ENG-1992 — Page 249

LAND, PUBLIC WORKS AND UTILITIES

million. Works also commenced on the extension to the Mid-Levels boulder fence behind Conduit Road together with in-situ stabilisation of large boulders in the boulder field behind the fence. Completion of this project will be mid-1993 at an estimated cost of $5.8 million. Stabilisation works were in progress to the slopes of an old landfill borrow area at Fung Shing Street, Ngau Chi Wan, with a contract sum of $6.9 million. Remedial works to four disused air raid precaution tunnels were completed at a cost of $9.2 million.

The Hong Kong Geological Survey continues to publish 1:20 000 scale geological maps and memoirs for the land and marine areas of the territory. During 1992, new geological maps for Silver Mine Bay, Kat O Chau and Cheung Chau were published. Geological maps at 1:20 000 scale are now available for more than 80 per cent of the territory. A seismotectonic study and a gravity survey of the territory were completed during the year. Large-scale (1:5 000) geological survey work is well underway in the development areas of North Lantau. Geophysical survey and borehole data for the mapping are being transferred into a computer database, and computer-aided cartography is being developed for map production. Engineering geology studies have been essentially completed in North Lantau, and have identified the major geotechnical constraints that could significantly affect the costs or timely implementation of the new airport and related projects and the future port-related developments in the area.

The Geotechnical Information Unit (GIU), which houses the largest collection of geotechnical data in Hong Kong, continues to serve as an important reference centre in its premises in the Civil Engineering Building in Ho Man Tin. The GIU served more than 4 000 users during the year.

The office's work on the use of underground space continued in 1992. Geoguide 4: Guide to Cavern Engineering, which is aimed at providing guidance on design and construction of caverns, has been published and is now on sale. The office also continued to carry out studies to establish cavern development opportunities on a regional basis, and preliminary engineering geological studies of specific sites for potential cavern projects. In 1992, four preliminary engineering geology studies for various cavern uses were completed. Geotechnical advice was also provided on cavern projects being planned or constructed by other departments.

The Marine Geotechnology Section provided advice and carried out research and development work on the marine geotechnical aspects of Port and Airport Development Strategy (PADS) projects, notably on foundations for marine structures and reclamations.

A comprehensively revised draft edition of Geoguide 1: Guide to Retaining Wall Design was circulated to private and public sector practitioners both in Hong Kong and overseas in 1992, and much valuable comment was obtained which assisted in finalising the document for publication.

The GEO manages the Public Works Central Laboratory at Kowloon Bay and five public works regional laboratories in various parts of Hong Kong. The six public works laboratories together employ over 150 staff, of whom 10 are professionals and 140 are of technical and clerical grades. Over 250 000 tests on various construction materials were carried out during 1992. The laboratories are accredited under the Hong Kong Laboratory Accreditation Scheme (HOKLAS) to provide calibration services, as well as to carry out tests on such construction materials as concrete, steel, aggregates, cement and pulverised fuel ash. Application for HOKLAS accreditation of bituminous materials testing is in hand.

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