For Information

Legislative Council Panel on Development

Follow-up Action to Meeting on 20 April 2011

160CD – Happy Valley Underground Stormwater Storage Scheme

Further to the meeting of Panel on Development held on 20 April 2011, the Administration provides the following supplementary information on the project 160CD – Happy Valley Underground Stormwater Storage Scheme.

(a) The dimensions of the proposed pump house in the project.

The proposed pump house is a single-storey building with a plan area of about 500 square metres (31 metres (m) long by 16 m wide) and a height of about 4 m above ground level.

(b) Details of: (i) the catchment areas of the proposed underground stormwater storage tank, and (ii) rain water collection facilities and drainage systems in the catchment areas; including an explanation on how the collection facilities and drainage systems will work with the stormwater storage tank to prevent flooding in Happy Valley and the vicinity areas.

The required details are as follows :

(i) The area of the catchment upstream of Happy Valley is about 270 hectares. Stormwater from the upstream part of the catchment (about 140 hectares) will be intercepted by the Hong Kong West Drainage Tunnel under construction for discharge to the sea near Cyberport. The remaining catchment (about 130 hectares) will be served by the proposed Happy Valley Underground Stormwater Storage Scheme (HVUSSS). A plan showing the catchment areas is at Enclosure 1.

(ii) If rain is not heavy, rain water in the catchment area of the proposed

HVUSSS will be collected by the existing drainage network and carried down-stream for discharging to the Victoria Harbour through the box culvert underneath Canal Road. At times of heavy rainstorms, part of the stormwater collected will be diverted to the proposed storage tank for temporary storage in order not to overload the drainage network thus preventing flooding at Happy Valley and the vicinity areas. After the rainstorms, the water in the storage tank will be released back to the box culvert underneath Canal Road for discharging to the sea.

CB(1)2220/10-11(01)

2

(c) Improvement works to the rain water collection facilities and drainage systems in

Happy Valley to address flooding in the wake of the flooding incident at San Francisco Tower. The original drainage system at San Francisco Tower collects stormwater upstream of Broadwood Road. To reduce the risk of flooding at San Francisco Tower and areas in its vicinity, a new drainage pipe has been constructed from Broadwood Road for diverting about 50% of rain water at Broadwood Road away from San Francisco Tower to Sing Woo Road. After the completion of the new drainage pipe in April 2010, there was no flooding report at San Francisco Tower in the last wet season.

(d) Measures for disposal of construction waste, e.g. excavated materials, generated

from the project, including the public fill reception facilities and landfills which will receive the waste; and ways to minimize possible nuisances to nearby residents in the transportation of waste from the project site.

We plan to transport the inert construction waste generated by the proposed works to Chai Wan Barging Point en route Wong Nai Chung Road (WNCR), Canal Road Flyover and Island Eastern Corridor. For the non-inert construction waste, we plan to transport it to Tseung Kwan O landfill via WNCR, Canal Road Flyover, Island Eastern Corridor and Eastern Harbour Crossing. To minimize the nuisance to nearby residents in the transportation of construction waste from the project site, we will implement the following measures during the construction stage :- Fully enclosed conveyance system on site At the start of the construction stage, a permanent access manhole and two underground pipes will be installed near the public car park at WNCR at the eastern side of the site. A conveying belt system will be installed inside the two underground pipes for carrying construction wastes to the car park where it will be transported away by dump trucks. The conveying belt system will be fully enclosed and all the dump trucks will be well-covered to minimize any nuisance to public. A plan showing the transportation route of the dump trucks and the conveying belt system is shown in Enclosure 2. Disposal of construction waste during non-peak hour We estimate that there would be a maximum 15 numbers of dump trucks per hour during the construction period. To minimize the loading to existing traffic, disposal of construction waste will only be carried out during non-peak hours (i.e. 9:30 – 17:00 in weekdays and 08:00 – 12:00 on Saturdays).

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(e) Measures the Administration would take to minimize possible disruption caused

to the sports activities at the Recreation Ground during construction even though works will be carried out in two phases.

The construction of the underground storage tank will be divided into two phases. Not more than three football / rugby pitches will need to be closed during each construction phase. The affected pitches in the second phase will only be closed after re-opening of the pitches in the first phase. In January 2011, we consulted the major users of the pitches, including the Hong Kong Football Association and Hong Kong Rugby Football Union about the arrangement. They had no objections to the proposed pitch closure arrangement.

(f) Whether the traffic impact assessment for the project has taken into account the

expected increase in traffic flow arising from the redevelopment of the Hong Kong Sanatorium and Hospital; if yes, the details of the expected increase in traffic flow and the scale of the redevelopment project.

The Hong Kong Sanatorium and Hospital (HKS&H) submitted its traffic impact assessment (TIA) report to the Transport Department (TD) in connection with the proposed redevelopment involving an increase in the number of beds from 438 to 800 in mid-2010. The TIA report was accepted by TD. The TIA for the proposed HVUSSS carried out from late 2010 and accepted by TD in March 2011, has taken into account the forecast traffic condition in Happy Valley during the construction period known at the time including traffic generated by the proposed redevelopment of the HKS&H. TD would follow up on assessment of the supplementary TIA to be submitted by HKS&H for Town Planning Board's consideration to ensure it is acceptable. We estimate that there would be a maximum 15 number of dump trucks per hour during the construction period of the proposed HVUSSS.

Development Bureau Drainage Services Department May 2011

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