ENG-1985 — Page 332

THE ENVIRONMENT

Construction and Operation of Facilities

257

Over the years, the government has made major investments in facilities for the collection, treatment and disposal of wastes. This programme continued in 1985. A major feature is the provision and operation of sewage treatment works, throughout the territory, by the Engineering Development Department and the Electrical and Mechanical Services Depart- ment. The overall intention in the planning and design of these sewage treatment works is to match discharges to the assimilative capacity of receiving waters. The principal sewage treatment works providing biological treatment are in Sha Tin, Tai Po, Shek Wu Hui and Yuen Long, with five smaller plants at Hei Ling Chau, Shek Pik, Tung Tau, Stanley Fort and Ah Kung Kok. Primary treatment to remove solid material is employed at Repulse Bay and Deep Water Bay, and screening plants are provided at other locations. In the current 10-year sewage treatment and disposal programme, priority is given to extensions of the existing works in Sha Tin, Tai Po, Shek Wu Hui and Yuen Long, in order to cope with increases in the population in these areas.

Principal achievements in the provision of municipal sewage treatment and disposal facilities during the year have been the completion of the Yuen Long sewage treatment works Stage I and the Shek Wu Hui works. Other works under construction include: Chai Wan screening plant, to be connected to an existing submarine outfall; Kwun Tong screening plant, for which the associated submarine outfall has been completed; Kowloon East submarine outfall, which is completed but awaits the completion of an associated pumping station before commissioning; Junk Bay sewage treatment works Stage I and submarine outfall; Mui Wo sewage treatment works and submarine outfall; Cheung Chau sewage treatment works Stage I and submarine outfall; Sha Tin sewage treatment works Stage II and Tai Po sewage treatment works Stages II and IVA. The total estimated project cost of the works under construction is $1,251 million.

Work to intercept dry weather flow in the Kai Tak nullah continued throughout the year. Dredging of organic sediment in the channel of Kowloon Bay Typhoon Shelter adjacent to the airport runway was completed. A start was made on implementing a scheme for oxygen injection into the water at the southern end of the nullah.

To improve the water quality of the Tuen Mun nullah and typhoon shelter, the dry weather flow in upper Tuen Mun nullah has been intercepted and is now discharged at the Pillar Point sewage outfall.

On average, over 6 500 tonnes of domestic, commercial and industrial wastes were collected and disposed of daily. The three municipal incineration plants in Kennedy Town, Lai Chi Kok and Kwai Chung, as well as the refuse composting plant at Chai Wan, all operated by the Electrical and Mechanical Services Department, processed 2 400 tonnes of the domestic and commercial waste collected daily by the Urban Services Department, Regional Services Department and private contractors. The remainder, as well as the in- cinerator and compost plant residues, was disposed of at controlled tips operated by the Engineering Development Department.

Following satisfactory trials in controlling emission of particles from the Kennedy Town incinerator, a contract was awarded for installing electrostatic precipitators in the plant's two remaining flue gas streams. This installation is expected to be com- pleted in May 1986 and, when operational, should greatly reduce particulate emissions from this incinerator. Also, as an alternative to the installation of electrostatic precipita- tors, consideration is being given to replacing the Lai Chi Kok incinerator by a new refuse transfer loading station to be supported by a high capacity controlled tip in the New Territories.