LAND, PUBLIC WORKS AND UTILITIES
A Working Party on Geotechnical Control Strategy was established in May 1993 and considered three options for a future control strategy. A report prepared by the working party contains a consideration of the three options and recommendations for the way forward in geotechnical control. Action is being taken to implement the recommendations, with a view to enhancing the effectiveness of geotechnical control.
Work to upgrade unsatisfactory old slopes to modern safety standards is continuing. Three consultancies were signed in 1994 to accelerate the Landslip Preventive Measures Programme. A detailed plan is being worked out to further accelerate the programme to complete the necessary upgrading works for slopes in the 1978 Slope Catalogue by the year 2000, subject to the availability of resources. During 1994, landslip preventive works were completed on 71 slopes and retaining walls, at a cost of $102 million. Preliminary studies were carried out on 2 893 slopes and retaining walls, and detailed geotechnical investigations were finished on 90 slopes and retaining walls.
A public works project on the 'Systematic Identification and Registration of Slopes in the Territory' (SIRST) was begun in July. The project will lead to a computerised Slope Information System containing important information on sizeable man-made slopes in the territory. Preparatory work for SIRST involves territory-wide systematic aerial photograph interpretation (API) and field checks to identify additional old fill slopes, cut slopes and retaining walls that have not previously been registered. The API study began in 1992, following the fatal landslide at Baguio Villas in Pok Fu Lam, and is continuing with increased staff resources through the use of seconded consultant aerial photograph interpreters.
The GEO operates the Landslip Warning System and a 24-hour emergency service to provide advice when landslips occur. GEO staff attending these incidents give advice on immediate measures to reduce danger, as well as on permanent remedial measures. Exceptionally heavy rainfall between July 22 and 26 resulted in about 200 landslip incidents. One of the landslips, which occurred on the evening of July 23 at Kwun Lung Lau Estate in Western District, resulted in five people being killed and three seriously injured. GEO staff carried out a detailed investigation into the cause of the landslip, which was independently reviewed by Professor N.R. Morgenstern of the University of Alberta. The findings of the investigation were published in November. The landslip was caused by leakage from defective sub-surface drainage systems which saturated the soil behind an exceptionally thin retaining wall. In the light of the findings, Professor Morgenstern made five recommendations to improve slope safety in Hong Kong. The government has accepted these recommendations and steps are being taken to implement them.
The GEO continues to be concerned about the landslip hazard to squatters on hillsides. The squatter clearance programme and work to improve village conditions over the last decade have significantly reduced such landslip hazards. During 1994, inspections of about 80 squatter villages in the New Territories were completed, and recommendations were made for the clearance of about 4 800 squatter huts and rehousing for their occupants on slope safety grounds. Since this work began in the early 1980s, some 65 000 squatters have been rehoused from steep hillsides because of concerns about landslips during heavy rainfall.
The GEO continued its public education campaign to increase awareness of the impor- tance of slope maintenance and the responsibility of land owners to maintain their slopes.
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