Planning, Design and Construction of New Sewerage Facilities

Harbour Area Treatment Scheme

The Harbour Area Treatment Scheme (HATS) is one of the most important governmental infrastructure projects in Hong Kong, aiming to improve the water quality of Victoria Harbour by collecting and treating sewage from both sides of the harbour. The project was carried out in two phases, with construction works spanning two decades at a total cost of $25.8 billion. The facilities of HATS Stage 1 and Stage 2A were fully commissioned in December 2001 and December 2015 respectively.

New penstock inside the Main Pumping Station No. 1 being installed

Layout plan of Harbour Area Treatment Scheme

Current Progress

To improve the operational flexibility and stability of the entire HATS system, the project team spent months on the preparation and planning of the replacement of two large penstocks located at 34 metres below ground level, inside the Main Pumping Station No. 1 of the Stonecutters Island STW. To accomplish these replacement works, bypasses of the preliminarily treated sewage from the upstream preliminary treatment works into Victoria Harbour were to be carried out on up to five occasions, each not exceeding two weeks within two years (from 2018 to 2020). Since the progress of the works was not only satisfactory but beyond expectation, such large-scale replacement works were successfully completed during the third bypass in March 2019 and there is no need to carry out the fourth and fifth bypasses in the fourth quarter of 2019 and the first quarter of 2020 respectively as envisaged in the original plan.

Upgrading of Mui Wo Sewage Treatment Works

The previous Mui Wo STW was commissioned in 1985, and provided secondary treatment to sewage collected from Chung Hau area, Ngan Wan Estate and the Mui Wo Ferry Pier area. In order to cater for the forecasted increase in sewage flow due to the increase in population and extension of the village public sewerage system, we engaged a consultant in 2007 to investigate the feasibility of upgrading the design capacity of the Mui Wo STW. The investigation proposed that the design capacity of the Mui Wo STW should be increased from about 1,190 cubic metres per day to about 3,700 cubic metres per day.

Current Progress

Construction works commenced in 2012 and was substantially completed and commissioned in April 2018. The project cost is about $967 million. During the course of upgrading, the contractor was requested to maintain the operation of the Mui Wo STW to ensure the quality of sewage treatment. The project also includes upgrading the sludge treatment and deodourisation facilities, together with landscaping and greening of the Mui Wo STW.

Mui Wo Sewage Treatment Works

Tolo Harbour Sewerage of Unsewered Areas

We are carrying out sewerage works in Sha Tin and Tai Po to improve both the water quality of Tolo Harbour and sanitation for 11 unsewered communities. The project involves building a sewage pumping station at Kau To, Shatin and laying about 12 kilometres of sewers for nine and two unsewered areas in Shatin and Tai Po respectively.

Current Progress

Construction works commenced in 2013 and completed in December 2018. The project cost is about $364 million.

Shek Wu Hui Effluent Polishing Plant

In line with the rapid development of North District, we will expand the treatment capacity of Shek Wu Hui STW from 93,000 cubic metres per day to 190,000 cubic metres per day in phases. The plant will be upgraded to an effluent polishing plant with tertiary treatment level. This is to ensure the discharge will comply with the stricter environmental requirements, thus protecting the ecological environment of Deep Bay. We will also take this opportunity to revamp its exterior, enhance its environmental performance and promote its educational function in water conservation so as to transform Shek Wu Hui STW into an iconic and multipurpose community facility.

Current Progress

Shek Wu Hui Effluent Polishing Plant is executed in stages. Advance works was commenced in mid-2015 and completed in 2019. The Main Works will be implemented in three phases starting from the third quarter of 2019 targeting for completion of the final phase by 2034. The estimated cost for advance works, investigation and design is about $500 million and the estimated cost for Main Works is about $13.2 billion.

Photomontage of the Shek Wu Hui Effluent Polishing Plant

Upgrading of San Wai Sewage Treatment Works Phase 1

In light of the increasing population in Yuen Long, Tin Shui Wai and Hung Shui Kiu, the project will increase the treatment capacity of San Wai STW from existing about 164,000 cubic metres per day to about 200,000 cubic metres per day. It will also upgrade the existing preliminary treatment of San Wai STW to chemically enhanced primary treatment with ultraviolet disinfection in order to improve the water quality in the north western water.

Current Progress

The project, procured through a Design-Build-Operate (DBO) contract, commenced in May 2016 and is scheduled for completion in 2020. Upon completion of construction works, the contractor will undertake the operation and maintenance of the new San Wai STW for a period of 10-15 years. The estimated project cost is about $3.14 billion.

Construction of Additional Sewage Rising Main and Rehabilitation of the Existing Sewage Rising Main between Tung Chung and Siu Ho Wan

The existing sewage rising main between Tung Chung and Siu Ho Wan is the only pipe for conveying sewage collected within the Tung Chung area and airport island to the Siu Ho Wan STW. It has been in operation for 20 years, and approaching its design life of 25 years. It is imperative to provide an additional sewage rising main to keep conveyance of the sewage, and thus allow inspection and rehabilitation of the existing one. Both rising mains are designed to meet the increased demand from the development of Hong Kong International Airport and Tung Chung New Town Extension, as well as enhancing the reliability of the sewage system.

The first works contract of the project includes the construction of sewage rising main of about 6.5 kilometres with a diameter of 1,200 millimetres and associated connection and ancillary works. The second works contract of rehabilitation works will follow upon completion of the new rising main. On completion of the works, the combined nominal capacity of the two rising mains will meet the sewage flows projected up to 2038.

Current Progress

The project commenced in August 2016 and will be implemented in phases for an anticipated completion date in 2025. The estimated project cost is about $1.36 billion.

Pipe laying in an open trench excavation under the temporary traffic arrangement (TTA) at Cheung Tung Road

Expansion of Village Sewerage

Over the years, DSD has strived to expand public sewerage systems to villages in a bid to improve hygienic conditions in rural areas, as well as the quality of nearby water bodies. Construction works for sewerage projects are currently underway in Tuen Mun, Sai Kung and the Outlying Islands.

Current Progress

As of March 2019, we have laid public sewerage for over 240 villages. The works for around 20 villages are underway and the schemes for around 245 villages are under planning and design.

Dry Weather Flow Interceptors at Cherry Street, Tai Kok Tsui

Polluted dry weather flow from stormwater systems running in Kowloon Tong, Mongkok and Yau Ma Tei districts becomes a major cause of the deterioration in water quality and the associated odour problem at the New Yau Ma Tei Typhoon Shelter (NYMTTS). In view of the situation, we are constructing an underground dry weather flow interceptor (DWFI) and a pumping station along the seafront of NYMTTS to intercept the polluted dry weather flow from the Cherry Street box-sulvert and deliver to Stonecutters Island STW for proper treatment and disposal.

Current Progress

Construction works commenced in December 2017 aiming for completion in 2022. The estimated project cost is about $313 million.

Photomontage of the dry weather flow interceptor at Cherry Street. After project completion, the landscaped area above the dry weather flow interceptor will be open to the public for enjoyment

Enhancement Works for Kwun Tong Sewage Pumping Station

To support local development of East Kowloon, the enhancement works for Kwun Tong SPS will involve the construction of an underground sewage balancing facility with a capacity of 16,000 cubic metres and provision of ventilation and odour control equipment. A landscaped deck at the roof will also be constructed to enhance the visual appearance of the pumping station and provide an open space of about 10,000 cubic metres for public recreation.

Current Progress

Construction commenced in December 2017 and is scheduled for completion in mid-2022. The estimated project cost is about $1.05 billion.

Photomontage of the enhanced Kwun Tong Sewage Pumping Station

Expansion of Sha Tau Kok Sewage Treatment Works,
Phase 1

The existing Sha Tau Kok STW was built in 1989 and is a secondary treatment works which provides treatment to the sewage collected from Sha Tau Kok Town, Yim Liu Ha, Tsoi Yuen Kok and Sha Tau Kok Chuen before discharging into Starling Inlet. To cope with the forecast increase in sewage flow in Sha Tau Kok sewage catchment, we will reconstruct the existing Sha Tau Kok STW to increase its capacity from about 1,660 cubic metres per day to about 5,000 cubic metres per day. The project also includes construction of approximately 1.7 kilometres of submarine outfall with diameter 450 millimetres and decommissioning of existing sewage pumping station and the associated rising mains.

Current Progress

Construction works commenced in November 2018 targeting for completion in 2025. The estimated project cost is about $2.04 billion.

Photomontage of the completed Phase 1 Sha Tau Kok Sewage Treatment Works

Construction in progress (Photo taken in July 2019)

Yuen Long Effluent Polishing Plant

The existing Yuen Long STW serves Yuen Long Town, Yuen Long Industrial Estate and Kam Tin areas with a design capacity of 70,000 cubic metres per day. We will expand the treatment capacity of Yuen Long STW in stages to 150,000 cubic metres per day to cope with the issue of ever-increasing sewage. The plant will be upgraded to an effluent polishing plant with tertiary treatment level. This is to ensure the discharge will comply with the stricter environmental requirements, thus protecting the ecological environment of Deep Bay. We will also take this opportunity to revamp its exterior, enhance its environmental performance, adopt renewable energy and incorporate extensive greening features and provide public co-use facilities for the benefit of the local community.

Current Progress

Environmental impact assessment was completed and Environmental Permit was granted in April 2019. Detailed design for the upgrading works is on-going. Construction will be implemented in two stages. Subject to funding approval, the construction of Stage 1 Works is scheduled for commencement in 2020 and targeted for completion in 2027. The estimated cost for investigation and design is about $98 million while the estimated cost for Stage 1 Works is about $6.8 billion.

Yuen Long Sewage Treatment Works

Design layout of Yuen Long Effluent Polishing Plant

Relocation of Sha Tin Sewage Treatment Works to Caverns

The Sha Tin STW is to be relocated to a cavern, to be excavated in Nui Po Shan on the opposite side of Shing Mun River. This will release 28 hectares of land on the existing Sha Tin STW site for other uses and improve the living environment of the district.

Current Progress

The future cavern complex for the relocated Sha Tin STW will be the largest of its type ever built in Hong Kong. It will be constructed by stages, namely: site preparation and access tunnel construction; main caverns construction; upstream serverage works; sewage treatment facilities installation; and decommission and demolition of existing Sha Tin STW.

The design work was completed in phases since 2017. In October 2018, we obtained the funding approval from the Finance Committee of Legislative Council and commenced the Stage 1 works – site preparation and access tunnel construction in February 2019. While the implementation programmes of the remaining stages of construction works are still under review, the total construction period of the project is estimated to be 13 years.

Relocation of Sha Tin Sewage Treatment Works to Caverns

Managing Underground Drainage and Sewerage Networks

DSD manages about 4,700 kilometres of underground drains and sewers. These underground pipes have been in service on average for 29 years. Over 2,030 kilometres of the underground pipes have been used for 30 years or more, with many of them showing signs of wear and tear. Structural failure of seriously deteriorated pipes may result in soil erosion and road subsidence, affecting the normal operation of the pipelines and bringing adverse impacts on traffic, environment and public safety.

In view of this, in addition to regular inspections, we are striving to implement a territory-wide rehabilitation programme in a risk-based approach for the aged stormwater drains and sewers. Condition surveys and rehabilitation of high risk underground pipes are being implemented in phases. At the same time, we will study and apply various cutting-edge technologies to efficiently maintain our underground pipe networks and achieve greater cost-effectiveness of our works. In 2018-19, we rehabilitated storm drains and sewers with a total length of about 14 kilometres, at a cost of about $172 million.