Provisional Legislative Council
PLC Paper No. CB(2) 241
(These minutes have been
seen by the Administration)
Panel on Planning, Lands and Works
Minutes of special meeting held on Friday, 29 August 1997, at 10:45 am in Conference Room A of the Legislative Council Building
Members present :
Hon Edward HO Sing-tin, JP (Chairman)
Hon KAN Fook-yee (Deputy Chairman)
Dr Hon Raymond HO Chung-tai, JP
Hon YUEN Mo
Hon CHENG Kai-nam
Hon IP Kwok-him
Members attending :
Hon LEE Kai-ming
Hon CHAN Choi-hi
Members absent :
Hon HO Sai-chu, JP
Hon Ronald ARCULLI, JP
Hon LEUNG Chun-ying, JP
Dr Hon Charles YEUNG Chun-kam
Hon LAU Wong-fat, JP
Hon CHOY Kan-pui, JP
Hon Timothy FOK Tsun-ting
Hon NGAN Kam-chuen
Public officers attending :
- Mr Bernard M T LAM
- Director of Civil Engineering
- Mr Raymond K S CHAN
- Government Geotechnical Engineer
- Geotechnical Engineering Office, Civil Engineering Department
- Mr K W MAK
- Assistant Secretary for Works (Works Policy)
Clerk in attendance :
Staff in attendance :
- Miss Odelia LEUNG,
- Chief Assistant Secretary (1)1
- Mrs Mary TANG,
- Senior Assistant Secretary (1)2
I. Discussion on slope safety
(PLC Paper No. CB(1)176(01))
Landslip Preventive Measures Programme
At the invitation of the Chairman, the Director of Civil Engineering (DCE) briefed members on the progress of implementation of landslip preventive measures by referring to statistical information tabled at the meeting. He emphasized that despite heavy cumulative rainfall this year, landslip fatalities were only two as against 27 and 138 in 1982 and 1972 respectively in which comparable cumulative rainfall had been recorded. Statistics showed that the annual landslide fatality rate in Hong Kong was on the low side as compared with Japan, Korea, USA and Canada. The figure was much better than Brazil which was comparable to Hong Kong in terms of geology, weather conditions and population density. In fact, the possible casualties of slope failure in Hong Kong should be more serious than these countries in view of a large population resided on hillsides or in the vicinity of slopes due to scarcity of flat land. Given its density of population, abundance of slopes, and weather conditions, Hong Kong had achieved significant progress in the area of slope safety.
2.According to DCE, the current 5-year Accelerated Landslip Preventive Measures (LPM) Programme concentrated mainly on man-made slopes in the existing Slope Catalogue compiled in 1977/78. Apart from implementing the LPM Programme, the checking of designs of new slopes and retaining walls constituted a major part of the Geotechnical Engineering Office (GEO) ' s routine activities. Some 11,500 geotechnical submissions were checked by GEO staff in 1996/97, including those for private developments and public works. This continuing effort provided a mechanism by which the number of substandard slopes had effectively been frozen at the 1977 level.
3. Members acknowledged the Administration ' s efforts in maintaining slope safety. They were pleased to note that Hong Kong compared well with other countries, despite its density of high-rise buildings on and adjacent to slopes. They, however, expressed concern about the need to review standards of slope safety and associated building requirements to keep pace with the changing environment. Referring to the recent Ching Cheung Road landslip, members queried the reliability of slope stability assessment as the slope in question had been examined and found to comply with safety standards. They sought information on improved measures to ensure slope safety.
4. In response, DCE explained that GEO had the responsibility to set standards for investigation, design, construction and maintenance of slopes. These standards were constantly kept under review. In setting standards, it consulted the profession in Hong Kong and experts in the field in other countries. It also sought advice from the Slope Safety Technical Review Board which was set up in 1995 for this purpose. The slope at Ching Cheung Road had been studied under the LPM Programme and that type of failure was very rare. From the information gathered so far, the rapid increase in ground water levels might have caused the landslip. A detailed study had been commenced to ascertain the exact cause. Once the results and conclusions of the investigation were available, careful consideration would be given to revising safety standards if it was deemed necessary in the light of the lessons learnt. The present standard was based on a factor of safety of 1.4.
5. DCE stressed that even if all possible LPM measures were implemented, this could not entirely prevent landslips from occurring under natural causes. The Administration aimed at reducing the chances of slope failure within available resources. It was estimated that on completion of the 5-year Accelerated LPM Programme by the year 2000, the risk from slope failure arising from the pre-1977 man-made slopes would be reduced by 50% as compared with the risk level in 1977 and a further 50% in another 10 years ' time. By then, there might be a need to assess the cost effectiveness of continuing the Programme and to consult the public on the merits of committing additional resources for further improvement which would likely be minimal.
6. On the possibility of further expediting the 5-year Accelerated LPM Programme, DCE explained that the Programme was based on a priority classification system which was developed and used by GEO to give the appropriate order of priority for investigation and upgrading. Slope investigations were time-consuming because these required detailed planning and studies. So far, 16 consultancy contracts and 12 works contracts had been awarded. Given its complexity, it would be unlikely that the LPM Programme could be advanced and completed earlier than its target completion date in March 2000. The Government Geotechnical Engineer of GEO (GGE/GEO) added that GEO had been utilising the resources of both the public and private sectors in a bid to meet the target completion date.
7. On the availability of an electronic landslip warning system, DCE explained that the present technology could only measure changes in ground water levels and other geotechnical conditions. It fell short of detecting and providing an instant alarm to the occurrence of landslip. GEO would be continuing its efforts to explore ways to improve the landslip warning system. Meanwhile, the public would be warned to stay away from dangerous slopes during heavy rains where upgrading works had yet to be completed. Warning signs had been posted along roads with a history of landslides and slopes scheduled for upgrading to provide advance warning to the public.
8. Regarding the 1977/78 Slope Catalogue, DCE explained that the Catalogue had not provided adequate information on the ownership of slopes. Since July 1996, the Lands Department had commenced the Systematic Identification of Maintenance Responsibility of Registered Slopes in the Territory (SIMAR). With the completion of SIMAR in 1999, comprehensive information on the maintenance responsibility of slopes would be available.
9. GGE/GEO supplemented that the ratio of private to public slopes in the 1977/78 Slope Catalogue was around 3:7. However, the ownership of a number of slopes could not be distinctly defined as either private or public because they encroached on both private and government land. GEO was compiling a new Slope Catalogue containing all sizeable man-made slopes. Based on the latest estimate, the total number of sizeable man-made slopes in the whole Territory was about 60,000. These included some 20,000 post-GEO slopes which had been checked to conform with modern safety standards, and some 30,000 additional pre-GEO slopes which had not been included in the 1977/78 Slope Catalogue. The latter had not been included because the 1977/78 Catalogue concentrated on man-made slopes in the urban areas of Hong Kong Island and Kowloon, and included only the larger man-made slopes in the New Territories. Of the 60,000 slopes, about 20,000 were private slopes and 40,000 were public slopes.
10. DCE said that in an effort to promote public awareness of the responsibility of private owners to maintain their slopes, the Administration had launched various publicity and education programmes. It had published the ' Layman ' s Guide for Slope Maintenance ' and the guide on ' What to do When You Receive a Dangerous Hillside Order ' for free distribution to interested members of the public. Where necessary, the Buildings Department would provide general advice on the appointment of authorised persons and contractors, and the administration of remedial works submissions required under the Buildings Ordinance, Cap. 123. In addition, GEO would assist owners who had genuine difficulties in complying with the order by providing advice on the appointment of geotechnical consultants and technical assistance, as resources permitted.
11. On compliance with safety standards in respect of private slopes, DCE explained that under the Buildings Ordinance, the Building Authority (BA) was empowered to issue orders to owners requiring them to inspect and repair dangerous slopes and the buried services affecting slopes. In emergency cases and/or cases where owners failed to comply with the order, BA would carry out repair works on their behalf. The relevant order would be registered at the Lands Registry and would remain so until the cost of works had been recovered by BA. In less severe cases, BA would issue advisory letters to owners advising them to undertake maintenance or repair works. GGE/GEO added that regular seminars had been organised for the committee members of Owners ' Corporations of private buildings with a view to assisting them in the maintenance of their slopes.
12. The Deputy Chairman suggested introducing an intermediate system of issuing advisory letters on landslide risk which should be registrable at the Lands Registry. He also advocated the need to amend the relevant legislation to enable registration of the advisory letters so as to help compel/encourage owners to regularly maintain their slopes to ensure their own safety and safety of anyone entering the property. DCE would seek legal advice on the possibility of registering advisory letters and would consider the necessary legislative amendments.
13. Regarding the maintenance of public slopes, DCE informed that the Highways Department was responsible for maintaining slopes affecting public roads whereas a number of other Departments were responsible for maintaining other public slopes allocated to them. Since last year, the Lands Department had undertaken the SIMAR study to systematically identify the maintenance parties for all man-made slopes. A technical circular had been issued requiring all maintenance departments to maintain their public slopes.
14. The Assistant Secretary for Works (AS/W) stressed the need for regular maintenance of all man-made slopes, both public and private. The Administration had devoted more resources to enhance slope safety in Hong Kong and was taking the lead in maintenance of all public slopes. Meanwhile, private owners were encouraged to take positive measures in maintenance of their slopes. Responding to members on introducing legislation to compel owners to maintain their slopes, AS/W confirmed that the Administration was considering such a mandatory Slope Safety Inspection Scheme, under which owners would be required to engage suitably qualified geotechnical engineers to ensure compliance of slope maintenance standards. However, prerequisites to the success of such a scheme were the availability of SIMAR results and effective legal sanctions for non-compliance in situations involving multiple ownerships. Experience would be drawn from the implementation of the mandatory Building Safety Inspection Scheme.
15.Regarding the landslip at Shum Wan, DCE explained that this was caused by the loose ground conditions of the natural slope and poor maintenance of the man-made slope above it. For mixed natural and man-made slopes, GEO would aim at achieving a factor of safety of 1.4. DCE stated that whilst priority was given to maintenance of man-made slopes, GEO was collecting and analysing information on susceptibility of natural hillsides to landslides.
16.As to whether priority would be given to study natural slopes in the vicinity of residential areas, DCE explained that this depended on the nature and degree of safety of the slope in question. He added that natural slopes adjacent to residential areas would normally have been modified to become man-made slopes in the course of development of the area. A territory-wide mapping exercise undertaken by GEO had resulted in compilation of an inventory of natural terrain landslides for reference by the profession and the public.
17.As for the safety of slopes adjacent to schools, DCE confirmed that priority had been given to checking these slopes. GGE/GEO supplemented that based on the information provided by the Education Department on 2,072 schools, 1,965 slope features were identified. Of these, 1,415 were low risk slopes which had either complied with safety standards, or had been rectified, or were under five meters. The remaining 550 slopes which required rectification had been included in the 5-year Accelerated LPM Programme. They comprised 350 private slopes and 200 public slopes. GEO had completed investigation on 200 such slopes and 66 Dangerous Hillside Orders had been issued. Rectification works had been completed on 13 of the 48 public slopes which required further improvement. The investigations on slopes affecting schools were expected to be completed by March 1999.
II. Any other business
18. Members agreed to discuss the mandatory Building Safety Inspection Scheme at the next regular meeting on 26 September 1997. Members were requested to contact the Panel Clerk on any suggested items for discussion at Panel meetings.
19.The meeting ended at 12:15 pm.
Provisional Legislative Council Secretariat
15 September 1997