For discussion PWSC(96-97)26
on 26 June 1996

ITEM FOR PUBLIC WORKS SUBCOMMITTEE
OF FINANCE COMMITTEE

HEAD 709 - WATERWORKS
Public Safety - Landslip prevention
53BL - Inspection of buried water-mains affecting slopes - consultants fees

Members are invited to recommend to Finance Committee the upgrading of 53BL to Category A at an estimated cost of $93.8 million in money-of-the-day prices.

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PROBLEM
PROPOSAL
PROJECT SCOPE AND NATURE
JUSTIFICATION
FINANCIAL IMPLICATIONS
PUBLIC CONSULTATION
ENVIRONMENTAL IMPLICATIONS
LAND ACQUISITION
BACKGROUND INFORMATION
Breakdown of estimates for consultants' fees

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PROBLEM

Leakage from buried water-mains will affect the stability of slopes and if left unattended for a long period may, in some cases, cause landslips.

PROPOSAL

2. The Director of Water Supplies (DWS), with the support of the Secretary for Works, proposes to upgrade 53BL to Category A at an estimated cost of $93.8 million in money-of-the-day (MOD) prices for employing engineering consultants to carry out systematic identification of all buried water-mains affecting slopes adjacent to housing estates and other developments¹ , and to carry out inspection and leakage detection on the identified water-mains.

PROJECT SCOPE AND NATURE

3. The scope of the project comprises the following works -

1. systematic identification of water-mains which if subject to leakage, may affect slopes adjacent to housing estates and other developments;
2. preparation of records of identified water-mains including location plans, previous inspection and leakage detection reports, together with a database containing an inventory of such records;
3. formulation of a regular inspection programme for identified water-mains;
4. development of a cost-effective leakage detection mechanism for identified water-mains; and
5. inspection and leakage detection of identified water-mains and updating of inventory records.

JUSTIFICATION

4. In November 1994, Professor Morgenstern submitted a report to the Governor on the adequacy of the Administration's approach to slope safety with suggestions for improvements. The Administration subsequently undertook to develop a programme to monitor and repair buried services to prevent slope failures caused by leaking water-mains buried in slopes adjacent to housing estates and other developments. Most of the slopes in Hong Kong are unsaturated with water and the soil mass is in a state of suction which helps to stabilise the slope. As water infiltrates into the slope, this suction is reduced and the slope becomes less stable. There are three potential sources of water that could enter into slopes, namely, groundwater table fluctuation, surface infiltration and leakage from buried services. Water-mains are one of the major buried services which can affect slope stability.

5. Based on information currently available, DWS has estimated that about 3 000 buried water-mains will require detailed investigation. Full scale investigation will require considerable resources over a specified period. Having examined ways and means of implementing such an investigation, DWS concludes that he cannot redeploy existing staff in his department to cover the substantial additional workload as they are fully stretched by the existing works programme. He proposes to engage engineering consultants to carry out the investigation over a period of about six years.

FINANCIAL IMPLICATIONS

6. DWS estimates the capital cost of the project to be $93.8 million in MOD prices (see paragraph 7 below), made up as follows -

7. Subject to approval, we will phase the expenditure as follows -

8. We have derived the MOD estimates on the basis of the Government's forecasts of the trend labour and construction prices for the period 1996 to 2003. The consultancy agreement will be in the Government Standard Form for an Investigation Assignment. We will tender the consultancy on a time charge fee basis because the exact amount of the works required cannot be fully defined at this stage. We will tender the leakage detection component under a standard re-measurement contract because the extent as well as the methods of detection may have to be varied to suit different sizes and materials of water-mains and site conditions. We will carry out minor civil works under DWS's maintenance term contracts on a re-measurement basis. A breakdown of the estimates for consultants' fees by man-months is at the Enclosure.

9. The project will not give rise to any recurrent expenditure.

PUBLIC CONSULTATION

10. We do not envisage any public objections to the works. We consider public consultation unnecessary.

ENVIRONMENTAL IMPLICATIONS

11. The commissioning of the consultancy study itself would have no major adverse environmental impact. For short term nuisance during investigation works, DWS will control dust, noise and site run-off nuisances to within established standards and guidelines.

LAND ACQUISITION

12. The project does not require land acquisition.

BACKGROUND INFORMATION

13. In 1994, the Secretary for Works undertook a review of slope safety policy and recommended the development of a programme to monitor and repair buried services at housing estates and other developments. We presented a summary of the initial findings of the review to the Legislative Council's Panel on Planning, Lands and Works on 20 December 1994, and published a report on the review on 3 March 1995.

14. The Administration has made a commitment in the 1995 Policy Address to inspect and repair public drains and water mains which may affect the stability of slopes.

15. We included this project in Category B in January 1996. We plan to commence the project in January 1997 for completion in September 2002. We will carry out repair works to the water-mains whenever any leakage is detected.

1 -- Housing estates include both public and private housing estates whereas other developments include densely used open spaces and recreational facilities, roads with high vehicular or pedestrian traffic density, public waiting areas, occupied buildings and buildings storing dangerous goods.

(KK90)

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Enclosure to PWSC(96-97)26

Breakdown of estimates for consultants' fees

Notes

1. The average estimated cost of a Professional per man month for items (a) and (b) is about equivalent to that of an Engineer on MPS point 44. The average cost of a professional per man month for items (c) and (d) is about equivalent to that of an Engineer on MPS 40. The average estimated cost per Technical man month is about equivalent to the cost per man month of a Technical Officer on MPS point 16.
2. A multiplier factor of 3 is applied to the average MPS point to arrive at the full staff costs including the consultant's overheads and profit, as the staff will be employed in the consultant's offices. (At December 1995, MPS pt. 44 = $60,475 p.m. MPS pt. 40 = $51,440 p.m. and MPS pt. 16 = $17,270 p.m.).
3. The figures given above are based on estimates prepared by the Director of Water Supplies. We will only know the actual fees when we have selected the consultant through the usual competitive system.

(KK90)

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