13.1.1.1 This EIA report has provided an assessment of the potential environmental impacts associated with the drainage improvement works at Ngong Ping, based on the preliminary engineering design information available. The EIA has been conducted, in accordance with the EIA Study Brief No: ESB-227/2011 issued under the EIAO for this Project. The drainage improvement works is a localised project and, as such, transboundary issues are not relevant to this project.
13.1.1.2 The findings of this EIA study have determined the likely nature and extent of environmental impacts predicted to arise from the construction and operation of the Project. Cumulative impacts are not predicted as no concurrent projects are expected. During the EIA process, environmental control measures were identified and incorporated into the planning and design of the Project to achieve the compliance with environmental legislation and standards during both the construction and operation phases. The Environmental Mitigation Implementation Schedules are presented in Section 11 of this EIA report. Details of individual environmental aspects are summarised below.
13.2.1.1 Potential air quality impacts from the construction works for the Ngong Ping drainage improvement works would mainly be related to construction dust from excavation, materials handling, spoil removal and wind erosion. With the implementation of hourly watering of all exposed areas and mitigation measures as defined in the Air Pollution Control (Construction Dust) Regulation and good site practices, no 1-hour, 24-hour or annual adverse residual impacts would occur, with residual impacts being localized, short term and temporary and unlikely to induce health concerns to the local community.
13.3 Noise Impact
13.3.1.1 The results of the construction noise assessment indicate that the noise levels at 1 NSR, after the implementation of all practical direct mitigation measures, would still exceed the stipulated noise criteria in some locations for a short duration of 1 week only. However, the residual impacts have been assessed and concluded to be temporary, reversible and unlikely to induce public health concerns to the community and as such, are considered to be minor and acceptable.
13.4.1.1 Potential water pollution sources during the construction phase have been identified as construction site run-off, direct disturbance to water courses, sewage from the workforce, potential risk of contamination from materials, chemicals and bentonite slurry. Mitigation measures including the implementation of the construction site practices in accordance with the EPD’s ProPECC PN 1/94 Construction Site Drainage, provision and management of portable toilets on-site and preventive measures to avoid accidental chemical spillages are recommended to mitigate any adverse water quality impacts and protect the health and welfare of the community as well as the environmental resources, based on which adverse residual impacts would not be anticipated.
13.4.1.2 Weir walls, of at least 500mm in height or equivalent, shall be constructed at all intakes and outfalls as planned to ensure the normal flow of existing watercourse is not interrupted during the operational stage and as such, secondary impacts on water quality and ecology associated with changes to the flow regime are not predicted.
13.4.1.3 Since Outfall A and Intake C and the associated works area are within the gabion channel, the construction and operation (maintenance desilting works, if any) of both shall comply with the Specific Conditions of EP-192/2004.
13.4.1.4 In order to avoid affecting the water quality in the downstream section
of the
· Storage of chemicals, oils, fuels and waste, including major stockpiles; and
· Maintenance operations for the construction plant.
13.4.1.5 Also, in order to protect the water gathering grounds, maintenance
works on construction plant and storage of chemicals and chemical waste should
be undertaken at the Site Office only. Overnight stockpiling of earth material
and cements at Works Section 6 in the
13.4.1.6 During operation phase, the maintenance operations to desilt the intakes are not expected to results in adverse impacts to water quality. However, good practice measures have been recommended to minimise any effects. Hydraulic jetting shall be avoided and the maintenance shall also only be undertaken during the dry season when flow in the watercourse is low. The disposal of the removed inert and non-inert materials shall be properly handled in accordance with the recommendations in Section 9 of the EIA Report.
13.5.1.1 The potential ecological impacts have been substantially reduced by
adoption of the terrestrial by-pass routing instead of direct widening and
training of the natural
13.5.1.2
The impacts on the agricultural land have been investigated to assess
how the construction works could affect the local communities. The impacts on
the fisheries activities are not relevant to this project and, therefore, have
not been assessed.
13.5.1.3 Ecological mitigation and enhancement measures, therefore, focus on protection of species of conservation interest that may be affected. Species specific mitigation measures including an “Updated Baseline Vegetation Survey”, a “Floral Protection Plan” and a “Floral Transplantation Plan” have been recommended to avoid and minimise direct and indirect impact on floral species of conservation interest. If required, a “Compensatory Planting Plan” shall be prepared before implementing the recommendations of the “Floral Transplantation Plan”. In terms of aquatic fauna, an “Aquatic fauna Translocation Survey” and an “Aquatic Fauna Translocation Plan” are recommended for translocation of aquatic fauna species of conservation.
13.5.1.4 The implementation of the good construction site practices in
accordance with the EPD’s ProPECC PN 1/94 Construction Site Drainage to control
indirect impacts due to sedimentation and contamination is of equal importance.
Specific restriction of works at the
13.5.1.5 Weir walls, of at least 500mm in height or equivalent, shall be constructed at all intakes and outfalls as planned to ensure the normal flow of existing watercourse is not interrupted during the operational stage. Hence, secondary impacts on aquatic ecology of the Study Area associated with changes to the stream flows are not predicted as a result of the implementation of the proposed project.
13.5.1.6 Since Outfall A and Intake C and the associated works area are within the gabion channel, the construction and operation (maintenance desilting works, if any) of both shall comply with the Specific Conditions of EP-192/2004 (see Section 2).
13.6 Landscape and Visual Impact
13.6.1.1 The project has unavoidable Landscape and Visual Impacts resulting primarily from areas of excavation for trenches and pipe jacking and the formation of intakes and outfalls arising during the construction phase. Further potential impacts are caused from temporary works and stockpile sites. In summary:
· The project is generally compatible with the statutory planning framework;
· Impacts have been minimised through careful consideration of alternatives and selection of alternative construction techniques;
· Insignificant Adverse Residual Impacts to Landscape Resources, Landscape Character or VSRs are generated by the Project at any stage;
13.6.1.2 It is considered that the Project would be generally in accordance with the planning goals and objectives for the study areas. Two areas are in potential conflict however, as follows:
· Stockpile Area 1 (SA1)
· Works Section 6
13.6.1.3 The following permanent loss of landscape resources is anticipated:
· 90m2 of natural rock and vegetation at the outfall close to the Ngong Ping Columbarium;
· A total of 612 existing trees have been surveyed covering the Project Area. Some 155 are proposed to be felled of which 65 are dead trees Those trees found to be directly in conflict with the construction works which cannot be retained have not been considered suitable for transplantation. None of the trees identified for removal are Registered Old and Valuable Trees. Application and approval for removal for all trees shall be obtained in accordance with Environment Transport and Works Bureau Technical Circular (Works) No, 3/2006.
13.6.1.4 A total of 15 VSRs are identified within the project. Moderate Adverse Visual Impacts might be anticipated during Construction Phase to 8 VSR’s without mitigation. During Operational Phase Slight Adverse Impacts may remain at Year 10 to VSR-01, Residents of Ngong Ping Village surrounding Works Sections 4&5.
13.6.1.5 The following mitigation measures are proposed to be undertaken:
Construction
Phase
· Reuse of Existing Rocks and Topsoil;
· No-intrusion Zone;
· Decoration of Hoarding; and
· Control of night-time lighting glare, however, currently no night-time working is proposed.
Operation Phase
· Compensatory Tree Planting - A minimum of 89 new trees will be provided within the site areas of the project;
· Horizontal Greening - Ground reinstatement with 3711m2 hydroseeding; and
· Reinstatement of Water Courses affected by the Project.
13.6.1.6 Following the introduction of landscape mitigation measures, the most significant Construction Phase Impacts to landscape resources are Moderate Adverse in 6 resource areas. During Operation Phase the most notable Residual Impacts are Moderate Adverse at Day 1 and Slight at Year 10.
13.6.1.7 Following the introduction of landscape and visual mitigation measures, the most significant Construction Phase Impacts to Landscape Character Area are Slight Adverse in 1 area. During Operation Phase Impacts are Insignificant at Day 1 and at Year 10.
13.6.1.8 Following the introduction of visual mitigation measures, the most significant Construction Phase Impacts to SVR’s are Moderate Adverse in 5 areas. During Operation Phase the most notable Impacts are Slight Adverse at Day 1 to just 1 SVR and Insignificant to all SVR’s at Year 10.
13.6.1.9 With reference to the criteria defined in Annex 10 of the EIAO-TM, it is considered that the Adverse Landscape and Visual Impacts resulting during Construction and Operation Stages are considered Acceptable with the prescribed Mitigation Measures applied
13.7.1.1 The archaeology assessment did not identify any areas of archaeological potential and no impacts are predicted. However, any antiquity or supposed antiquity discovered during the course of the excavation works will be reported to the AMO immediately.
13.7.1.2 The Built Heritage Impact Assessment has identified six built heritage resources that will require mitigation (NP-10, NP-11, NP-19, NP-20, NP-21 and NP-26). Mitigation in the form of a condition survey and vibration monitoring will be required for three of the resources (NP-10, NP-11 and NP-19) and the condition survey will recommend if vibration monitoring is required. A buffer zone of a minimum of 5 metres (or if due to site/engineering constraints, as large as possible buffer zone should be provided) is, also, recommended for resources which are close to either a works area or excavation area, namely NP-19, NP-20, NP-21 and NP-26. This should be achieved by temporary fencing and placed around the structures 2 weeks prior to the construction works commencing. The construction and operation of the drainage improvement works will not cause any adverse residual impacts if the above mitigation measures are implemented.
13.8.1.1 The quantity and timing for the generation of waste during the construction phase have been estimated. Measures, including the opportunity for on-site sorting, reusing excavated fill materials (on-site and off-site) etc., have been devised in the construction methodology to minimise the surplus materials to be disposed off-site. The annual disposal quantities for C&D materials and their disposal methods have also been assessed, together with secondary impacts associated with air quality, noise and visual impacts. Recommendations have been made for the Contractor for implementation of measures during the construction period to minimise the waste generation and any off-site disposal. The types and quantities of waste that would be generated during the operation phase have been assessed. Recommendations have been made to ensure proper treatment and disposal of these wastes. No construction work will be allowed to proceed until all issues on management of C&D materials have been resolved and all relevant arrangements have been agreed between the responsible Government department and party. Adverse residual impacts would not be anticipated during both the construction and operation phases of this Project and are not predicted to significantly affect the health or welfare of the local community.