This risk assessment document summarizes the hazards, risks, control measures, and residual risks associated with conducting trial trench excavations by hand to locate underground utilities at a construction site. Key steps include planning excavations based on utility drawings, scanning the work area to locate services, clearly marking identified and unidentified utilities, implementing traffic management plans if near roads, and using hand digging and excavators with spotters to expose utilities. Control measures such as permits, competent machine operators, exclusion zones around utilities, fall protection in trenches, illumination and signage are required. Residual risks include damage to undetected utilities and machine breakdown.

1. HEALTH SAFETY AND ENVIRONMENT Author: Approved:
RISK ASSESSMENT: 09 TRIAL TRENCHES (HAND DIGGING) TO MAS STANDARD
Issued: Rev. Date:
Revision: 0
Page 1 of 2 HSEQ -Rev-01(Aug-2018)
No
Specific Task Step
(In sequence of
works)
Hazard Details Consequence/Risk
Initial Risk
Rating Control Measures Residual Risks
Additional Control
Measures
RR
P S RR
1
Planned shallow
Excavation (Trial
Trench) in areas where
live services may be
presentincluding:
 Electrical;
 Water;
 Sewerage;
 Gas;
 Telecoms;
PRIOR TO
WORKS
 Presence oflive
underground services;
 Services not in area
specified on drawings;
 Heavy plant or
vehicles accessing
work area;
 Presence of
unmarked services;
 Risk of explosion due to gas line
rupture;
 Risk of flooding of trenches and
adjacentareas due to water main
damage;
 Risk of electrocution or fire due to
cable strike;
 Risk of hazardous waste entering
trenches or water systems due to live
sewerage damage;
 Risk of damage to low depth
underground services from heavy
vehicles;
 Risk of vehicles / Plant entering open
trenches;
4 3
12
HIGH
i. All existing utility service drawings reviewed for known service details and
position;
ii. NOC and Utility provider and ATC Excavation permits to be completed,
unique number added and recorded in log;
iii. Work Area, including access route for plant, to be CAT scanned to locate
exact position of service by competentpersons;
iv. Service clearly marked on ground, using posts,tags etc.;
v. Plant access route to be indicated;
vi. Any unidentified services marked on ground and drawing by Temporary
Works Coordinator or Temporary Works Supervisor;
vii. All services clearlycommunicated to all workers at briefings and TBT’s,
signed offand recorded;
viii. Permit/NOC/JSEA/Approved design Drawings copies to be with task
supervisor in work area for review;
ix. Supervision and PlantOperators instructed to stay within designated area
and access route;
x. All trench barriers to be planned and to RTA Traffic ManagementManual
if adjacentto live roads;
Workers not
complying with
controls
All supervision to monitor
operation;
Regular topic in TBT’s
LOW
2
Use of Excavator for
trial trenches and
backfilling
Note:
Wherever practicable
trial trenches shall be
hand dug to expose
services.
 Working with plant in
vicinity of workers;
 Working in vicinity of
underground services;
 Untrained operator;
 Workers struck by operating plant;
 Worker struck by reversing plant;
 Underground service strike;
 Material falling into trench;
 Damage to machine;
 Collapse ofexcavation due to
incorrectdesign/digging;
4 4
16
HIGH
i. Supervision and Plantoperators instructed notto machine excavate within
1.5m of marked service;
ii. Hand digging only to expose services communicated, only use
shovels markedat 1.2m for guidance;
iii. All operators to be Third Party approved for the type of machine,licence
available for review at all times;
iv. Machine in – Men out mantra to be adhered to. No personnel shall be
inside the trench when the excavator is working,when personnel are
inside the trench the excavator shall rotate away and be isolated;
v. No personnel in excavation when pipes etc. are being lowered into
position,to stand outside of excavation;
vi. Banksman to control excavator movements; Spotter to assistoperator to
observe and warn of any unidentified services;
vii. Daily checks on machine undertaken prior to commencing work;
Damage to
undetected
underground
services
Machine
breakdown
Hydraulic fluid spill
ATC Engineer shall
immediatelycontact
DEWA/Etisalat/Du as required
for action.
Area isolated.
Machine isolated and
quarantined until repaired.
Spoil removed and treated as
hazardous waste
LOW
RISK SCORE CALCULATOR
Use the Risk Score Calculator to Determine the Level of Risk of each Hazard
What would be the
CONSEQUENCE
of an occurrence be?
What is the LIKELIHOOD of an occurrence? Hierarchy of Controls
Frequent/Almost certain (5)
Continuous or will happen
frequently
Often (4)
6 to 12 times a year
Likely (3)
1 to 5 times a year
Possible (2)
Once every 5 years
Rarely (1)
Less than once every 5
years
Can the hazard be Eliminated or removed
from the w ork place?
Catastrophic (5)
Multiple Fatalities
High 25 High 20 High 15 Medium 10 Medium 5
Can the product or process be substitutedfor
a less hazardous alternative?
Serious (4)
Class 1 single fatality
High 20 High 16 High 12 Medium 8 Low 4
Can the hazard be engineered aw ay w ith
guards or barriers?
Moderate (3)
Class2 (AWI or LTI) or Class 1
Permanently disabling effects
High 15 High 12 Medium 9 Medium 6 Low 3
Can Administration Controls be adopted
I.e. procedures, job rotation etc.
Minor (2)
Medical attention needed, no work
restrictions. MTI
Medium10 Medium 8 Medium 6 Low 4 Low 2 Can Personal Protective Equipment &
Clothing be w orn to safe guard against
hazards?Insignificant (1)
FAI
Medium10 Medium 4 Low 3 Low 2 Low 1
Project Name: xxx
RA Ref No.: xxx
RA compilation
Date:
Review date:
Date:
Compiled by:
Reviewed by:
Approved by:
Overall Task Details
Trial Trenches on site to locate/expose underground services.Use ofexcavator
Note: Wherever practicable trial trenches shall be hand dug to expose cables
Classed as TemporaryWorks
Relevant Applicable MAS:
 00246 – Excavations;
 01413 – Underground services;
 00940 – PlantOperators.
Additional Training required:
TemporaryWorks Coordinator to be designated
NOC’s Required for task:
Dubai Municipality

2. HEALTH SAFETY AND ENVIRONMENT Author: Approved:
RISK ASSESSMENT: 09 TRIAL TRENCHES (HAND DIGGING) TO MAS STANDARD
Issued: Rev. Date:
Revision: 0
Page 2 of 2 HSEQ -Rev-01(Aug-2018)
No
Specific Task Step
(In sequence of
works)
Hazard Details Consequence/Risk
Initial Risk
Rating Control Measures Residual Risks
Additional Control
Measures
RR
P S RR
3
Trench (shallow
excavation) open in
site area
 Trench in working
areas with live traffic
movements and
pedestrians;
 Unprotected
excavation area;
 Damage to exposed existing live
underground services;
 Trench collapse;
 Falling/slipping into trenches;
 Overturning of Truck / machineryinto
trench;
 Incidentdue to poor illumination;
 Incidentdue to hazardous gas/fumes
entering trench;
 Collapse/damage ofstructures due to
undermining;
4 3
12
High
i. TemporaryWorks Coordinator / Construction Team to ensure Permitto
Excavate has been issued,communicated and signed bypersonnel prior
to any excavation/trench work;
ii. Excavation safety buffer, protection,design and traffic signs to be to ATC
Minimum Acceptable Standard,RTA Manual Chapter 3 requirements (as
applicable) and DM Code of Practice -Section 9;
iii. Any exposed services to be protected and adequatelysupported to avoid
damage;
iv. Any unidentified services discovered to be immediatelycommunicated to
management and work stopped;
v. All spoil to be maintained atleast2m from excavation;
vi. TemporaryWorks Coordinator to ensure trench design adhered to at all
times;
vii. All trenches below 1.2m depth to be benched/battered back to MAS
standards;
viii. Trench to be inspected dailywith written inspection reportweeklyby
TemporaryWorks Supervisor;
ix. Daily briefings to workers on working in excavations requirements by
supervision;
x. Use of stop blocks,barriers and other suitable means ofprotection used
to prevent vehicles entering trenches,warning tape is not to be used as
primaryprotection;
xi. Where practicable,access roads and pedestrian walkways to be
established awayfrom trenches;
xii. Suitable and sufficientsignage introduced to excavations;
xiii. Backfilling of trenches to be undertaken as soon as possible after
verification or completion ofworks;
xiv. Trenches to be suitablyilluminated during nighttimes;
xv. No changes withoutre-submittal ofdesign reviewed by the TWC, NOC
and Permits;
Vehicle entering
trench
Trench collapse
Incidentdue to
barrier removal
Emergencyservices called,
area cleared
Secure area
No removal of protection
barriers withoutprior approval
from management.
LOW
5
Maintenance of
Trenches
 Adverse weather;
 Trenches open for
long periods;
 Damage to trenches due to incident
or adverse weather;
 Incidentdue to removal of barriers
3 3
9
Med
i. Trenches checked after heavy rains,severe winds etc., stand by pumps
to be available as required;
ii. Weekly recorded inspections undertaken;
iii. Implemented warning signage maintained;
iv. Housekeeping inside trenches to be maintained,all rubbish and waste
material to be removed daily;
Low
6
Worker exposure to
direct sun
(as applicable)
 Workers exposed to
high summer
temperatures;
Worker ill health due to:
 Heat exhaustion,
 Heat stroke;
 Heat Stress.
3 4
12
High
i. Summer Hour Working plan to be designed and implemented;
ii. Municipality summer working hours observed and implemented
(12.30pm to 3.00pm restricted in direct sunlight);
iii. Workers instructed regarding working in the heat and signs ofheat
exhaustion etc. at Induction;
iv. Recovery cool rooms established on site;
v. Cool welfare areas established in all locations;
vi. Cool fresh water and electrolyte supplements to be maintained in all
areas;
vii. Pipe welders etc. provided with localised shelters;
New workers
boughtonto site
Regular topic in Toolbox Talks Low