PWSC(1999-2000)45
For discussion
on 16 June 1999
ITEM FOR PUBLIC WORKS SUBCOMMITTEE
OF FINANCE COMMITTEE
HEAD 707 - NEW TOWNS AND URBAN AREA DEVELOPMENT
New Territories North Development
Civil Engineering - Drainage and erosion protection
29CD - Main drainage channels for Ngau Tam Mei
Members are invited to recommend to Finance Committee -
- the upgrading of part of 29CD, entitled "Main drainage channel for Ngau Tam Mei phase 1 Yau Mei San Tsuen to Tai Sang Wai section", to Category A at an estimated cost of $442.5 million in money-of-the-day prices; and
- the retention of the remainder of 29CD, retitled "Main drainage channel for Ngau Tam Mei phase 2 - Ngau Tam Mei to Yau Mei San Tsuen section", in Category B.
PROBLEM
We need to construct a main drainage channel from Castle Peak Road near Yau Mei San Tsuen to Tai Sang Wai to alleviate the flooding hazard to the low-lying areas of Ngau Tam Mei (Yuen Long).
PROPOSAL
2. The Director of Territory Development, with the support of the Secretary for Works, proposes to upgrade part of 29CD to Category A at an estimated cost of $442.5 million in money-of-the-day (MOD) prices for the construction of a main drainage channel from Castle Peak Road near Yau Mei San Tsuen to Tai Sang Wai.
PROJECT SCOPE AND NATURE
3.The scope of 29CD comprises the construction of a main drainage channel from Ngau Tam Mei through Castle Peak Road near Yau Mei San Tsuen to Tai Sang Wai.
4.The part of 29CD we now propose to upgrade to Category A comprises -
a drainage channel of about 2.3 kilometres long from Castle Peak Road near Yau Mei San Tsuen to Tai Sang Wai;
- an inflatable dam and a low flow pumping station;
- an irrigation pumping station;
- roads and ramps with associated drainage and water works;
- four vehicular bridges;
- environmental mitigation measures including landscaping works; and
- an environmental monitoring and audit programme for works mentioned in paragraphs (a) to (f) above.
JUSTIFICATIONS
5. In recent years, extensive changes in land use and rapid development in Ngau Tam Mei have significantly aggravated the flooding problem in the area which is already susceptible to flooding due to its low-lying topography. The "North West New Territories Base Strategy Studies" (the Initial Study), completed in 1983, recommended a series of river training works to alleviate the flooding hazard in the North West New Territories, including the low-lying areas of Ngau Tam Mei. The "Territorial Land Drainage and Flood Control Strategy Study - Phase II" completed in 1993 under 52CD, also confirmed the recommendations of the Initial Study.
6. We will complete the works for the downstream area of Kam Tin River under 60CD in July 1999. The proposed drainage channel under 29CD will convey surface runoff arising from the upper and lower Ngau Tam Mei catchment areas including Yau Mei San Tsuen, Chuk Yuen Tsuen, San Wai Tsuen and Pok Wai into the Kam Tin main drainage channel. The new channel is capable of accommodating a 50-year return period rainstorm. It serves to alleviate flooding problem in the Ngau Tam Mei area and forms part of the overall flood alleviation programme in the North West New Territories.
7. To prevent back flow of tidal sea water from Deep Bay through the Kam Tin main drainage channel into the proposed channel causing undesirable impacts to the nearby environment, we will construct an inflatable dam and associated pumping facilities at the downstream end of the proposed drainage channel. Under normal weather conditions, we will inflate the dam to prevent sea water entering the channel. We will pump the flow from the area upstream of the dam into the Kam Tin main drainage channel. During heavy rainstorms when the upstream water level in the proposed drainage channel is high, we will deflate the inflatable dam to discharge flood water into Kam Tin main drainage channel. In order to supply water to some areas of farmland at the upstream end of the proposed drainage channel for irrigation, we will construct an irrigation pumping station near Yau Mei San Tsuen to pump water from the proposed drainage channel to the farmland.
8.To facilitate future maintenance of the proposed drainage channel and to ensure its smooth functioning, we need to construct roads and ramps. We will also construct four vehicular bridges for crossing the proposed drainage channel and connecting them to the existing roads affected by this drainage channel.
FINANCIAL IMPLICATIONS
9.We estimate the capital cost of the project to be $442.5 million in MOD prices (see paragraph 10 below), made up as follows -
| $ million
|
|---|
| (a) Drainage channel | 135.0
|
| (b) Inflatable dam, low flow and irrigation pumping stations | 84.0
|
| (c) Roads, drainage and associated waterworks | 76.0
|
| (d) Vehicular bridges | 42.0
|
| (e) Environmental mitigation measures (including landscaping works) | 10.0
|
| (f) Environmental monitoring and audit (EM&A) programme | 6.0
|
| (g) Resident site staff | 14.0
|
| (h) Contingencies | 36.0
______
|
| Sub-total | 403.0 | (at December 1998 prices)
|
| (i) Provision for price adjustment | 39.5
______
|
| Total | 442.5
______ | (in MOD prices) |
While resident site staff from the Drainage Services Department will provide some on-site supervision, there are not sufficient in-house resources to provide the entire complement of site staff required. The Director of Drainage Services (DDS) therefore proposes to employ additional resident site staff through consultants for supervising the geotechnical and EM&A components of the works. A breakdown by man-months of the estimate for consultants' resident site staff expenses is at Enclosure 1.
10.Subject to approval, we will phase the expenditure as follows -
| Year | $ million
(Dec 1998) | Price
adjustment
factor | $ million(MOD)
|
|---|
| 1999 - 2000 | 45.0 | 1.02625 | 46.2
|
| 2000 - 2001 | 108.0 | 1.06217 | 114.7
|
| 2001 - 2002 | 117.0 | 1.09934 | 128.6
|
| 2002 - 2003 | 90.0 | 1.13782 | 102.4
|
| 2003 - 2004 | 43.0 | 1.17765 | 50.6
|
| _______ | | ________
|
| 403.0 | | 442.5
|
| _______ | | ________
|
11.We have derived the MOD estimate on the basis of the Government's latest forecast of trend labour and construction prices for the period from 1999 to 2004. We will tender the civil engineering works under a standard remeasurement contract because the works involve extensive earthworks, the quantity of which may vary according to the actual ground conditions. The contract will provide for price adjustments as the contract period will exceed 21months. We will tender the electrical and mechanical works separately under a lump sum contract because we can clearly define the scope of the works.
12.We estimate the annually recurrent expenditure to be $5.89 million.
PUBLIC CONSULTATION
13.We consulted the San Tin Rural Committee and the Yuen Long District Board about the proposed works on 2 March 1993 and 15 April 1993. Members of the Committee and District Board supported the proposed project for the relief it would bring to the flooding problem in the Ngau Tam Mei area.
14.We presented the findings and the environmental mitigation measures recommended in the Environmental Impact Assessment (EIA) report to the Yuen Long District Board on 13 June 1996. Members had no objection to the findings and the recommended mitigation measures. We then consulted the EIA Subcommittee of the Advisory Council on the Environment (ACE) on the EIA study report on 1 July 1996. The ACE endorsed the study report with the conditions described in paragraph 19 below.
15.As the river training works involved filling below high tide level, we gazetted the proposed reclamation works under the Foreshore and Sea-bed (Reclamations) Ordinance on 21 October 1994. We received eight objections. We had a series of discussions with the objectors and one of them withdrew his objection. The remaining seven objectors maintained their objections against resumption of their land. On 18 April 1997, we gazetted an additional area of reclamation works located at the upstream of the proposed drainage channel near Yau Mei San Tsuen under the Foreshore and Sea-bed (Reclamations) Ordinance and received no objection.
16.We also gazetted the proposed road works ancillary to the drainage channel under the Roads (Works, Use and Compensation) Ordinance on 19August 1994. We received 11 objections. We had a series of discussions with the objectors. Subsequently, we amended the road scheme to revise the alignment of the road and three objectors withdrew their objections. The remaining eight objectors maintained their objections against resumption of their land.
17.We gazetted the amendments under the Roads (Works, Use and Compensation) Ordinance on 27 March 1997. We received four objections to the amendments including one from the remaining eight objectors mentioned in paragraph 16 above. After a series of discussions, we were able to persuade one objector, who objected to the traffic flow arrangement, to withdraw his objection. As a result of his request, we consulted the Yuen Long Provisional District Board on 26 February 1998 on the revised traffic flow arrangement and obtained their endorsement. The remaining three objectors maintained their objections against the resumption of their land.
18.On 29 September 1998, the Chief Executive in Council overruled the objections mentioned in paragraphs 15 to 17 above in the public interest and authorized the proposed road works and reclamation works of the project without modification.
ENVIRONMENTAL IMPLICATIONS
19.The project is a designated project under Schedule 2 of the EIA Ordinance (Cap. 499) and an environmental permit is required for the construction and operation of the project. In May 1994, we employed consultants to carry out an EIA study to assess the environmental impacts due to the construction and operation of a series of flood control projects in Yuen Long, Kam Tin and Ngau Tam Mei. Following completion of the EIA report in May1996, we consulted the ACE in July 1996. ACE endorsed the report on condition that (a) old river channels would be considered for restoration into wildlife habitats; (b) the disposal of contaminated mud should be to the satisfaction of the Fill Management Committee (FMC) and that such disposal would have no adverse effects on the environment; and (c) the proponents should review the conceptual off-site compensation measures in light of Government's latest policy on off-site compensation and report back to the EIA Sub-committee of the ACE their specific proposals for this project.
20.The EIA report concluded that the environmental impact of the proposed works could be controlled to within established standards and guidelines through the implementation of the mitigation measures as recommended in the EIA study. We will implement these measures. As regards the conditions set by ACE, the Agriculture and Fisheries Department (A&FD) is currently carrying out a study to address the restoration of the old river channels and off-site compensation, and will report the findings to the EIA Sub-committee after the completion of the study in end 2000. We have also obtained approval from the FMC for the arrangements to dispose of contaminated mud. The key measures in respect of dredging works include the use of a close mechanical grab, no stockpiling of contaminated mud, proper disposal of dredged materials and regular maintenance dredging. We estimate the cost of implementing the environmental mitigation measures ($10 million) and EM&A ($6 million) to be $16 million which has been included as part of the overall project estimate.
LAND ACQUISITION
21.We will resume about 16.7 hectares of agricultural land and 455 square metres of building land for the project. The land acquisition and clearance will affect 23 households involving 93 persons and 44 business/agricultural structures. The Director of Housing will offer eligible families accommodation in public housing in line with the existing policy. We will charge the costs of land acquisition and clearance, estimated to be $280million, to Head 701 - Land Acquisition.
BACKGROUND INFORMATION
22.We upgraded 29CD to Category B in 1987. We completed the preliminary design in late 1989 and started the public consultation in early 1990. The village representative of Chuk Yuen Tsuen and the Yuen Long District Board raised objections to the alignment of the proposed drainage channel. We revised the alignment of the drainage channel to avoid Chuk Yuen Tsuen but the village representative and the Yuen Long District Board still did not support the project. We made further revisions and the San Tin Rural Committee, the Yuen Long District Board and the village representative of Chuk Yuen Tsuen finally gave their support in mid 1993. Upon completion of the consultation, we went through the statutory procedures as mentioned in paragraphs 15 to 18 above and completed the statutory procedures in late 1998.
23.DDS has completed the detailed design and drawings for the proposed works using in-house resources. We plan to start the works in October1999 for completion in August 2002. A map showing the proposed works is at Enclosure 2. We will commence the remaining works under 29CD in early 2000 for completion in late 2002. A map showing the remaining works under 29CD is at Enclosure 3.
------------------------------------
Works Bureau
June 1999
(CD29-02.RTF)
Enclosure 1 to PWSC(1999-2000)45
29CD - Main drainage channels for Ngau Tam Mei
Breakdown of the estimate for consultants' fees
| Consultants' staff costs | | Estimated
man
months | Average
MPS*
salary
point
| Multiplier
factor
| Estimated
fees
($ million)
|
|---|
| Site supervision by resident site staff employed by the consultants | Professional
Technical | 105
78 | 40
16 | 1.7
1.7 | 11.2
2.8
______
|
| Total consultants' staff cost | 14.0
______
|
* MPS = Master Pay Scale
Notes
1.A multiplier factor of 1.7 is applied to the average MPS point to arrive at the full staff costs including the consultants overheads and profit, as the staff will be supplied by the consultants. (At 1.4.98, MPS pt. 40 = $62,780 p.m. and MPS pt. 16 = $21,010 p.m.)
2.The figures given above are based on estimates prepared by the Director of Drainage Services. We will only know the actual man months and fees when we have appointed the resident site staff.
(CD29-02.RTF)
