Frequently Asked Questions
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What is the purpose of the Public Engagement activities of the feasibility study on relocation of Sai Kung Sewage Treatment Works (SKSTW) to caverns?
We wish to maintain close dialogue and share the latest information of the Project with the public through the Public Engagement activities. We will collect public opinions and concerns, and work together with the public to enhance the relocation proposal.
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How do you make use of my view?
The consultant will collect and compile public views. We will introduce suitable enhanced and innovative elements based on the project situation in response to public concerns, with a view to further improving the relocation proposal. The result of the study will be shown in the second stage of Public Engagement activities and in this website.
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How can I express my opinions?
You may express your opinions via:
Email: enquiry@dsd.gov.hk
Mail: Consultants Management Division, Drainage Services Department,
42/F, Revenue Tower, 5 Gloucester Road, Wan Chai, Hong Kong
(Please specify "Relocation of Sai Kung Sewage Treatment Works to Caverns - Feasibility Study") -
Why is it needed to conduct the feasibility study on relocation of Sai Kung Sewage Treatment Works to caverns?
To support Hong Kong's sustainable development, the Government actively explores innovative approach to develop new land resources. One of the possible approaches is rock cavern development.
Civil Engineering and Development Department completed a study on “Enhancing Land Supply Strategy - Reclamation outside Victoria Harbour and Rock Cavern Development” in 2014. The study recommended a feasibility study on the relocation of Sai Kung Sewage Treatment Works to caverns, with a view to releasing the existing site (about 2.2 hectares) for housing and other beneficial uses. Through the feasibility study, we will ascertain whether the relocation proposal is technically feasible and financial viable.
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Why do you propose Tsiu Hang as site for relocation of Sai Kung Sewage Treatment Works?
According to the study on “Enhancing Land Supply Strategy - Reclamation outside Victoria Harbour and Rock Cavern Development” completed by the Civil Engineering and Development Department in 2013, the preliminarily proposed site for relocation of Sai Kung Sewage Treatment Works to caverns was Tsiu Hang.
Under the feasibility study of this project, the Consultant conducted a re-confirmation review of the proposed relocation site. When conducting the review, the Consultant identified and compared four areas in the vicinity of the existing SKSTW, including Tai Wan, Tsiu Hang, Tai Chung Hau and Pak Kong. The Consultant has considered several elements including geology, impact to existing sewerage system, land status, impact to the surrounding environment and traffic impact in the vicinity during the re-confirmation review.
After the review, the Consultant confirmed Tsiu Hang is the most suitable site for relocation of Sai Kung Sewage Treatment Works. In summary, Tsiu Hang has the following favourable conditions.
i. The geology of this area is revealed as strong to very strong volcanic rock with very close to closely spaced joints. Rockhead is indicated at approximately 10m to 20m below ground level which is suitable for cavern construction.
ii. The selected site is located in the proximity of the existing SKSTW and the existing submarine outfall. As such, relocating the SKSTW to this area can minimize the effect on the upstream sewerage and the downstream disposal network, thereby minimizing the disturbance to the whole Sai Kung District, reducing the construction and operation costs and shortening the construction period.
iii. As majority of the area belongs to government land, the relocation project does not involve large extent of private land resumption.
iv. The overall community and environment will be enhanced after the relocation.
v. With appropriate measures, the traffic impact due to the relocation of SKSTW could be minimized
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Will the relocation proposal cause any adverse impact to the surrounding environment?
The Consultant is conducting a preliminary assessment on the environmental impacts due to the relocation project during the construction and operation stages. The assessment includes air quality (odour), noise, water quality, ecology, cultural heritage, waste management and visual impact, etc. The Consultant will also propose suitable mitigation measures, to ensure the compliance with the requirements of relevant standards.
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Will the relocation proposal affect the existing outfall and the water quality of the Inner Port Shelter?
The existing Sai Kung Sewage Treatment Works is being operated such that the effluent quality will meet the requirements set down in the Discharge Licence issued by the Environmental Protection Department.
Currently, the treated effluent is discharged at 450m away from the coast of Inner Port Shelter via a submarine outfall with diameter 750mm after treatment in Sai Kung Sewage Treatment Works. The effluent of the relocated SKSTW will also be discharged to the offshore of Sai Kung Hoi via a submarine outfall.
According to the latest planning, the effluent quality of the relocated Sai Kung Sewage Treatment Works will maintain the existing effluent quality and would not affect the water quality of Inner Port Shelter. Meanwhile, Drainage Services Department will close liaise with Environmental Protection Department and relevant government departments to ensure the effluent quality will meet the planned use of the receiving water body. -
Will the relocated Sai Kung Sewage Treatment Works cause any odour issue to the nearby community?
The relocated SKSTW will locate inside cavern which can cover the source of odour. Hence, the odour impact to the community can be reduced. Nevertheless, the Consultant will also conduct an odour impact assessment to compare the odour impact to the nearby community due to the existing SKSTW and the relocated SKSTW. The assessment will analyze the odour impact to the nearby community due to the relocated SKSTW and propose suitable odour control measures.
The Consultant preliminarily proposed the following odour control measures:
i. Adopting the advantage of caverns as natural barriers for odour control;
ii. Covering up of odour sources;
iii. Preventing odour leakage through the access tunnels by applying negative pressure inside caverns;
iv. Installing deodourising units to clean up the collected foul air;
v. Discharging exhausted air at height to further enhance the dilution effect; and
vi. Enhancing the odour management of the sludge transportation (including adopting sludge carrying vehicles with enclosed containers, cleaning and drying the surface of the sludge carrying vehicles before leaving the caverns, carrying out regular monthly tests for the enclosed containers to ensure proper functioning, etc.).
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Will the sludge carrying vehicles cause any odour impact during operation of the relocated Sai Kung Sewage Treatment Works?
At present, there are about 20 vehicles per day taking sludge away from the existing Sai Kung Sewage Treatment Works. Although the incoming sewage will increase progressively in future, we will adopt advanced treatment technology to maintain the sludge production and hence the traffic volume of sludge carrying vehicles at a similar level. In addition, we will enhance the odour management of the sludge transportation, including adopting sludge carrying vehicles with enclosed containers, cleaning and drying the surface of the sludge carrying vehicles before leaving the caverns, carrying out regular monthly tests for the enclosed containers to ensure proper functioning, etc.