ENG-1999 — Page 291

LAND, PUBLIC WORKS AND UTILITIES

Mineralogical and geophysical studies of low strength clays that occur within the weathering profile are continuing.

A geochemical atlas of Hong Kong, showing the distribution of 36 elements in stream sediments, was published during the year, and a new volume describing the geology of Hong Kong is under preparation. A magnetic survey to assist in the mapping of the offshore rocks between Stonecutters Island, Cheung Chau and the Po Toi Islands has been completed. Updating and databasing of the geological maps in development areas continues to be a priority.

The Geotechnical Information Unit in the Civil Engineering Library houses the largest collection of geotechnical data in Hong Kong. It is open to the public, and served more than 29 000 users during 1999.

The GEO provides material testing and ground investigation services to support land production and infrastructure projects. It operates the Public Works Central Laboratory at Kowloon Bay and six Public Works Regional Laboratories in various parts of Hong Kong to carry out specific tests on construction materials and provide calibration services.

During the year, the office continued to provide specialist geotechnical advisory services to government departments to help them achieve a high standard of geotechnical works for public safety, and to assist them to identify cost-effective solutions. These services included the provision of ad-hoc geotechnical advice and the carrying out of feasibility studies, detailed investigations, design and advice during construction for a wide range of public works projects such as road improvement works at Ap Lei Chau North Coastal Road, Clearwater Bay Road and Fan Kam Road, drainage improvement for the North West New Territories Flood Protection Scheme, site formation at Chung Hom Kok for Teleport purposes, slopes and reinforced fill works at Tsing Yi North Coastal Road, reclamation works at Penny's Bay and Pak Shek Kok and tunnelling works for Stage I of the Strategic Sewage Disposal Scheme. The Slope Maintenance Audit Section continued to assist maintenance departments to improve their performance in discharging their slope maintenance responsibilities and audits of performance were conducted on three departments.

Fill Supply and Mud Disposal

The Fill Management Committee (FMC), formed in 1989, is responsible for identifying, investigating and managing fill resources and marine disposal areas required for developments in Hong Kong. Technical and administrative support for the committee is provided by the FMC Secretariat, established within the Geotechnical Engineering Office of the Civil Engineering Department (CED).

From 1990 to 1999, about 256 million cubic metres of marine fill (15 per cent from nearby regions in the Mainland) and 165 million cubic metres of land-based fill were used for reclamation projects. It is expected that a further 320 million cubic metres of fill will be required to meet the need for land for housing and infrastructure developments in Hong Kong over the next decade.

The CED managed the mud disposal facilities. In 1999, about 6.9 million cubic metres of uncontaminated mud generated from various projects were disposed of in open sea floor disposal grounds and in exhausted marine sand borrow pits. Around 4.1 million cubic metres of contaminated mud were placed in the purpose-dredged

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