PWSC(97-98)91
For discussion
on 10 December 1997
ITEM FOR PUBLIC WORKS
SUBCOMMITTEE OF FINANCE COMMITTEE
HEAD 705 - CIVIL ENGINEERING
Environmental Protection - Refuse disposal
45DR - Restoration of Northwest New Territories landfills, Part 2 and the Gin Drinkers Bay landfill
Members are invited to recommend to Finance Committee -
- the upgrading of part of 45DR, entitled " Restoration of Gin Drinkers Bay landfill - works', to Category A at an estimated cost of $273.5 million in money-of-the-day prices; and
- the retention of the remainder of 45DR in Category B, re-titled " Restoration of Pillar Point Valley landfill " .
PROBLEM
The Gin Drinkers Bay landfill, which has already been closed, may pose a threat to public safety and have adverse environmental impacts. We cannot put it to productive use.
PROPOSAL
2.The Director of Environmental Protection (DEP), with the support of the Secretary for Planning, Environment and Lands and the Director of Civil Engineering, proposes to upgrade part of 45DR to Category A at an estimated cost of $273.5 million in money-of-the-day (MOD) prices for the restoration of the Gin Drinkers Bay landfill.
PROJECT SCOPE AND NATURE
3.The original scope of 45DR comprises the restoration of 13 closed landfills. We divided the 13 landfills into Packages A, B, C and D at the feasibility study stage as detailed at Enclosure 1. We have upgraded parts of 45DR to Category A for the restoration of 11 landfills.
4.The current scope of 45DR comprises the restoration of the remaining two landfills at Gin Drinkers Bay and Pillar Point Valley. The part of 45DR that we now propose to upgrade to Category A comprises restoration works for the Gin Drinkers Bay landfill as follows -
- design and construction of a landfill gas management system to control gas emission and to prevent off-site gas migration;
- design and construction of a leachate1 management system to extract, collect, treat and dispose of the leachate;
- design and construction of an engineered capping layer (with low permeability) and a surface water drainage system; and
- improvements to the slope stability, landscaping of the landfill and other engineering works.
5.The site plan of the project is at Enclosure 2. The Lantau Airport Railway (LAR), which is under construction, crosses the landfill site. The Mass Transit Railway Corporation (MTRC) is responsible for providing mitigation measures to alleviate adverse environmental impacts from the landfill within the limits of the LAR boundary. The scope of this project therefore does not include the portion of site that is allocated permanently to MTRC for the LAR.
JUSTIFICATION
6.All landfills produce landfill gas and leachate. Landfill gas, which is a product of refuse decomposition, is malodorous and potentially asphyxiating, flammable and explosive. Leachate is highly polluting and, if not properly controlled, may result in serious contamination of water bodies. We need to fully restore the closed landfills to ensure that they pose no threat to public safety, have minimal adverse environmental impacts and can be put to productive use.
7.Municipal and industrial waste, when disposed of in landfills, does not exhibit homogenous geotechnical properties, as it is subject to a continuing biological degradation process. This results in differential settlement of the landfill surface and slope instability problems. We therefore need to improve slope stability at landfill sites. In order to reduce infiltration of rain water into the waste mass hence reducing the volumes of leachate to be treated, we need to construct an engineered capping layer on top of the flat surfaces of landfills. We also need to build a system of surface drains for proper drainage of the landfill sites.
8.We began filling operations in the Gin Drinkers Bay landfill in the 1960's. The site has become derelict land since its closure in 1979. Industrial buildings have subsequently been developed nearby. The landfill does not have proper landfill gas and leachate management systems. In 1993, we implemented priority remedial measures under 90DR " Restoration of urban landfills - priority works'. The works comprised the provision of a partial leachate collection and gas venting system at the Gin Drinkers Bay landfill. These works ensure that the landfill does not pose an immediate threat to the surrounding developments.
9.We now propose to fully restore the Gin Drinkers Bay landfill in order to properly control and minimise the adverse environmental impacts in such a way that the land can be put to productive use. The Regional Council plans to develop the site as a park after we have completed the restoration capital works. We shall ensure that the design of the restoration works will not conflict with that of the park facilities which will be built on the restored site.
10.After the commissioning2 of the restoration works, it would still be necessary to monitor the progress of restoration, mainly in terms of landfill gas migration and leachate pollution. New facilities, including a landfill gas management system and a leachate management system, will be in operation during this period and will require regular environmental control and maintenance. Such post-commissioning works also form part of the proposed works.
FINANCIAL IMPLICATIONS
11.We estimate the capital cost of the proposed works to be $273.5 million in MOD prices (see paragraph 12 below), made up as follows -
| | $ million |
|
|---|
| (a) | Landfill gas management system
| 13.5
|
| (b) | Leachate management system
| 19.7
|
| (c) | Capping and surface drainage system
| 38.4
|
| (d) | Slope stabilisation, landscaping and ancillary works
| 20.7
|
| (e) | Post-commissioning works for seven years (see paragraph 14 below)3
| 50.9
|
| (f) | Independent environmental auditor's fees (see paragraph 19 below)
| 5.9
|
| (g) | Consultants' fees during construction4
| 3.1
|
| (h) | Contingencies
| 14.3
|
| Sub-total | 166.5
| (at
December
1996 prices)
|
| (i) | Inflation allowance
| 107.0
|
| Total | 273.5 | (in MOD
prices)
|
A breakdown by man months of the estimates for consultants' fees is at Enclosure 3.
12.Subject to approval, we will phase the expenditure as follows -
| Year | $ million
(Dec 1996) | Price
adjustment
factor | $ million
(MOD)
|
|---|
| 1999 - 2000 | 1.9 | 1.26830 | 2.4
|
| 2000 - 01 | 100.1 | 1.38244 | 138.4
|
| 2001 - 02 | 7.9 | 1.50686 | 11.9
|
| 2002 - 03 | 7.9 | 1.64248 | 13.0
|
| 2003 - 04 | 7.9 | 1.79030 | 14.1
|
| 2004 - 05 | 7.9 | 1.95143 | 15.4
|
| 2005 - 06 | 7.9 | 2.12706 | 16.8
|
| 2006 - 07 | 7.9 | 2.31850 | 18.3
|
| 2007 - 08 | 17.1 | 2.52717 | 43.2
|
| 166.5 | | 273.5
|
13.We have derived the MOD estimate on the basis of the Government's forecasts of trend labour and construction prices for the period 1999 to 2008. We will tender the proposed works contract in the form of a " design-build-and-operate " (DBO)5 contract. The restoration works will be tendered under fixed-price lump-sum items and will not be subject to subsequent inflation as the works period will be less than 21 months, and the post-commissioning works will be under lump-sum items subject to adjustment for inflation as the works period will exceed 21 months.
14.We will carry out a review every five years, starting from the commissioning of the restoration works, to determine whether the landfill is completely restored and whether further post-commissioning works would be necessary. We will draw up the contract such that it can last up to 30 years, but we have the right to terminate the contract or amend the coverage of the contract provided that we give the contractor sufficient advance notice. We have included $50.9 million (at December 1996 prices) in the project cost for seven years of post-commissioning works. This will allow us sufficient time to carry out a review after the first five years which will take about six to nine months to complete, and if necessary, to give the contractor 12 months notice to terminate his contract. We will seek Members' funding approval for further post-commissioning works depending on the results of the review.
15.We estimate the annually recurrent expenditure to be $1.6 million.
PUBLIC CONSULTATION
16.We circulated the final report of the feasibility study for the restoration of urban landfills to all relevant District Boards in March 1993. We consulted the Kwai Tsing District Board on 14 September 1995 on the proposed restoration and afteruse of the Gin Drinkers Bay landfill. The Board had no objection to the proposed works.
17.We briefed the Advisory Council on the Environment on 21 February 1994 about the restoration works for the Shuen Wan landfill, Urban landfills (including Gin Drinkers Bay landfill) and Tseung Kwan O landfills, and obtained its support.
ENVIRONMENTAL IMPLICATIONS
18.We completed in December 1992 an initial Environmental Impacts Assessment (EIA) as part of the feasibility study for the restoration of Urban landfills including Gin Drinkers Bay landfill. The findings of the EIA indicated that the implementation of the restoration works would ensure proper control of the emission and off-site migration of landfill gas and leachate. This will ameliorate the environmental impacts of the landfill and enable the landfill site to be put to beneficial use.
19.The future DBO contractor will carry out a detailed EIA study on his proposal for the restoration of the landfill. We will require the contractor to appoint an independent environmental auditor to ensure that the facilities comply with the environmental control requirement. We have included $5.9 million (at December 1996 prices) in the project cost for employing the independent environmental auditor.
20.In addition, we will control dust, noise and site run-off nuisances during construction to within established standards and guidelines through the implementation of mitigation measures in the relevant works contract.
LAND ACQUISITION
21.The project works do not require land acquisition.
BACKGROUND INFORMATION
22.We included 45DR in Category B in August 1990. Details on the estimated costs of the works under 45DR and the implementation plan are at Enclosure 1.
23.We employed consultants under 59DR " Restoration of landfill sites - consultants' fees and investigations' to carry out feasibility studies and to develop an outline scheme for the restoration of Urban landfills and the Gin Drinkers Bay landfill. We also employed consultants under 88DR " Restoration of urban landfills - consultants' fees and investigations' to prepare the contract documents and arrange tender invitation and evaluation for the restoration works.
24.We intend to invite tenders for the restoration works of Gin Drinkers Bay landfill in March 1998. We plan to start the restoration works in February 1999 for completion in July 2000.
25.We plan to implement the remainder of 45DR in November 1999 for completion in April 2001.
Planning, Environment and Lands Bureau
November 1997
(LL293)
1. " Leachate " is a term used to describe liquid that has permeated through the waste mass.
2. The word " commissioning " in this context means to carry out certain performance tests to verify that the landfill facilities meet the performance requirements in the contract.
3. The average annual cost of the post-commissioning works is $7.3 million and will be paid to the contractor in monthly installments.
4. The restoration works require multi-disciplinary technical expertise in areas such as gas engineering, geotechnical engineering, horticulture, landscaping and land-use planning. We need to closely manage and supervise the works to ensure that the landfill meets acceptable environmental standards. DEP considers it necessary to employ consultants during the construction period to provide specialist advice on geotechnical engineering, electrical and mechanical engineering, landfill gas extraction, leachate treatment and landscaping to supplement his in-house staff.
5. To employ a single contractor to design, build and subsequently operate the facilities will ensure that continuous liability is borne by a single party, and the responsibility to develop and maintain acceptable environmental and safety standards also rests with one party. We will tender the restoration works for Gin Drinkers Bay landfill together with the restoration works for the Northwest New Territories landfills, Part 1 (157DR) under one single DBO contract. Finance Committee approved the upgrading of part of 45DR as 157DR to Category A in July 1995 for the implementation of the restoration works for Northwest New Territories landfills, Part 1.
Enclosure 1 to PWSC(97-98)91
45DR - Restoration of Northwest New Territories landfills,
Part 2 and the Gin Drinkers Bay landfill
Updated Cost Estimates and Implementation Plan
Package A-Shuen Wan landfill (35 ha.)
| Start Date | Completion
Date | Latest
Estimated
Cost
($ million)
|
|---|
| (a) Conceptual scheme(1)
| May 1992 | Oct 1993
| 7.4
|
| (b) Contract preparation and tendering(5)
| Nov 1994
| Jan 1996 | 9.6
|
| (c) Priority works(4) | Dec 1993 | Mid 1995
| 20.0
|
| (d) Main works(6)
| Dec 1996 | Dec 1997
| 185.0
|
| (e) Post-commissioning works(6) | Jan 1998
| Dec 2004 | 88.2
|
| Total | 310.2
|
Package B-Urban landfill comprising Gin Drinkers Bay (29 ha.), Jordan Valley (6.5 ha.), Ma Yau Tong Central (5.8 ha.), Ma Yau Tong West (6.6 ha.), Ngau Chi Wan (14 ha.) and Sai Tso Wan (14 ha.) landfills.
| Start Date | Completion
Date | Latest
Estimated
Cost
($ million)
|
|---|
| (a)Conceptual scheme(1) | Apr 1991 | Mar 1995
| 19.3
|
| (b)Contract preparation and tendering(2)
| Nov 1994
| Mar 1997 | 21.0
|
| (c)Priority works(3)
| Sept 1993 | Dec 1994
| 15.0
|
| (d)Main works (excluding those at Gin Drinkers Bay)(6)
| May 1997 | Jul 1998 | 194.6
|
| (e)Post-commissioning works (excluding those at Gin Drinkers Bay)(6)
| Aug 1998 | Jul 2005 | 155.4
|
| (f)Main works (at Gin Drinkers Bay)(8)
| Feb 1999 | Jul 2000 | 115.6
|
| (g)Post-commissioning works (at Gin Drinkers Bay)(8)
| Aug 2000 | Jul 2007 | 50.9
|
| Total | 571.8
|
Package C-Tseung Kwan O Stage I (60 ha.) & Stage II/III (35 ha.) landfills.
| Start Date | Completion
Date | Latest
Estimated
Cost
($ million)
|
|---|
| (a)Conceptual scheme(1) | May 1990
| Sept 1993 | 14.8
|
| (b)Contract preparation and tendering(5)
| Oct 1994 | May 1997 | 14.6
|
| (c)Main works(6)
| Jul 1997 | Sept 1998
| 581.0
|
| (d)Post-commissioning works(6) | Oct 1998
| Sept 2005 | 127.4
|
| Total | 737.8
|
Package D-Northwest New Territories landfills, Part 1 comprising Ngau Tam Mei (2 ha.), Ma Tso Lung (2 ha.), Siu Lang Shui (12 ha.) and Part 2 comprising Pillar Point Valley (53 ha.) landfills.
| Start Date | Completion
Date | Latest
Estimated
Cost
($ million)
|
|---|
| (a)Conceptual scheme(1) | Jan 1993
| Apr 1995 | 9.1
|
| (b)Contract preparation and tendering(5) | | | 15.7
|
| Part 1 | Jul 1997 | Dec 1997 | 6.6
|
| Part 2 | Apr 1998 | Sept 1998 | 9.1
|
| (c)Main works | | | 662.9
|
| Part 1(7) | Feb 1999 | Mar 2000 | 119.6
|
| Part 2(9) | Nov 1999 | Apr 2001 | 543.3
|
| (d)Post-commissioning works | | | 155.5
|
| Part 1(7) | Apr 2000 | Mar 2007 | 75.6
|
| Part 2(9) | May 2001 | Apr 2008 | 79.9
|
| Total | 843.2
|
| Grand Total | 2,463.0
|
Footnotes :
- Finance Committee approved the upgrading of part of 45DR as 59DR to Category A in January 1990 for studying and recommending improvement measures for the restoration of the 12 landfills (excluding the Sai Tso Wan landfill) under Packages A, B, C and D. The approved project estimate was $50.6 million at January 1993 prices.
- Finance Committee approved the upgrading of part of 45DR as 88DR to Category A in March 1993 for engaging consultants for the planning and implementation of restoration works for Package B. As part of the project, we have asked the consultants to formulate a general contract framework and to prepare general specifications for all restoration works contracts. The approved project estimate was $21 million at September 1994 prices.
- Finance Committee approved the upgrading of part of 45DR as 90DR to Category A in May 1993 for the implementation of priority restoration works for Package B. The approved project estimate was $15 million at May 1993 prices.
- Finance Committee approved the upgrading of part of 45DR as 92DR to Category A in June 1993 for implementing priority restoration works for Package A. The approved project estimate was $20 million at June 1993 prices.
- Finance Committee approved the upgrading of part of 45DR as 150DR to Category A in June 1994 for engaging consultants for the planning and implementation of restoration works for Packages A, C and D. The approved project estimate was $39.9 million at December 1993 prices.
- Finance Committee approved the upgrading of three parts of 45DR as 154DR, 155DR and 156DR to Category A in June 1995 for the implementation of the restoration works for Packages A, B (excluding Gin Drinkers Bay landfill) and C. The approved project estimates for 154DR, 155DR and 156DR were $273.2 million, $350 million and $708.4 million respectively at December 1994 prices.
- Finance Committee approved the upgrading of part of 45DR as 157DR to Category A in July 1995 for the implementation of the restoration works for Package D, Part 1. The approved project estimate was $195.2 million at December 1994 prices.
- We now invite Members to recommend to Finance Committee the upgrading of the works to Category A. The estimated project cost is $166.5 million at December 1996 prices.
- The estimated costs are at December 1996 prices.
(LL293)
Enclosure 3 to PWSC(97-98)91
45DR - Restoration of Northwest New Territories landfills,
Part 2 and the Gin Drinkers Bay landfill
Breakdown of estimates for consultants' fees
Consultants'
staff costs | | Estimated
man
months
| Average
MPS*
salary
point | Multiplier
factor | Estimated
fee
($ million)
|
|---|
Consultants' fee
for
construction stage
| Professional
Technical
| 20
20 | 40
16
| 2.1
2.1 | 2.33
0.78
|
| Total consultant's staff costsl | 3.11
|
* MPS = Master Pay Scale
1.A multiplier factor of 2.1 is applied to the average Master Pay Scale (MPS) point to arrive at the full staff costs including the consultants' overheads and profit, as the staff will be employed in the site offices. (At 1.4.96, MPS pt. 40 = $55,390 p.m. and MPS pt. 16 = $18,595 p.m.)
2.The figures given above are based on estimates prepared by the Director of Environmental Protection. We will only know the actual man months and actual fees when we have selected the consultant through the usual competitive lump sum fee bid system.
(LL293)
