HATS Stage 1 | Environmental Protection Department

Overview

Construction works of Stage 1 of the Harbour Area Treatment Scheme (HATS) commenced in 1994. This stage comprised the construction of a chemically-enhanced primary treatment (CEPT) plant at Stonecutters Island, an outfall tunnel, the comprehensive upgrading of seven preliminary treatment works and seven tunnels for collecting sewage from urban Kowloon, Tsing Yi, Kwai Chung, Tseung Kwan O and eastern Hong Kong Island and conveying it to Stonecutters Island. The tunnel system was completed in December 2001 for full commissioning of HATS Stage 1.

Following the full commissioning of Stage 1 in December 2001, around 75% of the sewage generated in the harbour area is now treated at the Stonecutters Island Sewage Treatment Works (SCISTW) and discharged through the outfall to the western harbour area.

Benefits

HATS Stage 1 has on average increased dissolved oxygen in the harbour waters by about 10%. In addition, the levels of key pollutants in the harbour area waters have generally decreased:

Unionised Ammonia (UIA) has reduced by 31%;
Nutrients, in terms of total inorganic nitrogen (TIN) and Orthophosphate (which in rich supply can increase the likelihood of red tides), have reduced by 16% and 36%; and
The overall E.coli level, which is an indicator of disease-causing microorganisms, has reduced by some 50%.

Milestones

The following achievements and events were significant in the development of HATS Stage 1.

Year	Achievements and events
1980	Enactment of the Water Pollution Control Ordinance to provide statutory powers for the control of effluents discharged to the aquatic environment.
1987	Commencement of the Sewerage Master Plan programme to improve local area sewerage systems.
1989	Formulation of the Strategic Sewage Disposal Scheme for Hong Kong.
1994	Enactment of the Water Pollution Control (Sewerage) Regulation to require the connection of wastewater from premises to the public sewerage system and the proper maintenance and operation of private wastewater treatment facilities. Declaration of the Victoria Harbour (Phase I) Water Control Zone. Commencement of work on construction of Stage 1 of the Harbour Area Treatment Scheme.
1995	Declaration of the Victoria Harbour (Phase II) Water Control Zone.
1996	Declaration of Victoria Harbour (Phase III) Water Control Zone - bringing the whole territory under water pollution control.
1997	Commissioning of a new chemically-enhanced primary sewage treatment plant at Stonecutters Island, as part of the Harbour Area Treatment Scheme.
2001	Full commissioning of Stage 1 of the Harbour Area Treatment Scheme.