Upgrading West Kowloon and Tsuen Wan sewerage – Phase 1, Hong Kong

Upgrading West Kowloon and Tsuen Wan sewerage – Phase 1, Hong Kong


This case study is part of the Spotlight Campaign for Water. To read more on how NEC Contract suite has been utilised in the Water Spotlight, please click here.


The Hong Kong government is improving the seawater quality of Victoria Harbour under an NEC3 Engineering and Construction Contract (ECC). Polluted urban runoff in the existing stormwater drainage systems in Mong Kok, Yau Ma Tei, Sham Shui Po and Tsuen Wan has been a major cause of the deterioration of water quality and associated odour problems in the coastal areas of West Kowloon and Tsuen Wan Bay.

The problem is largely due to continual redevelopment of West Kowloon and Tsuen Wan and declining efficiency of 43 existing dry-weather flow interceptors (DWFIs) in these areas. The DWFIs are intended to divert polluted dry-weather flows in the stormwater drains to the sewage system on non-rainy days so they can be conveyed to Stonecutters Island sewage treatment works for treatment.

To fix the problem, the government’s Drainage Services Department (DSD) let a four-year HK$141 million (£14 million) NEC3 ECC Option B (priced contract with bill of quantities) to Po Wing H.P. Drainpipe & Construction Company in September 2017. The design consultant is Atkins China Limited.

Multiple sites

The phase 1 works involves building a total of eight new DWFIs with flow restrictors, four each in West Kowloon and Tsuen Wan. The works also include upgrading 10 the 43 existing DWFIs with new desilting chambers and flow-restrictors, enhancement of another 18 and decommissioning 15. On completion of the contract in September 2021, it is estimated that the new and modified DWFIs will remove about 70% of the total annual pollution loading from their respective stormwater systems in Tsuen Wan and West Kowloon.

According to DSD project manager CM Choi, ‘We chose NEC because it provides a contractual partnering arrangement for the parties to work “in a spirit of mutual trust and co-operation”. The contract also enables fair risk sharing between the employer and contractor.

‘The time limitations for communications in NEC have significantly speeded up decision making and progress on the project. The NEC early warning process has also led to timely resolution of project risks at risk reduction meetings, helping us to maintain progress and remain on budget and schedule.’

Early warning benefits

He said the early warning process is proving to be an effective project management tool. ‘Most of our interceptors are located in busy urban areas with congested underground utilities. Whenever the original design is found to clash with existing underground utilities, or when the proposed construction sequence might cause undue impact on the public, the project manager issues an early warning to the contractor.

‘A risk-reduction meeting is then immediately arranged to review the design and construction sequence to maintain progress and minimise public impact. If there are changes to the works information, compensation events are assessed and issued in a timely manner to the contractor for time and cost compensation according to the contract.’

Choi added that by having the employer, project manager and contractor all working in a combined open-plan office also helped to enhance communication and enable potential risks to be resolved immediately.  

Benefits of using NEC

  • NEC provides a contractual partnering arrangement, with the employer, project manager and contractor working ‘in a spirit of mutual trust and co-operation’ to resolve project risks and complete the works successfully.
  • NEC enables fair risk sharing between the employer and contractor, with their respective risks clearly stated in contract documents. Compensation events are assessed use agreed defined cost to compensate the contractor in cost and time.
  • NEC sets clear time limits on periods for reply, which speeds up decision making. Both the project manager and contractor must reply to a communication within the specified time limits.
  • The NEC early warning process leads to proactive identification of project risks. Both the project manager and contractor cooperate at risk reduction meetings to reduce the risks, helping projects to be delivered on time and within budget.
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