Issue 21, July 2021

Delivering Environmental Infrastructure Excellence: Cheung Chau Sewage Treatment and Disposal Facilities

Responsible handling of sewage is important to maintaining safe and healthy communities. To ensure it is dealt with effectively and in a cost-effective way, the sewage generated from our daily lives is collected and treated in Sewage Treatment Works before discharging into water bodies. The existing Cheung Chau Sewage Treatment Works (CCSTW) and Pak She Sewage Pumping Station (SPS) have been operating for over 30 years, with most of their facilities reaching the end of their design life, serving around 65% of Cheung Chau’s existing population of 22,000.

With Cheung Chau’s projected population reaches approximately 38,000 in the near future, it calls for the demand to upgrade the water treatment facilities. The upgraded plant and facilities will not only provide a sustainable disposal pathway but also safeguard public health and the environment by restoring natural biodiversity into the surrounding water areas. ATAL is pleased to be awarded this major environmental project to upgrade the CCSTW and Pak She SPS to accommodate the outlying island’s population growth and development needs. In this project, we are responsible for the design, supply, delivery, installation, process start-up and testing and commissioning of the Preliminary Treatment Facilities, Membrane Bioreactor (MBR) Treatment Facilities, Sludge Digestion System, Sludge Dewatering System at CCSTW.

The implementation of the project, expected to be completed by 2026, will increase the CCSTW’s treatment capacity from 4,000 cubic metres per day (m3/day) to 9,800 cubic metres per day (m3/day); and the SPS’s capacity from 29,000 m3/day to 42,000 m3/day. The upgraded plant and facilities will integrate the gradual expansion of the village sewage infrastructure network to other unsewered areas of Cheung Chau in the future, providing not only a sustainable disposal pathway, but also safeguarding public health and the environment by restoring natural biodiversity into the surrounding water areas.

The Executive Director of ATAL Engineering Group, Ir Raymond Chan said, “Every community that is witnessing population growth relies on key infrastructure for stability and wellbeing. We are delighted to play an important role in expanding and upgrading Cheung Chau’s sewage system to support the needed system capacity. The project will create an exemplary community asset that sets the pace for a more sustainable Hong Kong.”

ATAL will adopt the leading best practice approach through the New Engineering Contract (NEC) arrangement to deliver the project on time, on budget, and to a higher standard. The current CCSTW operates a primary sewage treatment system that removes fine particles. The upgrade will involve enhancing its treatment standard to a secondary level that complies with the HKSAR Government’s effluent discharge standard. To achieve this, the MBR sewage treatment system will be applied for organic, nitrogen, and bacteria removal, as well as solid and liquid separation. The application of this improved treatment plant technology is critical to protect Cheung Chau’s waterways as components harmful to the environment and people’s health will be removed before the water is returned to nature.

The project also covers ancillary works, including building works, road works, drainage works, utility works, architectural and landscaping works. Capitalising on the opportunity to put into practice an eco-friendly design and project planning and management approach, a number of green initiatives have been bundled into the construction and operations phase, such as equipping the upgraded CCSTW with deodourisation unit and the fitting of acoustic louvre and silencer to reduce the noise impact. In addition, the spatial arrangement of the upgraded CCSTW facilities has been designed to minimise disturbance to the existing trees whilst more trees will be planted in and around the facilities to generate positive environmental and aesthetic outcomes.

“The design of the upgrade works will adopt an innovative, green, and low-carbon approach to improve the water quality of the surrounding water body. This aligns with our operation principles to achieve a sustainable environment for the community.” added Ir Chan.

Left: Upgrading design works are underway to the existing Cheung Chau’s Sewage Treatment Works and Pak She Sewage Pumping Station

Right: The completed CCSTW and Disposal Facilities will adopt a state-of-the-art eco-friendly design to serve Cheung Chau’s projected population of around 38,000