EXECUTIVE SUMMARY

ES1 INTRODUCTION

ES1.1 Background Information

Due to the obsolescence, age and operational problems, CLP’s 33kV equipment has been gradually phased out and uprated to 132kV in order to maintain the integrity of the network in transmission and distribution. The 33kV phasing-out programme commenced in 1980 in Kowloon Peninsula and now extends to the New Territories and Outlying Islands.

Mott Connell Limited (MCL) was commissioned by CLP Power Hong Kong Limited (CLP) in September 1999 to carry out the Route Options Assessment for 3 x 132kV electricity supply circuits leading from Pui O Substation at Lantau Island south to Cheung Chau Substations.

Cheung Chau is situated south-east of Lantau and has population of 24,000. The maximum demand in 1999 was 20MVA. Electricity supplies to Cheung Chau are provided by the Cheung Chau South and North Substations. These two substations are fed from the South Lantau / Pui O 33kV system via 3 overhead lines and submarine cable circuits (about 8km) and backup with a limited 11kV circuit. Due to the long sections of these 33kV overhead lines at onerous locations, they are susceptible to unfavourable weather conditions such as lighting/typhoon incidences which may cause supply interruption.

To improve the supply reliability, transmission efficiency and system performance, all the 33kV equipment and overhead transmission lines in Lantau will be decommissioned and replaced with 132kV. The South Lantau / Pui O 33kV phasing out programme includes replacement of the existing 3 x 33kV and 11kV, 20MVA transformers at Cheung Chau South and North Substations. These will be replaced by 132kV and 11kV, 35 MVA units via new 132kV underground and submarine cable circuits. The proposed 132kV circuits will be connected to Cheung Chau South Substation and are scheduled to be commissioned at the end of 2004. After commissioning of the proposed 132kV circuits, the existing 33kV overhead lines will be removed while the 33kV submarine cables will be retained in place for possible future use. They may be used at 11kV to serve as inter-connectors when necessary.

The objective of this assignment is to investigate the extent of the potential impacts caused by the provision of 3 x 132kV circuits, and to identify any mitigation measures which may be needed to ensure the new circuits can be installed without causing adverse impacts on local residents and the receiving environment.To improve the supply reliability, transmission efficiency and system performance, all the 33kV equipment, overhead transmission lines in Lantau will be decommissioned and replaced with 132kV. The South Lantau / Pui O 33kV phasing out programme includes replacement of the existing 3 x 33kV and 11kV, 20MVA transformers at Cheung Chau South and North Substations. These will be replaced by 132kV and 11kV, 35MVA units via new 132kV underground and submarine cable circuits.

The objective of this assignment is to investigate the environmental impacts for the proposed 3 x 132kV circuits such that the circuits can be installed without causing significant impacts on local residents and the environment.

This project is a Designated Project under Schedule 2, Q.1, of the Environmental Impact Assessment Ordinance (EIAO) as a portion of the underground tunnel falls within the “Country Park” zone. Therefore, CLP was instructed by the Environmental Protection Department (EPD) to undertake an Environmental Impact Assessment (EIA) Study to provide information on the nature and extent of environmental impacts arising from the construction and operation of the proposed designed project and related activities taking place concurrently.

The alignment of the proposed 3 x 132 kV supply circuit from the existing Pui O Substation on south Lantau Island, via Chi Ma Wan Peninsula via Adamasta Channel towards Cheung Chau North and Cheung Chau South Substations is shown in Figure ES.1.

ES1.2 Objectives of the EIA Study

The objectives of the EIA study are as follows:

(i) to describe the proposed project and associated works together with the requirements for carrying out the proposed project;

(ii) to provide information on the need of the power line and the consideration of alternatives for avoiding the country park as power transmission corridor;

(iii) to compare the main environmental impacts of different options and alignments with the proposed project and with the likely future environmental conditions in the absence of the project;

(iv) to identify and describe the elements of the community and environment likely to be affected by the proposed project and/or likely to cause adverse impacts to the proposed projects, including both the natural and man-made environment;

(v) to identify and quantify any potential losses or damage to flora, fauna and natural habitats;

(vi) to identify any potential landscape and visual impacts and to propose measures to mitigate these impacts;

(vii) to propose mitigation measures so as to minimize pollution, environmental disturbance and nuisance during construction and operation of the project;

(viii) to identify, predict and evaluate the residual (i.e. after practicable mitigation) environmental impacts and the cumulative effects expected to arise during the construction and operation phases of the project in relation to the sensitive receivers and potential affected uses;

(ix) to identify, assesses and specify methods, measures and standards, to be included in the detailed design, construction and operation of the project which are necessary to mitigate these environmental impacts and to reduce them to acceptable levels;

(x) to investigate the extent of side effects of proposed mitigation measures that may lead to other forms of impacts;

(xi) to identify constraints associated with the mitigation measures recommended in the EIA study; and

(xii) to design and specify the environmental monitoring and audit requirements, if required, to ensure the implementation and the effectiveness of the environmental protection and pollution control measures adopted.

ES1.3 Description of the Assignment

In order to fulfill the objectives of the Study, ~~this~~ the EIA has:

(i) determined the overall acceptability of any adverse environmental and health consequences that are likely to arise as a result of the proposed project;

(ii) identified the conditions and requirements for the detailed design, construction and operation of the proposed project to mitigate adverse environmental and health consequences wherever practicable; and

(iii) defined the acceptability of residual impacts after the proposed mitigation measures is implemented.

ES1.4 Site Location

The Study Area covers Pui O, Chi Ma Wan Peninsula, Cheung Chau and Adamasta Channel. Outline Zoning Plan (OZP) No. S/SLC/8 for the South Lantau Coast shows the different zonings of the Study Area on Lantau Island (Part print of the OZP is ~~shown~~ reproduced in as Figure ES.2). Encroachments of the potential cable routes on the Lantau South Country Park, coastal protection area, green belt, village type development are expected. Particular concerns are in Pui O area, Cheung Chau, Shap Long Kau Tsuen, Yim Tin Kong Tsuen, Ham Tin Tsuen and Tai Long Wan where residential developments exist.

In Cheung Chau, the 3 x 132kV circuits will be connected to the substations located in Cheung Chau north and south. The potential cable routes will impinge on the following areas.

· Cheung Chau Sai Tai Road, Tai Hing Tai Road, Praya Street and Pak She Praya Street in Cheung Chau central; and

· Sai Wan Promenade and Cheung Chau Typhoon Shelter in Cheung Chau south.

ES2 EVALUATION OF IMPACTS

ES2.1 Construction Impacts

ES2.1.1 Air Quality

A quantitative assessment on the construction dust impacts has identified that fugitive dust is the primary potential air pollutant during the proposed works. The assessments predicted an exceedance of hourly TSP dust criteria at the hostel, SR4 for the situation where no mitigation measures were in place. With the application of the established and practical dust suppression techniques such as regular watering twice a day, covering/dampening any stockpiles and dampening dusty materials before transportation and the control measures stipulated in the Air Pollution Control (Construction Dust) Regulation, the construction dust impacts can be reduced by more than 50% to an acceptable level. No residual air quality impact is expected. As a result, no routine air quality monitoring is recommended.A ~~qualitative~~ ~~assessment on the construction dust impacts has identified that fugitive dust is the primary potential air pollutant during the proposed works~~. ~~and t~~The ~~assessments have demonstrated that~~ ~~dust impact will be minimal~~ ~~with the application of~~ ~~. E~~established dust suppression techniques such as regular watering, covering/dampening any stockpiles and dampening dusty materials before transportation. Through the proper implementation of the recommended mitigation measures, dust generation will be further controlled and exceedance of the acceptable criteria is~~will~~ ~~not~~ be ~~expected. As a result, no routine air quality monitoring~~ ~~will be requiredis recommended~~.

ES2.1.2 Noise

The unmitigated noise levels associated with the installation of underground cable and construction of cable tunnel, would cause exceedance of the daytime construction noise criterion at the nearby NSRs. The most seriously affected area is Ham Tin Tsuen of Pui O, Lantau where unmitigated noise level of up to 92 dB(A) is predicted. Therefore, adequate control measures will be necessary for the installation of underground cable and construction of cable tunnel. Mitigation measures including the use of quiet plant and consideration of barrier effect are proposed to substantially minimise the noise level. Although the noise impact at all NSR would comply with the daytime construction noise criterion (i.e. 75 dB(A) for domestic premises), the Buddhist Wai Yan Memorial College (i.e. SR6) would still exceed the noise criteria (i.e. 70 dB(A) for schools) by 5 dB(A). By considering the short duration of this residual impact, re-scheduling the construction works at SR6 on Saturday (non-teaching period) or school holidays could minimise the noise impacts. Therefore, the residual noise impact could be alleviated.

For the construction of the tunnel, numerous of noisy PMEs such as drilling machine and rock bolt are involved. Construction noise impact at the nearby NSRs is expected. With the erection of the temporary vertical noise barrier at Pui O tunnel portal and adoption of quiet plants, the construction noise impact can be alleviated. The predicted noise levels with mitigation can comply with the noise criteria.~~This EIA has concluded that~~ ~~the predicted construction noise levels~~ ~~without mitigation~~ ~~construction noise levels~~ ~~at all the affected NSRs~~, ~~except for SR3~~, ~~will exceed the acceptable noise criteria. With the implementation of good site practice and practical noise mitigation measures, the construction noise impacts will be reduced.~~

After the implementation of noise mitigation measures, residual construction noise impact will only occur at SR5, the Buddhist Wai Yan Memorial College. However, it is anticipated that the exposure to high noise level is only a short duration (2 to 3 days). In addition, the road breaking activity in front of the school is recommended to be carried out during the non-teaching period of the school (i.e. Saturday afternoon and school holidays). This residual impact can be alleviated.

As noise exceedances during the construction phase are not predicted and the laying underground land cable is a trade practice well established by CLP, routine environmental noise monitoring is not required during construction. However regular site audits are recommended to be conducted to ensure the implementation of good site practices and appropriate mitigation measures.

ES2.2 Water Quality

Water quality impacts associated with the implementation of this Project are acceptable.

Direct burying is the preferred option for the cable laying as it is of shorter duration than dredging, has lesser and acceptable impacts than dredging and can fully comply with the WQO’s at the sensitive receivers all year round.

Full compliance with the WQO’s (throughout the year) has been predicted for the direct burying option, although confirmatory monitoring is proposed to ensure water quality at Tai Kwai Wan and Cheung Sha Wan Fish Culture Zone is not impacted by the cable laying works.

Dredging will not ~~For~~ be carried out for laying the entire length of the cables. Instead, ~~the~~ minor dredging works ~~which~~ need to be carried out for laying either end of the cables (due to the shallow depth of water). Tthe results indicate that the WQO’s can be achieved if the single trench dredging option is carried out during the dry season.

In the event that dredging needs to take place during the wet season (eg for reasons of programming) then practical mitigation measures will be needed to ensure compliance with the WQO’s. For the single trench option mitigation measures including the use of closed and sealed grabs and through controlling the rate of lifting will ensure the WQO’s can be achieved.

In the event that a three trench dredging option is considered then mitigation measures would need to reduce the impacts by 40% during the dry season (through the use of closed grabs) and by 85% during the wet season (using closed grabs, controlling the rate of lifting and reducing the dredging rate by a further 40%). All of the foregoing are practical measures which can be adopted to ensure compliance with the WQO’s.

For the high concentration observed within the typhoon shelter of Cheung Chau Wan the potential impacts are over-exaggerated because the work carried out in the typhoon shelter will be carried out by hand using qualified divers. Therefore the impacts will be significantly less than predicted by the model and no adverse water quality impact is expected.

The construction programme has scheduled the cable laying work during the dry season. The results of the assessment confirm that cable laying work can be carried out without any adverse water quality impact during the dry season. Even cable laying work is required during the wet season, the water quality can also comply with the WQO with the implementation of the above-mentioned mitigation measures.

The potential impacts from off-site runoff can be controlled to acceptable levels. There will be no adverse impact on water quality arising from the temporary working platform at Pui O. The facility is only required for the excavation of the tunnel. The working platform is small (180m²) and will be formed behind a seawall of concrete blocks with no gaps. Once the excavation has been completed the working platform will be removed and the shoreline reinstated.

An environmental monitoring and audit will be implemented to ensure the general mitigation measures are effective and that the actual water quality impacts are within the acceptable levels during the installation of submarine cables and the temporary working platform at Pui O Beach.~~Water quality impacts associated with the implementation of this Project are acceptable.~~

Full compliance with the WQO’s has been predicted for the direct burying option, although confirmatory monitoring is proposed to ensure water quality at Tai Kwai Wan and Cheung Sha Wan Fish Culture Zone is not impacted by the cable laying works.

For the single trench dredging option the results indicate compliance with the WQO’s at the sensitive receivers except during the wet season at Tai Kwai Wan. Practical mitigation measures can be implemented to reduce impacts to acceptable levels.

In the event that a three trench dredging option is considered then mitigation measures would need to reduce the impacts at Cheung Sha Wan fish Culture Zone to allow dredging during the dry season. For the wet season, mitigation measures would need to include reduction in losses of sediments (at least 50%) as well as the use of a silt curtain at Tai Kwai Wan to ensure compliance at Tai Kwai Wan.

The potential impacts from off-site runoff can be controlled to acceptable levels. Work at Pui O in respect of the tunnel excavation will not have an adverse impact on water quality as the working platform is small, a temporary facility and the area will be formed behind a seawall of concrete blocks with no gaps.

ES2.3 Fisheries

A review of existing information indicates that the Study Area supports fisheries resources and fishing operations. Impacts from the project will be confined to the formation of the temporary working area and more specifically the cable laying works. As the working platform is a temporary facility which will be removed to re-instate the shoreline following completion of the excavation works, and the preferred method for cable laying is direct burying for reasons given in the foregoing section, the extent of the impacts on fisheries are likely to be minor. The potential impact on the spawning and nursery ground is anticipated to be insignificant. Generally, mitigation measures which are recommended to control water quality impacts to within acceptable levels, are also expected to control impacts to fisheries resources. In addition to which, appropriate mitigation measures are proposed to minimise the impacts of the works on the marine environment.

It may be concluded that for direct burying method, short term exceedances of peak elevated SS levels take place especially during dry season. At Po Yue Wan these occur on neap tide for both the “slow” and “fast” advancing rates although it should be noted that average results fully comply with the WQO’s. ~~No short term exceedances occurred any of the sensitive receivers rather they are, not unexpectedly, observed in the Adamasta Channel and a Po Yue Wan which is not a water sensitive receiver.~~

Although the water quality impact is acceptable, it has been proposed that a “rest” period of 6 hours should be observed between the completion of one cable burying operation (by boat) and commencement of the next cable laying operation. The 6 hour period is based on the time taken for the sediments to resettle to acceptable levels as shown in the time history plots in Appendix F. Reference should be made to these plots relating to the Adamasta Channel and Po Yue Wan where peak concentrations are observed. ~~Since Po Yue Wan is not a water sensitive receiver, the predicted SS levels at all the water sensitive receivers comply with the relevant WQO. Therefore, the water quality impact is acceptable~~.

~~No exceedances of SS levels at all the monitoring locations are predicted with dredging one trench or three trenches simultaneously. Therefore, the water quality impact is acceptable.~~

The predicted results of the water quality modelling show that no exceedances of the WQO for suspended solids occur at the selected water sensitive receivers by using the direct burying method. Therefore, the water quality impacts caused by direct burying is acceptable.

For dredging, the predicted elevated suspended solids levels at all selected monitoring locations are well below the WQO requirements when one trench is dredged at a time. However, exceedances of suspended solids levels are predicted at Cheung Chau typhoon shelter, Po Yue Wan and Adamasta Channel when dredging three trenches simultaneously. With the implementation of the general mitigation measures and pollution prevention measures, the water quality impacts at the water sensitive receivers are not expected.

An environmental monitoring and audit will be implemented to ensure the general mitigation measures are effective and that the actual water quality impacts are within the acceptable levels during the installation of submarine cables and the ~~reclamation workstemporary working platform~~ ~~at Pui O Beach.~~

ES2.3 Fisheries

~~A review of existing information indicates that the Study Area supports fisheries resources~~ ~~and fishing operations~~. ~~As impacts resulting from the project will be confined to dredging and reclamation, no adverse impacts to fisheries resources are expected.Impacts from the project will be confined to reclamation and the chosen method of cable laying/protection which may be by dredging or by direct burying.~~ The size of impact due to dredging and reclamation is predicted to minor. Generally the mitigation measures which are recommended to control water quality impacts to within acceptable levels, are also expected to control impacts to fisheries resources. ~~Appropriate mitigation measures are recommended such as adoption of direct burying as a cable laying method~~ ~~using a shield over the face of the cutter to suppress release and dispersion of sediments to be water column, application of the closed grab and silt curtain in the event that dredging is selected.Therefore, no~~ ~~fisheries-specific~~ ~~mitigation measures are required.~~

ES2.4 Ecology

Terrestrial Ecology

Altogether 15 habitat types were found in the Study Area, including forest, tall shrubland, shrubland-grassland mixture, wetland, abandoned farmland, farmland, rocky shore, sandy shore, backshore shrubland, mangrove, brackish mudflat, plantation, wasteland, village area and stream. Based on the ecological conditions presented in the above sections, it is considered that the forest, wetland and mangrove have high ecological value. The brackish mudflat, abandoned farmland, tall shrubland, stream (S1 to S4) are regarded as having moderate ecological value, while the other terrestrial habitats are common and typical habitats in Hong Kong and most of the species identified are common and widespread and therefore considered to be of low ecological value.

The proposed 132 kV circuits will mainly be located on existing road/ footpaths. The impacts due to the construction and operation of the underground cable are considered to be low, and no adverse residual impact is expected. The most sensitive issue is the direct habitat loss (0.15 ha of tall shrubland) within the South Lantau Country Park, in which no unacceptable residual impact will be expected. Mitigation measures in the form of good construction practice and scrub compensatory planting are recommended to minimise potential disturbance to the surrounding environment.

Marine Ecology

Literature reviews of existing information supplemented with the results of recently undertaken field surveys on marine ecological resources indicate that the intertidal rocky shores within the Study Area are of medium ecological value whereas for the sandy habitats, low ecological value was assigned. Soft bottom subtidal habitats identified in the review were regarded as of low ecological value. A few isolated colonies of hard and soft corals were recorded on the subtidal hard surface habitats and were considered as of low ecological value. The waters near the ~~proposed reclamation~~temporary working platform at Pui O and submarine cable laying sites across the Adamasta Channel do not appear to be highly utilised by marine mammals and it is considered that this area does not contain critical habitat for the Indo-pacific Hump-backed dolphins and Finless Porpoises.

Potential impacts to marine ecological resources from the proposed construction works may arise either indirectly, e.g. through perturbations of the surrounding water quality, or directly as a result of habitat loss. A temporary loss of 180m²~~. A total of 0.055 ha~~ intertidal sandy shore habitat, small areas of rocky shore and 0.5 ha of subtidal soft bottom assemblages will be ~~permanently~~ temporarily lost as a result of the construction activities associated with the Project. However, the assemblages to be lost are of low-medium ecological value and given the small area to be directly affected, the impacts are unlikely to be severe. Indirect impacts during the construction process, such as an increase in SS levels and decrease in DO in the water column may impact intertidal and subtidal filter feeders and other marine organisms. However, the effects are not expected to be severe and no unacceptable impacts are predicted to occur.

Operational impacts to marine ecological resources are not predicted to occur through disturbances to water quality due to changes in the hydrodynamic regime of the area or an increase in marine traffic for cable maintenance and repair.

ES2.5 Cultural Heritage

Literature reviews of existing information supplemented with the results of field surveys on cultural heritage resources indicate that 31 historical buildings and features and two known archaeological sites are located within the Study Area. The proposed development has tried to avoid the heritage sites as far as possible but concerns have been raised regarding the potential impact on some of the identified sites.

Mitigation measures have been recommended to avoid impacts to cultural heritage resources; control of the construction work schedule during peak visiting hour at Pui O Tin Hau Temple; detail design of the underground cable construction to avoid and minimise the potential impact to the archaeological deposit at Bui O Public School (Site A) and inner raised beach at Pui O (Site B). The future road level of the proposed Chi Ma Wan Road widening shall be raised to allow adequate cover requirement for the cables which shall be laid above the concerned zone. If the avoidance of reaching the `no dig’ zone below existing ground level at both Site A and Site B is not possible, archaeological monitoring should be undertaken in this section during construction to preserve the archaeological deposit, if any, by record and take environmental samples for future study if necessary. The level of `no dig’ zone shall be agreed with AMO during the detailed design stage of the cable laying works. The construction contractor should cooperate with a qualified archaeologist appointed to undertake the monitoring to allow sufficient time for recording archaeological deposit and take environmental samples if necessary.

ES2.6 Landscape and Visual Impact

The Landscape and Visual Impact Assessment highlights that the significant adverse impacts will occur during the construction phase. Significant impacts are also restricted to particular locations, namely Pui O tunnel and Tai Long Wan tunnel portals and ~~Cheng~~ Cheung Chau landfall area. The disturbed coastline at temporary reclaimed works areas at Pui O tunnel portal and temporary access for delivery of materials at Tai Long Wan Landfall area will be reinstated to the existing coastline after construction. With mitigation measures such as shortening the construction programme, minimising the extent of the works areas, proposing advanced transplantation and planting works, finishing color of ancillary elements, and reinstatement of planting and shoreline (refer to Figure ES-3, ES-4, ES-5 and ES-6), the long term adverse impacts will be negligible. The alignment of the circuit is significantly constrained by the technical engineering requirements. However, the nature of the proposed works and construction methodology means that much of the cable can be constructed with minimal disturbance to the existing landscape owing to the limited working boundary along existing roads, footpaths. In conclusion therefore, the proposed works will have limited adverse impacts or negligible impacts on baseline condition with appropriate mitigation measures. In conclusion, the landscape and visual impacts are considered acceptable with mitigation measures.

ES2.7 Waste Management

In order to suitably manage the potential environmental effects associated with construction related wastes, full consideration must be given of the re-use of surplus clean material on site (where practicable), or within other development projects, once material balances are finalised. All mitigation measures and waste management procedures outlined within the EIA must be implemented in order to control or eliminate the potential impacts to the environment from waste generation and disposal.

ES2.8 Health Assessment

The predicted EMFs for the proposed underground cables, cables in tunnel and submarine cables will be well under the stipulated guideline limits issued by the ICNIRP. As such, the existence of EMF associated with the proposed project is not anticipated to pose any adverse impact on public health.

ES2.9 Marine Archaeological Impact Assessment

Based on the findings of the baseline review, geophysical survey and diver inspection, it was confirmed that no archaeological significant material was identified in the study area. Therefore any further archaeological investigation or mitigation measures are not required.

ES3 ENVIRONMENTAL MONITORING AND AUDIT

A comprehensive Environmental Monitoring and Audit (EM&A) programme has been recommended during construction and operation of the 132kV supply circuit from Pui O Substation to Cheung Chau Substations. The EM&A requirements cover air quality, noise, water quality, waste management, ecology, cultural heritage and landscape and visual assessment issues and are a full reflection of the recommendations made within the EIA Report. With the inclusion of the recommended EM&A requirements into the works programme it is anticipated that the works can be carried out with full compliance of the standards set by the EIA-TM.

ES4 CONCLUSIONS AND RECOMMENDATIONS

The overall conclusion is that the installation of the proposed 132kV supply circuit from Pui O Substation to Cheung Chau Substations would comply with all environmental standards and legislation, provided that the recommended environmental control measures are implemented. There is no residual impact on the environment except for construction noise. However, the residual noise impact can be alleviated by rescheduling the noisy construction activities and the duration being affected will be very short. Therefore, this residual impact is considered to be acceptable.

Recommendations are made for monitoring and auditing during the construction phase of the work to ensure compliance with the findings of the EIA Report.