For discussion PWSC(96-97)36
on 10 July 1996

ITEM FOR PUBLIC WORKS SUBCOMMITTEE
OF FINANCE COMMITTEE

HEAD 702 - PORT AND AIRPORT DEVELOPMENT
Territory Development
(Civil Engineering - Land development)
321CL - Reclamation and servicing of Tuen Mun Area 38 for special industries

Members are invited to recommend to Finance Committee -

1. the upgrading of part of 321CL, entitled “Upgrading of Pillar Point sewage treatment plant”, to Category A at an estimated cost of $106.6 million in money-of-the-day prices; and
2. the retention of the remainder of 321CL in Category B.

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PROBLEM
PROPOSAL
PROJECT SCOPE AND NATURE
JUSTIFICATION
FINANCIAL IMPLICATIONS
PUBLIC CONSULTATION
ENVIRONMENTAL IMPLICATIONS
LAND ACQUISITION
BACKGROUND INFORMATION

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PROBLEM

The existing Pillar Point sewage treatment plant will not be able to cope with the additional sewage flow anticipated to be generated from the proposed developments of the special industries area (SIA) and the river trade terminal (RTT) at Tuen Mun Area 38. We also need to construct a pumping station to pump the treated sewage from the Pillar Point sewage treatment plant via the replacement sewage submarine outfall to Urmston Road for disposal.

PROPOSAL

2. The Director of Territory Development (DTD), with the support of the Secretary for Planning, Environment and Lands, proposes to upgrade part of 321CL to Category A at an estimated cost of $106.6 million in money-of-the-day (MOD) prices for upgrading the Pillar Point sewage treatment plant.

PROJECT SCOPE AND NATURE

3. The scope of 321CL comprises -

1. reclamation of 33 hectares of land for special industries;
2. improvement to Tuen Mun Road and Wong Chu Road interchange;
3. construction of a new road from Tuen Mun Area 45 to Wong Chu Road;
4. re-construction of the sewage outfalls and construction of stormwater culverts; and
5. construction of a common user pier.

4. The part of the project we now propose to upgrade to Category A comprises -

1. replacement of four fine screens at the Pillar Point sewage treatment plant;
2. construction of one outfall pumping station; and
3. laying of the associated sewerage connection pipes.

JUSTIFICATION

5. The Pillar Point sewage treatment plant came into operation in 1981 to treat the sewage flow generated from Tuen Mun New Town. At present, the peak hour sewage flow to the Pillar Point sewage treatment plant is about 18 000 cubic metres per hour (m³/h) while the design capacity of the plant is about 20 000 m³/h. We expect that the Pillar Point sewage treatment plant will be able to meet the forecast increase in the sewage flow generated from Tuen Mun New Town up to 2011.

6. However, we anticipate that the proposed developments of SIA and RTT at Tuen Mun Area 38 upon completion scheduled for 2001 will generate additional sewage flow of about 3 800 m³/h. In order to cope with this situation, we need to expand the fine screens at the Pillar Point sewage treatment plant. The operation of the existing fine screens requires frequent flushing by sea water via sea water intake pipes to prevent blockage. The reclamation for the RTT will affect the existing sea water intake station and the sea water intake pipes. We will have to relocate the sea water intake station and extend the sea water intake pipes by about 700 metres if we want to retain these flushing facilities. As the necessary relocation and extension works will be very costly and the extended length of the intake pipes would be highly susceptible to blockage by marine growth and siltation, we propose to replace all four existing fine screens with a new and larger model which does not need flushing. The replacement fine screens will be able to cater for a maximum sewage flow of 24 000 m³/h.

7. The reclamation works for the RTT will also affect an existing 700-metre submarine outfall. We have entrusted to the t he RTT developer the construction of a 1 900-metre submarine outfall together with a 650-metre emergency sewage submarine outfall within the RTT site to replace the existing outfall under 502CL (please see paragraph 17 below). As the new outfall will require a much higher pressure head for discharging the sewage because of the extra length of the outfall pipeline, we need to provide a new pumping station and the associated sewerage connection pipes at the site of the Pillar Point sewage treatment plant to pump treated sewage from the sewage treatment plant via the replacement sewage submarine outfall to Urmston Road for disposal.

FINANCIAL IMPLICATIONS

8. We estimate the capital cost of the project to be $106.6 million in MOD prices (please see paragraph 9 below), made up as follows -

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

10. We have derived the MOD estimates on the basis of the Government’s forecasts of trend labour and construction prices for the period 1996 to 2000. We will tender the civil engineering works under a standard re-measurement contract because of the uncertain ground conditions. We will also provide for inflation adjustment in the contract as the construction period will exceed 21 months. We will tender the electrical and mechanical works under a fixed-price lump-sum contract because we can clearly define the scope of works in advance. As such, we will not provide for inflation adjustment in the relevant contract.

11. We estimate the annually recurrent expenditure to be $3.8 million. This will be charged to the Sewage Services Trading Fund. The sewerage works will, upon completion, become assets in the Fund valued at cost subject to the Legislative Council passing a resolution on appropriation of the assets to the Fund.

PUBLIC CONSULTATION

12. We presented the Expanded Development Study of Tuen Mun Area 38 to the Tuen Mun District Board in August 1990. The District Board did not object to the Pillar Point sewage treatment plant upgrading works. We also presented the results of the environmental impact assessment study covering the proposed reclamation, sewerage, drainage and road works in Tuen Mun Area 38 to the District Board in September 1994 and January 1995. The District Board again raised no adverse comment on the Pillar Point sewage treatment plant upgrading works. In fact, the District Board has on other occasions expressed concern about the off shore water quality at Tuen Mun Area 38 and has requested Government to further upgrade the sewage treatment capacity of the Pillar Point sewage treatment plant.

ENVIRONMENTAL IMPLICATIONS

13. The Director of Environmental Protection completed an environmental review in December 1994 and concluded that another separate environmental impact assessment was not required for the proposed works. We will design and equip the facilities with adequate pollution control measures to keep the noise level and odour emission arising from the operation of the facilities within established limits. In addition, we will phase the works to avoid disruption of the normal operation of the sewage treatment plant.

14. For short term impacts, we will add pollution control clauses in the works contract to control noise, dust and site run-off impacts during construction.

LAND ACQUISITION

15. The proposed works do not require land acquisition.

Background INFORMATION

16. We included 321CL in Category C in September 1988 and upgraded the project to Category B in November 1990.

17. On 9 June 1995, the Finance Committee approved the upgrading of part of 321CL to Category A as 500CL entitled “Reclamation and servicing of Tuen Mun Area 38 for special industries - stage I reclamation and associated infrastructure” at an estimated cost of $486.94 million in MOD prices. On 12 July 1995, the Finance Committee approved the upgrading of another part of 321CL to Category A as 502CL entitled “Reclamation and servicing of Tuen Mun Area 38 for special industries - sewerage and drainage works” at an estimated cost of $299.5 million in MOD prices. On 12 April 1996, the Finance Committee approved the upgrading of a further part of 321CL to Category A as 600TH entitled “Improvement to Lung Mun Road fronting Tuen Mun Area 38 and associated sewerage and drainage works” at an estimated cost of $221.7 million in MOD prices.

18. We started the stage I reclamation under 500CL in September 1995 for completion in late 1998. We also started the sewerage and drainage works under 502CL in April 1996 for completion in June 1998. We will start the Lung Mun Road improvement works under 600TH in September 1996 for completion in March 1999.

19. The Director of Drainage Services has completed the detailed design and drawings for the proposed works using in-house staff resources. We intend to start the proposed works in October 1996. We will complete the outfall pumping station and associated connection pipes by June 1998 and the entire project by September 1998.

20. We intend to carry out the remaining works of 321CL in stages starting from early 1997 for full completion in 2001.

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