For discussion
on 26 November 1997


Civil Engineering - Drainage and erosion protection
64CD - Rural drainage rehabilitation scheme

Members are invited to recommend to Finance Committee -

  1. the upgrading of part of 64CD, entitled "Rural Drainage Rehabilitation Scheme, stage 1, phase 1A - rehabilitation works at Ng Tung River" to Category A at an estimated cost of $231.1 million in money-of-the-day prices; and

  2. the retention of the remainder of 64CD in Category B.


The rural areas in the North-east and North-west New Territories have become more susceptible to local flooding during typhoons and heavy rainstorms in recent years due to silting and inadequate capacity of a number of watercourses in the area.


2.The Director of Drainage Services, with the support of the Secretary for Planning, Environment and Lands, proposes to upgrade part of 64CD to Catergory A at an estimated cost of $231.1 million in money-of-the-day (MOD) prices for the rehabilitation of the upper reach of Ng Tung River (also known as River Indus) and its tributaries, and the provision of proper access for future maintenance.


3.Project 64CD comprises two stages of works for the rehabilitation of a number of watercourses in the North-east and the North-west New Territories and the provision of proper maintenance access. The part of project we now propose to upgrade to Category A is part of the stage 1 works, which covers the upper reach of Ng Tung River and its tributaries as shown on the site plan at Enclosure 1. The scope of works comprises the following -

  1. construction of a 3.5-kilometre long drainage channel along a section of Ng Tung River from Tai Tong Wu to Gallipoli Lines;

  2. construction of a 700-metre long drainage channel along a section of Kwan Tei River from San Tong Po to the confluence with Ng Tung River;

  3. construction of a 170-metre long triple-cell box culvert to the east of Ping Che Road;

  4. construction of flood banks at Tan Shan River near Ng Uk Tsuen;

  5. construction of a total of 4.2-kilometre long maintenance access roads along the proposed drainage channels;

  6. demolition and reprovision of seven footbridges; and

  7. environmental mitigation works.

4.The remainder of 64CD comprises the construction of the remaining stage 1 works and the design, site investigation, and construction of the stage 2 works.


5.In recent years, the rural areas in the North-east and North-west New Territories have become more susceptible to local flooding during typhoons and heavy rainstorms. Our investigation has revealed that the main cause is the silting of the major watercourses, resulting in substantial reduction in the hydraulic capacity of the watercourses. Due to the lack of proper access, it is very difficult to carry out improvement works to the watercourses to rectify the situation. Furthermore, the conversion of farmland into open storage yards has aggravated the flooding problem during heavy rainstorms. This is due to the overloading of the drainage system by rainwater which, in the past, dissipated mostly as groundwater in the farmland.

6.Tne of the major watercourses in the North-east New Territories facing flooding problems is Ng Tung River and its tributaries. In order to alleviate the flooding hazard, we need to increase the existing capacity of Ng Tung River and Kwan Tei River by forming proper drainage channels. In addition, we need to provide proper access along the proposed channels to facilitate routine maintenance so that we can ensure the reliable performance of the channels.

7.We propose to construct a triple-cell box culvert at a section of Ng Tung River to the east of Ping Che Road in lieu of a drainage channel to minimise land resumption on an existing saw mill. Moreover, we propose to construct flood banks at identified locations along Tan Shan River to protect the nearby villages from flooding and at the same time minimise the environmental impact of the works on the Tan Shan River, which is of high ecological value for a wide variety of habitats.

8.There are seven footbridges across Ng Tung River and Kwan Tei River to provide necessary channel-crossing facilities for local residents. As these footbridges will obstruct the construction of the drainage channel, we need to demolish them during the construction of the drainage works but we will reprovision them under the project.

9.We will also implement the environmental mitigating measures recommended in the environmental impact assessment (EIA) study for the project to avoid unacceptable short term and long term environmental impacts.

10.If we do not implement the proposed works, local flooding shall remain a serious problem in these areas.


11.We estimate the capital cost of the proposed project to be $231.1 million in MOD prices (see paragraph 12 below), made up as follows -

$ million
(a) Drainage channels90.5
(b) Triple-cell box culvert9.6
(c) Flood banks3.9
(d) Road works10.4
(e) Footbridges26.4
(f) Environmental mitigation works3.9
(g) Consultants' fees for construction stage3.1
(h) Resident site staff cost21.9
(i) Contingencies16.6
Sub-total186.3(at December 1996 prices)
(j) Inflation allowance44.8
Total231.1(in MOD prices)

A breakdown by man month of the estimates for consultants' fees for construction stage and resident site staff cost is at Enclosure 2.

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

Year$ million
(Dec 1996)
$ million
1998 - 9980.01.16358 93.1
1999 - 200084.01.26830106.5
2000 - 0117.01.3824423.5
2001 - 025.31.506868.0
186.3 231.1

13.We have derived the MOD estimate on the basis of the Government's forecasts of trend labour and construction prices for the period 1998 to 2002. We will tender the works under a standard remeasurement contract. We adopt a re-measurement basis because we are uncertain about the quantities of earthworks. The contract will allow for adjustments to the tender price due to inflation as the contract period will exceed 21 months.

14.We estimate the annually recurrent expenditure to be $3.2 million.


15.We consulted the North District Board, the Sheung Shui Rural Committee and the Fanling Rural Committee on 10 October 1996, 5 December 1996 and 16 March 1997 respectively on the proposed works. Members of the District Board and the Rural Committees supported the implementation of the proposed works.

16.We gazetted the road scheme of the proposed works on 4 April 1997 under the Roads (Works, Use and Compensation) Ordinance and did not receive any objection. The Secretary for Transport authorized the road scheme on 20 June 1997.


17.We completed an EIA study in July 1996 under 67CD "Rural Drainage Rehabilitation Scheme - consultants' fees and investigations" for the proposed project. The study assessed the impacts upon water quality, ecology, visual and landscape features, noise and air quality, and those associated with the management of waste material, that would arise from the construction and operation of the proposed works and recommended mitigation measures.

18.For long term impact, we will implement the necessary environmental protection measures accoding to the recommendations in the EIA study. For short term impact during the construction stage, we will control noise, dust and site run-off in accordance with established standards and guidelines. We will formulate an Environmental Monitoring and Audit Manual and Programme to ensure the timely and effective implementation of the recommended mitigation measures.

19.The study has revealed that there will be no unacceptable residual impact, i.e. impact after mitigation, resulting from the construction or operation of the proposed works. The Advisory Council on the Environment endorsed the EIA study on 20 January 1997.


20.We shall resume about 5.5 hectares of private agricultural land for the implementation of the proposed works. The required land acquisition and clearance will affect 46 persons. The Director of Housing will offer them accommodation in public housing or temporary housing in line with the prevailing policy. We will charge the land acquisition and clearance costs estimated to be $140 million to Head 701 - Land Acquisition.


21.In March 1994, we upgraded 64CD to Category B for the implementation of the rehabilitation works to a number of watercourses in the North-east New Territories under the stage 1 works and the North-west New Territories under the stage 2 works.

22.In November 1994, we upgraded part of 64CD to Category A as 67CD " Rural Drainage Rehabilitation Scheme - consultants' fees and investigations' to engage consultants to conduct an EIA study for the whole project and carry out site investigations and detailed design for the stage 1 works.

23.We plan to implement the stage 1 works in two phases. The phase 1 works are for the rehabilitation of the upper reaches of Ng Tung River and Sheung Yue River (also known as River Beas) and their tributaries while the phase 2 works are for the rehabilitation of the remaining watercourses in the North-east New Territories.

24.We further divided the phase 1 works into two sub-phases, namely phases 1A and 1B. We have substantially completed the detailed design for phase 1A. We plan to start construction in May 1998 for completion in July 2000. We plan to start the construction of the phase 1B works in early 1999.

25.For the stage 2 works, we plan to commence construction in early 2000.

26.The proposed works form part of the overall river training works to the North-east New Territories. Other major projects concerning improvement works to Ng Tung River include the river training works under 53CD "New Territories North East development - main drainage channels for Fanling, Sheung Shui and hinterland" and 87CL "Shek Wu Hui development, package 4, site formation and roadworks", which will also start in 1998.

Planning, Environment and Lands Bureau
November 1997


Enclosure 2 to PWSC(97-98)74

64CD - Rural Drainage Rehabilitation Scheme

Details of Consultants' Fees

Breakdown of estimates for consultants' fees

staff costs
($ million)
(a)Consultants' fees for construction stage

(b)Site supervision by resident site staff employed by the consultants

Total consultants' staff cost24.96


1.A multiplier of 3 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 employed in the consultants' offices. (At 1.4.1996, MPS pt. 40 = $55,390 p.m. and MPS pt. 16 = $18,595 p.m.) A multiplier of 2.1 is applied in the case of site staff supplied by the consultants.

2.The consultants' fees for construction stage are based on the lump sum fees calculated in accordance with the consultancy agreement the Director of Drainage Services has with the consultants undertaking the design and investigation of the project. The costs for resident site staff are based on estimates prepared by the Director of Drainage Services. We will only know the actual man months and actual costs when the construction works have completed.