ENG-1984 — Page 356

274

THE ENVIRONMENT

respectively. The principal sewage treatment works providing biological treatment are in Sha Tin, Tai Po, Shek Wu Hui and Yuen Long, with four other smaller plants at Hei Ling Chau, Shek Pik, Tung Tau and Stanley Fort. Primary treatment to remove material that can settle is provided at Repulse Bay and Deep Water Bay, and there are several screening plants. 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 addition, screening will be provided, as well as improved outfalls, in Kwun Tong, Junk Bay, Ma On Shan, Sai Kung, Chai Wan, Kowloon East and Kowloon North West.

In 1984, the sludge treatment phase of the Sha Tin Treatment Works was commissioned, and this will provide sludge gas for the dual fuel engines which in turn generate electrical power for the works. The Shek Wu Hui, Tai Po Stage II and Yuen Long treatment works were commissioned, as were the sewage pumping and screening plants at Tuen Mun, Mong Kok and Central District. Small package plants utilising biodiscs were commissioned at Shek Pik Prison and A Kung Kok (near Sha Tin New Town). Construction of sewage works in Tai Po (Stage IV), Chai Wan, Kowloon East, Cheung Chau and Kwun Tong continued. Design work was in hand for a large sewage pumping station at Ma On Shan, a pumping station and primary treatment works for Junk Bay, a large screening plant for Sham Shui Po and numerous other smaller works.

Work to intercept dry weather flow in the Kai Tak nullah continued throughout the year. In addition, a scheme for oxygen injection into the water at the southern end of the nullah was being implemented. The scheme to intercept the polluted dry weather flow in the Tuen Mun nullah was commissioned. To improve the water quality of the Tuen Mun nullah and typhoon shelter, the intercepted flow is now discharged at the Pillar Point sewage outfall.

On average, over 6000 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, and the refuse composting plant at Chai Wan operated by the Electrical and Mechanical Services Department, processed the 2 650 tonnes of domestic and commercial waste collected daily by the Urban Services Department and private contractors. The remainder, as well as the incinerator and compost plant residues, was disposed of at the controlled tips operated by the Engineering Development Department. Following satisfactory trials in controlling the chimney emissions at the Kennedy Town plant, a contract was awarded for installing two more electrostatic precipitators in the remaining incinerators at Kennedy Town. This installation is expected to be completed in May 1986 and the quality of emissions from the plant will then be greatly improved. A programme for carrying out similar modification to the Lai Chi Kok incinerator is in hand. Products of the composting plant at Chai Wan are used by various authorities to condition soil used in landscaping. During the year, work continued on the preparation of the Jordan Valley controlled tip, which will replace the Ma Yau Tong controlled tip, and detailed design work was completed and preparatory work begun on the Junk Bay Stage II controlled tip. The restored land which becomes available following the completion of a controlled tip is assigned for recreational purposes or some other beneficial use.

In outlying areas, waste collection and disposal arrangements are being upgraded. All refuse collected on the island of Cheung Chau is carried by barge to the mainland for disposal, and this scheme implemented by the New Territories Services Department may be extended to other outlying islands. Further progress has been made with the programme to replace small village refuse incinerators, which are a source of environmental nuisance, with