ENG-2000 — Page 343

THE ENVIRONMENT

In addition, pollution control is now having a positive effect, and river quality is slowly improving. The percentage of rivers in the 'good' and 'excellent' categories increased from 27 per cent in 1986 to 74 per cent in 2000, and the percentage in the 'bad' and 'very bad' categories fell from 52 per cent in 1986 to 13 per cent in 2000.

Sewage Treatment and Disposal

To treat sewage from the main urban area, sewage collected by the local sewerage network on both sides of Victoria Harbour will be directed to a sewage disposal system for treatment and final disposal. The system is divided into Stage I, Stage II and Stage III/IV.

Stage I collects sewage from the urban areas of Kowloon, Tsuen Wan, Tseung Kwan O and the north-eastern part of Hong Kong Island. The 25 kilometres of collection tunnels up to 150 metres below the city were fully excavated by November. The remaining work will be completed in 2001. The Stonecutters Island sewage treatment works began operation in May 1997. It is the world's most efficient chemically enhanced primary treatment plant, removing pollutants almost as efficiently as a conventional secondary biological treatment plant. When Stage I is completed, the system will collect and treat some 70 per cent of the sewage that used to flow into Victoria Harbour.

The original proposal for Stage II comprised upgrading the treatment system and a deep tunnel from Stonecutters Island to discharge the treated effluent in oceanic waters to the south of Hong Kong.

Stage III/IV will collect sewage from the north and south-western part of Hong Kong Island and transfer the effluent to Stonecutters Island for treatment.

In the light of the experience gained during Stage I works, an International Review Panel was set up to examine whether the present plans remain the most cost-effective and environmentally friendly means for treating the sewage. The panel members presented their report in November. They have recommended upgrading the treatment process under Stage II to tertiary level, using compact technology. This may allow the long outfall to be replaced by local outfalls within Victoria Harbour. They have also given a number of options for Stage III/IV work, and recommended some further trials and assessments to confirm a final choice. Having examined the review report in detail and taken into account comments from the Legislative Council, the Advisory Committee on the Environment and the public, the Administration would recommend a way forward for the sewage disposal strategy.

Sewerage Master Plans

Hong Kong has been divided into 16 areas for which sewerage master plans have been drawn up. The plans identified works estimated at $13.2 billion to bring the sewers up to standard. They are being carried out in a phased improvement programme. The Chai Wan and Shau Kei Wan master plan was the first completed, in December 1997. This was followed by the Tsuen Wan, Kwai Chung and Tsing Yi master plan in November 1998. All remaining plans would be implemented by 2008. To meet the revised population projections and the Government's housing programme, the EPD has started to review the sewerage master plans for various districts. The first four reviews, which commenced in February 1999, cover Yuen Long and Kam Tin, Central and East Kowloon, Tsing Yi, Tuen Mun and the

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