Growth led to $800m project
AS the Hong Kong's residential population grew and its industrial activity increased during the 1980s, it became apparent that the territory's mode of sewage collection could no longer provide adequate protection against water pollution.
With quality of the local waters deteriorating and the local beaches threatened, a sewerage master plan study completed in 1989 recommended sewerage facilities to be constructed on Hong Kong Island South from Shouson Hill to Shek O.
The construction began in July 1990 and the project is expected to be completed in mid-1996 at a cost of about $800 million.
Such major projects come under the planning of the Projects and Development Branch (PDB) of the Drainage Services Department (DSD).
After the projects have been studied, planned, designed and approved, they are contracted out to private firms.
Under the Hong Kong Island South project, 12 kilometres of sewers and pumping mains, four subsidiary pumping stations and a central pumping station will collect all sewage flow from Repulse Bay, Middle Bay, the South Bay area, Deep Water Bay and Shouson Hill and transport it to the Aberdeen sewage plant for treatment.
In the Shek O and Rocky Bay areas, two kilometres of sewers and pumping mains, a pumping station and a sewage screening plant under construction will collect polluted water for treatment and disposal via a submarine outfall off Tai Tau Chau.
A similar project involving 10 kilometres of sewers and pumping mains and an underground sewage treatment plant will collect all sewage from Stanley, Tai Tam, Ma Hang, Chung Hom Kok and the Red Hill area for treatment and disposal into the deep sea. Apart from the new construction, refurbishment of existing systems will also be carried out in these areas.
Among the major projects of the PDB is the Stanley underground sewage treatment works.
The first of its kind in Southeast Asia, the plant has been carved from underground in three caverns of granite, each 120 metres long, 15 m wide and 17 m high, with more than 450 m of ventilation tunnels, shafts and road access.
The benefits of the caverns is that the environment is readily controlled and not subject to the weather. The underground construction has also had a reduced impact on the environment, both during construction and while operational.
Constructed to serve the 27,000 residents of the Stanley area, the project was recently completed and test runs are being conducted.
Operational by late summer, the plant will perform a nitrifying-denitrifying process followed by disinfection.
The treated effluent will then be disposed of through a long sea outfall into Sheung Sz Mun. The sludge from the final settlement tanks will be disposed of in a landfill.
Another part of this project is the reclamation of 0.7 hectares at Stanley Bay. This was undertaken to provide land for the expansion of Stanley and for a new trunk sewer to convey sewage from Ma Hang to the Stanley main pumping station.
The reclaimed land also allows for emergency vehicular access for ambulances and fire-fighting vehicles to reach the eastern end of the main market and for recreational uses such as a soccer pitch.
Evidence of this project can been seen in the construction of the sea wall completed earlier this year.
Further examples of the work of the PDB is the redevelopment of the Seaview promenade.
