The document discusses maintenance of sewage treatment works (STW) along the sewage conveyance network in Hong Kong. It includes a table listing 34 STW, the equipment at each location, estimated and actual days spent on maintenance from December 2012 to December 2013. The infrastructure includes tunnels carrying sewage from Kowloon and Hong Kong Island to the primary treatment plant at Stonecutters Island. Maintenance involves over 600 pieces of equipment across multiple STW and requires high management and engineering skills.

1. Exhibit 1: Sewage Conveyance Network in Hong Kong Exhibit 2: The depicted picture of StoneCutters Island Sewage Treament Works (SCISTW)
(Courtesy of DSD HKSAR) (Courtesy of DSD HKSAR)
Background: The Harbour Area Treatment Scheme (HATS) Stage 1 was comissioned in 2001.
The infrastructure work included a construction of a sewage collection and treatment plants for areas on both sides of Victoria Harbour. The system consists of a 23.6 km long network of tunnels deep underground, each day carrying 1.4 million
tonnes of sewage from Kowloon and the northeastern part of Hong Kong Island to a chemically enhanced primary sewage treatment plant at Stonecutters Island.
The project included carrying out daily operations and maintenance (O&M) and planning overhauls for all STW along the sewage conveyance tunnels under the HATS stage 1.
This is a relatively large scale maintenance project involving 34 STW in which a total number of 627 equipment operating simultaneously. This is a very delicate operation demanding both high management skill and engineering know-how and
needing round-the-clock attention.
Squad- Done Estim Spent Estimate 12 20 13 20 14 20 15
Location Equipment day Unit Unit days days Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov
Kwai Chung Coarse Screen 45 4 6 180 270 3 3 1 1 1
PTW Fine Screen 45 3 4 135 180 1 1 2 2 2 1 (1)
Fine Screen Conveyor 45 3 4 135 180 1 1 1
Inlet Screen 45 2 2 90 90 1 1 1 1 1
Screening Press 45 3 4 135 180 1 1 1 1 1 1 (1)
Classifier 45 2 4 90 180 1 1 1 1 1
Screw Pump 75 1 6 75 450 1
Coarse Screen Conveyor 45 1 3 45 135
Collection Conveyor 45 2 3 90 135 1 1 1 1 1 (1)
Common Fine Screen Conveyor 45 2 3 90 135 1 1 1 1
Submersible sewer pump 90 0 2 0 180
Deodorisation Unit 45 14 14 630 630 3 3 3 2 2 4 4 2 2
Penstock 45 0 1 0 45
Ventilation Fan 30 4 6 120 180 2 2 1 1 (2)
Exhaust Fan 30 4 6 120 180 2 2 1 1 (2)
Air Blower 30 0 5 0 150
Tsing Yi Coarse Screen 45 1 1 45 45 1 1
PTW Deodorisation Unit 45 6 6 270 270 2 2 1 1 2 2 2 1
Penstock 45 0 1 0 45
Air Supply Fan 30 4 4 120 120 4 4 2
Fine Screen 45 3 3 135 135 1 1 1 1 1 1 (1)
Screening/Grit Conveyor 45 5 7 225 315 1 1 1 1 1 2 2 2 (2)
Classifier 45 2 2 90 90 1 1 1 1 1
Air Blower 30 0 2 0 60 (1)
Screw Pump 75 0 3 0 225 (1)
Washpactor 45 2 2 90 90 1 1 1 1 1
To Kwa Wan Screw Conveyor 45 6 9 270 405 2 4 4 2 2 (2)
PTW Screw Pump 75 1 7 75 525 1 1 1 (1) (1)
Coarse Screen 45 2 3 90 135 1 1 1
Fine Screen 45 3 5 135 225 1 1 1 1 1 1 1 (1)
Deodorisation Unit 45 9 10 405 450 3 6 8 2 1 1 1
Detritor 45 4 4 180 180 1 1 1 1 2 1 2 1 1
Washpactor 45 1 2 45 90 1 1 (1)
Penstock 45 0 1 0 45
Grit Classifier 45 4 4 180 180 1 1 1 1 2 1 2 1 1
Hung Hom Bay Centrifugal Pump 90 1 6 90 540 1 1 1 1 1
SPS Check Valve (600mm) 0 1 6 0 0 1 1 1 1 1
Inlet Screen 45 0 2 0 90 (1)
Penstock 45 2 6 90 270 1 1
Deodorisation Unit 45 4 4 180 180 2 4 4
Air Relief Valve 45 2 10 90 450 1 1
Ventilation Fan 30 0 2 0 60 (2)
Supply Fan Unit 30 0 3 0 90 (3)
Whampoa Garden Centrifugal Pump 90 1 3 90 270 1
SPS Check Valve (400mm) 0 1 3 0 0 1
SPS Deodorisation Unit 45 3 3 135 135 3 3 2
Supply Fan Unit 30 0 2 0 60 (2)
Container Terminal 9 Submersible sewer pump 90 0 2 0 180
SPS No.1
Container Terminal 9 Submersible sewer pump 90 0 2 0 180
SPS No.2
Kai Tak No.1 Centrifugal Pump 90 0 2 0 180
DWFI PS Check Valve (400mm) 0 0 2 0 0
Ventilation Fan Unit 30 0 3 0 90
Kai Tak No.2 Centrifugal Pump 90 0 2 0 180
DWFI PS Check Valve (400mm) 0 0 2 0 0
Mechanical Coarse Screen 45 0 2 0 90
Ventilation Fan Unit 30 0 2 0 60 (2)
Kowloon East Centrifugal Pump 90 1 2 90 180 1 1 (1)
DWFI PS Check Valve (400mm) 0 0 2 0 0 (1)
Ventilation Fan Unit 30 0 3 0 90 (3)
Wan Hoi Street Submersible sewer pump 90 0 2 0 180
SPC
Chai Wan Coarse Screen 45 1 3 45 135 1 1 1 (1)
PTW Fine Screen 45 2 3 90 135 1 1 1 1 1
Detritor 45 0 2 0 90 (1)

2. Classifier 45 1 1 45 45 1 1 1
Centrifugal Pump 90 0 4 0 360 (1)
Grit Classifier 45 0 1 0 45
Screening/Grit Conveyor 45 1 3 45 135 1 1 1 (1)
Washpactor 45 2 2 90 90 1 1 1 1 1 1
Penstock 45 0 1 0 45 (1)
Deodourisation Unit 45 2 7 90 315 2 2 2 (3) (2)
Shau Kei Wan Fine Screen 45 0 3 0 135 (1)
PTW Coarse Screen 45 0 2 0 90 (2)
Grit Trap 45 1 3 45 135 1 1 1 (1)
Air Blower 30 1 2 30 60 1 1 1 (2)
Screw Pump 75 1 4 75 300 1 1 1 1 (1)
Screening/Grit Conveyor 45 0 4 0 180 (2) (2)
Washpactor 45 0 2 0 90 (1)
Penstock 45 0 1 0 45 (1)
Grit Classifier 45 0 2 0 90 (1)
Deodourisation Unit 45 4 4 180 180 3 3 1 1
Dehumidifier Unit 45 0 1 0 45 (1)
Kwun Tong Coarse Screen 45 1 4 45 180 1 1 1 (1)
PTW Penstock 45 0 1 0 45 (1)
Fine Screen 45 4 4 180 180 1 1 1 1 1 1 1 2 2 1
Washpactor 45 1 2 45 90 1 1 1
Screw Pump 75 1 6 75 450 1 (1)
Deodourisation Unit 45 4 10 180 450 1 1 1 1 (1)
Detritor 45 2 4 90 180 1 1 1 1 1 (1)
Screening/Grit Conveyor 45 0 9 0 405 (2) (2)
Grit Classifier 45 2 4 90 180 1 1 1 1 1
Kwun Tong Submersible sewer pump 90 2 6 180 540 1 1 1 1 1 (1)
PS
Cheung Sha Wan Check Valve (400mm) 45 0 4 0 180
SPS Hydraulic Penstock 45 0 2 0 90
Washpactor 45 0 1 0 45
Deodourisation Unit 45 0 3 0 135
Ventilation Fan Unit 30 1 1 30 30 1 1
H.V. Main Sewage Pump 90 1 7 90 630 1 (1)
Non Return Valve 0 1 6 0 0 1 (1)
Supply Fan Unit 30 6 8 180 240 2 2 4 4
Air Relief Valve 45 2 10 90 450 2 2 (2)
Roof Exhaust Fan Unit 30 3 10 90 300 3
Gate/Actuator Valve 45 0 6 0 270 (1)
Cheung Sha Wan Deodourisation Unit 45 0 1 0 45
SCP Roof Exhaust Fan Unit 30 3 7 90 210 3 3 3
Screen Conveyor System 45 1 2 45 90 1 1
Mechanical Raked Screen 45 0 3 0 135
Screen Press 45 0 2 0 90
Axial Fan Unit 30 0 2 0 60
Washwater System 45 0 1 0 45
West Kowloon No.1 Main Centrifugal Pump 90 0 3 0 270 (1)
SPS Non Return Valve 0 0 3 0 0 (1)
Mechanical Raked Screen 45 0 2 0 90 1 1 1
Washwater System 45 0 1 0 45
Dehumidifier Unit 45 0 1 0 45
Axial Fan Unit 30 0 6 0 180
Deodourisation Unit 45 0 2 0 90
Roof Exhaust Fan Unit 30 0 10 0 300
Hydraulic Penstock 45 0 1 0 45
Gate/Actuator Valve 45 0 4 0 180
Anchor Street Hydraulic Penstock 45 0 1 0 45
SPS Washwater System 45 0 1 0 45
Mechanical Raked Screen 45 2 2 90 90 1 1 1 1
Main Centrifugal Pump 90 1 3 90 270 1 1 1 1 (1)
Non Return Valve 0 1 3 0 0 1 1 1 1 (1)
Axial Fan Unit 30 4 4 120 120 2 2 2 2 2 2
Deodourisation Unit 45 2 4 90 180 1 2 2
Roof Exhaust Fan Unit 30 9 11 270 330 4 4 2 2 4 4 3
Gate/Actuator Valve 45 0 4 0 180
Water Boat Dock Mechanical Raked Screen 45 1 2 45 90 1
SPS Hydraulic Penstock 45 0 1 0 45
Washwater System 45 0 1 0 45
Main Centrifugal Pump 90 1 3 90 270 1 1 1 1 (1)
Non Return Valve 0 1 3 0 0 1 1 1 1 (1)
Axial Fan Unit 30 4 4 120 120 2 2 3 1
Deodourisation Unit 45 0 4 0 180
Roof Exhaust Fan Unit 30 5 12 150 360 3 3 1 1 3 2 (3)
Gate/Actuator Valve 45 0 5 0 225
Sham Shui Po No.1 Washwater System 45 0 1 0 45
SCP Screen Conveyor System 45 1 1 45 45 1
Supply Air Jet Fan Unit 30 0 2 0 60
Mechanical Raked Screen 45 1 2 45 90 1 1 1 1
Roof Exhaust Fan Unit 30 1 4 30 120 1 1
Sham Shui Po No.2 Mechanical Raked Screen 45 2 3 90 135 1 1 1 1 1
SCP Screening Press 45 1 2 45 90 1 1 1
Deodourisation Unit 45 0 1 0 45
Axial Fan Unit 30 3 6 90 180 1 3 2
Screening Conveyor System 45 1 1 45 45 1 1
Roof Exhaust Fan Unit 30 0 6 0 180
Tai Hang Tung Main Floodwater Pump 90 0 1 0 90
Stormwater Swing Check Valve 0 0 1 0 0
Storage Tank Axial Fan Unit 30 0 4 0 120
Roof Exhaust Fan Unit 30 0 2 0 60
Kau Wa Keng Submersible sewer pump 90 0 2 0 180
DWFI SPS
Hoi Fai Road Submersible sewer pump 90 0 2 0 180
Public Cargo
Working Areas
SPS
Access Chamber No.1 Supply Air Fan Unit 30 0 2 0 60
Exhaust Fan Unit 30 0 2 0 60
Air Relief Valve 45 0 2 0 90
Tseung Kwan O Centrifugal Pump 90 0 7 0 630 (1)
PTW Detritor 45 3 3 135 135 1 1 1 1 1 1 1 (1)
Coarse Screen 45 2 2 90 90 1 1 1 1
Fine Screen 45 2 5 90 225 2 2 1 (2)
Grit Classifier 45 4 4 180 180 2 2 2 2 1 2 2

3. Deodorisation Unit 45 11 11 495 495 2 2 4 4 5
Washpactor 45 2 2 90 90 1 1 1 1 1
Penstock 45 0 1 0 45 (1)
Screening/Grit Conveyor 45 2 7 90 315 1 1 1 1 1 1 (2)
Tseung Kwan O Centrifugal Pump 90 2 3 180 270 1 1 1 1 1 1 1 1 1
PS
Tseung Kwan O Penstock 45 0 4 0 180
Desilting Plant Radial Gate 45 0 4 0 180
Kwun Tong Screw Pump 75 1 5 75 375 1 1 1 1 (1)
Intermediate Penstock 45 0 2 0 90
SPS
Yau Tong Coarse Screen 45 2 2 90 90 1 1 1 1 1
SPS Screening/Grit Conveyor 45 1 1 45 45 1 1
Centrifugal Pump 90 1 3 90 270 1 1 1 (1)
San Po Kong Submersible Sewer Pump 90 1 3 90 270 1 1 1 (1)
SPC
Kowloon Bay Submersible Sewer Pump 90 1 1 90 90 1 1 1 1
DWFI PC
Ngau Tau Kok Submersible Sewer Pump 90 1 1 90 90 1
DWFI PS
Received Overhaul Works Order 242 627 = 39 % (by equipment) Legends:
10665 28845 = 37 % (by squad-day)
1 2 3 4 5 6 7 8 The past events
Planned Overhaul Works Order 0 627 = 0 % (by equipment)
0 28845 = 0 % (by squad-day) 1 On-going overhaul: One Equipment
Estimated Total 242 627 = 39 % (by equipment) (1) Planned overhaul: Awaiting Mutual Agreements
10665 28845 = 37 % (by squad-day)
Last updated 2014/7/2