For discussion FCR(95-96)71
on 17 November 1995


Subhead 700 General other non-recurrent

Members are invited to approve a commitment of $30 million for engaging consultants to carry out a study on the underground assets of the Water Supplies Department and to digitize water mains records.


We do not have sufficient information on the condition of our underground water supply system. Our system of using paper drawings to record the alignment and size of watermains is outdated.


2. We propose to engage consultants -

  1. to study the condition and performance of our underground water supply system and to develop a comprehensive and cost-effective management plan for the system; and
  2. to digitize our present paper drawings of the system to make full use of computerized mapping systems for easy updating, retrieval and information exchange.


Underground asset management study

3. Our water supply system is growing rapidly. It comprises 5 500 kilometres of water mains. The majority of the fresh water mains were laid in the 1950s and 1960s to service the rapid development on Hong Kong Island, in Kowloon and in the older new towns such as Tsuen Wan. Many of the salt water mains were laid in the 1970s in the same areas. While water mains generally have a long designed life - 50 years for fresh water mains and 20 years for salt water mains, they are approaching the end of their designed life and need to be replaced.

4. At the same time we are experiencing an increasing number of main bursts due to causes other than construction activities. In 1990-91 there were 696 bursts. In 1994-95 this number increased to 766. In the first six months of 1995-96 there were 508 main bursts. Main bursts affect water supply, disrupt traffic and are costly to repair. The number of bursts is likely to continue to grow with the ageing of the system unless we can devise a suitable and cost-effective preventive maintenance plan.

5. Water Supplies Department (WSD) has been trying to devise a long-term preventive maintenance and replacement strategy with a view to achieving saving on emergency repair costs. However, WSD has insufficient easily accessible information on the condition of its underground assets, in particular the older parts of the system. We need to conduct an underground asset management study so that we can undertake preventive maintenance or replacement systematically and with the minimum disruption to the public.

Digitization of watermain record plans

6. In order to implement a long term maintenance and replacement plan, we need easily accessible and up-to-date water mains records. At present, WSD uses paper drawings to record the alignment and size of water mains and updates these drawings manually. Whenever substantial changes are made, the department has to redraw the whole water mains record plan. Manual updating is time-consuming, repetitive and error-prone. Very often operational staff have to supplement out-dated water mains record plans by their own personal recollection of network or ground surface details or other second-hand information. This is unsatisfactory and ineffective.

7. With the exception of WSD, all major utility operators in Hong Kong are already at various stages of converting paper utility inventory records into digital format to facilitate electronic data exchange. Without digital mapping facilities, WSD will not be able to exchange electronic data with the other utilities, or to improve its efficiency. Lack of such facilities will also hinder other utility operators' efforts to co-ordinate quick and reliable information exchange on utility records. This may lead to a higher incidence of damage to underground watermains by other utilities during road excavation work, thereby causing increased inconvenience to the public.


Non-recurrent cost

8. The proposed consultancy will be on a lump sum basis and take 24 months to complete. The Director of Water Supplies (DWS) estimates that the non-recurrent expenditure will be $30 million, made up as follows -

Underground asset management study$ million
(a) Developing an asset management planning methodolgy 2.0
(b) Compiling base data and initial models 5.2
(c) Refining and developing an asset management plan 4.8
(d) Computer support 3.6
(e) Training of WSD staff 0.6
(f) Contingency for items (a) to (e) 0.8
Sub-total 17.0
Digitization of watermain record plans $ million
(g) Requirements definition, selection and customization of platform for digitization 3.5
(h) Implementation of data conversion 6.8
(i) Computer support 1.7
(j) Printing equipment 0.2
(k) Training of WSD staff 0.3
(l) Contingency for items (g) to (k) 0.5
Sub-total 13.0

9. As regards paragraph 8(a), the cost of $2 million is for developing a detailed planning methodology for all aspects of the underground asset management study.

10. As regards paragraph 8(b), the cost of $5.2 million is for structuring, collecting and collating essential base information for the underground asset management study.

11. As regards paragraph 8(c), the cost of $4.8 million is for compiling an asset management plan specifying future requirements of capital and operating expenditure and the associated benefits.

12. As regards paragraph 8(d), the cost of $3.6 million is for the acquisition, installation and implementation of information systems to support asset management planning.

13. As regards paragraph 8(e), the cost of $0.6 million is for training WSD staff on all aspects of the asset management planning methodology.

14. As regards paragraph 8(g), the cost of $3.5 million is for the selection of the optimal technical solution and development of a system for digitization.

15. As regards paragraph 8(h), the cost of $6.8 million is for the actual conversion of WSD's paper watermain record plans to a digital format for storage as computer records.

16. As regards paragraph 8(i), the cost of $1.7 million is for the purchase and installation of hardware and software for implementing digital mapping in the drawing offices.

17. As regards paragraph 8(j), the cost of $0.2 million is for the purchase of equipment for producing hard copies of the computerised records.

18. As regards paragraph 8(k), the cost of $0.3 million is for training existing drawing office staff in digital mapping.

19. The estimated cashflow is as follows -

$ million
1995-96 1
1996-97 15
1997-98 14

Subject to Members’ approval of the proposal, we shall include sufficient provision in the annual Estimates for the purpose.

Annual recurrent cost

20. Following the establishment of an asset management system, DWS will require one Senior Engineer and two Technical Officers as well as $100,000 in other departmental expenses to control, maintain and operate the system. Meanwhile, digitization of watermain records will improve efficiency in the keeping and retrieval of the watermain records resulting in savings of two existing Technical Officer posts. The net staff increase is therefore one Senior Engineer at a notional annual mid-point salary cost of $733,980. Digitization will also obviate the need for additional Technical Officers to meet the increasing demand for continuous updating of the existing manual system.


21. At the Finance Committee meeting on 3 November 1995, Members considered FCR(95-96)65 and approved supplementary provision of $99 million to meet increased expenditure on emergency repairs of waterworks facilities. Members were informed that WSD was planning to draw up a long term improvement and replacement programme for existing installations and to develop an integrated asset management strategy for the water supply network with a view to improving cost-effectiveness in maintenance of waterworks facilities and to minimise unforeseen expenditure on emergency repairs.

Works Branch
November 1995

Last Updated on 2 December 1998