ENG-2005 — Page 344

298 The Environment

Intruder Alarm and Neighbourhood Noise

The Police Force handles complaints about intruder alarms and neighbourhood noise from domestic premises and public places. In 2005, the police dealt with some 3 000 complaints.

Water Quality and Sewerage

Water pollution has increased with urban development and population growth, and Hong Kong now produces about 2.8 million cubic metres of sewage every day. In the past, the lack of proper treatment for most of the sewage from older urban areas around Victoria Harbour resulted in poor water quality there but, after the first stage of the Harbour Area Treatment Scheme (HATS) opened at the end of 2001, there has been a marked and sustained improvement.

In addition, pollution control at source has yielded positive effects, and river quality has also improved. The percentage of rivers in the 'good' and 'excellent' categories increased from 34 per cent in 1986 to 81 per cent in 2005, and the percentage in the 'bad' and 'very bad' categories fell from 45 per cent in 1986 to 14 per cent in 2005.

Sewage Treatment and Disposal

At present, the public sewerage system covers 93 per cent of the population and collects about 2.6 million cubic metres of waste water every day. About 70 per cent of the collected sewage receives chemical or higher levels of treatment before being discharged. The significant improvement in the sewage infrastructure over the past decades has been made possible by a territory-wide programme of construction of new sewerage facilities, which include the HATS and the sewerage improvement works identified under 16 Sewerage Master Plans (SMPs).

Under the first stage of the harbour scheme, sewage is collected from the urban areas of Kowloon, Tsuen Wan, Kwai Tsing, Tseung Kwan O and the northeastern part of Hong Kong Island for treatment at a plant on Stonecutters Island. There are also a number of preliminary treatment works at collection nodes, 23.6 kilometres of conveyance tunnels up to 150 metres deep, and a 1.7-kilometre-long tunnelled outfall which disperses the treated effluent into the western anchorage area away from core Victoria Harbour.

The system has performed well and brought about marked improvements in water quality. Some soft and hard coral communities, which are very sensitive to the quality of the marine water environment, have started to revive in Victoria Harbour according to a survey by a local marine conservation society.

The Government now proposes to implement Stage 2 in two phases. The first phase (HATS Stage 2A) will involve building deep tunnels to bring the untreated sewage from the remaining parts of Hong Kong Island to the Stonecutters Island Sewage Treatment Works. The treatment works is to be expanded to provide centralised chemical treatment for all sewage from the whole of the HATS catchment with fast-track provision of disinfection. The target year for completion of this phase is 2013/14. Under the second phase (HATS Stage 2B), new biological treatment