Deep Bay Link
(ACE-EIA Paper 14/2002)
For advice
Purpose
This paper presents the key findings and recommendations of the Environmental Impact Assessment (EIA) Report for the Deep Bay Link (hereinafter known as the Project), submitted under Section 6(2) of the Environmental Impact Assessment Ordinance (EIAO). The Highways Department (HyD) and their consultants will make a presentation. Comments from the public and ACE will be taken into account by the Director of Environmental Protection when he makes his decision on the approval of the EIA report under the EIAO.
Advice Sought
2. Members' views are sought on the findings and recommendations of the EIA report.
Need for the Project
3. According to HyD, the capacity of the existing three vehicular boundary crossings between Hong Kong Special Administration Region (HKSAR) and Shenzhen is insufficient to cope with the present and expected future traffic demand between the two areas. The HKSAR and Shenzhen government proposed to provide a fourth vehicular boundary crossing which is now known as the Shenzhen Western Corridor (SWC). The SWC will run from Ngau Hom Shek in the Northwest New Territories, spanning across Deep Bay and enter into the newly reclaimed land at Shekou. The Deep Bay Link (DBL) that is this Project will serve as the strategic highway linking the SWC to Hong Kong's highway network.
Description of the Project
4. According to the EIA report submitted by HyD, the DBL is a 5.4 km long dual-3 lane carriageway connecting the SWC at Hgau Hom Shek to the Yuen Long Highway at Lam Tei, where traffic could gain access to the road network including Route 3 Country Park Section to the east and Tuen Mu Road to the west (as shown in Figure 1). It will also provide access to Ha Tsuen and the proposed Hung Sui Kiu New Town.
5. The DBL is a Designated Project under Item A.1, Schedule 2 of the EIAO (ie. a road which is an expressway, truck road, primary distributor road or district distributor road including new roads, and major extensions or improvements to existing roads). Construction of the Project will start in 2003 for completion in 2006.
Alignment Selection
6. During the EIA and preliminary design process, different road alignments were considered with a view to avoiding potential environmental impacts as well as to satisfying engineering, programming requirements and local concerns over the disturbance to burial grounds. The decision to relocate the boundary control facilities of the HKSAR governments and the associated vehicle holding areas (total 24 hectares), which previously formed an integral part of the Project, to Shekou for facilitating the immigration and customs procedures will alleviate the air quality impact from the DBL to the proposed New Town at Hung Shui Kiu and substantially reduce the loss of habitat close to Deep Bay. Depressed road and tunnel options were also considered within the alignment corridor but these were found not practicable by HyD due to physical constraints such as the presence of Castle Peak Road and Light Rail Transit as well as engineering, sight line, safety and connection requirements.
Specific Environmental Aspects to Highlight
7. The key environmental issues identified for the Project are impacts on air quality, noise, water quality, ecology & fisheries and landscape & visual.
Air Quality Impact
8. With the implementation of dust suppression measures required under the Air Pollution Control (Construction Dust) Regulation, adverse dust impact due to construction activities is not expected.
9. The EIA has considered the cumulative effects from major highways in the vicinity of the Project including the proposed Route 10, Yuen Long Highway, and the proposed Hung Shui Kiu New Town. The EIA shows that the air sensitive receivers within 500m from the project boundary would not be subjected to any exceedance in the Air Quality Objectives during the operation phase. The air assessment was based on a conservative assumption that all crossboundary vehicles on the road network within the assessment area would use fuel with a higher sulphur content and thus with higher emission factors. Another conservative assumption in the assessment is the use of year 2011 emission factors for design traffic flow at year 2021, given the emission factors would be further improved beyond 2011 due to technology advancement.
Noise Impact
10. With the use of quiet plant, on-site movable barriers, purpose-built site hoarding, restricting the number of viaducts piers to be constructed concurrently and limiting the number of boring machines, construction noise at the affected sensitive receivers can be controlled to within the established noise limit except a village house at Tsoi Yuen Tsuen which will be subject to 78dB(A) for a period of 5 weeks.
11. Some of the existing dwellings and future residential developments along the DBL will be subject to traffic noise from the Project. A package of direct noise mitigation measures, comprising semi-enclosures and 2m to 5.5m high roadside noise barriers, has been proposed to ensure the noise criteria under the Technical Memorandum can be met. Upon exhausting all practicable direct noise mitigation measures, residual road traffic noise is expected at 5 existing sensitive receivers due to the noise from existing roads. The affected sensitive receivers would not be eligible for indirect technical remedies.
Water Quality Impact
12. The major water quality concern during construction is the potential impact on Deep Bay water quality arising from the discharge of wastewater with high levels of suspended solid generated from bore piling work at bridge piers adjacent to the coastline. The EIA report recommends an on-site collection and treatment system, consisting of chemical coagulation, sedimentation and pH adjustment, to control the suspended levels of treated effluent to below 30mg/l. Potential water quality impacts during operation relate to the discharge of storm runoff from road surface and accidental spillage of chemical or toxic substances from vehicles to Deep Bay. Road surface cleaning using vacuum air sweepers will be carried out twice-weekly at the section of DBL close to Deep Bay. The EIA report recommends an accidental spillage emergency action framework to deal with oil and chemical spills. With mitigation measures in place, the residual water quality impacts during construction and operation stages would not be unacceptable.
Ecology and Fisheries Impacts
13. The major ecological concerns relate to the impacts on fishponds, abandoned ponds, egretry, plantation and streams near Ngau Hom Shek and the coastal habitat along Deep Bay. The EIA recommends a package of mitigation measures including-
- a 0.73 hectare wetland compensation area to be created as a 1:1 compensation for the loss for abandoned fishponds of moderate ecological value;
- 12.7 ha of native and landscape tree planting for the loss of 8.7 ha of plantation, orchard, shrub, and woodland;
- provision of culverts as wildlife corridors where the Project crosses streams to maintain ecological connectivity;
- protection against disturbance by roadside planting, noise barriers and boundary fencing; and
- where encroachment of Ngau Hom Shek egretry is unavoidable, the existing trees and bamboos used by egrets will be removed outside the breeding season before the commencement of construction of the Project to avoid egret mortality. Furthermore, bamboos from Ngau Hom Shek egretry will be transplanted to the proposed wetland compensation area as a potential alternative egretry site. The field survey conducted from November 1999 to May 2000 covering the dry and wet seasons did not record Savanna Nightjar, Eurasian Eagle Owl and Pitcher Plant. Effectiveness of the proposed wetland compensation area would be monitored under a Habitat Creation and Management Plan to be produced during the detailed design stage. With the implementation of the proposed mitigation measures, the residual ecological impact arising from the Project is considered minor and acceptable.
The residual fisheries impact is considered minor and acceptable as only 0.73 ha of abandoned fish ponds will be lost due to the Project. Together with the implementation of water quality mitigation measures mentioned in the Water Quality section above, potential residual impacts to oyster beds and inter-tidal fishing activity would not be unacceptable.
Landscape and Visual Impacts
Landscape and visual impacts are mainly due to the disturbance to the woodlands along the alignment of the Project and the intrusion arising from elevated structure together with the noise enclosures and roadside barriers. The EIA report has recommended a package of mitigation measures which comprise provision of screen planting and earth mounding, retaining in-situ some 1,600 existing trees, transplanting about 370 trees and replanting approximately 6,500 trees of native woodland species on areas disturbed by the Project. With the mitigation measures in place, the predicted residual impacts would not be unacceptable.
Environmental Monitoring & Audit (EM&A)
An EM&A programme has been proposed in the EM&A manual submitted together with the EIA report and included a detailed Implementation Schedule. The EM&A requirements will be enforced as Environmental Permit conditions.
Public Consultation
HyD has made the EIA report, EM&A manual and Executive Summary available for public comment under the EIAO on 23 July 2002. Members will be briefed on any comments received from the public at the meeting.
Environmental Protection Department.
July 2002
