For discussion
on 20 January 1999

PWSC(98-99)62

ITEM FOR PUBLIC WORKS SUBCOMMITTEE
OF FINANCE COMMITTEE

HEAD 709 - WATERWORKS
Water Supplies - Fresh water supplies
227WF - Mainlaying between Au Tau treatment works and Yuen Long Town - remaining works

Members are invited to recommend to Finance Committee -

1. the upgrading of part of 227WF, entitled "Mainlaying between Au Tau treatment works and Yuen Long Town - advance mainlaying work along Kam Tin Road" to Category A at an estimated cost of $17.68 million in money-of-the-day prices; and

2. the retention of the remainder of 227WF in Category B.

PROBLEM

By 2003, the existing trunk main between the Au Tau treatment works and the Yuen Long Town will not be able to cope with the anticipated increase in water demand arising from the planned developments in the Tuen Mun - Yuen Long Corridor and the north-western part of Tuen Mun.

PROPOSAL

2. The Director of Water Supplies (DWS), with the support of the Secretary for Works, proposes to upgrade part of 227WF to Category A at an estimated cost of $17.68 million in money-of-the-day (MOD) prices for the laying of a fresh water main in conjunction with the roadwork for widening of Kam Tin Road.

PROJECT SCOPE AND NATURE

3. The full scope of works under 227WF comprises the laying of about 4 500 metres of 1 400 millimetres diameter fresh water main between the Au Tau treatment works and Yuen Long Town along Kam Tin Road, Castle Peak Road, Fung Yau Street East, Fung Yau Street South, Ma Tong Road, Ma Tin Road and Shan Ha Road.

4. The part of 227WF we now propose to upgrade to Category A comprises the laying of about 730 metres of 1 400 millimetres diameter fresh water main along Kam Tin Road under the works described in paragraph 3 above.

JUSTIFICATION

5. In view of the rapid developments in the Tuen Mun areas, DWS envisages that the population in areas currently served by Tuen Mun treatment works will increase from 430 000 in 1998 to 498 000 in 2003 and to 595 000 in 2006. Together with the demand arising from other industrial and commercial developments under planning, the daily water demand is expected to increase from 180 000 cubic metres in 1998 to 233 000 in 2003 and to 314 000 in 2006.

6. As we mentioned in the paper PWSC(97-98)65 on 234WF (see paragraph 7 and footnote 4 below), the existing Tuen Mun treatment works will not be able to cope with the increase in water demand by year 2003. We need to provide a trunk main of about 11 kilometres long and related facilities to transfer water from Au Tau treatment works in Yuen Long to Tan Kwai Tsuen for further distribution to Tuen Mun areas. We are carrying out the project in several phases.

7. We upgraded part of the project to Category A as 229WF¹ in January 1997 for the construction of Tan Kwai Tsuen fresh water service reservoir stage II and laying of about 600 metres of fresh water trunk main in Tuen Mun Area 52. We also constructed a small section of the trunk main across Shun Tat Street as advance work under Category D item 67AWF². We plan to commence the construction of a pumping station at Tan Kwai Tsuen and laying the remaining part of the trunk main between Tuen Mun and Tan Kwai Tsuen later this year. As for the section of trunk main between Au Tau and Tan Kwai Tsuen, we upgraded two phases of the project to Category A as 233WF³ and 234WF⁴ in late 1997 for laying of two sections of the trunk main along Fung Yau Street and between Shan Ha Road and Tan Kwai Tsuen respectively. We are now proposing the laying of about 730 metres of trunk main along Kam Tin Road. We plan to commence the construction of the remaining sections of trunk main between Au Tau and Tan Kwai Tsuen in late 2000.

8. The existing fresh water supply system in the area between Au Tau and Yuen Long Town is able to cope with the demand up to year 2003. We are assessing and reviewing the demand situation arising from new developments under planning in the area. We will make cross connections between the new trunk main and the existing fresh water supply system to cater for further increases in demand in Yuen Long Town and Tuen Mun - Yuen Long Corridor.

9. The Director of Highways (DHy) is about to enter into a roadwork contract under 560TH⁵ "Improvement to Kam Tin Road, Stage 1" for the widening and reconstruction of Kam Tin Road. The mainlaying works described in paragraph 4 above will fall within the project boundaries of 560TH. To avoid unnecessary repetitive road opening and interface problems arising from two contractors working on the same site, we will incorporate this section of mainlaying works into the roadwork contract under 560TH.

FINANCIAL IMPLICATIONS

10. We estimate the capital cost of this phase of the project to be $17.68 million in MOD prices (see paragraph 11 below), made up as follows -

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

12. We derived the MOD estimates on the basis of the Government's latest forecast of trend labour and construction prices for the period 1999 to 2003. We will incorporate the proposed mainlaying works into DHy's roadwork contract on a remeasurement basis with provision for price adjustments because the construction period will be longer than 21 months.

13. We estimate the additional annually recurrent expenditure to be $54,200.

14. This phase of the project by itself would lead to an increase in water charges⁶ by a maximum of 0.01% in real terms by 2003.

PUBLIC CONSULTATION

15. We consulted the Environmental Improvement Committee of the Yuen Long Provisional District Board on 28 May 1998. The Committee supported the project.

ENVIRONMENTAL IMPLICATIONS

16. The Director of Environmental Protection (DEP) vetted the Preliminary Environmental Review (PER) conducted by DWS in February 1996. The PER concluded that the project would have no long term environmental impact and no Environmental Impact Assessment would be required. We will control noise, dust and site run-off nuisances during construction to comply with established standards and guidelines through the implementation of mitigation measures in relevant contracts. We have included in the project estimate of 227WF the cost of implementing suitable mitigation measures to control short term environmental impacts.

LAND ACQUISITION

17. The proposed mainlaying works do not require any land acquisition.

BACKGROUND INFORMATION

18. We upgraded 227WF to Category B in September 1996. As regards the works which we now propose to upgrade to Category A, DWS has completed the detailed design using in-house staff resources. We plan to start the proposed mainlaying works in this phase in April 1999 for completion in October 2001 to tie in with the roadworks programme under 560TH.

19. DWS is continuing with the design works for the remaining sections of trunk main under the remaining part of 227WF. We plan to start construction works for these sections in late 2000 for completion in early 2003.

Works Bureau
January 1999

1. We commenced the works for 229WF in March 1997 for completion in December 1999.

2. We completed Category D item 67AWF in October 1998.

3. We commenced the works for 233WF in June 1998 for completion in early 1999.

4. We commenced the works for 234WF in May 1998 for completion in October 2000.

5. DHy upgraded 560TH - "Improvement to Kam Tin Road, Stage 1" to Category A in December 1998. DHy plans to start the roadworks not later than April 1999 for completion by October 2001.

6. The increase in water charges is calculated on the assumption that the demand remains static during the period from 1998 to 2003 and the amount of Government subsidy into waterworks operations is to be contained at the present price level.