13 CONCLUSIONS & ENVIRONMENTAL OUTCOMES
13.1 INTRODUCTION
This Section presents a summary of the key potential environmental outcomes associated with the construction and operation of the Project.
13.2 WATER QUALITY
Section 4 describes 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. 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.
At the Tai Po landing point it was predicted that elevations of suspended sediments in excess of 10 mg L-1 only occur within less than 50 m of the dredging operations at the shore approach with the adoption of a silt curtain.
An EM&A programme was devised to confirm that the assessment of the localised impacts of the jetting operations was accurate and that the operation would be environmentally acceptable.
13.3 WASTE MANAGEMENT
Section 5 identifies the key waste management issues during the installation of the proposed pipelines. The installation methodology and expected waste generation rates were examined. An impact assessment for these activities was undertaken and a Waste Management Plan (Annex H) has been proposed for the Project.
It is expected that the following identified waste types will be generated from the construction of the Project:
* 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;
* 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 (approximately 13kg day-1 during peak construction).
The quantity of waste materials arising from the construction phase is not expected to be unduly high, but practical measures will be taken to avoid, minimise and recycle wastes. Mitigation measures relating to good practice have been recommended to ensure that adverse environmental impacts are prevented and that opportunities for waste minimisation and recycling are followed. With the implementation of the recommendations, 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 impact is anticipated.
No waste generation is expected after the completion of the installation of the pipelines, hence mitigation measures are not required.
13.4 MARINE ECOLOGY
The alignment for the submarine pipelines was studied in detail through a route options assessment in order that a preferred alignment was selected that avoided direct impacts to habitats or species of high ecological value.
For this impact assessment 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 marine sensitive receivers of high ecological value:
* Subtidal Hard Surface Habitats (Wong Wan Tsui)
* Subtidal Hard Surface Habitats (Fung Wong Fat)
* Subtidal Hard Surface Habitats (South Wong Chuk Kok Tsui)
* Subtidal Hard Surface Habitats (Wong Chuk Kok Tsui)
* Subtidal Hard Surface Habitats (Gruff Head)
* Subtidal Hard Surface Habitats (Chek Chau)
* Subtidal Hard Surface Habitats (Tung Ping Chau)
* Ting Kok and Kei Ling Ha Mangal SSSIs
* Hoi Ha Wan, Yan Chau Tong and Tung Ping Chau Marine Parks
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.
Impacts arising from the proposed jetting and dredging works are predicted to be largely confined to the pipelines alignment, they are not expected to cause adverse impacts to marine sensitive receivers of high ecological value (habitats or species). Jetting and dredging working practices are predicted to ensure that water quality impacts are within acceptable levels (as defined by the WQOs and tolerance criteria) and also to mitigate impacts to marine ecological resources. The marine ecological sensitive receivers listed above 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. 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. Based on the ecological value of the habitats discussed in the previous sections and the resultant working practices, the residual impacts can be determined. The residual impacts occurring as a result of the laying of the gas pipelines are 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. 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 after the pipelines have been laid.
To protect against unacceptable impacts to marine ecological resources, an EM&A programme has been designed to specifically detect and mitigate any unacceptable impacts to marine ecology.
13.5 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.
Potential impacts to fisheries resources and fishing operations may arise from disturbances to benthic habitats on which the fisheries resources depend for food, or through changes to key water quality parameters, as a result of the installation of the gas pipelines. 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 to within acceptable levels are also expected to mitigate impacts to fisheries resources.
13.6 HAZARD TO LIFE
A risk assessment of the proposed gas receiving facility at the Tai Po Gas Production Plant and associated twin gas pipelines has been undertaken. The study considered releases that may occur as a result of loss of containment from the proposed facilities. The scope of the study is 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) 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:
* Gas Receiver Station;
* Route Option 2 (Tai Po Industrial Estate) for the onshore pipelines; and
* 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, it is expected that no insurmountable risk associated with the Project is envisaged. Mitigation measures to further reduce the risk levels associated with the Project have been recommended for consideration.
13.7 LANDFILL GAS ASSESSMENT
A qualitative hazard assessment of the migration of landfill gas and leachate/contaminated groundwater has been undertaken. It is concluded that the potential for landfill gas and leachate to affect the proposed Project during the construction and operational phase is very low. During construction, similar 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 during construction and operational phases.
13.8 AIR QUALITY
Potential air quality impacts arising from the construction and operation of the gas pipelines and the GRS have been evaluated. As the number of barges required for the pipelaying operation 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 GRS 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 GRS will utilise heat from steam/hot water generated within the existing gas production plant and no flare will be required at the GRS. As such, air quality impacts from the operation of the pipelines and GRS at Tai Po are not expected.
13.9 CULTURAL HERITAGE
A comprehensive baseline review identified no land based or submerged cultural heritage resources within the Study Area.
A comprehensive Geophysical Survey has been conducted within a 700 m pipeline corridor and ten anomalies were identified. 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.
13.10 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.
Regardless of the results of the construction noise impact assessment for restricted hours, the Noise Control Authority will process the Construction Noise Permit (CNP) application, if necessary, based on the NCO, the relevant technical memoranda issued under the NCO, and the contemporary conditions/situations.
13.11 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.
13.12 ENVIRONMENTAL OUTCOME
No unacceptable residual impacts are predicted for the construction and operation of the Project. This section presents the environmental outcome of the Project.
13.12.1 Environmentally Sensitive Areas Protected
The EIA process has facilitated integration of environmental considerations into the design process for the Project. The principal measures identified are those achieved through the careful routing of the pipelines and the installation methodology/pipeline design. In addition, a number of mitigation measures have been identified to minimise the potential for adverse environmental impacts to occur. The mitigation measures are detailed in full in the Implementation Schedule (Annex G). These measures will be implemented by Towngas and enforced by EPD by means of the EIAO.
One of the key environmental outcomes has been the ability to plan, design and ultimately construct the Project so that direct impacts to sensitive receivers are avoided, as far as practically possible. Towngas has undertaken a detailed assessment of alternatives for routing the pipelines, which has included consultations will local fishers, green groups and Government Departments. A number of alternative pipeline routes were studied and the preferred alignment avoids direct impacts to ecologically sensitive habitats and species. Key sensitive receivers avoided include:
* Corals fringing Tolo Channel and Mirs Bay;
* Landing at Tap Mun and Wong Chuk Kok Tsui;
* Marine Parks at Tung Ping Chau, Yan Chau Tong and Hoi Ha Wan;
* Artificial Reef Deployment sites in the Marine Parks and Long Harbour; and,
* Sites of Special Scientific Interest (SSSIs) at Ting Kok and Kei Ling Ha Mangal.
13.12.2 Environmentally Friendly Designs
In preparing the design and installation method for the submarine pipelines, a key concern was to take steps so that indirect impacts to water quality sensitive receivers, through disturbance to the seabed, were avoided or minimised. Consequently, the following approaches were taken to achieve the above.
* Bundle Configuration: The pipelines were designed as a bundle configuration so they can be laid in the same trench. Consequently the area of direct impact was reduced and hence the magnitude of potential impacts to ecological resources was reduced.
* Reduction in Indirect Impacts: The alignment chosen for the two pipelines was located at a sufficient distance from ecological sensitive receivers so that the temporary dispersion of sediment from the installation works was not predicted to affect the receivers at levels of concern (as defined by the WQO and tolerance criteria). By laying the pipelines in the same trench, the horizontal spread of suspended sediment was predicted to be restricted to a confined area in the centre of the Tolo Channel. Should the pipelines have been laid in separate trenches the horizontal spread of suspended sediment would have been much larger.
* Installation Equipment: The use of injection jetting along the majority of the route has minimised the severity of perturbations to water quality and hence allowed compliance with the WQOs at the sensitive receivers. This careful selection of installation equipment has helped avoid impacts to sensitive ecological receivers.
* Adoption of Acceptable Working Rates: The modelling work has demonstrated that the selected working rates for the dredging and jetting works will not cause unacceptable impacts to water quality. Consequently, unacceptable indirect impacts to marine ecological resources have been avoided.
13.13 OVERALL CONCLUSIONS
The EIA has critically assessed the overall acceptability of any environmental impacts likely to arise as a result of 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. Where necessary and practicable, the EIA has specified the conditions and requirements for the detailed design, construction and operation of the Project in order to mitigate environmental impacts to acceptable levels.
This EIA Study has predicted that the Project will comply with all environmental standards and legislation after the proposed construction stage mitigation measures are implemented. The EIA has thus demonstrated the acceptability of any residual impacts from the Project and the protection of the population and environmentally sensitive resources. Where appropriate, EM&A mechanisms have been recommended before and during construction to verify the accuracy of the EIA predictions and the effectiveness of recommended mitigation measures.
In conclusion, it is considered that the EIA provides a suitable basis for the Director of Environmental Protection to consider granting the Environmental Permit to allow the construction and operation of the Project.