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Environmental Measures and Outcomes

Content > Preserving Hong Kong's Natural Heritage... > Protecting the Environment for All > Kai Tak Airport North Apron Decontamination > 1,800 Mega Watt Extension... > West Rail > International Theme Park... > Removal of Sediment in Cheung Sha Wan Fish Culture Zone > Cyberport Development at Telegraph Bay > Felling of Five Chimneys at Tsing Yi Power Station > KCR East Rail Extension > East Rail Extension

Removal of Sediment in Cheung Sha Wan Fish Culture Zone

Photo of Tightly sealed mechanical grabs to minimise spillage.
Tightly sealed mechanical grabs to minimise spillage.

Photo of Silt curtains were installed at the dredging site next to the fish culture zone
Silt curtains were installed at the dredging site next to the fish culture zone

Project Description

The Cheung Sha Wan Fish Culture Zone is located near Chi Ma Wan Penunsula off the coast of Lantau Island. Bottom sediment under the Cheung Sha Wan Fish Culture Zone (FCZ) contains a large amount of organic matter accumulated over the years. The organic sediment adversely affects the surrounding marine habitats, the associated marine life and the productivity of the FCZ.

To achieve improvements in the marine environment, the removal of bottom sediments at FCZ by dredging was proposed. The zone area and dredged area of Cheung Sha Wan FCZ were 214,200m2 and 228,000m2. The proposed sediment volume to be dredged was about 147,000 m3, and the average dredging rate was 175 m3/hr. The removal of anoxic sediments and the bulk of trapped nutrients would improve the local water quality and reduce the risk of local red tide and upwelling of anoxic and toxic gases.

The Environmental Permit (EP), EP-008/1998, was issued on 9 November 1998 and conditions set out in the Permit were implemented. Site inspections were conducted during construction and post project monitoring. The dredging work was started on 20 November 1998 and completed on 20 January 1999.


Mitigation Measures and Outcomes

  1. Silt curtains were installed between the dredging site and the temporary relocation site and placed not more than 100 metres away from dredging operation throughout the dredging process.
  2. To shorten the period of disturbance to the FCZ and the environment, the dredging operation was carried out within the shortest time possible and finished within two and a half months.
  3. Mechanical grabs were used throughout to avoid spillage and to seal tightly while being lifted.
  4. Barges and grab dredgers were fitted with tight-fitting seals.
  5. Adequate freeboard was maintained on barges to prevent spillage of material into the sea.
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