2......... Project Description
3......... ENVIRONMENTAL IMPACT ASSESSMENT
Description of the Assessment Area
4......... Environmental Monitoring and Audit
List of Figure
Figure 1.1 Location of the Project Site
Appendix 1 Impacts Summary
1.1 The “Landslide Preventive Works at Po Shan, Mid-levels – Design and Construction (Natural Terrain Risk Mitigation Works)” (hereinafter known as the “Project”) will be implemented by the Geotechnical Engineering Office, Civil Engineering and Development Department (CEDD), Government of the Hong Kong Special Administrative Region.
1.2 The objective of this Project is to carry out necessary landslide preventive works on local repair of the hillside to minimize slope deterioration and shallow instability. Figure 1.1 shows the location of the Project.
1.3 This Executive Summary provides the key findings of the Environmental Impact Assessment (EIA) Report, including an assessment of potential environmental impacts from the construction and operation phases of the Project, and recommendations for mitigation measures to comply with environmental legislation and standards.
1.4 The EIA study has been prepared in accordance with the guidelines provided in the Technical Memorandum on Environmental Impact Assessment Process (EIAO-TM). The general approaches and methodologies adopted for this EIA study are described below.
Existing Environment Condition
1.5 The characteristics of the existing environment were reviewed for identification and prediction of environmental impacts. Baseline surveys were conducted to determine the existing environmental conditions on the Project site and environs likely to be affected by the Project. The baseline conditions of the key issues as identified in the EIA Study Brief including ecology, landscape & visual, noise, water quality and air quality are described in the assessment.
1.6 The EIA Study was undertaken in accordance with the guidelines on assessment methodologies given in Annexes 12 to 19 of the EIAO-TM.
1.7 Quantitative approach was adopted for assessing the construction noise impacts. The predictions were conducted based on well-proven, internationally accepted methods.
1.8 The applied methodologies for the Project had previously been adopted in other EIA studies. They have been generally accepted for use in predicting environmental impacts and for comparison of assessment results with the EIAO-TM requirements. Limitations are however envisaged of these methodologies. The accuracy of the prediction result will be affected by uncertainty in input data such as sound power levels of construction plants to be used on-site. The most realistic data have been used in the prediction in order to provide a result with as small as possible the quantitative uncertainty.
1.9 Mitigation measures are proposed to alleviate the potential impacts predicted, The proposed mitigation measures were adopted in other environmental assessment study with similar construction works. Environmental Monitoring and Audit programme is recommended to ensure the recommended mitigation measures could effectively mitigate the impacts to comply with the corresponding criteria.
2.1 The proposed Project mainly comprises:
(i) The scope of works includes the installation about 700 numbers of soil nails and about 60 numbers of raking drains on the natural terrain within the concerned area. The length of the soil nails is about 20m with a spacing of 2m horizontally and 3m vertically; the length of raking drains is about 10m with a spacing of 5m horizontally and 15m vertically.
(ii) Rock slope stabilisation works will be provided for the rock outcrop / boulders at the upper portion of the natural terrain. Measures such as scaling, installation of rock bolts / dowels, construction of concrete buttress and provision of wire mesh protection will be provided where necessary.
(iii) No tree felling will be proposed under this Project.
2.2 There are interactions with another designated project “Agreement No. CE 28/2004 (GE) Landslide Preventive Works at Po Shan, Mid-levels – Design and Construction” (under Environmental Permit EP-235/2005/A) on-going during the same period within the captioned area which will also be carried out by the Project Proponent.
2.3 Based on the latest information, the Project is scheduled to commence in November 2007 for completion in August 2008.
3.1 An EIA Study in response to Study Brief No. ESB-158/2006 was conducted in accordance with the guidelines on assessment methodologies provided in the Technical Memorandum on Environmental Impact Assessment Process (EIAO-TM). The general approach for the assessment included:
3.2 Description of the environment and baseline conditions for the impact assessment
3.3 Impact identification
3.4 Impact prediction & evaluation
3.5 Impact mitigation
3.6 Uncertainties in the assessment of impacts were considered when drawing conclusions from the assessment. In carrying out the assessment, realistic worst case assumptions were made in order to provide a conservative assessment of environmental impacts.
3.7 The main findings of the EIA study are summarised below.
Description of the Assessment Area
The majority of the
proposed works are located within the Pok Fu Lam Country Park and Special Area
at Po Shan Area of Mid-levels.
3.9 The location of the soil nail installation has been carefully selected and adjusted such that impacts on the vegetations in the natural woodland are avoided / minimized. The main impact on habitats resulting from the proposed works would be limited to approximately 0.65ha natural woodland for soil nailing, and a small scale of shrubland and developed area for site access and site office. No tree felling would be required under this Project.
3.10 Sediment and runoff if uncontrolled, would carry pollutants (adsorbed onto the particle surfaces) into the streams and drainage culvert in the vicinity of the proposed works area. However, the impacts are considered limited as the two streams and drainage culvert are not within the proposed works area. Mitigation measures would be implemented to control construction site runoff and drainage from the works areas, and to prevent runoff and drainage water with high levels of suspended solids from entering nearby water bodies. With the implementation of adequate construction site drainage and provision of sediment removal facilities, no site runoff and discharge to the nearby stream courses and drainage culverts would be resulted. It is anticipated that unacceptable water quality impacts on the two streams and drainage culvert would not arise. Hence, the impacts to the species of conservation importance, including Lesser Spiny Frog, Hong Kong Cascade Frog and Mountain Crab recorded adjacent to or within the streams and drainage culvert in the vicinity of the proposed works area are considered to be minor.
3.11 One specimen of Common Tutcheria and several individuals of Small Persimmon within the works area might be affected. A detail vegetation survey conducted by a suitably qualified botanist/ecologist with over 7 years relevant experience would be required to identify the plant species of conservation interest potentially affected by the proposed works. These identified individuals would be labelled on site prior to the commencement of works for better protection. A specific monitoring programme would be conducted to check on the health and condition of these plants during the construction phase. Planting of suitable shrubs/herbs would also be provided to compensate for the loss of understorey vegetation.
3.12 One faunal species of conservation interest, Short-nosed Fruit Bat, recorded in the works area would be disturbed by the construction phase activities. Mitigation measures are recommended to minimise construction phase disturbance and Chinese Fan-palm would be planted near the existing bat roost to provide suitable habitat for the bats after the completion of landslide preventive works.
3.13 Apart from bats, three avifauna species of conservation importance, including Black Kite, Collared Scops Owl and Greater Coucal were also recorded during the surveys. The most probable cause of disturbance to the bird populations would be disturbance impact by noise generating construction works and increased human activities. With the use of effective quiet machinery, construction phase noise disturbance would be minimised.
3.14 Mitigation measures and good site practices are recommended to minimise dust and water quality impacts to surrounding habitats.
3.15 With the implementation of the recommended mitigation measures, the ecological impacts resulting from the proposed works during construction phase are considered to be acceptable.
Landscape and Visual
3.16 With the implementation of
mitigation measures, the anticipated landscape impacts due to the landslide
preventive works at Po Shan, Mid-levels will be acceptable. There is expected
to be some minor impact upon the existing woodland within the works area. There
are a total of approximately 362 trees within the soil nails and raking drains
working boundary. However, no trees will be felled or requires transplanting
due to the proposed landslide preventive works. The rest of groundcover / scrub
will be affected.
3.17 After the full implementation of
mitigation measures, the visual impact will be acceptable. Residents in the
medium rise development along
3.18 The assessment predicted that with the use of quieter equipment, movable noise barriers, noise enclosure and noise insulating fabric, construction noise levels at all representative noise sensitive receivers (NSRs) would comply with the relevant noise criteria.
3.19 It is envisaged that only about two construction vehicles per day would be induced by the proposed Project Thus, no adverse traffic noise impact from the traffic induced from the Project would be expected.
3.20 Cumulative construction noise impacts of concurrent project adjacent to the subject site were predicted based on latest programme of the concurrent construction activities. Assessment results indicated that no adverse cumulative noise impact would be envisaged..
Construction Water Quality
3.21 The key issue in terms of water quality during the construction phase of the Project would be the potential for release of sediment-laden water from works areas during site clearance and the proposed soil nailing and rock slope stabilization works. Minimisation of water quality deterioration could be achieved through implementing adequate mitigation measures such as control measures on site runoff and drainage from the works areas to minimise construction runoff, and on-site treatment of site runoff and drainage prior to discharge. Proper site management and good housekeeping practices would also be required to ensure that construction wastes and other construction-related materials would not enter the drainage culvert. Sewage effluent arising from the construction workforce would also be handled through provision of portable toilets.
3.22 With the implementation of these recommended mitigation measures, the construction works for the Project would not be expected to result in unacceptable impacts on water quality. Site inspections should be undertaken routinely to inspect the works areas in order to ensure the recommended mitigation measures are properly implemented.
Construction Air Quality
3.23 No adverse dust nuisance during the construction phase would be expected with the implementation of dust suppression measures stipulated in Air Pollution Control (Construction Dust) Regulation and good site practices. A monitoring & audit programme is proposed to check whether the recommended mitigation measures are implemented effectively.
3.24 Wastes generated by the construction activities are likely to include C&D material, general refuse from the workforce and chemical waste from the maintenance of construction plant and equipment. Provided that these identified waste arisings are handled, transported and disposed of using approved methods and that the recommended good site practices are strictly followed, adverse environmental impacts would not be expected during the construction phase.
3.25 A summary of the environmental impacts associated with the Project are presented in Appendix 1. For each key environmental issue, the predicted impact level, relevant criteria, recommended mitigation measures and residual impact at the sensitive receivers have been clearly summarised.
4.1 An environmental monitoring and audit (EM&A) programme has been recommended for implementation during the construction and operation of the Project to ensure compliance with environmental legislation and standards during Project implementation.
5.1 The proposed project will carry out landslide preventive works on local repair of the hillside to minimize slope deterioration and shallow instability.
5.2 This EIA study has identified and assessed potential environmental impacts of the proposed project. All direct and indirect, as well as cumulative impacts likely to arise during the construction and phase of the Project have been evaluated using suitable and agreed evaluation methods. With the implementation of the recommended mitigation measures, the Project would be environmentally acceptable and no adverse residual impacts would be expected.