The existing Yuen Long Sewage Treatment Works (YLSTW) commissioned in 1984 serves Yuen Long Town, Yuen Long Industrial Estate and Kam Tin areas with a design capacity of 70,000 cubic metres per day. Due to future needs, the existing YLSTW will be upgraded to Yuen Long Effluent Polishing Plant (YLEPP) with tertiary treatment level and increased capacity from 70,000 square metres per day to 150,000 square metres per day in 2 stages. isThe YLEPP can facilitate the future development of Yuen Long District via in-situ reconstruction without requiring additional land.

In addition, YLEPP is located in the vicinity of recognized sites of conservation importance. They include Inner Deep Bay Site of Specific Scientific Interest (SSSI), Mai Po Marshes SSSI, Mai Po Marshes Nature Reserve and Mai Po Inner Deep Bay Ramsar Site, nearby fishponds and mangrove/mudflat along the embankments and at the confluence of Shan Pui River and Kam Tin Main Drainage Channel. According to pre-construction survey, active night roost areas were observed. Four ardeid species including the Chinese Pond Heron Ardeola bacchus, Great Egret Ardea alba, Little Egret Egretta garzetta, and Grey Heron Ardea cinerea were observed utilizing the roosting sites. The project team has to ensure that the ecological environment and bird habitats are not adversely affected by the project.


Main Works

The project is divided into 2 stages. Contract No. DC/2019/10 - Main Works for Stage 1 commenced on 9 November 2020 and Contract No. DE/2020/01 - E&M Works for Sludge Dewatering Building, Administration Building and Renewable Energy Facilities for Stage 1 commenced on 13 June 2022. Information for Stage 2 works is to be announced later.

Stage 1 works include the following principal elements:
Contract No.: DC/2019/10
1) Demolition and reconstruction of part of the existing YLSTW including inlet works, primary treatment, biological treatment and tertiary treatment facilities;
2) Demolition and reconstruction of sludge treatment facilities;
3) Demolition and reconstruction of the administration building, storage building, switchgear house and transformer house; and
4) Other ancillary works include utilities diversion, walkway, necessary building services, landscape works and local improvement works for the community such as riverside promenade and viewing decks, etc; and
5) Environmental mitigation measures include comprehensive odour control/mitigation measures such as fully-enclosing all treatment units and provision of ventilation and deodourisation system.

Contract No.: DE/2020/01
1) Provision of electrical and mechanical facilities for the Sludge Dewatering Building;
2) Installation of photovoltaic panels at Inlet Works, Primary Treatment Building, Mainstream Bioreactor Building, Sludge Dewatering Building and Sludge Thickening Building; and
3) Provision of building services including the fire services installation for the Sludge Dewatering Building and Administration Building.


Sustainable Development

BEAM Plus assessment is Hong Kong’s leading initiative to offer independent assessments of building sustainability performance. During the design stage, YLEPP had been taken into consideration to design for sustainability and to reduce the environmental impact of buildings throughout their life cycle. Through strategic planning of layout, careful selection of material, promotion of efficient energy use, maximization of water utilization and reduction of effluent, improvement of indoor environmental quality, and adoption of BIM technology, YLEPP buildings were able to adopt sustainability into the design and thus reached the BEAM Plus platinum rating.

Site Aspects
- Apply mitigation measures to reduce air, noise and water pollution during construction
- Disposition of buildings and provision of shades to provide a pleasant microclimate
- Use of pervious material in over 50% of hard landscaped area
- Greenery areas in over 30% of total assessment area

Materials Aspects
- Use of recycled construction materials
- Use of sustainable sources / recycled timber for timber and composite timber
- Use of materials manufactured locally to reduce the environmental impacts arising from transportation
- Recycle of construction waste
- Provision of facilities for the collection, sorting and disposal of waste and recoverable materials

Energy Use
- Offset energy consumption within the building by using renewable energy systems to generate electricity (Photovoltaic panels and combined heat and power system)
- Use of high-efficiency air conditioning

Water Use
- Use of water efficient device to reduce the consumption of fresh water
- Use of appropriate flushing devices to reduce sewage volumes

Indoor Environmental Quality
- Provision of access for persons with disability in Administration Building
- Provision of amenity features (e.g. Store Room, Changing and Shower Room) to enhance building functionality
- Plumbing and drainage design to reduce the potential for transmission of harmful bacteria viruses and odours
- Use of lighting sensor to provide appropriate lighting provisions in occupied spaces

Innovations and Additions
- Use of BIM technology to improve coordination between stakeholders
- Use of twin tank system for both potable and flushing water systems to ensure continual water supply during tank cleaning


Environmental Monitoring

YLEPP Project is a designated project under Schedule 2 of the Environmental Impact Assessment Ordinance (EIAO) (Cap. 499). The statutory Environmental Impact Assessment (EIA) was conducted and the EIA report and Environmental Monitoring and Audit (EM&A) Manual was approved by EPD (Register No.: AEIAR-220/2019) on 25 April 2019. An Environmental Permit (EP) (EP No. EP-565/2019) was issued by EPD on 26 April 2019.

The major requirements imposed during construction phase of YLEPP are summarized as follows:
1) All percussive piling works and demolition using excavator-mounted breakers shall not be carried out from November to March to avoid construction noise impact to the overwintering / migratory waterbirds;
2) Minimize overspill of light to ecological sensitive areas, use of directional down lighting, tight control of lighting periods and intensity to reduce potential impact to nearby ardeid night roost and waterbirds;
3) No construction works with Powered Mechanical Equipment (PME) within 100m from the night roost after 18:00 during wet season and after 17:30 during dry season;
4) Noise barriers with absorptive materials of at least 4m high shall be erected along the northern, eastern and western sides of the Project boundary.


Project Progress

Construction of preliminary treatment facilities and biogas holder, excavation and lateral support works for sludge thickening building and E & M installation at primary treatment facilities are in progress.



Source of Information and Pictures: Official Website of Drainage Services Department