File Ref. : WB(W) 224/32/05

INTRODUCTION

At the meeting of the Executive Council on 14 July 1998, the Council took note of the strategy adopted to deal with the maintenance of man-made slopes and the upgrading of those slopes which do not meet current safety standards.

BACKGROUND

Basic Strategy

2 As a result of the intense urban development in Hong Kong, a large number of cut-slopes, fill slopes and retaining walls are formed on hillsides adjacent to buildings and highways. The Geotechnical Engineering Office (GEO) was set up in 1977 to tackle the problem of existing slopes and to ensure the safety standards of newly formed slopes. The basic strategy is to upgrade and maintain these slopes systematically so as to reduce progressively the likelihood of landslides affecting life and property to an acceptable level within the shortest possible time.

3 Under an on-going Landslip Preventive Measure (LPM) Programme introduced in 1977, geotechnical studies are conducted to identify and prioritise pre-1977 government slopes for upgrading. Priority is given to slopes that have a lower degree of stability and the failure of which will affect the community more directly. By upgrading the slopes of higher priority first, we are able to reduce the overall landslide risk by the greatest degree within the shortest possible time. We estimate that on completion of the current five-year accelerated LPM Programme in early 2000, the LPM Programme alone will have reduced the overall landslide risk to the community by 50% against that which existed in 1977.

4 The upgrading of slopes is also achieved by incorporating slope improvement works as part of both public and private development projects. The number of sub-standard slopes has been contained by checking the design and construction of new slopes and ensuring that they comply with the latest standards. Removal of risk is also achieved by the clearance of squatters who live in the vicinity of unstable slopes.

5 The maintenance of slopes is another important element in the slope safety strategy through regular inspection and repair of surface protection and the clearance of drainage, etc. Departments have been given the task to maintain government slopes alongside the maintenance of their facilities. For example, Highways Department maintains road-side slopes; Water Supplies Department maintains slopes affecting their reservoirs and catchwaters; and Housing Department maintains slopes affecting their estates.

6 As regards private slopes, GEO conducts "safety screening" in respect of pre-1977 slopes, and owners are required to rectify unstable slopes through the service of Dangerous Hillside Orders issued under the Buildings Ordinance. Since 1992, we have carried out continuous public education and publicity campaigns to impress upon private owners their responsibility for maintaining their slopes and that slope maintenance is essential to their safety. We have also put into place a computerised slope information system, code of practice, layman's guide and telephone hotline to assist the public in this regard.

RECENT DEVELOPMENT

7 Two new exercises were introduced in 1994 and 1996 respectively to create a more comprehensive register of man-made slopes and to assign the responsibility for the maintenance of those slopes on unallocated government land previously not assigned to any department.

New Catalogue of Slopes

8 In 1994, we began a major project to catalogue all sizeable man-made slopes in Hong Kong. Preliminary studies of all pre-1977 slopes in this New Catalogue were completed in March 1998, and the remaining work for the cataloguing exercise will be completed by September 1998.

9 Results from the cataloguing exercise indicate that the total number of sizeable man-made slopes will likely reach 60 000. About 18 000 slopes have been created after 1977, and since the design and construction of these slopes have been checked by GEO, they generally do not require further upgrading. Of the 42 000 pre-1977 slopes, about 62% (or some 26 000) are classified as low consequence slopes (i.e., they are near roads with low to moderate traffic, near open spaces or within country parks, etc.). They are of a lower priority and will be upgraded by enhanced maintenance and redevelopment. The remaining 38% (or 16 000) are classified as high consequence slopes (i.e., slopes near major developments, squatters and major roads). Government slopes falling under this category are being upgraded through the LPM or through development projects, whereas private slopes are being dealt with through safety screening.

10 During the course of cataloguing pre-1977 slopes, a preliminary stability assessment was also carried out for each slope and urgent landslip preventive action initiated where signs of immediate and obvious danger were detected.

Systematic Identification of Maintenance Responsibility of Slopes (SIMAR)

11 In 1996, Lands Department commenced the important task of systematically identifying the maintenance responsibility of each and every man-made slope registered in the New Catalogue. The study will be completed in 1999. Lands Department is now notifying the responsible government departments of the SIMAR results for their maintenance action.

12 As regards government slopes not falling within the clear responsibility of any department, Lands Department, as Government's land manager, has joined forces with other maintenance departments to take up the maintenance responsibility. This new arrangement took effect in April this year and ensures that every government slope will receive proper maintenance.

13 We also plan to open the SIMAR results for public access so that private slope owners will know who is responsible for maintaining which slope. The availability of such information will promote voluntary slope maintenance by private owners. It will also facilitate the introduction of a proposed mandatory slope maintenance scheme which is currently under consideration.

EXPANDED SLOPE UPGRADING AND MAINTENANCE PROGRAMME

14 In view of the additional number of slopes identified by the New Catalogue, and to further reduce the likelihood of injuries and loss of property suffered by the community as a result of landslides, we have drawn up an expanded upgrading and maintenance programme as our long term strategy to cover those slopes not yet dealt with by the current programme.

15 The expanded LPM Programme will commence in early 2000 when the current LPM Programme is completed. Over the 10 years until 2010 we will upgrade another 2 500 pre-1977 substandard government slopes which affect developments and major roads. We will incur capital cost of about $6,300 million over the expanded programme, and increase the staff working on the LPM Programme from 160 to 203. We will bid for the necessary funds in the normal way as and when we embark on the programme.

16 Apart from the expanded LPM Programme we will adopt an integrated approach to government road and development projects to ensure that slopes affecting or affected by these projects are upgraded to current safety standards as part of the implementation of these projects. The cost for slope upgrading will be charged to the respective project votes.

17 We will improve as far as practicable the stability of the remaining government slopes through the application of an "enhanced maintenance" approach. Through this we can introduce quick improvement to the stability of a large number of slopes which do not urgently require full scale upgrading works. Resources will be made available under the regular slope maintenance vote. We will also continue to clear squatters away from unstable slopes.

18 With the measures described in paragraphs 15 to 17 above we estimate that by 2010 all high consequence government slopes which may affect major developments, squatters and major roads will have been dealt with.

19 We will continue to maintain regularly all government slopes. The recurrent cost for maintaining the 40 000 government slopes will be in the order of $800 to $1,000 million per year involving 450 staff. Already 206 posts have been made available to the departments responsible for maintaining slopes. We will bid for any additional funds in the normal way if necessary in future.

20 For private slopes, we will continue with the current "safety screening" for pre-1977 slopes and will boost the number of slopes to be screened to 300 per year. By 2010 all high consequence private slopes will have been dealt with by safety screening and the service of Dangerous Hillside Orders, maintenance and redevelopment.

21 We are considering a mandatory slope safety inspection scheme after the SIMAR study has been completed. The intention is to ensure that private slope owners will maintain their slopes and upgrade substandard slopes pro-actively instead of waiting until the slopes show signs of instability and become the subject of statutory orders. We will proceed prudently by strengthening our public education and information services on private slope maintenance.

22 Through the above-mentioned measures we will progressively reduce the chance of landslides affecting life and property arising from pre-1977 slopes and by 2010 will have reduced the overall landslide risk of all pre-1977 slopes to the community to below 25% of that which existed in 1977.

Further Review

23 We will conduct a thorough review of slope maintenance in 2000 when the number of slopes to be maintained by each department and by private owners are clearly known.

PUBLICITY

24 There has been a continuous education and publicity programme on the issue of slope safety. Through the publication of various reports, press conference as well as questions and debates in the Legislature, members of the public are generally aware of the Government's efforts in improving slope safety. We will continue to report regularly to the Panel on Planning, Lands and Works of this Council. A briefing for journalists highlighting the new LPM Programme and enhanced maintenance strategy will be held at an appropriate time.

ENQUIRIES

25. For enquiries concerning this brief, please direct them to Mr MAK Ka-wai, Assistant Secretary (Works Policy)2 at telephone number 2848 6154.



Works Bureau
20 July 1998
File Reference : WB(W) 224/32/05