3 ENVIRONMENTAL IMPACTS

The nature and extent of the environmental impacts associated with the construction and operation phases of the Project are summarised below. Specific mitigation measures for the Project, as well as environmental monitoring and auditing procedures, have been developed during this EIA. The Implementation Schedule of the recommended measures is presented in Annex G of the EIA Report.

3.1 WATER QUALITY

The impacts to water quality arising from the construction and operation of the submarine pipelines supplying gas from the LNG receiving terminal in Shenzhen to the Towngas Gas Production Plant in Tai Po have been assessed in the EIA Report. The purpose of the assessment was to evaluate the acceptability of predicted impacts to water quality from the construction and operation of the gas pipelines.

Computer modelling of sediment dispersion has been used to assess construction impacts in terms of the laying of the pipeline, which will be carried out using two methods:

* dredging trenches in the Yantian Fairway and the Shenzhen approach (outside HKSAR waters); and

* jetting for the majority of the pipelines route.

The trench dredging in the Yantian Fairway and the Shenzhen approaches was examined quantitatively. It was determined that the impacts from the dredging would comply with the WQOs and coral tolerance criteria. Consequently impacts to the hard, soft and black corals within the Tung Ping Chau Marine Park are not predicted to occur.

Computer modelling was used to simulate the loss of sediment to suspension during the jetting operations. The assessment concluded that any sediment disturbed by the works would settle rapidly back onto the sea bed and the suspended sediment elevations would be of short duration. This means that there would be little transport of suspended sediment away from the jetting operations and that it would not impact upon sensitive receivers. Consequently impacts to the hard, soft and black corals along Tolo Channel and within the Hoi Ha Wan Marine Park are not predicted to occur.

The predicted modelling results at the various sensitive receivers are summarised below.

Coral Areas

The sediment plumes generated during the dredging works are confined to the alignment of the pipelines with concentrations decreasing with distance from the jetting works. The assessment of the dredging works indicated that the SS plumes were confined to open waters and did not impinge on any coastlines in Hong Kong waters. The modelling results indicate that at all of the 13 coral sensitive receivers the maximum depth averaged SS elevations comply with the tolerance criterion of 10 mg L-1 elevation for both the wet and dry seasons for both construction methods (jetting and dredging). The elevations of SS occur over very short periods, ie 6 to 12 hours and that concentrations return rapidly back to levels of less than 1 to 2 mg L-1. Due to the short-term nature of the elevations, the impacts to hard, soft and black corals are not expected to be unacceptable.

The results of water quality modelling show that under the proposed jetting and dredging rates, the sediment deposition rate at all the coral sensitive receivers are well below the threshold tolerance level of 100 g m-2 day-1. The suspended sediment and sediment deposition criteria utilised in the assessments have been applied in previous EIAs (1)(2)(3)(4)(5)(6) in Hong Kong. EM&A results from projects that have adopted the criteria have indicated that no adverse impacts to corals have occurred. The worst case scenario prediction for jetting operations shows that the deposition event at Pak Sha Tau (medium ecological value habitat) would be approximately 60 g m-2 day-1 which is well below the threshold tolerance level of 100 g m-2 day-1. The hard, soft and black coral habitats found along the Tolo Channel are therefore not predicted to be affected by sedimentation.

Marine Parks, Proposed & Gazetted Artificial Reef Deployment Areas

The information from the modelling indicates that none of the WQOs are exceeded as a result of the jetting and dredging (in both Hong Kong and Mainland waters) operations with very small temporary elevations of SS at 1.2 mg L-1 for Hoi Ha Wan and <0.1 mg L-1 for Yan Chau Tong and Tung Ping Chau. Depletions of DO and elevations of nutrients and Chlorophyll a levels as a result of the project were reported as undetectable and compliant with the relevant WQOs. Consequently, the marine habitats of ecological importance within the marine parks are unlikely to be affected by the proposed construction works.

Fish Culture Zones

Plumes of SS dispersed from the construction works do not affect any of the Fish Culture Zone (FCZ) sensitive receivers at concentrations greater than 50 mg L-1 (tolerance threshold for culture fish). The maximum depth averaged SS elevations at each of the FCZs is less than 3 mg L-1, which is well within the acceptable range and is not expected to cause unacceptable impacts.

Sites of Special Scientific Interest

As both of the Ting Kok and Kei Ling Ha Mangal SSSIs are located remotely from the pipelines alignments, impacts were not expected. This statement has been confirmed by the modelling work which indicates that the maximum depth averaged SS elevations at these locations are less than 1 mg L-1 and therefore well within acceptable levels.

Beaches

Three non-gazetted beaches are located within the area of interest, Sha Lan and Ha Mei (close to the Ting Kok SSSI) and Hoi Ha in the Marine Park. As all of these beaches are located remotely from the pipelines alignments, impacts were not expected. This statement has been confirmed by the modelling work which indicates that the maximum depth averaged SS elevations at these locations are less than 0.1 mg L-1 and can be considered to be undetectable and therefore acceptable.

Water Intakes

There are two water intakes in the area of interest, at the Tai Po Industrial Estate (approx 230 m from pipelines) and at the Marine Laboratory of the Chinese University (880 m from pipelines). The maximum depth averaged SS elevations at the Marine Laboratory were considered to be undetectable (< 0.01 mg L-1). At the Tai Po Industrial Estate the maximum depth averaged SS concentrations from the jetting works do not exceed the intake criterion of (10 mg L-1). Although no exceedances are predicted, given the low level of the intake in the water column and the shallow water depth at the site, Towngas has elected as a precautionary measure to install a silt curtain during seawall excavation works and for jetting works within 2 km of the seawall at Tai Po.

Fisheries Protection Areas

There are two proposed Fisheries Protection Areas (FPAs) within the Study Area at Long Harbour and in Tolo Channel. Impacts to the FPA in Long Harbour have been avoided through the routing of the pipelines. However, the pipelines pass directly through the Tolo Channel FPA. The elevations of SS within this FPA are confined largely to the pipelines alignment and overall depth averaged values are less than 25 mg L-1. Therefore, impacts to the FPA through elevated SS levels are considered to be of low severity and of short duration.

An EM&A programme has been devised to confirm that the assessments of the localised impacts of the jetting operations in Hong Kong waters, and dredging in Mainland waters, were accurate and that the operation would be environmentally acceptable.

3.2 WASTE MANAGEMENT

The EIA identifies the key waste management issues during the construction of the project. An impact assessment for the construction activities was undertaken and a Waste Management Plan has been proposed for the Project. It is expected that the following waste types will be generated.

* C&D Materials - approximately 3,200 m3 of excavated materials will be generated within a period of 180 days, of which approximately 50% could be used for backfilling of the onshore trenches;

* A total of about 220,000 m3 of uncontaminated (Category L) dredged materials will need to be disposed of at the designated marine dumping areas;

* Chemical waste (in the order of hundreds of litres);

* Sewage from the on-site construction workforce; and

* General refuse (a maximum of approximately 13 kg day-1).

The quantities of materials arising from the construction phase are not expected to be unduly high, but practical mitigation measures will be taken to avoid, minimise and recycle wastes and to reduce environmental impacts. With the implementation of the proposed measures, the potential environmental impacts associated with the storage, handling, collection, transport, and disposal of wastes during construction will meet the criteria specified in the EIAO-TM. No unacceptable environmental impacts are anticipated.

No waste generation is expected after the completion of the installation of the pipelines, hence mitigation measures are not required.

3.3 MARINE ECOLOGY

The alignment of the submarine pipelines was studied in detail through a route options assessment, in order to avoid direct impacts to habitats or species of high ecological value.

Literature reviews of existing information coupled with extensive field surveys of marine ecological resources have been undertaken. The information gathered on baseline conditions has identified the following high ecological value marine sensitive receivers. The locations of the sensitive receivers relative to the proposed pipelines alignment are shown in Figure 3.3a.

* Subtidal Hard Surface Habitats (Wong Wan Tsui) (C5)

* Subtidal Hard Surface Habitats (Fung Wong Fat) (C6)

* Subtidal Hard Surface Habitats (South Wong Chuk Kok Tsui) (C8)

* Subtidal Hard Surface Habitats (Wong Chuk Kok Tsui) (C9)

* Subtidal Hard Surface Habitats (Gruff Head) (C7)

* Subtidal Hard Surface Habitats (Chek Chau) (C11 and C12)

* Subtidal Hard Surface Habitats (Tung Ping Chau) (C13)

* Ting Kok SSSI (SSI1)

* Kei Ling Ha Mangal SSSI (SSI2)

* Hoi Ha Wan Marine Park (MP1)

* Yan Chau Tong Marine Park (MP2)

* Tung Ping Chau Marine Park (MP3)

Potential impacts to marine ecological resources and the above sensitive receivers may arise from direct disturbances to habitats, or through changes to key water quality parameters. The loss of the low ecological value subtidal assemblages present within the jetting/dredging areas and the loss of those on the artificial seawall at Tai Po are considered to be acceptable as the habitats are of low ecological value. Infaunal organisms and epibenthic fauna are expected to recolonise the sediments after the pipelines have been laid.

Jetting and dredging working practices have been specified to ensure that water quality impacts are within acceptable levels (as defined by the WQOs and coral tolerance criteria) and also to mitigate impacts to marine ecological resources. The marine ecological sensitive receivers are all located at sufficient distances from the pipelines alignment so that impacts from the jetting/dredging operations are predicted to be of small magnitude, of very short duration and within the relevant standards and criteria. It was determined that the impacts from the dredging would comply with the WQOs and coral tolerance criteria. As discussed in Section 3.1, the criteria utilised in the assessments have been applied in previous EIAs in Hong Kong. EM&A results from projects that have adopted the criteria have indicated that no adverse impacts to corals have occurred. Consequently impacts to the marine ecological resources within the Tung Ping Chau Marine Park, in particular hard and soft corals are not predicted to occur (see Section 3.1). The jetting operation was predicted to cause little transport of suspended sediment away from the jetting operations, the plumes would be compliant with the WQOs and coral tolerance criteria and would not impact upon sensitive receivers.

Elevations of SS in the water column at the sensitive receiver locations are very small and within the tolerance level (ie 10 mg L-1) of the hard, soft and black corals. Impacts to the hard, soft and black corals at all the high ecological value sensitive receiver locations due to sediment deposition are unlikely to occur as sediment deposition rates from the pipelines installation works are predicted to be less than 100 g m-2 day-1 which is below the threshold value for hard, soft and black corals. Consequently, impacts are predicted to be within environmentally acceptable levels (see Section 3.1).

The residual impacts occurring as a result of the laying of the gas pipelines are the temporary loss of the low ecological value subtidal assemblages present within the jetting/dredging areas and the loss of those on the artificial seawall at Tai Po. The residual impacts are considered to be acceptable as the habitats are of low ecological value and because infaunal organisms and epibenthic fauna are expected to recolonise the sediments and seawall. The cumulative impact assessment has concluded that there will be no unacceptable adverse cumulative impacts to water quality or marine ecology.

To ensure that there are no unacceptable impacts to marine ecological resources, an EM&A programme has been designed to specifically detect and mitigate any unacceptable impacts to water quality and marine ecology.

3.4 FISHERIES

Reviews of existing information on commercial fisheries resources and fishing operations located within the Study Area have been undertaken for this impact assessment. Information from a study on fishing operations in Hong Kong indicates that fisheries production values from along the pipelines' alignment are highly variable.

The Fish Culture Zones (FCZs) located in the vicinity of the proposed pipelines include Yim Tin Tsai, Yim Tin Tsai (East), Yung Shue Au, Lo Fu Wat, Kau Lau Wan, Sham Wan and Tap Mun (Figure 3.3a).

Potential impacts to fisheries resources and fishing operations may arise from temporary disturbances to benthic habitats on which the fisheries resources depend for food, or through short term changes to key water quality parameters, as a result of the installation of the gas pipelines (see Section 3.1).

As impacts arising from the proposed dredging or jetting works are predicted to be largely confined to the specific works areas and of short duration, they are not expected to cause adverse impacts to any fishing grounds or species of importance to the fishery. While no special mitigation measures are required for fisheries resources, constraints on jetting and dredging operations recommended to control impacts to water quality are also expected to mitigate impacts to fisheries resources.

3.5 HAZARD TO LIFE

The hazard to life study considered releases that may occur as a result of loss of containment from the proposed facilities. The scope of the study was as follows:

* external impacts such as dropped objects and anchor drop/drag;

* spontaneous failures, e.g. due to corrosion or material defect; and

* natural hazards, e.g. earthquakes and subsidence.

With reference to historical data, the likelihood of loss of containment from the proposed facilities was qualitatively assessed. The consequences of the resultant leak include jet fires, sea surface 'pool' fires and flash fires. Based on the frequency and consequence assessments, the likely levels of risk from various sections of the proposed facilities were determined using a risk matrix. The results of the assessment are presented below.

* No high risk areas were identified.

* The risks associated with Route Option 1 (Tai Po Waterfront Park) (Figure 2.1a) of the onshore pipelines and the Mirs Bay East and North Tung Ping Chau sections of the subsea pipelines were assessed to be low.

* Moderate risk levels were determined for the following areas:

o Gas Receiver Station;

o Route Option 2 (Tai Po Industrial Estate) (Figure 2.1a) for the onshore pipelines; and

o All sections of the subsea pipelines, except for the Mirs Bay East and North Tung Ping Chau sections.

Based on the results of the qualitative risk assessment, no insurmountable risk associated with the Project is envisaged. Mitigation measures to further reduce the risk levels associated with the Project have been recommended.

3.6 LANDFILL GAS ASSESSMENT

As elements of the Project fall within the Shuen Wan Landfill (SWL) Consultation Zone, a qualitative hazard assessment of the migration of landfill gas and leachate/contaminated groundwater from the neighbouring SWL has been undertaken. It is concluded that the potential for landfill gas and leachate to affect the proposed Project during the construction and operational phases is very low.

During construction, hazards may arise from the flammability or the potential asphyxiating properties of landfill gas and/or the potentially toxic nature of leachate. Whilst the risks associated with landfill gas and leachate are expected to be very low, precautionary measures have been recommended for the avoidance of environmental impacts.

3.7 AIR QUALITY

Potential air quality impacts arising from the construction and operation of the Project have been evaluated. As the number of barges required for the pipelaying operations will be limited, emissions of gaseous pollutants from these barges are not expected to exceed the AQOs. Air quality impacts associated with dust generation and gaseous emissions from on-site plant and vehicles during the construction of the onshore pipelines section and the Gas Receiver Station in Tai Po will be small. With the implementation of dust suppression measures in accordance with the Air Pollution Control (Construction Dust) Regulation, an adverse dust impact is not anticipated.

During operation, the Gas Receiver Station will utilise heat from steam/hot water generated within the existing gas production plant and no flare will be required at the Gas Receiver Station. As such, air quality impacts from the operation of the pipelines and Gas Receiver Station at Tai Po are not expected.

3.8 CULTURAL HERITAGE

A comprehensive baseline review identified no land based or submerged cultural heritage resources within the Study Area. A detailed Geophysical Survey has been conducted within a 700 m pipeline corridor and ten anomalies were identified and avoided at the route planning stage. The anomalies are likely to be small vessels (in various states of preservation) that have been deposited within the last 50 years and are possibly associated with fishing in the area. They are not considered to have archaeological potential.

3.9 NOISE

Potential noise impacts arising from the construction and operation of the Project have been evaluated. The assessment identified that there are no noise sensitive receivers within 300 m of the Project works. An assessment of impacts of the construction and operation works indicated that unacceptable noise impacts will not occur. As some marine works during construction may take place in the evening and night-time periods, assessments were conducted to determine whether the works would be acceptable. It was concluded that the predicted noise levels would not be of concern to the identified noise sensitive receivers.

3.10 ENVIRONMENTAL MONITORING AND AUDIT (EM&A)

During construction of the Project, environmental monitoring will be necessary to assess the effectiveness of measures implemented to mitigate potential water quality, marine ecology and landfill gas impacts. Regular environmental auditing is also recommended to ensure that potential impacts from other sources are adequately addressed through the implementation of the mitigation measures defined in this EIA Report.

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(1) ERM (2001). Focussed Cumulative Water Quality Impact Assessment of Sand Dredging at the West Po Toi Marine Borrow Area. Environmental Monitoring and Audit Manual. Updated Manual for HAM Dredging and Marine Contractors.

(2) Hyder (1997). Sand Dredging and Backfilling of Borrow Pits at the Potential Eastern Waters Marine Borrow Area, EIA Report, CED, 1997.

(3) ERM (2001). Environmental Consultancy Services For The Proposed 11kv Cable Circuits From Tai Mong Tsai To Kiu Tsui, CLP Power, 2001.

(4) ERM (1998). Environmental Impact Assessment of Backfilling Marine Borrow Areas at East Tung Lung Chau, CED, 1998.

(5) ERM (2002). Environmental Consultancy Services for proposed 132kV Cable Circuits from a Kung Wan to Sai Kung Pier, CLP Power, 2002.

(6) ERM (2002). 132kV Submarine Cable Installation for Wong Chuk Hang - Chung Hom Kok 132 kV Circuits, The Hongkong Electric Co, January 2002.