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LAND, PUBLIC WORKS AND UTILITIES
The Hong Kong Geological Survey published one 1:20 000 scale geological map for part of Lantau Island, and four 1:5 000 scale detailed geological maps of North Lantau. A 1:100 000 scale map of the geology of Hong Kong and an explanatory document are under preparation. The computerised borehole database for the urban areas of Hong Kong Island and Kowloon is expanding, facilitated by the new requirement for contractors and consultants to submit ground investigation records in a standardised, computer-readable format.
The extensive collection of historical and recent aerial photographs was supplemented by satellite data. These were used to monitor suspended sediment offshore and for studies of areas affected by severe landslips, including Lantau Island in 1993. Engineering geological studies are underway on slopes adjacent to Tung Chung new town, which is presently under construction.
The GEO's Geotechnical Information Unit (GIU) houses the largest collection of geotechnical data in Hong Kong. It served more than 2 900 users during the year. Draft versions of guides to pile design and construction and to slope maintenance were produced and circulated for public consultation.
Further major ground investigations were undertaken for the Lantau Port and Tseung Kwan O development studies and the Strategic Sewage Disposal Scheme. Additional drilling and geophysical surveys were conducted for the Fill Management Study (Phase IV) on potential land and marine borrow areas across the territory. Several investigations of - - landslips were also undertaken, using high quality drilling and sampling techniques. In all, over 230 land and marine ground investigations (including geophysical surveys) and over 100 laboratory test schedules were completed. An additional one-year laboratory testing term contract was let to cope with the demand for the testing of samples recovered from marine ground investigations.
The GEO manages the Public Works Central Laboratory at Kowloon Bay and seven public works regional laboratories in various parts of the territory. These laboratories are accredited under the Hong Kong Laboratory Accreditation Scheme (HOKLAS) to carry out specific tests on construction materials, and to provide laboratory calibration services. Over 60 tests have now been accredited. An application has been made for the accreditation of a series of soil tests to new testing standards. A new section of the laboratory is being equipped to extend the services to cover rock mechanics testing.
Fill Management
The territory's fill resources are managed by the Fill Management Committee, whose secretariat is a division of the Geotechnical Engineering Office. The committee was set up in 1989 to make decisions on the reservation, allocation and efficient utilisation of fill resources for government and major private projects.
Up to the end of 1994, some 270 million cubic metres of marine fill had been allocated or reserved and, of this amount, approximately 200 million cubic metres had been extracted from the seabed for reclamation projects.
A further 465 million cubic metres of fill from both land and marine sources are needed for reclamations over the next 15 years.
A second role of the committee is to plan the marine disposal of dredged mud, including contaminated mud, and to allocate disposal capacity at the gazetted marine spoil grounds.