Advisory Council on the Environment

Report of the 47th Environmental Impact Assessment Subcommittee Meeting

(ACE Paper 43/99)
for advice


At its meeting on 4 October 1999, the Subcommittee considered the following EIA reports:

(a) Route 16 Investigation Assignment - Alternative Alignment Study

(b) Sha Tin Sewage Treatment Works, Stage III Extension


2.Members are requested to advise whether the two EIA reports mentioned in paragraph 1 above should be endorsed.


Route 16 Investigation Assignment - Alternative Alignment Study
(ACE EIA Paper 23/99)

3.Route 16, connecting West Kowloon and Sha Tin, is designed to overcome anticipated traffic problems at the Lion Rock Tunnel, Tate's Cairn Tunnel and Tai Po Road, as recommended by the Updating of the Second Comprehensive Transport Study completed in 1992. The EIA for original (Conforming) alignment was endorsed by the ACE in February 1998. Subsequently, Highways Department (HyD) initiated design changes (Alternative Alignment) at Kowloon side mainly to improve safety and traffic operation. A separate EIA was therefore prepared to address the changes.

4.On traffic noise impact, the EIA recommended a series of mitigation measures including roadside noise barriers, cantilevered barrier and semi or full enclosures. With these mitigation measures, 900 dwellings and 24 classrooms affected by Route 16 would benefit from noise reduction of 1 to 29 dB(A). However, there would be approximately 1800 dwellings and 26 classrooms subject to traffic noise levels exceeding the criteria mainly due to noise contribution from existing roads and would not be eligible for indirect technical remedies.

5.The total woodland loss would be 8.6 ha for the project. On-site compensatory replanting of 11.5 ha was therefore recommended. In addition, part of the future drainage channel would be designed to mimic natural stream habitats to compensate the ecological loss.

Views and Recommendations of EIA Subcommittee's Members

6.Members discussed the report at the meeting. Queries mainly focussed on the need for the project, the noise impact, the ecological compensation measures and the hazard assessment.

7.On the need for the project, the proponent stated that the alternative alignment which would involve widening of the Route 16 in the Kowloon side to a dual 3-lane mainline structure was proposed due to the updated traffic demand forecasts based on the Traffic Impact Assessment conducted in conjunction with the preliminary design assignment of Route 16 and the interim findings of the Third Comprehensive Transport Study (CTS-3). It was predicted that otherwise the traffic capacity of that section would be exceeded by about 20% in the Planning Year 2006, i.e. two years after the commissioning of the Route 16.

8.On the noise impact of the project, the proponent confirmed that all direct mitigation measures to mitigate the problem at source would be exhausted so as to meet the requirements in the Technical Memorandum of EIA Ordinance. The proponent confirmed that the schools subject to potential noise problems were still in the planning stage. They ensured that the issue would be well aware of as well as taken into account by concerned departments.

9.On the ecological aspect, the proponent stated that they were reviewing the layout plan of the toll plaza with a view to minimize the land required and hence the woodland area to be taken up. The proponent also clarified that subject to detailed investigation, it was considered possible to have 3 ha. cut slopes compensatory replanting at Butterfly Valley despite its gradient.

10.On the hazard assessment, the project proponent confirmed that the relocation of the chlorine building for the Tai Po Road Water Treatment Works (WTW) was agreed by Water Supplies Department and would form a contractual obligation for the contractor of the project to ensure its timely implementation. The proponent also undertook to implement and monitor all recommendations made in the report to ensure the risk guidelines were met as required.

11.The Subcommittee agreed to recommend to the Council to endorse the report, subject to the provision of further information by the proponent on the forecasts of traffic demand arising from CTS-3 which would demonstrate the need for the project.

[Notes : The project proponent submitted to the Subcommittee further information on the forecasts of traffic demand as stated in para. 11 on 13 & 15 October 1999 respectively. At the EIA Subcommittee meeting held on 1 November 1999, Members agreed to recommend to the Council to endorse the report without conditions.]

Sha Tin Sewage Treatment Works, Stage III Extension
(ACE EIA Paper 24/99)

12.The project is proposed for providing additional capacity for the Sha Tin Sewage Treatment Works (STW) to cope with the significant increases in sewage flows created by the population growth within the catchment of the Sha Tin STW. The STW is already treating approximately 33% more flow than its current design capacity. Recent population projections have predicted faster population growth than had previously been anticipated.

13.The major environmental issues identified are operational impacts regarding odour at nearby sensitive receivers and water quality impact to Victoria Harbour where the treated effluent will be discharged. For the odour problem, the EIA recommended that it is more effective to control the odour generated from the effluent at the upstream pumping stations. As such, injection of oxygen (or air or nitrate) at the upstream sewage pumping stations in Sha Tin and Ma On Shan respectively of the STW would be applied on a continuous basis to achieve the standard.

14.The treated effluent from the extended STW would be subject to the licensing control under the Water Pollution Control Ordinance and would be discharged to Victoria Harbour via the Kai Tak Nullah, under the Tolo Harbour Effluent Export Scheme. The water quality model predicted that the project would not have an adverse impact at the sensitive receivers and would not impair the overall water quality within Victoria Harbour.

View and Recommendations of EIA Subcommittee's Members

15.Members discussed the report at the meeting. Queries mainly focussed on the impact of odour and water quality as well as alternative disinfection methods.

16.The project proponent confirmed that they would ensure the required standard of odour stipulated in the Technical Memorandum of EIA Ordinance would be met, though the facilities were not fully enclosed. The proponent considered injection of nitrate a more effective measure to reduce the odour impact at that stage but undertook to look into the issue thoroughly in the detailed design process.

17.On the disinfection method, the project proponent explained that UV disinfection method was preferred to chlorination since the latter would produce harmful by-products and cause environmental problems. It was also confirmed that the treated effluent from the extended STW was secondary effluent which would only have negligible impact on the water quality of the Victoria Harbour. The proponent also clarified that any contaminated soil produced in the construction and operation period would be disposed at strategic landfills. The disposal requirement would be incorporated into the tender document of the project.

18.The Subcommittee agreed to recommend to the Council to endorse the report without condition.


Planning, Environment and Lands Bureau
November 1999


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