURBIDITY – MONTHLY REPORT
.1 Daily report of the average, high and low raw water turbidity in NTU.
.2 Provide monthly average, monthly high and low.
20. WATER QUALITY RAW WATER pH – MONTHLY REPORT
21. WATER QUALITY LIMITS
.1 Include plant and water distribution system for current, range, high alarm and high
advisory for raw and finished water turbidity, pH, temperature, pre and post chlorine
residual, HFS residual.
22. DAILY RESERVOIR LEVEL SUMMARY

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.1 For each hour.
23. DAILY WATER CONSUMPTION SUMMARY
.1 For each hour, for each zone and the total for each zone and the daily total.
24. DAILY PUMPING STATION PRODUCTION SUMMARY
.1 Include flow rate, pressure, reservoir level, operating pump(s) and Electrical power
consumption for HLPS and the PS for each pressure zone.
25. ZONE CONSUMPTION ANNUAL REPORT
.1 Include average, maximum and minimum day and the date of occurrence, the total for
each month. Include annual average day, maximum and minimum day, maximum and
minimum hour for the year for each pressure zone.
26. TOTAL WATER CONSUMPTION ANNUAL REPORT
.1 For each month, provide average day, maximum and minimum day and the date of
occurrence, the total for each month. Include annual average day, maximum and
minimum day, maximum and minimum hour for the year for the entire water supply
system.
27. TOTAL WATER CONSUMPTION SUMMARY ANNUAL REPORT
.1 For each zone, provide average day, maximum and minimum day and the date of
occurrence, the total for each month. Include annual average day, maximum and
minimum day, maximum and minimum hour for the year for the entire water supply
system.
28. ANNUAL PUMPING STATION PRODUCTION SUMMARY
.1 For each month, provide the pumpage volume of finished for each zone. Provide the total
for each month for each zone and the annual total.
29. ANNUAL SUMMARY OF PUMP RUNNING TIMES
.1 For each pumping station, show the total hours of running time for each pump.
30. MONTHLY SUMMARY OF PUMP RUNNING TIMES
31. MONTHLY PRODUCTION SUMMARY
.1 For each day, provide the pumpage volume for each zone pumping station. Provide also
the daily total pumpage volume by day and zone.
32. RAW WATER CHLORINE RESIDUAL MONTHLY REPORT
.1 Include average, high and low residual level.
The above should be capable of being printed on the screen or on a laser printer. In addition, it
should also be capable of being trended in accordance with 9.4.1 and printed on the screen and a
laser printer.

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18.11.3 Wastewater Treatment Plant Operating Statistics
The following operating statistics for wastewater treatment plant shall be produced for each 8-
hour shift. Each display page shall be configured for a 3 shifts period with sub-total for each shift
and the grand-total for each 24-hour period. At the end of each week, each calendar month and
on an annual basis, provide a summary for the year for the following:
1. WATER QUALITY LIMITS
2. WATER QUALITY – DAILY REPORT
3. WATER QUALITY – GENERAL
4. PLANT FLOWS SUMMARY – RAW & TREATED
5. PLANT FLOW MONTHLY REPORT – RAW FLOW
.1 Include Monthly average, high, low and total.
6. PLANT FLOW ANNUAL REPORT – RAW FLOW
.1 Include Annual average, high, low and total.
7. PLANT FLOW MONTHLY SUMMARY
.1 Include daily average, minimum, maximum for raw and treated wastewater.
8. PLANT FLOWS – DAILY REPORT
.1 Include maximum and minimum rate for raw and treated wastewater.
9. CHEMICAL CONSUMPTION SUMMARY – DAILY REPORT
.1 Include average dose and total consumed.
10. CHEMICAL TREATMENT – DAILY REPORT
.1 Include current dose, daily average, set point, current residual, daily total consumed and
status. Include total daily raw and treated wastewater processed.
11. CHEMICAL TREATMENT – MONTHLY REPORT
.1 Include total consumed and average dosage rate.
12. CHEMICAL TREATMENT – ANNUAL REPORT
13. WATER QUALITY RAW WATER TURBIDITY – MONTHLY REPORT
.1 Daily report of the average, high and low raw water turbidity in NTU.
.2 Provide monthly average, monthly high and low.
14. WATER QUALITY RAW WATER pH – MONTHLY REPORT
15. MONTHLY TREATMENT SUMMARY
.1 For each day, provide the collection volume for each drainage area. Provide also the daily
total collection volume by day and area.

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18.12 Archival of Historical Data
Data collected at the PLC/RPU site shall be transferred to the SCADA workstation. At fixed
periods, the data is transferred to the fileserver for long term storage. Short term access to the
data shall be by reading the data from the remote workstation.
18.13 Process Control Graphic User Interface
18.13.1 Process Control Display
Process control display shall commence with the overall system followed by more detailed
graphic display for each subsequent smaller process area. There shall also be screen display
developed for specific purposes such as a screen display for all reservoirs or a screen display
showing all the pumping stations, etc.
Each process screen shall be designed to appear as similar to the actual layout of the system as
possible.
Two-dimensional graphical representations shall be used on all process display screens.
18.13.2 Standard Colour Convention – Process Stream
The following table lists the standard colour conventions for process Stream:
Element Colour Convention
Potable Water Light Blue
Raw Water Dark Blue
Influent Water from WWTP Light Green
Effluent Water from WWTP Dark Green
Chlorine (Liquid) Chemicals - Orange
Chlorine (Gas) Gas - Yellow
Aluminum Sulphate
Ammonia
Polymer
Sulphur Dioxide
Hydrofluosilicic Acid (Fluoride)
Ferric Chloride
Natural Gas
Digester Gas
WTP/WWTP Sludges Brown
WTP Backwash Wastewater
WWTP RAS/WAS
WTP Settled Backwash
WWTP Supernatant

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Values appearing at various locations on the screen shall represent current value for flows, levels
pressures, etc.
18.13.3 Standard Colour Convention – Pump/Motor/Valve
The colour convention for pump/motor/valve and miscellaneous details shall be as follow:
Device/Status Colour Convention
Pump/Motor
Running Red with Text
Off Green with Text
Alarm Flashing Magenta
Valve
Opened Red with Text
Transition Half red and half green
Closed Green with Text
Modulating Percentage open is displayed beside valve. Valve colour
is green when less than 5% open and red when greater
than 5% open.
Isolating Grey
Alarm Flashing Magenta
Miscellaneous
Hi or HiHi Alarm Flashing Magenta
Lo or LoLo Alarm Flashing Magenta
Background Process - White
Control - Black
Text Description - White on Pop-Up
- Black on Process Screen
18.14 Symbols
Use standard symbols on a process overview screen. Comply with the following practices when
developing graphics:
1. Symbols should reflect the P&ID drawings
2. It must be consistent, intuitive and user friendly
3. It should be developed for both dynamic and static equipment
4. Use ISA symbols (2-D)
18.15 Watchdog Program
A watchdog program shall be provided where specified in the Request for Proposal.

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The watchdog program, as defined herein, is a software program designed to track all changes
made to the HMI and PLC/RPU logic software or database.
The watchdog program may be custom written software to be provided by the Consultants to
meet the intent of this requirement.
The following is the information that must be tracked by the watchdog program:
1. Date
2. Time
3. Name of authorised personnel and security code
4. Name of authorising Supervisor and security code
5. Block of software or database changed
All such changes shall be saved in a file which cannot be erased unless authorised by the
Supervisor.
18.16 System Security
Security of workstations, plant networks and field controllers shall be installed to only permit
access by authorised personnel with the required security clearance.
Security system shall be configured based on three levels of security. These are the workstation
operating system (Window NT), the Network Access (for e-mail, corporate applications etc.) and
the SCADA HMI (operator verification). Each of these will be one of two levels – administrator
or user. The administrator (Supervisor and/or Manager) will assign the rights and privileges of
the users on the network.
The SCADA system security shall be dependent on a logon system and the use of distinct logons
for the MHI is required.
18.17 SCADA System Operation Manual
18.17.1 General
Provide Operation Manuals in accordance with the Project Guidelines. This includes operating
procedure descriptions for both PLANT-MANUAL and PLANT-AUTO operation of the facility
in the following sequence:
1. LOCAL Control
2. PLANT MANUAL
The sections covering PLC/RPU based operation will be developed from the English language
process narrative and the logic flow diagrams produced. Allowance will be made in the
Operational Manual for inclusion of this Chapter.

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Hard copy, disk and CD-ROM to be provided for all custom ladder logic and SCADA system
application software installed, as well as all original disks and CD-ROMs provided under the
contract for the software packages.
18.17.2 SCADA System Operation Manual Requirements
As a minimum, the SCADA System Operation Manual shall include the following sections.
Section 1 INTRODUCTION
1.01 General Information
1.02 Control System Standards
1.03 System Configuration (See Note 1)
1.04 System Architecture
Section 2 HARDWARE & SOFTWARE
2.01 System Overview
2.02 Hardware – Central Hardware
2.03 Hardware – RPU Hardware
2.04 Software – Central Software
2.05 Software – RPU Software
2.06 Hardware Configuration
2.07 Software Configuration
2.08 Replacement/Addition of Workstation
Section 3 THE BASICS
3.01 The First Step
3.02 Disk Operating System
3.03 Microsoft Windows
3.04 Using Microsoft Windows
3.05 List of Running Programs
3.06 Windows Applications
3.07 Main Group
3.08 Accessories
3.09 PC Anywhere
3.10 Backup Basics
3.11 Spread Sheet and InTouch
3.12 The Second Step
3.13 HMI Software
3.14 Using the HMI Software
3.15 Plant/System Automation through the HMI
3.16 Troubleshooting
3.17 To Exit Windows
Section 4 PROCESS DISPLAY
4.01 Process Displays
(Process Displays shall include all displays configured in the HMI
and how to use them. It shall starts from the intake to the furthest

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pressure zones; all plant processes; all chemical treatment
processes; all pumping stations and reservoirs.)
Section 5 EQUIPMENT CONTROL
5.01 Device Control Mode
5.02 Equipment Control Displays & Popup Menus
5.03 Device Alarms
5.04 Transmitter
5.05 Process Area #1 (repeat for each major process area)
5.06 Facility Security
Section 6 USING THE HMI BUTTONS
6.01 Top Row Buttons
6.02 Exit
6.03 Alarms
6.04 History
6.05 Map
6.06 Process
6.07 Systems
6.08 Reports (List and show all reports that will be generated)
6.09 Trends (List and show all reports that will be generated)
6.10 Options
6.11 Setpoints
6.12 Area
6.13 Previous
6.14 Next
Section 7 PROCESS NARRATIVE
7.01 Provide all process narratives and for each process, include the
following minimum information:
i. System Description
ii. Equipment
iii. Control Mode
iv. I/O Points
Program Variables
Virtual Points
Field Points
v. Control Logic
Normal Operation
Fault Response Operation
Hardwired Interlocks
Associated Alarms
7.02 Include all Auto Control Programs Narratives
Section 8 SYSTEM FAILURE
8.01 Communication Failure - Workstation

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8.02 Communication Failure - Remote Workstations
8.03 Workstation Failure and Restart Procedure
8.04 System Crash and Restart Procedure
8.05 Power Failure and Backup Generator
8.06 Trouble Shooting SCADA System
Section 9 SYSTEM SECURITY
9.01 SCADA Access Security
9.02 Passwords
9.03 Changing Password and Authorization
9.04 Watchdog Program
9.05 Function of Watchdog Program
9.06 Watchdog Historical Data
9.07 Erasure of Watchdog Data and Authorization
Section 10 WASA AM/FM/GIS
10.01 Integration of WASA AM/FM/GIS System
10.02 Accessing into the SCADA System from WASA System
10.03 E-Mail
Appendix A POINT LISTS
Appendix B SCADA SYSTEM EQUIPMENT LISTING
Appendix C SOFTWARE LISTING
Appendix D REDUCED SET OF CONTRACT DRAWINGS
In assembling the information for the SCADA system for the Operation Manual, the Consultants
shall provide all the information of all workstation or view node software to be included under
Section 2.06 - Hardware Replacement:
1. Hardware:
.1 Monitor Manufacturer, Model and Resolution
.2 Computer Manufacturer, Model, Hard Drive Specification, Input/Out put ports,
Video Card Specifications, Manuals
.3 LAN Card Manufacturer, Model, Configuration Settings, Jumper Settings, LAN Card
Software, Installation and Operations Manuals
.4 I/O Cards Manufacturer, Model, Configuration Settings, Jumper Settings, IRQ and
COM Port Addressing, Manuals
.5 Modem(s) Manufacturer, Model, Configuration Setting, Setup Procedure for leased
Line Configuration, Specification for 2 or 4 wire, Manufacturer’s Manuals
2. Network LAN Hub Manufacturer, Model, User Manuals, Type of Cabling (e.g. 10
Base T)
The SCADA Software information shall be provided in the Operation Manual and the minimum
requirements are as follow:
1. Software

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.1 Operating System
.2 Office Applications
.3 All configuration settings for communications
.4 Port settings
.5 Device settings (video, mouse, etc.)
.6 Alarm Logger Configuration
.7 Alarm Printing
.8 Historical Logging Configuration
.9 Node configuration (communication, addressing, etc.)
2. PLC Software
.1 Node addressing for all PLC’s in the SCADA Network
.2 All port, jumper, etc. configuration settings
18.17.2.1 Replacement or Addition of Workstation
The procedure for the replacement and or addition of a workstation shall be provided as follows:
1. Step by step instructions on how to replace a work station which has failed. How a new
computer would be configured to replace the existing workstation.
2. Step by step instructions on how to add a new work station to the system.
3. Step by step instructions explaining how to upgrade the SCADA system strategy (on all work
stations) via a laptop computer. Note details which would be specific to each work station.
4. Detailed description of report writing macro and a step by step account of how to integrate a
new workstation into the automatic report output.
18.18 System Architecture
The system architecture is based on the following requirements:
1. The workstation operating system is to be Microsoft Windows
2. Database application software conforms to existing.
3. Networking at all levels is based on an Ethernet backbone.
4. The in-plant communications network is hard-wired to avoid delays and failures in
communication (details to be developed during the pre-design phase).
5. Communication between the plants and the remote sites is to be optimal to avoid delays in
data transmission.

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18.19 SCADA Control Strategy
The SCADA and control strategy shall be developed for each plant (the same application will
apply to the remote stations linked to the plant) and must be capable of being updated from all
view nodes through a single node. It must have the capability to monitor and control the plant
and all the remote stations from any SCADA node within the plant’s LAN.
The SCADA system’s server must be provided with full redundancy backup, thereby insuring
the ability to switch to a backup server if the main server fails. This will provide the continual
ability to control the plant and sites from individual client nodes if the main server fails.
To ensure the security and integrity of the SCADA system, fire-walls and virus detection
software shall be installed on all SCADA nodes.
The SCADA system shall be configured to provide the ability to use portable computers to dial
into any LAN to view and control the processes.
18.20 Network Requirements
Reliable and high speed communication network of the SCADA system for water and
wastewater systems.
18.21 SCADA Software
The standard requirements for HMI general configuration requirements for the system (server
and client nodes) are as follows:
1. Single product HMI
2. A server-client configuration is required where there will be one server node and several
client nodes
3. Each server will be a runtime node
4. The client node can be configured to be either a runtime node that allows control and
monitoring features or a view only node
5. The server node will contain the application and all client (view) nodes will point to this
directory on the server to run the application
6. The client nodes will maintain a copy of the application as well for redundancy
7. There will be one backup client node capable of operating as the server for redundancy
8. Visual Basic scripting will be used to notify and update the client nodes so that system
development can be completed on one node and automatically copied to the client nodes
9. Use of a browser package that provides Internet visualization to view factory information
anywhere and anytime

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18.22 Database Software
A real-time relational database that acquires and stores plant data will be implemented on the
SCADA nodes. The database will have client applications that can be used to access this data for
viewing, analysis, reporting, etc.
1. The database will be used as a real-time database for data storage and analysis; there will be
one database server and several database clients
2. One server can be used for both the database and HMI software
3. The database server will be used to store all the data and the client nodes will be configured
to provide the required analysis and summary/report generation
18.23 Communication Links
Due to the high reliance of the SCADA network project on communication links, use high-speed
communication to avoid delays which may be critical in various processes. For fast and reliable
communication, the following strategy shall be implemented:
1. All in-plant communication to be hardwired (no modems)
2. ISDN (Two 64kb channels per connection) service to be used at all sites unless this service is
not available
18.24 PLC/RPU Programming Standard
18.24.1 PLC Program Structure
The programming of PLCs shall be carried out in a uniformly structured manner, which shall be
as follows:
1. Main Program
2. Start-Up Sequence
3. Output I/O Task
4. Input I/O Task
5. Input Conditioning
6. Data Communication
7. Alarm Handling Subroutine
8. Duty Selection
9. Automatic Control Logic
10. Equipment Control Logic Tasks
11. Device Driver Modules

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18.24.2 PLC Programming Protocol
Consultants shall comply with IEC-61311 programming format. No program(s) will be accepted
by WASA if it does not conform to this requirement. In addition, the Consultants shall also
observe the following programming protocol when carrying out PLC or HMI programming. This
may be verified through a third party retained to perform the peer review work.
1. Data addresses that are to be communicated to other controllers, operator interfaces, and/or
SCADA workstations are to be grouped together.
2. The adoption of a predefined program structure that orders the common tasks to be used in
PLC/RPU programs.
3. Use function blocks or subroutines to avoid repetitive blocks of identical logic. If these are
not available, consider common flags/variables instead of repeated code.
4. Use the status of any field input only once in the I/O task to drive a logic relay/bit or
register/word (point). This “translation” of all field inputs forms the first portion of the I/O
task. One function of the “translation” is to ensure a ‘positive logic’ sequence in the
development of the code. These logic points are then used by all other logic, rather than the
field inputs. Debounce timers/ramps are required for all inputs and are included here.
5. Outputs are addressed as per inputs noted above, that is, all tasks except the I/O task address
outputs through logic points. The I/O task then uses these logic points to drive the field
outputs. The writing of all field outputs should be grouped together at the end of the I/O task.
Any field output may be written at only one location in the code.
6. Place all checks for device response together in the I/O task, with a timer for each device.
7. Group all registers/words and relays/bits that are of interest to monitoring personnel in
sequential blocks. This includes setpoints, timer limits, tuning constants, and status flags.
This simplifies the transfer of this data to supervisory systems. Maintain the “translated” field
inputs in separate block(s) from other data.
8. Use constants in the code only where it is unlikely they will ever be changed.
9. Layout I/O points having identical functions for successive devices in identical, consecutive
blocks. For example, group the start/stop outputs for all low lift pumps in similar order and in
adjacent terminals.
10. Avoid latches.
11. Avoid jumps.
12. Avoid drum sequencer.
13. Use an IBM compatible workstation to program the PLC and use the manufacturer’s
programming software to fully document the code.
14. Label every register/word, relay/bit, and rung with a name or comment.
15. Do not sacrifice program clarity and simplicity to achieve higher execution speed and smaller
code size.

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16. Monitor and alarm all available diagnostic data such as task and I/O board errors.
17. Where PID loop control is required, disable the derivative factor.
18. Configure all alarm points in software to be TRUE when in alarm. (In general, field wiring of
alarms is FALSE when in alarm.)
19. Include logic for simulation of normal field feedback. This is used in factory and site testing
as well as training.
20. Include minimum times for equipment to be running and stopped, to prevent possible output
‘chattering’.
21. Include interlocks to prevent simultaneous starts of major equipment (in auto mode only).

159. Water And Sewerage Authority (WASA)
Water and Wastewater Design Guideline Manual Mechanical Standards
19-1 October 2008
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Section 19 Mechanical Standards
19.1 General
Comply with applicable Acts, Codes or Design Guidelines as detailed in Section 3.0, Design
Standards.
Mechanical systems shall be designed to provide ease of operation and maintenance. Choice of
material and equipment shall be based on WASA standard and where such standard has not been
provided, it shall be based on the track record of the material or equipment in a similar Trinidad
& Tobago facility. All design shall comply with Trinidad & Tobago National Plumbing Code,
AWWA Standards of Practice and Specifications, relevant codes or design guidelines. The
design must as much as it’s applicable, include mechanism for water conservation, including but
not limited to pressure control devices, low flush toilets, low volume faucets, etc.
19.2 Valves
Valves shall comply with EN 593 and ISO 5996. All valves and actuators shall have at least 5
years of operating service in Trinidad & Tobago, and to be supplied by regional based vendors.
All valves used for potable water supply system shall be certified for potable water use.
Orient valves and valve operators to meet the following requirements:
1. Ease of operation
2. Limit interference with structures and with any other equipment or piping
3. Space allowance requirement for maintenance and disassembly
4. Valves mounted higher than 2 m shall be provided with chain for opening or closing
Specify valves operators, for both manual and electric valves, with indicator to clearly indicate
whether the valve is in the opened, closed or partially opened/closed position. The indicator must
be visible from 3 meters away, under normal plant operating conditions.
19.3 Fittings
Flanges shall be Class 125, ANSI B16.1, for operating pressures up to 250 pounds per square
inch. For operating pressures above 250 pounds per square inch, flanges shall be Class 250,
ANSI B16.1.
Above-ground fittings shall be flanged, welded, or coupled. Nuts and bolts shall be hot dip
galvanized steel or epoxy painted.
Below ground fittings shall be welded or coupled. Nuts and bolts shall be grade 316 stainless
steel.
Gaskets shall be Butyl or EPDM.

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19.4 Pumps
All materials and equipment supplied shall be suitable for being delivered, store and operated
under tropical conditions of high temperature, high humidity, heavy rainfall, mildew and fungus
conductive environment. All equipment and motors shall be supplied with corrosion resistant
metal nameplates fitted securely in an location, which can be easily read, complete with stamped
inscriptions of the following information where applicable:
1. Electric motors will meet the requirements of IEE 60034-1, 60034-5, 60034-6 and 60034-8.
2. For pumps, fans, valves, valve operators, instruments, etc.:
.1 Model Number
.2 Serial Number
.3 Head
.4 Capacity
.5 Impeller Diameter
.6 Efficiency
.7 Performance rating
.8 Other information required to uniquely identify the equipment
.9 Performance data in SI metric units
3. Bearings requirement:
.1 All rotating equipment shall be provided with bearings selected on the basis of life
expectancy at rated conditions of service of at least 100,000 working hours.
.2 Bearings for electric motors shall be constructed so that no oil or grease can escape from
them.
4. Alemite-type or buttonhead grease fittings shall be provided for bearing lubrication.
5. Equipment Operating Characteristics:
.1 Mechanical equipment furnished shall operate satisfactory without excessive wear,
excessive lubrication or undue attention required by the operating staff. All rotating parts
shall be in true dynamic balance and operate without vibration caused by mechanical
defects, faulty design or misalignment of parts. In general, the limit of vibration velocity
is 1mm/sec for equipment. A more stringent requirement may be specified in the detailed
equipment specifications.
6. Equipment Guards:
.1 To be provided for all couplings, belts, chain drives and extended shafts.
.2 It shall be securely mounted, suitably reinforced and neatly formed of at least 12 gauge
steel perforated sheet or expanded sheet metal.
.3 It shall be hot-dip galvanized after fabrication.
.4 It shall be painted yellow in colour.

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7. Base Plates:
.1 Equipment base plates shall be of heavy cast iron or of welded structural steel with a
minimum thickness of 13 mm. For mounting equipment and driver base, the plates shall
be at least 20 mm thick. Surfaces for mounting equipment and driver shall be machined
to an arithmetical average roughness height of less than 125 micro-inches.
.2 For equipment where leakage or condensation may occur, provide base plates with a drip
lip and drain connections to the exterior of the base. Piping shall be provided from the
drain connections to the building drainage system. Bossed connection to drip lips shall be
below the gutter invert and shall be at least 25 mm N.P.T.
.3 In general, equipment shall be installed directly on machined bases without shims. Where
shims are required, provide stainless steel shims under driver mounting feet.
8. Equipment Noise Level:
.1 Equipment shall be designed for quiet operation with the overall sound pressure level at
any equipment not exceeding 85 decibels when measured on the “A” weighting network
(IEC 60034-9). A more stringent requirement may be specified in the equipment
specifications.
19.5 Piping & Equipment Identification
19.5.1 General
All pipes inside the plant or valve house shall be colour coded in accordance with WASA
requirements for pipe identification in water and wastewater treatment plants. These color
requirements have been covered by the TTBS standard for pipe codes/colors. Provide arrows
indicating the direction of flow.
All inlet, internal and outlet piping for pumping station shall be provided with isolation valve(s)
to permit isolation/removal of pump(s) for maintenance work without impacting on the integrity
or operational capability of the pumping station itself.
The labelling of all pipes shall conform to WASA.
All piping, fittings and valves, mechanical and electrical equipment including sleeves through
floors, shall be painted.
Piping and equipment shall be properly identified as provided herein.
All existing equipment, piping etc shall be protected from paint splashes when new equipment or
piping is painted.
19.5.2 Security equipment
All security guards and railings shall have a yellow colour to conform to WASA requirements.

162. Water And Sewerage Authority (WASA)
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19.5.3 Piping Identification Labels
All piping shall be labelled to conform to WASA requirements as stated in applicable TTBS
standard. If not covered, then the following standard based on ASME A13.1-2007 could be
applied. Identify exposed piping and ductwork in locations as follows:
19.5.4 Colour Legend
19.5.4.1 Group #1
Piping System Label Band
Background
Letter/
Colour
Max. Label
Intervals
Max. Band
Intervals
Flammable Materials
Propane Gas
Natural Gas
Hydraulic Oil
Fuel Oil
Digester Gas
Yellow Black 3 m 3 m
19.5.4.2 Group #2
Piping System
Label Band
Background
Letter/
Colour
Max. Label
Intervals
Max. Band
Intervals
Fire Fighting
(Protection)
Standpipe System
Sprinkler System
Halon Fire Protection
Carbon Dioxide Fire
Protection
Red White 3 m 3 m

163. Water And Sewerage Authority (WASA)
Project Design and Technical Specifications Manual Mechanical Standards
19-5 October 2008
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19.5.4.3 Group #3
Piping System
Piping
Colour
Label
Band
Back-
ground
Letter/
Colour
Max. Label
Intervals
Max. Band
Intervals
Dangerous Substances:
Boiler Feed
Boiler Blow Off
Acid Drain
Compressed Air > 670 kPa
Ferric Chloride
(High Temp Dom.)
(Hot Water)
LP Stream
LP Condensate
Hp Steam
Lp Condensate
Purple White Black 3 m 3 m
19.5.4.4 Group #4
Piping System
Piping
Colour
Label
Band
Back-
ground
Letter/
Colour
Max. Label
Intervals
Max. Band
Intervals
Other Chemical
Substances:
Alum
Chlorine Solution
Polymer Solution
Lime Solution
Sodium or Calcium
Hypochlorite Solution
Glycol Solution (Heating)
Diesel Exhaust
Orange White Black 3 m 3 m

164. Water And Sewerage Authority (WASA)
Project Design and Technical Specifications Manual Mechanical Standards
19-6 October 2008
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19.5.4.5 Group #5
Piping System
Piping Colour Label
Band
Back-
ground
Letter/
Colour
Max. Label
Intervals
Max. Band
Intervals
Process Drainage
Raw Water
Clarified Water
Treated Water
Dom. Cold Water
Dom. Hot Water Sup.
Dom. Hot Water Ret.
Chilled Water
Condenser Water
Hot Water Heating
Storm Drain
Plumbing Vent
Effluent Water
Compressed Air
Instrument Air
Vacuum
Nitrogen
Sanitary Drain
Filtrate (San)
Return Sludge
Waste Sludge
Raw Sludge
Scum
Supernatant
Olive green
Aqua
Dark blue
Lt. green
Lt. green
Lt. green
Blue
Lt. Grey
Lt. Grey
Lt. Grey
Lt. Grey
Lt. Grey
Safety Blue
White
White
Orange
Dk. Grey
Dk. Grey
Mid-Brown
Mid Brown
Dk. Brown
Dk. Brown
Lt. Brown
Green
Green
Green
White
Red
Red
Green
Green
Red
Green
Green
Green
Green
Green
Green
Green
Green
Green
Green
Green
Green
Green
Green
White
White
White
White
White
White
White
White
White
White
White
White
White
White
White
White
White
White
White
White
White
White
White
6 m
6 m
6 m
6 m
6 m
6 m
6 m
6 m
6 m
6 m
6 m
6 m
6 m
6 m
6 m
6 m
6 m
6 m
6 m
6 m
6 m
6 m
6 m
Not
Required
19.5.5 Method of Application
On painted piping system (pipes up to and including 45 mm o.d.), labels shall be 2 mil
vinyl/polyester of sufficient lengths to wrap completely around the pipe with a minimum of
8 mm overlap. Colours to meet WASA Standards. Label complete with permanent adhesive.
On painted piping system (Pipes over 45 mm o.d.), labels shall be 10 mil PVC sleeve complete
with two-sided permanent tape and liquid weld. PVC to be 25/50 fire rated. Sleeve shall be of
sufficient length to wrap completely around the pipe with a minimum 25 mm overlap. Colours to
meet WASA Standards.

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On unpainted piping systems (pipe up to and including 45 mm o.d.), labels shall be
vinyl/polyester of sufficient length to wrap completely around the pipe with a minimum 8 mm
overlap. The label shall be 300 mm long complete with 100 mm colour banding at each end with
colours to meet WASA Standards for colour banding. The labels shall be supplied as a one-piece
unit and permanently self-adhesive.
On unpainted piping systems (pipe over 45 mm o.d.), labels shall be. 10 mil PVC sleeve
complete with two-sided permanent tape and liquid weld. PVC to be 25/50 fire rated. Sleeve
shall be of sufficient length to wrap completely around the pipe with a minimum 24 mm overlap.
The label shall be 300 mm long complete with 100 mm colour banding at each end with colours
to meet WASA Standards for colour banding. The labels shall be supplied as a one-piece unit.
Directional arrows are required with each of the above labels.
19.5.6 Sizes of Characters
Provide the following sizes of characters for labels:
Outside Pipe Diameter Letter Size
Pipe less than or equal to 25 mm 12 mm
Pipe greater than 25 mm but less than or equal to 50 mm 25 mm
Pipe greater than 50 mm but less than or equal to 300 mm 38 mm
Pipe Greater than 300 mm 50 mm
Ducts 50 mm
19.5.7 Location of Labels
Application of Labels shall conform to the following:
1. Apply identification label and directional arrows at or near the following locations:
.1 Both sides of valves
.2 All branch fittings and elbows
.3 Both sides where pipes and ducts pass through walls, floors and ceiling
.4 Straight runs at maximum distance, centre to centre, as indicated above
.5 Where circumstances make contents or direction of flow doubtful
2. Apply labels in positions that allow them to be easily read from normal operating positions.
3. All labels to be installed in a workmanlike manner.

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19.5.8 Pumps & Valves Colour Schedule
Pump Type
Colour Schedule
WASA Code
Sump Pump Light Grey
Sodium Hypochlorite Metering Pump Light Grey
Hydrofluosilicic Acid Metering Pump
Aluminium Sulphate Metering Pump
Chlorination Metering Pump Light Grey
Ferric Chloride Metering Pump
RAS Pump
Sludge Loading Pump
Wastewater Pump (Normally in Wastewater PS)
Washwater Pump Light Blue
High Lift Pumps Light Grey
Low Lift Pumps Light Grey
Valve Type Purpose
Colour Schedule
WASA Code
Manually operated butterfly valves Cell isolation Light blue
Electrically operated butterfly
valves
Automatic reservoir level control Light blue
Check valves with lockable device Direction of flow control, lockable device to
keep valve open for reverse flow application
Light blue
Gate valves Reservoir drainage Light grey
Valves Chemical solution Light grey
Valves Plumbing and drainage system Light grey
Equipment Colour
Emergency Standby Diesel Generator Light Grey
Equipment Guard Red
Air Blower Light Grey

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19.5.9 Nameplates
All equipment, except electrical, shall be provided with a nameplate with the following
information stamped on it:
1. Pump
.1 Type
.2 Model
.3 Serial Number
.4 Rated Capacity (L/S)
.5 Rated Dynamic Head (TDH m)
.6 Number of Stages (Vertical Turbine Pump)
.7 Speed
.8 Diameter of Suction/Discharge
.9 Impeller Diameter
.10 Seals
.11 Bearing Details
.12 Weight
.13 Year of Manufacture
2. Drive Unit
.1 Size
.2 Type
.3 Serial Number
.4 Electrical Requirements
.5 Current Draw
.6 Frame Number
.7 Rated Temperature Rise
.8 Continuous Service Factor
.9 Bearing Details
.10 Weight
.11 Year of Manufacture
3. Submersible Pump
.1 Nameplate for submerged portion
.2 Nameplate for non-submerged portion

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Project Design and Technical Specifications Manual Mechanical Standards
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19.5.10 Equipment Name Tags
Special equipment name tags shall be provided to identify equipment. The equipment name tags
shall be black embossed or engraved on polished rectangular aluminium tags 50 mm high, 1.5
mm thick and long enough to display adequately all the identification characters. The
identification characters will be alpha numeric and 10 mm high and should be attached with at
least two stainless steel self-tapping screws or black nylon ties where screws fasteners are not
practical.
19.6 Equipment
19.6.1 Bearings
All equipment bearings shall have a minimum rating life of 100,000 hours, unless specified
otherwise.
19.6.2 Pump Shaft Seals
1. Single, mechanical pump shaft seals, unless specified otherwise.
2. Non-destructive, cartridge type, self-aligning seals of the stationary design, which requires no
wearing sleeve for the shaft.
3. Pump shaft shall have no reduction in size through the seal area.
4. For all contaminated water services, drill and tap for installation of seal water supply.
5. Stainless steel spring or Hastelloy C spring.
6. Buna-N or Viton O-rings for clean water applications. Specify Viton O-rings for sludge,
wastewater, scum or grit applications.
7. Faces:
.1 Wastewater, Sludge – Sintered silicon (or tungsten) carbide on carbon
.2 Potable water – Tungsten carbide on carbon
19.6.3 Couplings
Provide flexible coupling for all equipment with drives over 0.4 kW and less than 120 kW and
where the driver is directly connected to the driven unit.
19.6.4 Equipment Guard
Provide guard on moving parts fabricated of 1.5 mm sheet steel and galvanize after fabrication.
Equipment guard is to be removable to facilitate maintenance of moving parts. Make provision
to extend lube fittings through guard. All guards shall be yellow painted.
19.6.5 Gauge Taps and Test Plugs
Provide gauge taps on the suction and discharge side of pumps, blowers and compressors and
install gauges at each location.

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19.6.6 Alignment
All rotating equipment is to be set and aligned in accordance with the more stringent
requirements of either the equipment manufacturer or the following:
1. Level base, use machinists level on all machined surfaces.
2. Base is to be true and levelled.
3. Alignment of shafts, soft foot of motor and couplings shall be performed by reversed dial,
rim to rim and face to face. Soft foot will be rim to rim vertical and horizontal mode.
.1 Soft foot of motor shall be checked to be within a tolerance of 0.03 mm
.2 Shaft shall be aligned within a tolerance of ±0.025 mm to 0.070 mm
.3 Piping strains to pump shall be within a tolerance of ±0.025 mm to 0.070 mm
19.7 Equipment Maintenance Requirements
Provide a minimum of one (1) meter of clear space around all equipment for maintenance work.
For equipment that requires replacing in the future, it shall be provided with electrical and
mechanical isolation devices to permit removal without interfering with the operation of the
process or facility. Isolation devices shall be as close to the equipment as possible and shall not
require the use of a ladder for access. Isolation devices must be visible from the equipment to be
removed.
In designing the layout of the equipment, the Consultants shall make provisions for its removal.
No equipment shall be designed such that it cannot be removed and if it is to be designed in that
manner, the intention must be identified by the Consultants and accepted by WASA. In addition,
all required lifting devices for removal of equipment must be in place or can be put in place to
facilitate its removal. All lifting device shall be engineered for the purpose intended.

170. Water And Sewerage Authority (WASA)
Water and Wastewater Design Guideline Manual Ventilating & Air Conditioning Standards
20-1 October 2008
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Section 20 Ventilating & Air Conditioning Standards
20.1 General
Comply with applicable Acts, Codes or Design Guidelines as detailed in Section 3.0, Design
Standards and also with The Trinidad & Tobago Building Code.
Installation shall meet and/or exceed the requirements of:
a) ASHRAE Guide and Data Book
b) SMACNA Sheet Metal and Duct Construction Standards (Low and High Velocity)
c) CIBS Building Services Code
d) CIBS Commissioning Codes
e) ARI Standards
f) Other relevant ASHRAE, SMACNA and ARI publications
g) Trinidad & Tobago ASHO Act
20.2 VAC System
The ventilation systems shall be designed to maintain acceptable working and living
environments for personnel and non-destructive conditions for equipment. H2S gas detectors
shall be installed when such risks are present to working staff in wastewater treatment plants or
pumping stations.
Provide the proper design, sizing and selection of equipment according to the purpose of each
specific room or space. Humidity, temperature and rates of ventilation should be properly
determined according to each specific environment to meet all codes and security standards. The
design shall take into account both normal and emergency operation requirements.
Provide separate ventilation systems in laboratories.
Ventilation openings shall be screened with a sufficiently fine mesh to prevent entry by birds,
rodents, snakes, and bugs.
Provide air conditioning or humidity control when electronic equipment (Control panel) is
located in a room.
Power supply of equipment should be compatible with the new, future or existing site building.
Provide refrigeration piping, chill water piping and condensate drainage when required.
Engineering site supervision should be provided during construction.

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Project Design and Technical Specifications Manual Ventilating & Air Conditioning Standards
20-2 October 2008
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20.3 Minimum Air standard
Ventilation networks shall be designed in order to avoid any hazard or discomfort by the
working staff in the plants. The concentration of pollutants shall meet at minimum the following
guidelines:
H2S : 4 mg/Nm3
or less
NH3 : 3 mg/ Nm3
or less
Methyl Mercaptan : 1 mg/ Nm3
or less
20.4 System Redundancy
Where ventilation is designed to assure security of workers, per example to avoid intoxication by
H2S emanations in wastewater treatment plants, the system must be of a higher quality and more
robust. The robustness consists, but is not limited to, assuring 100% redundancy of ventilation
systems, in order to avoid any hazard for the working staff in the plants.
20.5 VAC Control System
Controls for the VAC system shall be digital with individual Application Specific Controllers
(ASCs) for each zone. Avoid the use of pneumatic control systems.
Design the system to permit verification of cooling demand of the VAC system and provide all
necessary field instrumentation.
20.5.1 VAC Master Control
The cooling requirements for each zone shall be achieved by a dedicated control unit linked to
the master control system. However, the zone control unit must be capable of being over-ridden
manually from the VAC master control system.
20.6 Verification of VAC System
Consultants should request from the contractor that they provide all as-built drawings, Operation
and Maintenance manuals for review and approval upon completion of project. They also have to
emphasise shop drawing’s review for mechanical equipment and materials prior to purchase by
contractors.
20.7 Location of air intakes
The Consultants must consider the source and direction of the upwind to allow for adequate
positioning of air intakes for the VAC system. As a general rule, the prevailing wind in Trinidad
& Tobago is from the North East.

172. Water And Sewerage Authority (WASA)
Water and Wastewater Design Guideline Manual Diesel Generator Standard
21-1 October 2008
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Section 21 Diesel Generator Standard
21.1 General
This section covers the requirements for the design and installation of diesel generators and all
related ancillary equipment.
21.2 Power Supply
Where possible, all plants shall be provided with two feeds from local utility power supply grid
network. Where this requirement can be met, the provision of standby diesel generators may not
be required.
Comply with Section 4.4 Standby Power, for the installation of diesel generator in the facility.
Where required by WASA, the Consultants shall specify the required synchronizing equipment
to permit the generator to synchronize with local power supply grid for peak shaving.
Power ratings for standby power are defined by ISO 8528-1 as the power available in the event
of a main power network failure up to a maximum of 500 hours per year of which up to 300
hours may be run continuously. Load factor may be up to 100% of standby power. No overload
is permitted.
21.3 Approvals
The Consultants are responsible for securing of all required approvals including the EMA and
WASA and/or any other such regulations or Acts etc, that are in force at the time of award of the
engineering assignment.
Determine the output capacity of the generator in accordance with the facility backup power
requirements.
Prepare, submit and obtain approval for noise attenuation requirements for the proposed
emergency diesel generator and emissions.
21.4 Noise Attenuation
Arrange for a qualified Acoustics Engineer to prepare a noise attenuation report. Noise level
shall be site specific and provide adequate protection to operators. Consult Trinidad & Tobago
regulations such as the OSHA Act and Noise Pollution Control Rule.

173. Water And Sewerage Authority (WASA)
Project Design and Technical Specifications Manual Diesel Generator Standard
21-2 October 2008
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21.5 Diesel Generator Power Requirements
21.5.1 Water Supply System
For potable water supply pumping stations, where the water distribution system floats on a
storage reservoir, the diesel generator shall be sized to meet the pump(s) electrical power
requirement for the average day demand.
Ensure that the generator is capable of meeting the inrush power demand under all operating
conditions. Specify reduced voltage starting for electric motors. Sequence pumps are to come on-
line one at a time when power fails and power supply is from the generator.
In a closed loop system where system storage is not available, the standby power shall be sized
to meet the pumping system power requirements for maximum hour plus fire flow demand.
21.5.2 Wastewater Pumping Station
For wastewater pumping stations, the standby power generator requirements are identical to the
water supply system requirements and it shall be sized to meet the pumping system power
demand under peak flow conditions.
21.5.3 Ancillary Electrical and Mechanical Equipment
In addition to the above, provide electrical power from the diesel generator to the following
during power outages:
1. ventilation system
2. SCADA system
3. Chemical system (where applicable)
4. Blowers for aeration system (for wastewater treatment plant)
21.6 Diesel Generator System Operation
The diesel generator is required to meet the power demand of the facility in the event of local
power supply grid network power outages in order to maintain minimum operation services. The
equipment that is to be maintained in service by the diesel generator will be reviewed and
finalized at the Pre-Design stage.
An automatic transfer switch in compliance with UL 1008 standard, shall be included as part of
the diesel generator power supply system. The automatic transfer switch senses power outage
and:
• initiates start-up of the diesel generator;
• automatically transfers power supply to the emergency generator;
• on resumption of normal power supply, transfers load back to normal power supply;
• times the engine running without load and allows it to cool down and then shuts it off.

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21.7 Diesel Engine Requirements
21.7.1 General
1. The perspective of a bi-fuel engine must be assessed in the preliminary stage or as indicated
by WASA.
1.2.The diesel engine net continuous power output at the engine flywheel, including de-rating
and deductions, shall be equal to the generator net input power. The power rating should be
rated for Standby power.
2.3.Diesel engine operating speed shall be 1800 revolution per minute, unless otherwise
approved by WASA.
3.4.Engine shall be naturally aspirated or turbo charged, two or four stroke cycle with
pressurized induction having a minimum of four cylinders and removable wet liner. It must
be suitable for operation on commercial Grade No.2 diesel fuel oil.
4.5.Engine shall conform to EPA Tier 1-3 Emissions standards.
21.7.2 Flame Detection System
1. Dedicated infrared flame detector sensors shall be supplied and installed for each diesel
generator and integrated into the fire alarm panel and monitored as individual alarm zones.
2. Infrared flame detector sensors shall also be monitored by the PLC and an alarm shall be sent
to the plant Central Control Room.
21.7.3 Fuel System
1. Fuel system shall include injection equipment including fuel pump(s) and injectors with fuel
rack or shutdown solenoid, energised to run (maximum fuel at start) and lift pump with the
required minimum suction lift capability with check valves to maintain prime.
2. It shall be supplied with factory installed primary filter(s) and a secondary fuel filter/water
separator. Fuel filter(s) shall be of the replaceable element type.
3. Fuel line piping shall be fully secured to the engine for the fuel supply, injector and bleed
return. Provide flexible connectors, bronze corrugated type for the suction and return lines,
located in a horizontal plane and secured at one end to the engine base.
4. Fuel line shall be provided with automatic shut-off system which may be initiated by the
PLC following a signal.
21.7.4 Speed Governor
1. Diesel engine speed governors shall be mechanical or hydraulic type and shall be provided
with micrometer screw type manual speed adjustment, shutdown lever and over speed stop.
2. Engine speed shall be maintained at plus or minus two (2) percent regulation, steady state,
and at eight (8) percent speed regulation, transient peak no load to full load and full load to
no load and at plus or minus one (1) percent stability at any constant load and free from
further hunting or oscillation.
Formatted: Bullets and Numbering

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3. The recovery time, from start of load to steady state condition, shall be better than three (3)
seconds.
21.7.5 Fuel Tank
1. All diesel fuel tanks shall have a Vent to the exterior.
2. In addition to the integrated day tank, fuel tanks shall be provided and sized for 48 hours of
continuous operation of the emergency standby diesel engine operating under full load.
3. Fuel tanks shall be of the double walled type and shall be floor mounted, with tapped
connections for fill, vent, supply, return and drain. It shall be provided with a sight-glass for
fuel level indication and condensate drain and cock.
4. Provide fuel level indicator(s) at the loading station. All required fuel line accessories shall
be provided including manual shut-off valve and primary fuel filter, all with nipples required
for connection.
21.7.6 Oil Lubricating System
Oil pumps must be engine driven gear type, with strainers and adjustable pressure relief valves,
full pressure lubrication systems complete with oil filter(s) full flow element types and a sump
drainpipe with gate valve and plug to extend 100 mm beyond bedplate.
21.7.7 Intake and Exhaust System
1. Air intake filter shall be of the dry replaceable element type located close to the inlet
manifold.
2. Exhaust silencer shall be provided with condensate cock, plug and ASA flanges. Silencer
capacity is to be sized so that the backpressure at the engine when loaded at 110% capacity,
shall not exceed the manufacturer’s recommendation.
3. The noise emitted from the exhaust pipe shall not exceed the limits for the stationary engines,
which requires that the noise at the property line shall not exceed 50 dbA in residential areas.
This will dictate the type of silencer that will be required for the diesel engine.
21.7.8 Cooling System
1. Cooling of diesel engines by municipal water is not permitted under any circumstances and
engines shall be cooled by a radiator complete with fan, shroud, fan guard and air duct
adaptor flange.
21.7.9 Ventilation System
1. Ventilation systems shall be complete with fans; dampers etc to meet the required air volume
for engine combustion and ventilation requirements.
2. Ventilation fans and dampers must be operating before the diesel engine is permitted to start.
3. Separate ventilation shall be provided for the room.

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21.7.10 Gauges
1. The following gauges shall be provided as a minimum:
.1 Lube oil pressure gauge
.2 Lube oil temperature gauge
.3 Coolant temperature gauge
.4 Electrical tachometer gauge, scaled in rpm to approximately 120 percent of rated speed
.5 Exhaust pyrometer(s)
21.7.11 Battery Start System
1. Diesel engines shall be started by an electrical cranking motor with power provided from
storage batteries, which may either be 12 or 24 volts system.
2. Battery charger to be specified for 230 volts AC input. Locate charger outside the control
panel.
21.7.12 Failure Annunciator
1. Annunciators shall be of individual visual type with long life lamp(s) removable from the
panel front complete with manual alarm reset features and clearly labelled.
2. Relays shall be dry relay contacts with 230 V, 3 A minimum contacts. Relay shall be
normally closed and to open under alarm conditions. Provide a common alarm relay for:
.1 Over-crank – nominal setting 20 seconds
.2 Overspeed – nominal setting 110 percent rated speed
.3 Low oil pressure – nominal delay 10 seconds
.4 High engine temperature
21.8 Generator Requirements
21.8.1 General
1. Generator shall be sized to meet the standby power loading requirements. Generator output
supply shall be 400/230V, 3 phase 60 Hz, unless specified otherwise. It shall be horizontal
synchronous type in protected enclosure with ground lug and readily accessible terminal box.
2. The generator revolving field shall be of amortisseur winding and have a brushless exciter
connected directly to the generator shaft, with easily removal bolt-on diodes.
3. It shall be provided with Class H insulation or better.
4. It shall be provided with protective devices to sense generator overload condition and supply
output contacts for SCADA and/or generator trip function.

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21.8.2 Voltage Regulator
1. Voltage regulator shall be an automatic, static type with ‘Fail-safe’ features, i.e. no excess
voltage if the regulator fails when located on the engine control panel.
2. Control potentiometers arranged for clockwise rotation to increase the related function.
Control rheostat or tapped choke, voltage range shall be plus or minus 2 percent of nominal
volts.
3. It shall be capable of generator voltage build-up without batteries and protected against fault
during under speed running.
21.9 Control System
Refer to Section 17 – Instrumentation & Control and Section 18 – SCADA System for control
system requirements.
Control panel shall have the following controls:
• manual Start/stop control switch
• Man-Auto-off Switch
• Battery condition monitor
• Current / voltage monitoring on all phases
• Frequency meter
• Rune time meter
• kWh meter
Alarms relays shall transmit the followings signals to the SCADA system:
• Start
• Stop
• Uncommanded stop
• Overload
• High temperature
• Overspeed
• Infrared flame detection

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Section 22 Treatment Plant Operation Manual
22.1 General
The Consultants shall prepare the structure and format of the Operation Manual for water and
wastewater treatment plants as follows.
The Unit Operation Descriptor shall conform, as a minimum, to the included table of contents of
the Manual. A Descriptor is a typical task to be performed for a Unit Operation. Depending on
the Unit Operation, it may or may not require all of the Descriptor listed in a table of contents.
22.2 Operation Manual Requirements
The Operation Manual shall be prepared in Microsoft WORD, version currently used by WASA,
or as an online interactive document running under Microsoft Windows XP or VISTA. The
Consultants shall ensure that the online text version, CD-ROM copy and the hard copy version
must be identical. Date of issue of CD-ROM and hard copy must also be clearly identified.
22.3 Format of Operation Manual
The Consultants are required to prepare and submit hard copies. In addition, submit two
complete sets of CD-ROM of the Operation Manual when approved by the Project Manager.
The hard copy of the Operation Manual shall be bound in binders.
The spine of the binder shall be lettered with the full identification title of the project e.g.
[Name of Plant] WASTEWATER TREATMENT PLANT
PROJECT No.
The front cover of the manual of the respective binders to be printed as follows:
POMORIE WASTEWATER TREATMENT PLANT
PROJECT NO.
OPERATION MANUAL
VOLUME 1
CONSULTANT:

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22.4 Water Treatment Plant Operation Manual
The following is the Table of Contents for Water Treatment Plant Manual:
1. Table Of Contents
2. Introduction
2.1 Record of Revision
2.2 Title Page
2.3 Acknowledgement
2.4 Table of Contents
3. Operation Manual Overview
3.1 Technical Information
3.2 Operation Manual Organization
Section 1: Introduction
Section 2: Operation Manual Overview
Section 3: Plant Overview
Section 4: Unit Operations
Section 5: Design Parameters & Dimensions of Each Process Unit
Section 6: Appendices
4. Plant Overview
4.1 General
4.2 Plant History
4.3 Utility Classification
4.4 Operator Classification
4.5 Distribution System Classification
4.6 Certificate of Approval and Design Brief
4.7 Water Quality
4.8 Public Relations
4.9 Plant Tours
4.10 Requests for Information/Literature
4.11 Complains
4.12 Vandalism/Theft
4.13 Spill/Pollution
4.14 Injuries
5. Detailed Unit Operations
5.1 SOURCE
10 Lake
20 River
30 Groundwater
5.2 RAW WATER HANDLING
10 Intake
20 Intake Pipe

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30 Screening
40 Low Lift Pumping
50 Pipeline
5.3 PARTICULATE REMOVAL
10 Microstraining
20 Flash Mixing
30 Flocculation
40 Clarification
50 Filtration including membrane ultra filtration or sand
60 Filter Backwash System
70 Sludge Handling
5.4 DISINFECTION
10 Pre-Chlorination
20 Post Chlorination
5.5 OTHER PROCESSES
10 Taste and Odour Control
20 pH Control
30 Fluoridation
40 Coagulation
50 Coagulation Aid
60 Dechlorination
5.6 STORAGE AND TRANSMISSION
10 Clearwell
20 Reservoir
30 High Lift Pumping
40 Elevated Tanks
50 Pumping Stations
60 Pressure Zones
70 Distribution System
5.7 COMMON UTILITIES
10 Heating, Ventilating, Air Conditioning
20 Plant Service Water
30 Plant Instrumentation/Air
40 Power Supply and Distribution
50 Emergency Standby Diesel Generator
60 Security/Alarm System
70 Communications
80 Supervisory Control and Data Acquisition
90 Laboratory

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6. Appendices
6.1 REFERENCE
6.2 CONVERSION TABLE
6.3 DIRECTORIES
Plant Personnel
Treatment Plants
Municipal Participants
MOE Personnel
Local Contractors
Equipment Service Representatives
Emergency
Media
6.4 FORMS
Index
6.5 GLOSSARY
Acronyms and Abbreviations
Water Treatment Chemicals
General terms
7. List of Figures
8. Drawing Number/Section/Title
9. “As-Built” Contract Drawing Title
22.5 Wastewater Treatment Plant Operation Manual
The following is the Table of Contents for Wastewater Treatment Plant Operation Manual:
1. Table Of Contents
2. Introduction
2.1 Record of Revision
2.2 Title Page
2.3 Acknowledgement
2.4 Table of Contents
3. Operation Manual Overview
3.1 Technical Information
3.2 Operation Manual Organization
Section 1: Introduction
Section 2: Operation Manual Overview
Section 3: Plant Overview
Section 4: Unit Operations
Section 5: Design Parameters & Dimensions of Each Process Unit
Section 6: Appendices

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4. Plant Overview
4.1 General
4.2 Plant History
4.3 Utility Classification
4.4 Operator Classification
4.5 Wastewater Collection System
4.6 Certificate of Approval and Design Brief
4.7 Wastewater Effluent Quality
4.8 Public Relations
4.9 Plant Tours
4.10 Requests for Information/Literature
4.11 Complains
4.12 Vandalism/Theft
4.13 Spill/Pollution
4.14 Injuries
5. Detailed Unit Operations
5.1 WASTEWATER PUMPING STATIONS
10 Wastewater Pumping Stations
20 Odour Control
5.2 PRETREATMENT
10 Inlet
20 Fine Screening
30 Screenings Compactor
40 Grit Removal
50 Odour Control
5.3 PRIMARY CLARIFICATION
10 Primary Clarifier
20 Primary Sludge Pumping Facility
30 Primary Scum Pumping Facility
40 Odour Control
5.4 AERATION SYSTEM
10 Aeration Tank
20 Air Blower Equipment
30 Fine Bubble Diffuser System
40 Dissolved Oxygen Control
50 Odour Control
5.5 SECONDARY CLARIFICATION
10 Secondary Clarifier
20 Return Activated Sludge Pumping
30 Secondary Scum Pumping
40 Odour Control

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5.6 SLUDGE THICKENING/DEWATERING FACILITIES
10 Waste Activated Sludge
20 Digested Sludge
30 Thickening
40 Dewatering
50 Odour Control
5.7 INCINERATION
10 Preheating
20 Sludge Feed
30 Continuous Emissions Monitoring
40 Gas Scrubbing
50 Auxiliary Fuel System
60 Fluidized Bed (Air/Sand)
5.8 FLOW METERING FACILITIES
10 Metering Facilities
5.9 CHLORINATION FACILITIES
10 Chlorination Storage Facilities
20 Chlorine Contact Tank
5.10 CHEMICAL TREATMENT FACILITIES
10 Chemical Feed Systems
20 Chemical Storage Facilities
5.11 AEROBIC/ANAEROBIC DIGESTION FACILITIES
10 Aerobic/Anaerobic Digester
20 Sludge Handling Facilities
30 Odour Control
5.12 ULTRA-VIOLET DISINFECTION SYSTEM
10 Ultra-Violet Disinfection System
20 UV Lamp Cleaning System
5.13 VENTILATION & AC
10 Administration Facility
20 Pre-Treatment Facility
30 Wastewater Pumping Station
40 Blower Building
50 Sludge Dewatering Facility
60 Tertiary Treatment Facility
70 UV Disinfection Facility
80 Digester Gas Control Building

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5.14 SLUDGE LOADING/UNLOADING FACILITY
10 Digested Sludge Loading Facilities
20 Digested Sludge Pumping Facility
30 Digested Sludge Overflow Control & Cleanup
5.15 POWER SUPPLY AND DISTRIBUTION
10 Administration Facilities
20 Wastewater Pumping Station
30 Air Blower Building
40 Return Sludge Pumping Facility
50 Sludge Dewatering Facility
60 Emergency Standby Diesel Generator
70 UV Facilities
5.16 SAMPLING & MONITORING
10 Equipment
20 Raw/Activated Sludge Sampling
30 Digested Sludge Sampling
40 Flow Monitoring
50 Influent
60 Effluent
70 Dewatered/Thickened Sludge Sampling
80 Sludge blanket level monitoring
90 Dissolved Oxygen Monitoring
5.17 SAFETY & SECURITY
10 General
20 Sewers
30 Confined Spaces
40 Electrical Hazards
50 Mechanical Equipment Hazards
60 Explosion and Fire Hazards
70 Bacterial Infection Hazards
80 Chlorine Hazards
90 Ferrous/Ferric Chloride Hazards
100 UV Hazards
110 Safety Equipment
120 Process Chemical Handling & Storage
130 Facility Security
140 Emergency Response Program
150 References
160 WASA Compliance Manual
5.18 MAINTENANCE RECORDS
10 Process Operations and Daily Operating Reports
20 Monthly Reports

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30 Annual Reports
5.19 SUPERVISORY, CONTROL AND DATA ACQUISITION
10 Refer to SCADA Operation Manual
6. Appendices
6.1 REFERENCE
6.2 CONVERSION TABLE
6.3 DIRECTORIES
Plant Personnel
Treatment Plants
Municipal Participants
WASA Personnel
Local Contractors
Equipment Service Representatives
Emergency
Media
6.4 FORMS
Index
6.5 GLOSSARY
Acronyms and Abbreviations
Wastewater Treatment Chemicals
General Terms
7. List Of Figures
8. Drawing Number/ Section/Title
9. “As-Built” Contract Drawing Title
22.6 Training on the Use of the Operation Manual
The Consultants will be required to train the operators on the use of the Manual.
Prior to the project being closed out, the Consultants are required to:
1. Revise and bring the Manual completely up to date
2. Provide two copies of the Manual on a CD-ROM
3. Revise and bring the hard copies up to date

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22.7 Training of WASA Staff
22.7.1 Training Provided by the Contractor
Consultants shall integrate measures for providing training to WASA’s personnel/operators by
skilled trainers retained by the General Contractor specifically for the purpose, in the proper
operation and maintenance of the equipment and systems provided and installed under his
contract.
The following information shall be submitted:
1. Lesson planned for each training session by the manufacturer’s representatives.
2. All training manuals, handouts, visual aids and other reference materials shall be provided to
attendees.
3. Date, time, and subject of each training session and identity the qualifications of the
individuals to be conducting the training.
4. Concurrent classes will not be allowed in training schedule.

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Section 23 CARTOGRAPHIC CONCEPTS
CARTOGRAPHY
Cartography is the art, science and technology of making maps, together with their study as
scientific documents and works of art. It is also the process of designing compiling and
producing maps.
Section 24 THE COMMUNICATION CHANNEL
As a Cartographer, CAD Designer or GIS Operator, you must be aware of the vital responsibility
to communicate as clearly as possible, to produce a useful map.
The following channel of communication is noted:
• From REALITY - (The Geographic Environment), a number of exercises can be done:
CENSUS; SURVEYS; REMOTE SENSING and COMPILATION.
• Information received is recognized by the CARTOGRAPHER or GIS OPERATOR and a
series of steps follows that can be termed GENERALISATION. They are: SELECTION’
CLASSIFICATION; SIMPLIFICATION and SYMBOLIZATION.
• Producing a MAP that the MAP USER can do the following easily: READING; ANALYSIS
and INTERPRETATION.
• Finally having THE MENTAL IMAGE OF REALITY by imagining what is supposed to be
there.
24.1 OBJECTIVES & LIMITATIONS AFFECTING DESIGN
MAP CREATION (Objectives)
• Convey geographic information.
• Highlight important geographic relationships.
• Illustrates analysis results.
CARTOGRAPHIC DESIGN (Factors)
• Objective: Determines the map’s final form.
• Audience: Determines the map’s level of complexity.
• Reality: Determines the authenticity of the portrayed facts.
• Scale: Determines how much information can be placed on the map sheet.
• Technical Limits: Determines the quality of what can really be produced using available
hardware and software.
• Thematic Limits: Determines how far to reduce the number of thematic categories.
• Locational

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• Generalization: Determines, for the purpose of enhancing clarity, how far to move a feature
from its original location, or how far to reduce the number of co-ordinates depicting a
feature.
Section 25 SYMBOLOGY used in QUANTITATIVE and QUALITATIVE
CARTOGRAPHY
a. Qualitative Symbology: Whatever symbols chosen should not show relative importance,
unless its necessary to highlight one or more features, so that they stand out.
b. The SHAPE, COLOUR, TEXTURE and ORIENTATION / ARRANGEMENT of symbols
are varied to show differences.
c. Quantitative Symbology: Data describing relative importance (e.g. more or less - and high
verses low) and other numeric data showing numeric differences.
d. The SIZE, COLOUR, VALUE and INTENSITY of symbols are varied to show differences.
25.1 THE BASIC STEPS FOR MAP DESIGN
There are three basic steps in Map Design:
1. The initial Imagination / Visualization.
2. The Development of a Graphic Plan.
3. The Preparation of Specifications.
Design HINTS to improve your maps.
Remember: ...
• Colours on the computer screen and on paper do not necessarily appear the same.
• Not everyone has 20/20 vision.
• Your taste may not represent that of the majority.
• Consider the final production process.
• Select useful symbol properties to suit the purpose.
• The overall theme of the map must be known & seen at a glance.
25.1.1 GENERALIZATION
Generalization is the process involving selection, classification, simplification, and finally
symbolization. There are two types, like there are two (2) types of maps, THEMATIC and
LOCATIONAL.
25.1.1.1 SYMBOLOGY - Classes of Symbols
There are four (4) basic symbol classes:
1. POINTS : To display point features at certain x,y locations.
2. LINES : To display linear features that are series of x,y locations.
3. AREAS : To display any two (2) dimensional areal extent bounded by a set of lines.
4. TEXT : To display descriptive information about features.

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Section 26 THE GRAPHIC CHARACTERISTICS & INTERPRETATIONS
The graphic characteristics are as follows:
• COLOUR : red, yellow, green, etc.
• GRAYTONE/VALUE : how light or dark the colour is.
• SIZE : how large or small the symbol is.
• SHAPE : the symbol’s form (i.e. circular, triangular etc.)
• TEXTURE : The spacing of the component marks within the symbol.
• ORIENTATION : the direction of arrangement of elongated symbols or the direction of
components within the symbol.
• PLACEMENT : the location of the map components within the visual field.
26.1.1.1 PERCEPTION OF GRAPHIC VISUALS
It is said that the human brain perceives a graphic image in a series of consecutive, organized
steps.
1. The image or graphic visual is taken in.
2. The eye isolates more important visual elements.
3. Followed by the visual elements of lesser importance.
26.1.1.2 EYE LIMITATION
The human eye cannot distinguish between more than twelve (12) colours at one time. It cannot
distinguish more than seven or eight different shades of the same colour in a single view.
26.1.1.3 TEXTURE VIBRATION
A symbol component that occupies 50% of a given space creates a visually unpleasant effect.
Section 27
Section 28 CARTOGRAPHIC DESIGN ISSUES
28.1 CLARITY & LEGIBILITY
ls used in cartography must be clear and legible. They must be precisely and correctly delineated. They must be
large enough so that they can be easily read at the viewer’s distance from the map.
28.1.1.1 VISUAL CONTRAST
This is the most important element in Cartography Design. By this, it is possible to identify the
different symbols used in a map.

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28.1.1.2 PATTERNS
This is the systematic repetition of a mark within an area.
VISUAL BALANCE
Deals with laying out the map’s basic shapes in such a way, that the selected shapes appear to be
in balance throughout the entire map.
VISUAL HIERARCHY
This can be created by varying the graphic characteristics.
COLOUR
Colour gives the Cartographer an additional, powerful, array of tools to work with in designing
effective graphic images. It has become essential in many situations.
TEXT
Like “Visual Contrast”, TEXT is a critical element in Cartographic Design. It conveys critical
information to the map-reader. The following text characteristics must be adhered to:
• Typeface and font.
• Size and scale.
• Spacing.
• Colour.
• Contrast to background.
Section 29 PLANNING A MAP’S DESIGN & LAYOUT
In planning a design and layout the following topics must be kept in mind:
• The Graphic Outline : This is the ‘key’ initial step.
• The Geographic Features : This comprise features from coverage (multiple or portions of)
from your
database. This is referred to as “Map Body”.
• Other Map Objects : These are objects that assist in interpreting the geographic
information.
e.g. Title, Legend, North Arrow, Scale Bar, Neat lines, Source Information and Descriptive Text.
29.1
29.2
CARTOGRAPHIC PRODUCTION STANDARDS
Introduction
The GIS Section produces several different types of maps and as such the need to have standard
formats to plot them is important. The following are currently used as standardize:

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..1.1.1 LINE FEATURES
THEME TYPE THICKNESS COLOUR
LABEL TEXT
COLOUR FONT SIZE
RIVERS ALL 0.01 to 2.0 BLUE BLUE ARIAL 3.5 to 7.0
ROADS MAIN 0.01 to 2.0 GRAY 80% 50% GRAY ARIAL 3.5 to 7.0
ROADS ALL OTHERS 0.01 to 2.0 GRAY 50% 40% GRAY ARIAL 3.5 to 7.0
WATER MAINS ALL 0.01 to 2.0 RED RED 3.5 to 7.0
SEWER MAINS ALL 0.01 to 2.0 GREEN GREEN 3.5 to 7.0
COAST 0.01 to 2.0 BLACK
BOARDERS MAP AREA 0.25 to 5.0 BLACK
LAYOUT 0.25 to 3.0 BLACK
POINT FEATURES
FEATURE TYPE
SIZ
E COLOUR SYMBOL
FILE/SYMBOL
LIBRARY
BUILDINGS 2-40
GRAY
80%-30% SQUARE 1 ESRI
APPURTENANCES LEGEND 1. AVL
MAN HOLE SEWER 5-10 BLACK MANHOLE
WATER/WASTE
WATER
GUAGE RAINFALL
10-
40 BLUE WATER
ENVIRONMENT
AL
STREAM 10- BLUE CIRCLE 18 ESRI

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20
WELLS
OBSERVAT
IONS 5-40 GREEN
WELL
DRILLED
INDUS. VTILITIES
PRODUCTI
ON 5-40 BLUE
WELL
DRILLED
INDUS. VTILITIES
SPRING 5-20 RED CIRCLE 21 ESRI
INTAKE 5-20 GREEN TRIANGLE 7 ESRI
STORAGE TANK
10-
40 BLUE
ENCLOSED
STORAGE
WATER/WASTE
WATER
WATER
TREATMENT
PLANT
10-
30 BLACK
TREATMENT
PLANT
WATER/WASTE
WATER
BOOSTER
STATIONS
10-
30 BLACK
PUMP
STATION
WATER/WASTE
WATER
SEWER
TREATMENT
PLANT
10-
30 GREEN STEP TRANS UTILITIES
SEWER PUMPING-
STATION
10-
30 BLACK LIFT STATION
WATER/WASTE
WATER
POLYGON FEATURES
THEME
Section 30 TYPE/NAME OUTLINE
WIDTH
FILL
COLOUR
LABEL TEXT
COLOUR FONT SIZE
BUILDINGS PRESIDENTIAL 0-1
SODALITE
BLUE
COMMERCIAL 0-1 LIGHT APPLE
PUBLIC 0-1 DARK AMBER
GOVERNMENT 0-1 HELIOTROPE
POLICE STATION 0-1
CRETEAN
BLUE
POST OFFICE 0-1 FIR GREEN
FIRE STATION 0-1 MARS RED

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T&TEC 0-1
SOLAR
YELLOW
TSTT 0-1 PEONY PINK
SCHOOL 0-1
SAHARA
SAND
RELIGIOUS 0-1
OLIVENITE
GREEN
HOSPITALS/HEALTH C 0-1
SEVILLE
ORANGE
INDUSTRIAL 0-1 60% GRAY
COUNTIES ST GEORGE 0.5 to 5
ROSE
QUARTZ BLACK
ARIAL-
BLACK 5-50
ST DAVID 0.5 to 5 LIGHT APPLE BLACK
ARIAL-
BLACK 5-50
ST ANDREW 0.5 to 5 30% GRAY BLACK
ARIAL-
BLACK 5-50
CARONI 0.5 to 5
SODALITE
BLUE BLACK
ARIAL-
BLACK 5-50
NARIVA 0.5 to 5
RHODOLITE
ROSE BLACK
ARIAL-
BLACK 5-50
VICTORIA 0.5 to 5
YUCCA
YELLOW BLACK
ARIAL-
BLACK 5-50
ST PATRICK 0.5 to 5
BERYL
GREEN BLACK
ARIAL-
BLACK 5-50
MAYARO 0.5 to 5 SUGILITE SKY BLACK
ARIAL-
BLACK 5-50
THEME TYPE/NAME
OUTLINE
WIDTH
Section 31 FILL COLOUR
LABEL TEXT
RED GREEN BLACK COLOUR FONT SIZE
WARDS Erin 0.25 to 3.0 190 232 255 Black Arial Black 3-30
Toco 0.25 to 3.0 211 255 190 Black Arial Black 3-30
Blanchisseuse 0.25 to 3.0 178 178 178 Black Arial Black 3-30
St.Anns 0.25 to 3.0 255 190 190 Black Arial Black 3-30
Valencia 0.25 to 3.0 211 255 190 Black Arial Black 3-30

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THEME TYPE/NAME
OUTLINE
WIDTH
Section 31 FILL COLOUR
LABEL TEXT
RED GREEN BLACK COLOUR FONT SIZE
Diego Martin 0.25 to 3.0 255 255 190 Black Arial Black 3-30
Matura 0.25 to 3.0 255 190 232 Black Arial Black 3-30
Tacarigua 0.25 to 3.0 190 210 256 Black Arial Black 3-30
Arima 0.25 to 3.0 233 255 190 Black Arial Black 3-30
POS 0.25 to 3.0 232 190 255 Black Arial Black 3-30
Moruga 0.25 to 3.0 255 235 190 Black Arial Black 3-30
Manzanilla 0.25 to 3.0 190 255 232 Black Arial Black 3-30
Cunupia 0.25 to 3.0 156 156 156 Black Arial Black 3-30
Tamana 0.25 to 3.0 255 127 127 Black Arial Black 3-30
Cedros 0.25 to 3.0 255 255 115 Black Arial Black 3-30
Turure 0.25 to 3.0 115 255 223 Black Arial Black 3-30
San Rafael 0.25 to 3.0 223 115 255 Black Arial Black 3-30
Chaguanas 0.25 to 3.0 178 178 178 Black Arial Black 3-30
Couva 0.25 to 3.0 255 167 127 Black Arial Black 3-30
Montserrat 0.25 to 3.0 209 255 115 Black Arial Black 3-30
Charuma 0.25 to 3.0 115 223 255 Black Arial Black 3-30
Cocal 0.25 to 3.0 255 115 223 Black Arial Black 3-30
Point-A-Pierre 0.25 to 3.0 190 232 255 Black Arial Black 3-30
Guayaguayare 0.25 to 3.0 104 104 104 Black Arial Black 3-30
Savana Grande 0.25 to 3.0 211 255 190 Black Arial Black 3-30
Ontoire 0.25 to 3.0 255 255 190 Black Arial Black 3-30
Naparima 0.25 to 3.0 255 190 232 Black Arial Black 3-30
San Fernando 0.25 to 3.0 190 210 255 Black Arial Black 3-30
Trincity 0.25 to 3.0 233 255 190 Black Arial Black 3-30
La Brea 0.25 to 3.0 232 190 255 Black Arial Black 3-30
Siparia 0.25 to 3.0 255 235 190 Black Arial Black 3-30
DISTRICTS North East 0.5 to 50 190 232 255 Black Arial Black 5-50
North West 0.5 to 50 210 255 190 Black Arial Black 5-50
North Central 0.5 to 50 178 178 178 Black Arial Black 5-50
Port-of Spain 0.5 to 50 255 190 190 Black Arial Black 5-50
San
Fernando/Central 0.5 to 50 211 255 190 Black Arial Black 5-50
South East 0.5 to 50 255 255 190 Black Arial Black 5-50
South West 0.5 to 50 255 190 232 Black Arial Black 5-50

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THEME TYPE/NAME
OUTLINE
WIDTH
Section 31 FILL COLOUR
LABEL TEXT
RED GREEN BLACK COLOUR FONT SIZE
HYDROLOGICAL North Coast 0.5 to 50 190 232 255 Black Arial Black 5-50
North Oropouche 0.5 to 50 210 255 190 Black Arial Black 5-50
West 0.5 to 50 178 178 178 Black Arial Black 5-50
Peninsula/Caroni 0.5 to 50 255 190 190 Black Arial Black 5-50
Nariva 0.5 to 50 211 255 190 Black Arial Black 5-50
Central/West Coast 0.5 to 50 255 255 190 Black Arial Black 5-50
Ortorie 0.5 to 50 255 190 232 Black Arial Black 5-50
Southern Range 0.5 to 50 190 210 255 Black Arial Black 5-50
South Oropuche 0.5 to 50 233 255 190 Black Arial Black 5-50
Cedros Peninsula 0.5 to 50 232 190 255 Black Arial Black 5-50
DISTRIBUTION Toco 0.25 to 2.0 190 232 255 Black Arial Black 2-20
San Juan-Santa
Cruz 0.25 to 2.0 211 255 190 Black Arial Black 2-20
D'abadie (Arouca) 0.25 to 2.0 178 178 178 Black Arial Black 2-20
Tacarigua
(Tunapuna) 0.25 to 2.0 255 190 190 Black Arial Black 2-20
Ariam (North) 0.25 to 2.0 211 255 190 Black Arial Black 2-20
Ariam (South) 0.25 to 2.0 255 255 190 Black Arial Black 2-20
Diego Martin
(North) 0.25 to 2.0 255 190 232 Black Arial Black 2-20
Diego Martin
(South) 0.25 to 2.0 190 210 256 Black Arial Black 2-20
Barataria/Laventille 0.25 to 2.0 233 255 190 Black Arial Black 2-20
Sangre Grande 0.25 to 2.0 232 190 255 Black Arial Black 2-20
Caroni 0.25 to 2.0 255 235 190 Black Arial Black 2-20
Central North 0.25 to 2.0 190 255 232 Black Arial Black 2-20
Central South 0.25 to 2.0 156 156 156 Black Arial Black 2-20
POS 1&2 0.25 to 2.0 255 127 127 Black Arial Black 2-20
Mayaro 0.25 to 2.0 255 255 115 Black Arial Black 2-20
N/Grant-R/Claro 0.25 to 2.0 115 255 223 Black Arial Black 2-20
P/Town- Moruga 0.25 to 2.0 223 115 255 Black Arial Black 2-20
San Fernando/PAP 0.25 to 2.0 178 178 178 Black Arial Black 2-20
Naparima 0.25 to 2.0 255 167 127 Black Arial Black 2-20

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THEME TYPE/NAME
OUTLINE
WIDTH
Section 31 FILL COLOUR
LABEL TEXT
RED GREEN BLACK COLOUR FONT SIZE
La Brea/Fyzabad 0.25 to 2.0 209 255 115 Black Arial Black 2-20
Debe/Erin 0.25 to 2.0 115 223 255 Black Arial Black 2-20
Pt. Fortin/Cedros 0.25 to 2.0 255 115 223 Black Arial Black 2-20
Blanchisseuse 0.25 to 2.0 190 232 255 Black Arial Black 2-20
St.Joseph 0.25 to 2.0 104 104 104 Black Arial Black 2-20
BILLING Pt.Fortin/Cedros 0.25 to 2.0 190 232 255 Black Arial Black 2-20
Toco 0.25 to 2.0 211 255 190 Black Arial Black 2-20
Blanchisseuse 0.25 to 2.0 178 178 178 Black Arial Black 2-20
S/Juan-Laventille 0.25 to 2.0 255 190 190 Black Arial Black 2-20
Sangre Grande 0.25 to 2.0 211 255 190 Black Arial Black 2-20
Dibe/Maraval 0.25 to 2.0 255 255 190 Black Arial Black 2-20
Carenage-D/Martin 0.25 to 2.0 255 190 232 Black Arial Black 2-20
Santa Cruz 0.25 to 2.0 190 210 256 Black Arial Black 2-20
D'abadie/Tacarigua 0.25 to 2.0 233 255 190 Black Arial Black 2-20
O'mera/Malabar 0.25 to 2.0 232 190 255 Black Arial Black 2-20
POS 0.25 to 2.0 255 235 190 Black Arial Black 2-20
Arima 0.25 to 2.0 190 255 232 Black Arial Black 2-20
Maturita 0.25 to 2.0 156 156 156 Black Arial Black 2-20
Central North 0.25 to 2.0 255 127 127 Black Arial Black 2-20
Central South 0.25 to 2.0 255 255 115 Black Arial Black 2-20
Caroni 0.25 to 2.0 115 255 223 Black Arial Black 2-20
Cumuto 0.25 to 2.0 223 115 255 Black Arial Black 2-20
Rio Claro 0.25 to 2.0 178 178 178 Black Arial Black 2-20
Biche 0.25 to 2.0 255 167 127 Black Arial Black 2-20
Princess Town 0.25 to 2.0 209 255 115 Black Arial Black 2-20
Naparima 0.25 to 2.0 115 223 255 Black Arial Black 2-20
Mayaro 0.25 to 2.0 255 115 223 Black Arial Black 2-20
San Fernando 0.25 to 2.0 190 232 255 Black Arial Black 2-20
La Brea/ Pt.Fortin 0.25 to 2.0 104 104 104 Black Arial Black 2-20
Penal/Erin 0.25 to 2.0 211 255 190 Black Arial Black 2-20
Moruga 0.25 to 2.0 255 255 190 Black Arial Black 2-20
Cedros 0.25 to 2.0 255 190 232 Black Arial Black 2-20

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Each Layout should display:
1. Cardinal Points (must North, South, East and West
2. Scale Bar: Double Alternating
3. Scale Text: Optional
4. WASA logo: Symbol Code- 0=Blank, 1=Black, colour = 5 (0, 168, 135) (RBG)
5. Title: Rockwell Extra Bold (18pts – 200pts)
6. Reference Grid
7. Map Data:
a. Grid: UTM ZoneN, Datum: Naparima 1955, Projection: Transverse Mercator,
Units of Measurement: Metre, Spheroid: International
b. Grid: Tobago, Projection: Cassini, Unit of Measurement: Metre, Spheroid: Clarke
1858
c. Grid: UTM Zone 20N, Datum: WGS 84, Projection Transverse Mercator, Units of
Measurement: Metre
8. Legend: Title Arial, (0.5pts – 100pts), Labels Arial (0.5pts – 80pts)
9. Legend order: points, line, polygon, text
10. Sea Label: Times New Roman
11. Map must also show the following information usually placed under the Company Logo:
WATER AND SEWERAGE AUTHORITY
Section 32 Systems optimization GIS Section
File Path (Net Id, Location on PC, file extension)
Date (date/month in text/year)
32.1 CADE STANDARDS
The Water And Sewerage Authority, Systems Optimization Department, CAD/E Section
produces various types of drawings that are categorized as ‘Design’ and ‘As-Built’ drawings:
Civil, Mechanical, Electrical, Architectural and Survey Works.
32.2
..1.1 Types of Drawings
Design (Proposed) and As-Built Drawings for:
• Civil Engineering Works
Water and Sewer Pipeline Systems, Bridges, roads section and details, dams, intakes etc
• Mechanical Engineering Works
Vat and Flange details, pumps, steel supports, piping arrangements, layouts and details Value
chamber details. Thrust blocks, Pressure indicator, Jim Pole detail, Plinth
detail, spool piece etc.
• Electrical Engineering Works

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Schematic and block diagrams, schedules, floor plans, electrical site plans, motors, instrument panel
detail arrangement, panel assembly, panel support details etc.
• Architectural and Structural Works
• Elevations, floor plans, foundation plans and details, roof plans and details, section or
buildings, fence post and hinge details etc.
• Land and Engineering Surveying
Profiles, Cadastral, Traverses, Site Plans, Location Plans, Vicinity Plans etc
32.3 Miscellaneous Drawings
All drawings that are not categorized with the types mentioned above are considered
miscellaneous drawings. Examples are: Organizational Structural Charts, Sketches, Schematic
Drawings and Diagrams, Signs, Report Covers etc.
32.4 STANDARDS
For any organization to function efficiently, it must be guided by appropriate standards. This
document contains information on the various components of drawing production that is
currently used by the Systems Optimization Department. Updates to this document will be made
only with the approval of the Manager, Systems Optimization Department.
Quality Production of Drawing
• All drawings must have a ‘Titled Border’ and unless specified otherwise, use the
appropriate standard ‘Title Blocks’ (Borders) available.
• Show the Drawing’s Title in the space provided in the Title Block of the standard border.
It must say specifically what the drawing is representing.
• Yellow should be used at a minimum, if it must be used in drawings. Black should be the
predominant colour in the entire drawing. Center lines and dimensions lines in their
standard colours.
• Ensure all words are spelt correctly.
Design (Proposed) and As-built Drawings
These drawings should consist of the following:
• Ground (alignment) and street names
• Existing and Proposed mains and sizes
• Appurtenances
• Detail of interconnection
• Street name, North sign, mains and sizes must be included in each viewport
• Viewport scale 1/500
• Location/ File Path in Title Block
• As-built sheet (see sample page 6)
CAD File Specifications

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Layers
32.4.1 L
A
Y
E
R
S
32.4.2
32.4.3
USE
(In order of pen weight
from light to dark)
groundplan Black
Continuou
s
Light Lines
waterwa Blue
Continuou
s
Dark Lines
Detail Circle Cyan
Continuou
s
Light Lines
Matchline Red Dashdot Dark Lines
Text Black
Chainage Red
Continuou
s
Light Lines
Text Styles
32.4.4 T
E
X
T
N
A
M
E
32.4.5 TE
XT
ST
YL
E
32.4.6 USE
1 Simplex Narrow Generally used for labelling of
Chainage
2 RomanD
32.5 Narrow
For general text headings
Road Name
E.g. COCONUT DRIVE.
3 Txt.shx Arial Narrow or
Bold
Generally used for Size Main
NEW 100mm PVC main

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Section 33
As-
Built Sample Template
33.1.1.1 Civil Engineering Works
Already setup with Land Development Desktop software. Colour, Linetype etc.
Survey Drawings
Layers

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Land and Engineering Surveying
Cadastral (Surveys Drawing)
A Cadastral Drawing shows the location, identification and legal description of the, access,
appurtenances, encumbrances, improvements or other conditions that may affect a property for the
title company. The quantification of appurtenances, encumbrances and total areas of the property
required by the appraisers to assist in validating the purchase price and the inventory of parcels
and the identification/perpetuation of lines and corners of the property for land management
purposes.
Use Standard cadastral Sheet
• Buildings to be hatch in gray
• North Arrow in Cyan at the Top Right of the Viewport
33.1.2 LAYERS 33.1.3 C
O
L
O
U
R
33.1.4 L
I
N
E
T
Y
P
E
USE (in order of pen
weight from 0.00-2.11)
Road Outline BLACK Continuous 0.00
Major Contours GREEN Continuous 0.00
Minor Contours GREY Continuous 0.00
Stations BLACK Circle 0.00
Iron put/Iron Found RED Circle 0.00
Wire Fence GREEN Dashed X 0.20
Trees BLACK Continuous 0.00
Text BLACK Continuous 0.00
Electricity Pole BLACK Circle 0.00
Telephone Pole BLACK Circle 0.00
Retaining Wall BLACK Dashed-Dot 0.00
Colour of Road BROWN
(255,214,160)
Continuous 0.00
Colour of Parcel PINK
(255,219,237)
Continuous 0.00
Colour of Drain
Reserve, River and the
Sea
BLUE
(210’226,240)
Continuous 0.00
Houses Black Continuous 0.00
Earthen Drain BLACK Arrow 0.00

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Text Styles
33.1.5 T
E
X
T
N
A
M
E
33.1.6 T
E
X
T
S
T
Y
L
E
33.1.7 USE
1 Simplex Regular Bearings, Distances, Ir.
put, Ir. Fd.
2 Arial black
33.2 Re
gul
ar
Road Name, Neighbors
Drawing Scales
33.2.2 33.2.3 C
I
R
C
L
E
(Ir. Put/Ir.
Put)
33.2.4 TEXT
HEIG
HT
33.2.5 NEIG
HBO
UR
(Adjoining
Parcels)
1 1/500 0.4 0.75 1.0
2 1/750 0.6 1.13 1.5
3 1/1000 0.8 1.5 2.0

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4 1/1250
33.3 1.0
1.88 2.5
5 1/1500 1.2 2.25 3.0
6 1/2000 1.6 3.0 4.0
7 1/2500 2.0 3.75 5.0
7 1/2500 2.0 3.75 5.0
Architectural and Structural Works
These drawings should consist of the following:
• Elevations
• Floor Plans
• Foundation Plan & Beam and Column Details
• Roof Plan & Details
• Sections of Building
• Fence Post & Details
• Site Plan/Location
• Drainage Details
• Standard Drawing Block/Sheet (see Page 12)
CAD File Specifications
Layers
33.3.1 LAYERS 33.3.2 C
O
L
O
U
R
33.3.3 L
I
N
E
T
Y
P
E
USE (in order
of pen weight
from light to
dark)
Hatch, Plants, Tiles, etc. COLOUR 9 Continuous Light Lines
Centre Lines/Section
Lines, Grid lines,
Hidden Detail Lines,
Stairs, Dimension, Roof
Sheeting, RC Columns,
Roof Outline etc.
COLOUR 8 Centre,
Dashdot,
Hidden,
Continuous
Light Lines
Fixtures BROWN 30 Continuous Medium Lines
Windows, Railing, Roof CYAN Continuous Medium Lines
Walls, Details,
Foundation
MAGENTA Continuous Medium Lines
Doors BROWN 41 Continuous Medium Lines
Electrical, Rafters RED Continuous Medium Lines

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Ring Beam,
Reinforcement
BLUE Continuous Dark Lines
All Text WHITE Continuous Dark Lines
DIMENSIONS CYAN Continuous Dark Lines
Text Styles
33.3.4 TE
XT
NA
ME
33.3.5 TE
XT
ST
YL
E
33.3.6 USE
1 Simplex Narrow Generally used for labelling of
building fixtures. E.g. WC, FB,
SH etc.
2 Romantic
33.4 Narro
w
For general text headings i.e. room
names, room numbers, etc.
E.g. MASTER BEDROOM, etc.
3 Arial Arial Narrow or
Bold
Generally used for dimensions and
drawing names E.g. FLOOR
PLAN, etc.

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Architectural and Structural Works Sample Template
33.4.2 Electrical Engineering Works
• Text and Dim Line in Blue.
• Text Roman Simplex. Oblique 15. Height 1.75mm or 2mm
• Sub-title, Roman Duplex; Height 2.5mm or 3mm
• Lines are Color-Coded
R Red

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Y Yellow
B Blue
N Green
• Rest of line work in Black/White
• Symbol in Blue.
Symbols are to be created in accordance to the nature of the drawings and must be specified in a
menu box which must be usable at all times.
CAD File Specifications
Layers
33.4.3 L
A
Y
E
R
S
33.4.4 C
O
L
O
U
R
33.4.5 L
I
N
E
T
Y
P
E
33.4.6 L
I
N
E
S
I
Z
E
S
Ground wire Green Continuous Set as Default
Positive wire Red Continuous Set as Default
Negative wire Black Continuous Set as Default
Positive wire Yellow Continuous Set as Default
Text Styles
33.4.7 T
E
X
T
N
A
M
E
33.4.8 TE
XT
ST
YL
E
33.4.9 T
E
X
T
S
I
Z
E
33.4.10 USE
1 Simplex Narrow 5mm Generally used for labelling of
streets and street names.
2 Romantic
33.5 Narrow 33.6 6
Headings and labeling of all
drawings.

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mm
3 Arial Arial Narrow or
Bold
3 mm Appurtenance
33.7 Schematics
The drawings should comply with the following:
• The Schematic diagram block sheet must be used for all Schematic drawings.
• All data required on the sheet must be entered.
• All symbols used in the Schematic diagram must be from the block symbols set for
Schematic diagram only, unless otherwise stated.
• All symbols used in the Schematic diagram must be included as part of the Symbol Key in
the sheet.
• Street names should be indicated in blue using text style Romans.shx, for example,
WARREN STREET.
• The height of the street name in the view port should be between 2.5 – 3 mm.
• The main size and the type of main are to be labeled in red using Romans.shx. for example,
100 PVC.
• All existing mains to be indicated in black/white continuous lines.
• All proposed Appurtenances, Mains etc are to be indicated in green.
• Whenever the Schematic diagram is modified, the revised date must be entered on the
Schematic sheet.
CAD File Specifications
Layers

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33.7.1 LAYERS 33.7.2 C
O
L
O
U
R
33.7.3 L
I
N
E
T
Y
P
E
USE
(in order of pen weight from
light to dark)
Street name Blue Continuous Medium Lines
Appurtenances Red Continuous Medium Lines
Proposed Appurtenances Green Continuous Medium Lines
Size Red Continuous Light Lines
Existing main Black Continuous Dark Lines
Proposed mains Green Continuous Dark Lines
Proposed mains size Green Continuous Light Lines
Schematic Sample Template
..1.1 Sketches
These drawings are not drawn to scale, they are consistently used to specify areas in which work
is to be done or in drafting terms (Proposed work to be done). These drawings are not to be used
for accurate measurement; they are only for proposals. Drawing standards that have been set are
to be met at all times to ensure proper quality control is maintained and kept.

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CAD File Specifications
Layers
33.7.4 LA
YE
RS
33.7.5 C
O
L
O
U
R
33.7.6 LI
N
E
T
Y
P
E
33.7.7 LI
N
E
SI
ZE
S
Roadway Black Continuous Default
Pipelines Blue Polylines 1.3mm
Appurtenances Red Continuous Default
Text Styles
33.7.8 T
E
X
T
N
A
M
E
33.7.9 TEX
T
STY
LE
33.7.10 T
E
X
T
S
I
Z
E
33.7.11 USE
1 Simplex Narrow 5mm Generally used for labelling of
streets and street names.
2 Romantic
33.8 Narrow 33.9 65
mm
Headings and labeling of all
drawings.
3 Arial Arial Narrow or
Bold
3 mm Appurtenance

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Section 34 Symbology
The following standards are used when producing surveying type drawings
WATER SYMBOLS - SCALE 1: 500

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BLOCK
NAME
BLOCK
ALIAS
BLOCK
DESCRIPTION
DEFAULT
SCALE
FACTOR
ASSOCIATED
LAYER
COLOUR
MAP 3 SP Stand Pipe 1.5 W-SYM RED 1
FIREH FH Fire Hydrant 1.5 W-SYM RED 1
VALVE 1 SV Gate Valve 1.8 W-SYM RED 1
VALVE 2 V2 Gate Valve 1.8 W-SYM RED 1
AVALVE AV Air Valve 1.2 W-SYM RED 1
WVALVE WO Washout Valve 2.5 W-SYM RED 1
RED R Reducer 1.8 W-SYM RED 1
RVALVE RV Reflux Valve 1.8 W-SYM RED 1
PVALVE PRV
Pressure Reducing
Valve
1.8 W-SYM RED 1
BVALVE BV Butterfly Valve 1.6 W-SYM RED 1
METER M Meter 1.5 W-SYM RED 1
PUMP PRV Pump Set 2 W-SYM RED 1
PDN PD Pipe Down 1 W-SYM RED 1
PUP PU Pipe Up 1 W-SYM RED 1
SMH SMH Sewer Main Hole 1 S-SYM GREEN 3

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SURVEYING/MAPPING LINE TYPES - SCALE - 1:500
UTILITY SERVICE LINE TYPES- SCALE - 1:500
LINE
SYMBOL
LINE
TYPE
LINE
DESCRIPTI
ON
ASSOCIAT
ED LAYER
BLOCK
INSERTI
ON
SPACING
THIC
K-
NESS
COLO
UR
COLOU
R CODE
Continuous
Polyline
Water Main
(Proposed/AS-
Built) PW-LIN 0.5 Blue 5
Dashed
Polyline
Water Main
Existing AW-LIN 0.5 Blue 5
Continuous
Polyine
Sewer Main
(Proposed/AS-
Built) PS-LIN 0.5 Brown 9
Dashed
Polyline
Sewer Main
(Existing) XS-LINE 0.3 Brown 9
Border
Polyline
Electricity
Cable E-LIN 0 Yellow 2
Phantom
Polyline
Telephone
Cable T-LIN 0
Magenta
A 6
LINE
SYMBOL
Section 35 LINE
TYP
E
LINE
DESCRIPTION
ASSOCIATED
LAYER
BLOCK
INSERTION
SPACING
THICK-
NESS
COLOUR
COLOUR
CODE
Converted Dashed
Polyline
Earthen Drain Drains 1 0 Cyan 4
Dimension Leader
Kerb and Slipper
Drain
Drains 1 Cyan 4
Converted Dashed
Polyline
Cutting Ground 0 White 7
Converted Dashed
Polyline
Cliff Ground 0 White 7
Converted Dashed
Polyline
Wire Fence Property 0 White 7

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Divide
Polyline Gas/Oil Line G-LIN 0 Red 1
SURVEYING/MAPPING SYMBOLS - SCALE - 1:500
BLOCK
NAME
BLOCK
ALIAS
BLOCK
DESCRIPTIO
N
DEFAULT
SCALE
FACTOR
ASSOCIATE
D LAYER
COLO
UR
COLOUR
CODE
Map 1
Map 2
S Survey Station 0.85 Control White 7
UP Utility Pole 0.9 Utility White 7
Map 4 4 White 7
Map 5 5 White 7
Map 6 6 White 7
Map 7 FP Fence Post 0.9 Property White 7
Map 8 White 7
Map 9 White 7
Sign SGN Sign 3.5 Ground White 7
TVS TVS Traverse Station Control White 7
TGS TGS Trig Station Control White 7
MM MM Mile Mark Control White 7
BM BM Bench Mark Control White 7
T1 Tree 4 Vegetation Green 3
T2 Tree 4 Vegetation Green 3
T3 Tree 4 Vegetation Green 3

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T5 Tree 4 Vegetation Green 3
SURVEYING/MAPPING ABBREVATION DICTIONARY
..1.1.1.1 ABBREVIATION MEANING
ABT ABUTMENT
AVE AVENUE
b
CORNER OF
BUILDING
B BOTTOM
BM BENCH MARK
BEG BEGINNING
BE BOTTOM EDGE
BR BRIDGE
BDR BOX DRAIN
BF BLOCK FENCE
BV
BUTTERFLY
VALVE
CI CAST IRON
CONC CONCRETE
CL CENTRE LINE
CTR
CENTRELINE OF
TRACE
CRD
CENTRELINE OF
ROAD
CP CONCRETE

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..1.1.1.1 ABBREVIATION MEANING
PAVEMENT
KRB KERB
KSDR
KERB AND
SLIPPER DRAIN
CULV CULVERT
DI DUCTILE IRON
DRN DRAIN
DW DRIVEWAY
EOR EDGE OF ROAD
EDG EDGE
EDT EDGE OF TRACE
EDR EARTHEN DRAIN
E EAST
EP
ELECTRICITY
POLE
FH FIRE HYDRANT
GP GATE POST
GS GROUND SHOT
h
CORNER OF
HOUSE
IDR INVERT DRAIN
I INVERT
IR FD IRON FOUND
IR PT IRON PUT
JCT JUNCTION
LP LAMP POST
SDR SLIPPER DRAIN
L LEFT
MM MILE MARK
mm MILLIMETER
M METER
N NORTH
PRV
PRESSURE
REDUCING VALVE
PS PUMP SET
PD
PIPE
DOWNWARDS
PR PIPELINE ROUTE
PU PIPE UPWARDS

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..1.1.1.1 ABBREVIATION MEANING
PVC
POLY VINYL
CHLORIDE
R RIGHT
RW RETAINING WALL
RED REDUCER
RD ROAD
RV REFLUX VALVE
RIV RIVER
RCP
REINFORCED
CONCRETE PIPE
S SOUTH
STL STEEL
SV SLUICE VALVE
SP STAND PIPE
SPK FD SPIKE FOUND
SPK DT SPIKE PUT
ST STREET
STM STREAM
SGN SIGN
SMH
SEWER MAIN
HOLE
T TOP
TBM
TEMPORARY
BENCH MARK
TP TELEPHONE POLE
TR TRACE
T2, T5, .. TREE
W WEST
w WIDE
WO WASHOUT VALVE
WF WIRE FENCE
VRG GRASS VERGE
X CROSSING
INT INTERSECTION
AV AIR VALVE
PL PROPERTY LINE
SWK SIDEWALK
SOF SOFFIT

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PLUS
EMH
FIREH
VALVE1
AVALVE
WVALVE
RED
RVALVE
PVALVE
BVALVE
METER
PUMP
PDN
PUP
SMH
MAP1
MAP2
MAP7
SIGN
TRI
TGS
CIRPLP
RHO
TREE1
TREE2
TREE3
TREE4
GIS SURVEYS
TOPOGRAPHICAL SURVEY AND MAPPING SYMBOLS LIBRARY
SH
EMH
FH
SV
AV
WO
RD
RV
PRV
BV
M
P
PD
PU
SMH
S
UP
BP
SGN
TVS
TGS
KM
BM
T1
T2
T3
T4
GRAPHIC
SYMBOL
BLOCK FILE
NAME
FIELD
CODE
DEFAULT SCALE
FACTOR
1:000 1:500
ASSOCIATED
LAYER
LAYER
COLOURBLOCK DESCRIPTION
0.3000
0.0030
0.0030
0.0055
0.0035
0.0085
0.0055
0.0055
0.0055
0.0050
0.0045
0.0060
0.0023
0.0023
0.0020
0.0018
0.0020
0.0025
0.0070
0.4500
0.4200
0.3800
0.55
0.0090
0.0090
0.0095
0.0090
BLACK
MAGENTA
RED
RED
RED
RED
RED
RED
RED
RED
RED
RED
RED
RED
RED
GREEN
GREEN
GREEN
GREEN
RED
RED
TOPO-SPOTS
ELECT-MH
W-SYM
W-SYM
W-SYM
W-SYM
W-SYM
W-SYM
W-SYM
W-SYM
W-SYM
W-SYM
W-SYM
S-SYM
CONTROL
UTILITY
PROPERTY
SIGN
CONTROL
CONTROL
CONTROL
VEGETATION
VEGETATION
VEGETATION
VEGETATION
CONTROL
TOPO SPOTS
ELECTRICAL MANHOLE
FIRE HYDRANT
SLUICE VALVE
AIR VALVE
WASHOUT VALVE
REDUCER
RELUX VALVE
PRESSURE REDUCING VALVE
BUTTERFLY VALVE
METER
PUMP SET
PIPE END DOWN
SEWER MANHOLE
SURVEY STATION
UTILITY POLE
BOUNDARY POST
SIGN
TRAVERSE STATION
TRIG STATION
KILOMETER MARK
BENCH MARK
TREE
PALM TREE
MANGO TREE
TREE
PIPE END UP W-SYM RED
RED

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NAME PATTERN
SYMBOL
LINE
DESCRIPTION
GL
EL
ML
TV
WF
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
TL
BF
COLOURLAYER
1(RED)
2
3(GREEN)
220
7
7
7
7
141
BLUE
30
40
CYAN
MAGENTA
7
G-LIN
E-LIN
M-LIN
CABLETV
PROPERTY
GROUND
GROND
DRAINS1
DRAINS2
XW-LIN
XS-LIN
HOUSES
BUILDINGS
T-LIN
PROPERTY
LINETYPE
PATTERN LINE
PATTERN LINE
PATTERN LINE
PATTERN LINE
PATTERN LINE
CONTINOUS
CONTINOUS
CONTINOUS
DASHED
DASHED
PHANTOM2
CONTINOUS
CONTINOUS
PATTERN LINE
PATTERN LINE
LINETYPE
GIS SURVEYS
TOPOGRAPHICAL SURVEY AND MAPPING SYMBOLS LIBRARY
GL
EL
ML
TV
WF
R1
R2
D1
D2
XW
XS
H
B
TL
BL
GAS LINE
ELECTRICAL LINE
METHANOL LINE
CABLE TV LINE
WIRE FENCE
ROAD EDGE
ROAD EDGE
CONC.DRAIN
EARTHEN DRAIN
EXIST. WATER LINE
EXIST.SEWER LINE
HOUSE
BUILDING
TELEPHONE LINE
BLOCK FENCE

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The following are symbols used for Schematic Drawing

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The following are symbols used for the Emergency Evacuation Drawing
1. Additional symbols may be needed for the Emergency Evacuation drawings symbol
set.
2. The text style used for labeling the symbols is Stencil

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35.2 10 Golden Draughting Rules
1. Never draw a line unless you understand what it represents.
2. A drawing should be laid out to allow clear interpretation of the data.
3. Sections/Elevations should be drawn as projections of the plan whenever possible; the plan
grid should line up with the elevation grids for easy reference.
4. Sections/details should all be lined up so that the floors can be easily identified and related.
5. Annotation should be kept to a minimum and always be orientated so that it reads from the
bottom or the right-hand side of the drawing.
6. Annotation should be as close to the information to which it relates, but clear of linework.
Note arrows (leaders) should never cross.
7. The use of abbreviations should be avoided unless space on the drawing dictates otherwise.
8. Always ensure that the drawing is independently checked and approved before issuing.
9. Symbols should be consistent on all drawings.
10. Certain standards notes should always be considered.
35.3
35.4 Standard Title Block Data Entry
The following are lists of instructions to be used when editing the title block information
35.5 Project Title
• Here the name of the project should be entered.
• Note: Text should be all CAPS.
• E.g. MARAVAL WATER TREATMENT BUILDING UPGRADE WORKS
35.6 Job Title
• Here the name of the drawing should be entered.
• Note: Text should be all CAPS.
• E.g. PROPOSED GROUND FLOOR LAYOUT

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35.7 Sheet
• Here the sheet number is entered. If the project consists of more than one drawing the
total amount of drawings should be indicated on each sheet.
• E.g. Sheet # 5 Of 13
35.8 Drafted By
• Here the drafting technician should enter his/her name.
• E.g. F. Wellington
Note: If the drawing is modified, the drawing should be saved as another version. In the example
the figure two indicates that the drawing has been updated.
• E.g. ARC-PRO-FPLAN-MARAVAL-MARAVALWATERTREATMENTPLANT-2
35.9 Designed By
• Here the designer of the proposed drawing should include his/her name.
Checked By
• Here the drawing should be check and the person checking the drawing should indicate
his/her name.
35.10 Approved By
• Here the person or body that is responsible for the works being done, should sign here
indicating that the drawings has meet the required standards.
35.11 Scale
• The scale of the drawing on the present sheet should be indicated here.
35.12
35.13 File Path
• Here the location where the drawing could be found should be indicated by the use of a
file path.
• E.g. GIS103/STAFF/ARCHITECTURAL/ ARC-PRO-FPLAN-MARAVAL-
ARAVALWATERTREATMENTPLANT-2.DWG
35.14 FILE NAMING CONVENTION
Naming Convention was developed to enable anyone to identify the contents of a CAD file without actually opening
the file. This is important so that anyone who is aware of the convention rules can easily identify
files when necessary.

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e naming rules developed were modeled after one used by the Connecticut Department of Transportation whose
approach seemed to best fit our needs. A series of discussions were held with the major stakeholders
(CAD/E and IT Staff) to determine the specific requirements of our CAD file name and the working
model is described below.
re two major categories of file names; General and Block.
al Name
neral Name would be applied to any drawing file used as a working drawing. These would fall into the categories of
Architectural, Mechanical, Electrical, Survey or Schematic, which are defined later.
ype/Sub-Type/Sub-Sub Type/Location/Location-Type(Facililty)/Version.dwg
FILE NAME
COMPONENT
DESCRIPTION
CAD Type General Grouping of CAD drawings
Sub-Type Division of the CAD type (adding more
specificity)
Sub-Sub Type Further division of the sub-type (adding
more specificity)
Location Geographic place of the drawing contents
e.g. Arima
Location-Type (Facility) Area office or other facility e.g. Booster
Version Checkpoint of currency of drawing
35.14.1
35.14.2 Block Name
The Block Name would be applied to any drawing used as a block or in a symbol library. A
block is any collection of related, scalable, CAD Objects that can be used in many drawings of
the same type.
Syntax:
CAD Type/Blk/BlockName/User-DefinedIdentifier.dwg
FILE NAME
COMPONENT
DESCRIPTION
CAD Type General Grouping of Cad drawings

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Blk Block
Block Name Name of the Block
User-Defined Identifier Identifier devised by user to define the
block contents
Section 36 The following diagrams illustrate the categories of CAD files (CAD Type)
and their sub classifications (Sub-Type).
Section 37 Main CAD Types
• Architectural – any drawing related to a building
• Schematic – line model of linear type network
• Survey – drawing from field survey data
• Engineering – design of networks or other infrastructure
• Electrical – any drawing related to an electrical configuration that pertains to
mechanical, engineering and architectural works
Key
CAD TYPE
SUB-TYPE
SUB SUB-TYPE

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Section 38 ARCHITECTURAL
Architectural
Proposed Existing
Plumbing
Electrical
Complete Floor Plan
Elevation
Roof Plan
3-D
Structural
Location
Plan
Site Plan
Plumbing
Electrical
Complete Floor Plan
Elevation
Roof Plan
3-D
Structural
Location
Plan
Site Plan

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Section 39 SCHEMATIC
Schematic
Proposed Existing

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Section 40 SURVEY
Survey
Surveys GPS

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Section 41 ENGINEERING
Engineering
Network
Infrastructure Mechanical
Waste Water
Water
Miscellaneous
(Pipe Fitting)
Reservoir
Building
Booster
Station
Pump & Vat
Details
Pipe
Arrangements
Appurtenance
Details

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Section 42 ELECTRICAL
Electrical
Existing
Schematic Block Schematic Block
Wiring Wiring
Proposed

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• After some testing and research, it was agreed by all that in the case of the Location
component of the file name, the whole place name would be used to avoid confusion.
• A list of common abbreviations was developed to help reduce the amount of typing.
Both the CAD application and Operating System are able to handle the long names.
• It was assumed that this trend could be applied to present and future incarnations of the
applications.
CADTYPE CODE
LOCATION
PRE FIX/SUB FIX
CODE
ARCHITECTUR
AL
ARC AVENUE AVE
SCHEMATIC SCH BOULEVARD BLVD
SURVEYING SUV CENTRAL
CNTR
L
ENGINEERING ENG DRIVE DR
ELECTRICAL ELEC EAST EST
GARDENS GDNS
SUBTYPE CODE JUNCTION JUCT
PROPOSED PRO LOWER LWR
EXISTING EXT MOUNT MT
BLOCK BLK NORTH NRT
SURVEYS SUV NUMBER NO
GPS GPS PARK PRK
NETWORK NTW PHASE PHS

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INFRASTRUCTU
RE
INF ROAD RD
MECHANICAL MEC SAINT SNT
SETTLEMENT
STLM
T
..1.1.1.1 SU
B-SUBTYPE
CODE STREET STR
3D 3D SOUTH STH
COMPLETE
COMP
L
TOWN TWN
ELECTRICAL ELECT TRACE TR
ELEVATION ELEVA UPPER UPR
FLOORPLAN FPLAN VALLEY VLY
ROOFPLAN RPLAN VILLAGE VILL
PLUMBING
PLUM
B
WEST WST
WATER
WATE
R
SITEPLAN SPLAN
CADASTRAL
CADA
S
TOPOGRAPHIC TOPOG
ASLAID ASLAD
SEWER
SEWE
R
BUILDING BLDG
RESERVOIR RESEV
BOOSTERSTATI
ON
BSTAT
MISCELLANEO
US
MSCEL
WIRING WIR
Section 43 EXAMPLE
CADType-SUBType-SUBSUBType-LOCATION-USERIdentifie -
Version.dwg
xxx-xxx-xxxxx-Location-Identifier-#.dwg
e.g. ARC-PRO-COMPL-FOURROADS-PUMPINGSTATION-1.dwg =
Complete set of architectural drawings for the Four Roads Pumping Station (elevations, site plan, floor plan, electrical etc)

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