12. CONCLUSIONS AND summary of envirOnmental outcome
Terrestrial and Marine Ecological Impact
Table 12.1 Summary of Key Environmental Outcomes / Benefits
12.1 This EIA study has provided an assessment of the potential environmental impacts associated with the construction and operation of the proposed Road P1 Advance Works at Sunny Bay on Lantau Island according to the latest information available.
12.2 The environmental issues below have been assessed in the EIA Study, in accordance with the EIA Study Brief (No. ESB-105/2002) registered under the EIAO for the Project:
· Noise impact
· Air quality impact
· Water quality impact
· Waste management implications
· Terrestrial and marine ecological impact
· Fisheries impact
· Cultural heritage impact
· Landscape and visual impacts
12.3 Specific mitigation measure requirements for the Project, as well as environmental monitoring auditing procedures, have been developed during the detailed assessments. The Implementation Schedules of the recommendations are presented in Section 13.
12.4 The potential noise impact arising from daytime construction activities on the noise sensitive receivers (NSRs) at Luk Keng Tsuen located in the vicinity of the work sites was assessed. Noise generated from the use of PME associated with the construction activities proposed for the Project would be the main concern.
12.5 Unmitigated cumulative noise levels arising from the construction activities of the Project at the representative NSRs were predicted. The results indicated that in the absence of mitigation measures, cumulative noise levels at the NSRs would exceed the EIAO-TM noise criterion of 75dB(A) by 1-3dB(A).
12.6 In order to alleviate the construction noise impacts at the NSRs, noise mitigation measures including the adoption of good site practices and the use of quieter plant would be necessary to protect the representative NSRs from the construction noise impacts. With the recommended mitigation measures in place, all NSRs comply with the EIAO-TM daytime construction noise criterion. No adverse residual construction noise impact would be expected.
12.7 Road traffic noise impacts from open road sections were assessed for both normal and hypothetical emergency scenarios. Modelling results indicated that, for the two scenarios assessed, the representative NSRs at Luk Keng Tsuen would fall within the EIAO-TM road traffic noise criterion of 70dB(A). No mitigation measure would be needed.
12.8 Potential air quality impacts arising from the construction of the proposed Project would include dust from construction activities and gaseous emissions from the construction plants and vehicles. Material handling, wind erosion and truck movement on unpaved roads would be the major dust generating activities. Cumulative construction dust impact due to concurrent project was not envisaged.
12.9 Having taken into consideration the prevailing humid site conditions, limited scale of the proposed works, materials handled generally of high moisture content, large separation between the dust emission sources and receivers, dust reduction as a result of the implementation of construction dust control measures as stipulated in the Air Pollution Control (Construction Dust) Regulation under the APCO, and in the absence of concurrent construction activities in the Sunny Bay area, it would be envisaged that proposed Project would not result in exceedance of the TSP levels as set out in the HKAQO.
12.10 Dust suppression measures stipulated in the Air Pollution Control (Construction Dust) Regulation should be implemented to control dust emission from the site. In addition, good site practices and a comprehensive dust monitoring and audit programme were recommended to minimise cumulative dust impacts. With the recommended mitigation measures in place, no adverse residual construction dust impact would be envisaged.
12.11 Vehicular exhaust emissions from open road sections would be the major air pollutant sources during the operation phase of the Project. Cumulative air quality impacts for the normal as well as emergency scenarios were assessed by using CALINE 4 model. No exceedance of the AQO criteria was predicted at all representative ASRs during the operation phase. Therefore, no mitigation measure is required.
12.12 The dredging works for the reclamation formation for the Road P1 Advance Works were identified to be the key water quality issue for the Project. Potential water quality impacts associated with the dredging works were assessed by predicting the increases in suspended sediment concentrations due to fine sediment lost to suspension.
12.13 Sensitive receivers identified within the study area include the Ma Wan Fish Culture Zone and Dragon Beach, which are located at approximately 4km from the proposed works area of the Project, and Anglers’ Beach which is located at approximately 5km from the proposed works area. The assessment results show that with the use of closed grab dredger and the frame type silt curtains at the works area, the elevations in suspended sediment (SS) concentration generated from the dredging activities would be expected to be well below the allowable elevation under the WQO at these sensitive receivers. Other mitigation measures for the construction of the reclamation were specified in the NLDFS-EIA and comprised operational constraints (i.e. limiting the rates of working, the sequence of construction) and general working methods to prevent adverse impacts on water quality.
12.14 Potential water quality impact arising from the release of contaminants from sediment disturbed during the dredging works was also assessed. Sediment quality data obtained as part of this Project for the proposed dredging area indicated the level of contamination to be low and therefore adverse impacts on water quality were not predicted. The potential water quality impacts arising from construction runoff and drainage and other land-based construction activities were assessed qualitatively and no adverse impacts were identified.
12.15 Overall, no unacceptable residual impacts would be expected during the construction phase with the full implementation of the recommended mitigation measures for the reclamation formation and land-based construction activities of the Project.
12.16 In accordance with the recommendations of the NLDFS-EIA, silt traps should be installed on storm drains serving developed and landscaped/managed areas of the Project, and polluted stormwater discharges should be relocated away from Sunny Bay. With the implementation of the recommended mitigation measures, it is anticipated that the water quality impacts associated with the operation phase of the Road P1 Advance Works would be minimal and acceptable.
12.17 A review of the sediment quality data from the marine ground investigation indicated that the majority of marine sediments to be dredged for the construction of the seawall were classified as Category L. The total dredged volume for the Project was estimated as approximately 700,000 m3, of which 8,000 m3 of sediments were classified as Category M requiring Type 2 confined marine disposal. With the implementation of the recommended mitigation measures and management procedures in accordance with the requirements of ETWB TCW No. 34/2002, no residual impact was predicted.
12.18 Other waste types generated by the construction activities are likely to include C&D material (rock armour and fill material from piling and excavation works), general refuse from the workforce and chemical wastes from the maintenance of construction plant and equipment. Provided that these identified waste arisings are to be handled, transported and disposed of using approved methods and that the recommended good site practices are to be strictly followed, adverse environmental impacts would not be anticipated.
12.19 Terrestrial ecological data from the Sunny Bay area presented in the NLDFS EIA Report was reviewed. Surveys were conducted to confirm the validity of and update existing data. Habitats identified in the Sunny Bay area were generally of low to low moderate value. Two plant species of conservation interest (the locally restricted tree Thespesia populnea and the locally common but regionally endangered herb Diospyros vaccinioides) were recorded in the Assessment Area during recent surveys. Fauna recorded in the Assessment Area were generally common and widespread species in Hong Kong, although several birds of conservation interest were recorded from Sunny Bay (Little Egret (Egretta garzetta), Chinese Pond Heron (Ardea cinerea), Collared Crow (Corvus torquatus)). Direct impacts to terrestrial habitats and species resulting from the Project would be limited to the loss of very small areas of very low-low value habitats. No species or areas of conservation interest would be affected. Limited indirect impacts to wildlife resulting from construction and operation phase disturbance were predicted. Given the tolerance of wildlife (particularly avifauna in Sunny Bay) to existing high levels of disturbance, construction and operation phase activities are anticipated to have only minor impacts. Potential terrestrial ecological impacts resulting from the Project were found to be minor and acceptable.
12.20 Findings of the NLDFS EIA Report regarding the Assessment Area were reviewed based on recent literature and field surveys. This indicated that the ecological value of intertidal artificial seawall, sandy shore, mangrove and subtidal benthic habitats were low. Of medium ecological value were the Assessment Area’s natural rocky shore and marine mammal habitat. During surveys conducted in 2002/03, the mudflat at Sunny Bay was found to support a 0.8 ha dense cover of the locally rare seagrass, Halophila ovalis, which is of high conservation importance. Although no seagrass was recorded from Sunny Bay during a survey conducted in April 2005, it was considered that H. ovalis could re-establish on the mudflat in the future. Accordingly, the mudflat was considered of moderate-high ecological value.
12.21 The key marine ecological sensitive receivers in the Assessment Area were therefore the Indo-Pacific Hump-backed Dolphin, Sousa chinensis. And the mudflat in Sunny Bay, which could support the locally rare and declining seagrass H. ovalis.
12.22 Sousa chinensis is regularly sighted in North Lantau waters year round, but apparently has a higher abundance in the Assessment Area in autumn and winter months. By strictly observing the recommended mitigation measures to control water quality as well as minimise physical dangers due to marine traffic and works, it is anticipated impact on dolphins would be low and environmentally acceptable.
12.23 Of key concern was that if the seagrass H. ovalis re-establishes in Sunny Bay, it may be indirectly impacted by increases in turbidity associated with the release of suspended sediment during dredging for the Project. However, according to the assessment, provided that mitigation by deployment of two layers of silt curtain is implemented within the works boundary of the works, indirect impacts on any seagrass present were considered to be minor. Elevations in suspended sediment levels elevations (predicted to be between 2.3 mg L-1 and 3.9 mg L-1) at the previous location of the seagrass bed (when submerged by the tide) would be within allowable levels under the WQO standard and of lower magnitude than natural variation in ambient conditions at the site.
12.24 The proposed reclamation would result in the permanent loss of 3 ha of disturbed seabed area and loss of 0.5km of sloping artificial seawall which would be partly compensated by construction of 450m of vertical seawall and 100m of sloping seawall and provide habitats for colonisation of intertidal organisms.
12.25 In summary, potential marine ecological impacts resulting from the Project were assessed as being minor and acceptable.
12.26 With reference to the findings of the NLDFS EIA Report, a literature review has been conducted to incorporate the latest relevant information for determining impacts on fisheries arising from the Project.
12.27 Fisheries production in the Assessment Area are generally low when compared to other fishing grounds in Hong Kong, although the value of the Sunny Bay fisheries were ranked as moderate-high No important spawning or nursery area was identified in the vicinity of the proposed works. Overall, fisheries in the Sunny Bay area were considered of moderate importance.
12.28 The proposed reclamation would result in the direct loss of a small portion (3 ha) of potential fishing area. The loss of this area is anticipated to have a very low effect on fisheries production of Hong Kong as a whole.
12.29 Indirect impacts through impact to water quality due to dredging were assessed. Sediment levels in the water would not be elevated to levels that would impact fisheries of the Sunny Bay fisheries area or impact cultured fish at the Ma Wan fish culture zone.
12.30 Provided that mitigation measures to protect water quality are fully implemented, specific mitigation measures to protect fisheries resources are not necessary. In a similar way, monitoring and audit activities for detecting and mitigating any unacceptable impact on water quality would also serve to protect fisheries resources, and so an EM&A programme for fisheries is not recommended.
12.31 The marine archaeological investigation did not reveal any anomalies or targets of potential archaeological significance. The Sunny Bay Archaeological Site and Luk Keng Tsuen Archaeological Site are located well outside the proposed advance works area. No adverse cultural heritage impact would therefore be expected.
12.32 It is consider that both the landscape and visual impacts associated with the Road P1 Advance Works are acceptable with mitigation measure as described in Annex 10 of the EIA-TM. The project will complement the landscape and visual character of its setting, follow the relevant planning objectives and maintain a high standard design of overall landscape and visual quality.
12.33 The findings of this EIA study have provided information on the nature and extent of environmental impacts arsing from the construction and operation of the Project. The EIA has, where appropriate, identified mitigation measures to ensure compliance with environmental legislation and standards.
12.34 Overall, the EIA study for the proposed Road P1 Advance Works has predicted that the Project would comply with all environmental standards and legislation with the implementation of the proposed mitigation measures for construction and operation phases. This EIA has also demonstrated the acceptability of the residual impacts from the Project and the protection of the population and environmentally sensitive resources. Table 12.1 summarises the environmental outcomes/benefits from the implementation of the Project and the recommended mitigation measures. Environmental monitoring and audit mechanisms have been recommended, where necessary, to verify the accuracy of the EIA predictions and the effectiveness of recommended mitigation measures.
Table 12.1 Summary of Key Environmental Outcomes / Benefits
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Area/Issue |
Environmental Outcomes / Benefits and Mitigation Measures |
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Purpose and Scope of the Project |
The purpose of the proposed Project is to advance the construction of a part of the Road P1 works at Sunny Bay to provide a second entrance/exit to and from the proposed theme park and other developments in Penny’s Bay to relieve large number of park visitors, in case of emergency situation. The Project scope includes reclamation works (about 3 ha) and construction of seawall for forming the road embankment, and the construction of Slip Roads 5 and 6, Road A and the Road P1 Roundabout. The proposed Project would result in environmental changes in respects of noise, air quality, water quality, terrestrial ecology, marine ecology, fisheries, cultural heritage, and landscape and visual impacts. |
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Alignment options selection |
Three alignment options were considered for the proposed P1 Advance Works. The recommended option has the following benefits: · tally with the current configuration of Road P1 between Sham Shui Kok and Sunny Bay, and providing flexibility for the future alignment of Road P1; · with the permanent alignment of slip roads constructed over NLH and AEL, one-time disturbance to the existing live traffic along the strategic transportation network connecting to the airport is accomplished; · the land-take and reclaimed area minimized, reducing impact on tidal current and water quality; and; · lengthy lead-time in land clearance of log ponds in Sunny Bay avoided.
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Construction Method |
Erection of bridge decks using balanced-cantilever construction method is selected to minimize the disturbance to operating railways and traffic along NLH. Pre-bored steel H-piles is selected to minimize the required working space within works area of PBRL contracts. The use of pre-bored steel H-piles would reduce construction phase environmental impacts such as noise, dust and water quality impacts from piling works on sensitive receivers in the vicinity of the Project site. The concrete units required for the road/bridge structures would be pre-fabricated outside Hong Kong, construction noise, dust and water quality impacts arising from which at the Project site would thus be avoided. Since the scale of the proposed Project would be limited, the quantity of pre-cast concrete units necessary for the construction of the Project would not be substantial. Insurmountable off-site environmental impacts would not be envisaged. Dredging for reclamation works is avoided to minimize the disposal of soft material. Dredging of marine sediment would be undertaken under the seawall area for construction of the seawall foundation only, and not under the reclaimed area, minimizing disturbance of the marine bottom sediment and thereby release of suspended solids or bound organic and inorganic constituents. |
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Noise |
NSRs at Luk Keng Tsuen would be impacted by noise arising from the construction of the Project. For the unmitigated scenario, the construction of the proposed Project would result in minor exceedance (about 1-3dB(A)) of the daytime construction noise criterion as set out in the EIAO-TM. With the adoption of quieter plant and good site practices, all representative NSRs at Luk Keng Tsuen would comply with the noise criterion. About 6 dwellings would be protected from the construction noise impact. No adverse residual construction noise impact would be envisaged. Traffic noise impacts associated with the operation phase of the Project was assessed for both the normal and emergency traffic scenarios. Modelling results indicated that the traffic noise levels predicted at all NSRs at Luk Keng Tsuen would be within the EIAO-TM noise criterion of 70dB(A). No mitigation measure is required. |
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Air quality |
Dust suppression methods and good site practices were proposed to protect ASRs in the vicinity of the work sites. A dust monitoring and audit programme was recommended to verify the effectiveness of recommended mitigation measures. Air quality impact due to vehicle emissions associated with the operation phase of the Project was assessed. Modelling results indicated that the predicted air pollutant levels would be well within the HKAQO criteria. No mitigation measure is required. |
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Water quality |
With the implementation of the proposed mitigation measures during dredging and filling works, including use of tight-closing grabs and deployment of silt curtain system, the potential water quality impact would be effectively minimized. Impacts from land-based construction activities could be controlled to comply with the WPCO standards by implementing the recommended mitigation measures in accordance with ProPECC PN 1/94. A water quality monitoring and audit programme was recommended to ensure the effectiveness of the proposed mitigation measures. Since polluted stormwater discharges would be relocated away from Sunny Bay, the water quality impact associated with the operation phase would be minimal and acceptable. |
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Waste management implications |
The majority of marine sediments to be dredged for construction of the seawall were classified as Category L. The total dredged volume was estimated as approx. 700,000 m3, of which 8,000 m3 of sediments were classified as Category M requiring Type 2 confined marine disposal. With the implementation of the recommended mitigation measures and management procedures in accordance with ETWB TCW No. 34/2002, no residual impact was predicted. |
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Ecology Terrestrial Ecology
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Marine Ecology |
Potential marine ecological impacts resulting from the Project were assessed as being minor and acceptable. Key potential impacts to marine ecology were the effects of sediment released by dredging on the Sunny Bay mudflat, which may support seagrasses, and potential impacts of works on dolphins. With mitigation measures to control water quality impacts, including the deployment of silt curtain, elevations in suspended sediment at Sunny Bay mudflat would not exceed WQO levels and would be less than natural variation of ambient conditions at the site. No impact to any seagrass present on the mudflats is therefore expected. The approximate area of potential seagrass habitat protected by means of silt curtain and other measures for controlling water quality impact would be 0.8 ha. By strictly observing the recommended mitigation measures to control water quality as well as minimise physical dangers due to marine traffic and works, it is anticipated impact on dolphins would be low and environmentally acceptable. |
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Fisheries |
The project would result in the permanent loss of 3ha of sea area within the Sunny Bay area. The loss of this fishing area would have a relatively low impact on Hong Kong capture fisheries production as a whole. |
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Cultural Heritage |
Based on the findings of the marine archaeological investigation, no anomalies or targets of potential archaeological significance was identified. The Sunny Bay Archaeological Site and Luk Keng Tsuen Archaeological Site are located well outside the proposed works area. No adverse cultural heritage impact would thus be expected. |
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Landscape and Visual |
The project would result in the permanent loss of 3ha of sea area within the Sunny Bay. Most of the features identified within the assessment area are man-made such as road network, viaducts, railway tracks, railway stations and transport interchange. Taking into account of this baseline condition, it is considered that even without implementation of any mitigation measures, the change brought by the Project would not be apparent in visual terms. |