ENG-1993 — Page 451

THE ENVIRONMENT

The Eastern Buffer and Western Buffer Water Control Zones were declared on June 1. The Eastern Buffer Water Control Zone covers Chai Wan and Shau Kei Wan, while the Western Buffer Water Control Zone covers Tsing Yi Island, part of Tsuen Wan (to the west of Tai Chung Road), Sham Tseng, Aberdeen, Ap Lei Chau and Pok Fu Lam. This includes six gazetted beaches along Castle Peak Road.

The Southern and Tolo Harbour Supplementary Water Control Zones, which cover the catchments of Tai Tam, Shek Pik, Plover Cove and Shing Mun Reservoirs, were also declared on June 1. All water-gathering grounds in the New Territories are now covered by the water control zones.

The Victoria Harbour Water Control Zone, which will be the last water control zone to be declared, will shortly be covered, in phases.

The Western Buffer Water Control Zone has, among all the existing water control zones, the highest concentration of electroplaters, printed circuit board manufacturers, and bleaching and dyeing factories. Together, they generate over 20 000 cubic metres of industrial effluent daily, mostly untreated. Control efforts are now focussed on these industries to reduce the pollutants, in particular the toxic metals and alkaline waste, which greatly affect the water quality of the Rambler Channel.

All trade effluents discharged into a water control zone must be covered by a licence, which will specify the maximum amount of pollutants that may be discharged. The standards vary from place to place in accordance with the conservation goals and water quality objectives for the receiving water body. Licence standards usually follow a set of published guidelines.

Considerable efforts are made to ensure that effluents meet the standards set in licences. In 1993, Environmental Protection Department inspectors took more than 4 000 effluent samples and conducted over 13 000 laboratory tests.

These control measures have had great success. For example, in Tolo Harbour, the first water control zone, more than 100 'expedient' connections were rectified. The organic pollution load on the harbour has been reduced by 75 per cent. Concentrations of heavy metals in the processed sludge of the Sha Tin sewage treatment works have been reduced to such an extent that the sludge now meets the stringent standards that apply to marine disposal. In the Southern Water Control Zone, over 90 per cent of private sewage treatment plants now operate satisfactorily and the water quality of many popular bathing beaches has improved as a result.

In Yuen Long and Tuen Mun, a total of 16 000 cubic metres per day of industrial and commercial effluents have been diverted from storm drains to the foul sewerage system. This is equivalent to the organic pollution load from a population of over 80 000 people. In the established zones of Port Shelter and Junk Bay, the reduction is as much as 70 and 50 per cent, respectively, of the organic pollution load.

In all control zones, the department estimates that so far, it has achieved an average of about 50 per cent reduction in the target pollution load by enforcing the Water Pollution Control Ordinance. Even more positive results are expected when the controls have been fully implemented.

Pollution in the once notorious Ho Chung River the black river of Sai Kung has improved dramatically due to effective control of the major industrial polluters. An interceptor scheme, diverting further pollution away from the river for treatment, is expected to be in operation by early 1994.

387