This Executive Summary summarises the results of the Environmental Impact Assessment (EIA) for the Improvement Dredging for Lamma Power Station Navigation Channel (the “Channel”). The EIA accompanies an application for an Environmental Permit (EP) and has been prepared in accordance with the requirements of the Environmental Impact Assessment Ordinance (EIAO).

The existing Channel was originally formed in 1981 to facilitate the delivery of coal to the existing Lamma Power Station (LPS) by ocean going vessels. As a mainly coal-fired power station that relies on coal-fired units for base load operations, access for ocean going vessels carrying coal to LPS is essential for ensuring the continuity of electricity supply to Lamma and Hong Kong Islands. In order to maintain safe clearance of these vessels through the Channel, dredging of naturally accumulating sediment in the Channel is required.

The project proponent, The Hongkong Electric Company Limited (HK Electric), has commissioned Mott MacDonald Hong Kong Limited to carry out an environmental impact assessment (EIA) to confirm the environmental acceptability of the Improvement Dredging for Lamma Power Station Navigation Channel (hereafter referred to as “the Project”).

The Project is classified as a Designated Project under C.12 of Part I Schedule 2 of the EIAO, a dredging operation exceeding 500,000 m³, and a project profile for an EIA Study Brief was submitted to the Environmental Protection Department (EPD) on 15 December 2014 under Section 5(1)(a) of the EIAO. On 27 January 2015, EPD issued an EIA Study Brief for the Project (ESB-282/2014). The EIA report has been prepared according to the study brief requirements, which identified six key environmental assessment aspects to be addressed, including water quality, marine ecology, fisheries, hazard to life, noise and waste management implications arising from the construction and future operation of the Project.

This Executive Summary provides the key findings of these assessments and recommendations for future mitigation measures to ensure compliance with environmental legislation and guidelines.

2 Project Description

2.1 Scope and Location of the Project

The Project will provide and maintain safe clearance for ocean going marine vessels delivering coal shipments to LPS via the Channel, through the dredging of naturally accumulating sediment from the seabed. Hong Kong Marine Department stipulates the current minimum channel depth for safe marine passage to be no less than 15.5 metres below Chart Datum (-15.5 mCD) (approximately 15.65 metres below Profile Datum (-15.65 mPD)). In order to ensure this minimum depth is met, the Channel must be dredged and maintained at a level below this depth.

The Project area is approx. 262 ha and covers the main part of the Channel as well as the immediate area surrounding the Channel. The project area is indicated in Figure 2.1.

2.2 The Need for the Project

LPS is the only power station supplying Hong Kong and Lamma Islands with electricity. As coal forms part of the fuel mix and is delivered to LPS via the marine route, there is a need to maintain the Channel to ensure safe passage for ocean going vessels delivering coal supplies to LPS.

Historically, natural siltation varies across the Channel with an average annual rate ranging from 0.07 m to 0.19 m per year. To ensure that the natural siltation does not raise the seabed level to above -15.65 mPD (which is the minimum seabed level required to maintain safe passage for the vessels used to deliver coal to LPS), periodic improvement dredging of the Channel has historically, and will continue to be required as long as the Channel remains in use.

2.3 Consideration of Alternatives and Selection of Preferred Option

Alternative options were considered in the determination of the preferred Project option, including Channel alignments, dredging methods and the need for operation dredging (the target channel depth and associated dredging quantity and frequency). The environmental benefits and dis-benefits of these alternatives and the identified preferred options are presented in Table 2-1.

Table 2-1: Summary of Options Evaluation and the Preferred Option

Alternative Option	Environmental Dis-benefits	Environmental Benefits	Preferred Option
Channel Alignment Options
Existing Alignment	· Closer proximity to ecologically sensitive areas along west Lamma coastline	· Natural bathymetry lends itself to reduced dredge requirements · Sediment quality (confirmed as uncontaminated) and siltation rates are known · Increased distance from ecologically sensitive areas along northern Lamma coastline	ü Preferred Channel Alignment
Option 1 - Approach from the North	· Larger dredge volumes · New marine habitat areas directly affected · Unknown sediment quality and future siltation rates · Close proximity to ecologically sensitive areas along northern Lamma coastline	· Increased distance from ecologically sensitive areas along west Lamma coastline	û
Option 2 - Approach from the West	· Larger dredge volumes · New marine habitat areas directly affected · Unknown sediment quality and future siltation rates · Closer proximity to ecologically sensitive areas along Cheung Chau coastline	· Increased distance from ecologically sensitive areas along the Lamma coastline	û
Option 3 - Approach from the Southwest	· Larger dredge volumes compared to existing Channel · New marine habitat areas directly affected	· Increased distance from ecologically sensitive areas towards the north of Lamma and along west Lamma coastline	û
Dredging Method Options
Grab Dredger	· Suspended solids (SS) released throughout the water column	· Widely used in Hong Kong waters · Water quality impacts significantly reduced through silt –curtain application	ü Preferred Dredging Method
Suction Dredger (Plain)	· Mitigation measures cannot be applied to further minimise water quality impacts	· Water quality impacts can be insignificant · Efficient technology resulting in efficient dredge programme	û
Suction Dredger (TSHD)	· Mitigation measures cannot be applied to further minimise water quality impacts	· Widely used in Hong Kong waters · Water quality impacts can be insignificant · Efficient technology resulting in efficient dredge programme	ü Preferred Dredging Method
Bucket Dredger	· Noise impacts from operation · Water quality impacts from high rate of SS release	None	û
Backhoe Dredger	· Water quality impacts from high rate of SS release	None	û
Channel Depth (Quantity and Frequency) Options/ Need for Operation Dredging
- 16.5 mPD	· Relatively shorter recurrence frequency	· No increase in dredging area · Less sediment quantity required for dredging and disposal · Duration of construction phase and dredging quantity would be minimised by rotating between selected high spot dredging and full re-profiling	ü Preferred channel depth (and target dredge quantity/ frequency)
- 17.0 mPD	· Large sediment quantity required for dredging and disposal · Long dredging duration and associated marine ecology disturbance and sediment release · Larger dredging area required to form stable slopes	· Longer interval between dredging periods	û

Separately, consideration was given to vessel sizes which may reduce the operation dredging requirement. However the limited market availability of smaller vessels meeting the gearless requirement for unloading at LPS jetty would jeopardise security of coal supply and delivery to LPS, which makes this alternative infeasible.

2.4 Works Programme and Interface with Concurrent Projects

The initial improvement dredging of the Channel to a target depth ^[1] of - 16.5 mPD constitutes the construction phase of the Project for the purpose of the EIA study. The preliminary estimated sediment quantity to be dredging during construction phase is up to approx. 3.2 million m³, however the actual quantity is subject to detailed bathymetry survey before commencement of construction. The construction phase is scheduled to commence in 2019. While the Contractor is yet to be engaged, it is expected that construction can be completed between 12 months and 18 months, subject to the Contractor’s arrangements.

Given the rate of natural siltation in the Channel, periodic improvement dredging to a target depth of - 16.5 mPD will be required throughout the operation phase to maintain sufficient clearance in the Channel. Based on historical siltation rates in the Channel, it is estimated that the recurrent improvement dredging during operation phase will be required approximately once every 4 to 10 years in order to maintain sufficient clearance. As full re-profiling of the Channel would not be required for every recurrent dredging event, the dredging volumes would be minimised to approx. 0.9 Mm³ for recurrent dredging events every 4 years or so, which would delay the full re-profiling to every 10+ years, with an estimated dredging volume of up to approx. 2.9 million m³ (to re-profile the whole Channel with stable slopes). These dredging quantities represent the upper limit for environmental assessment purpose. Actual dredging quantities may vary due to siltation and will be subject to detailed bathymetry survey before commencement of each recurring dredging event.

During the construction and operation phases, the following planned and committed developments in the vicinity may have concurrent environmental impacts with the Project:

§ Planning and Engineering Study on Future Land Use at Ex-Lamma Quarry Area at Sok Kwu Wan, Lamma Island - Feasibility Study

§ 1,800MW Gas-fired Power Station at Lamma Extension

§ Development of a 100MW Offshore Wind Farm in Hong Kong

§ Integrated Waste Management Facilities at an Artificial Island near Shek Kwu Chau

§ Providing Sufficient Water Depth for Kwai Tsing Container Basin and its Approach Channel.

3 Summary of Environmental Impact Assessment

3.1 Water Pollution

The water quality impact assessment has been conducted in accordance with Annexes 6 and 14 of EIAO-TM as well as the technical requirements stipulated in Clause 3.4.2 and Appendix B of the EIA Study Brief No. ESB-282/2014. The study area covers the Western Buffer and Southern Water Control Zones (WCZs). Water sensitive receivers (WSRs) were identified in within this study area, including seawater intakes, beaches, corals, fish culture zones and ecologically sensitive areas / areas of conservation importance. Sediment sampling was conducted to ascertain the elutriation potential of various contaminants in the sediment and to determine the sediment oxygen demand. Water quality criteria were identified for assessment of water quality impacts due to Project activities

3.1.1 Construction Phase

The key potential water quality impacts arising from construction activities of the Project include release of SS and turbidity due to dredging activities and release of contaminants and/or impact on dissolved oxygen due to disturbance of sediment. To assess the key potential water quality impacts due to the project, hydrodynamic modelling was undertaken to quantify SS and contaminant release. The Project area was divided into four working zones and a ‘backwards’ modelling approach was adopted to determine the maximum allowable dredging rates at each zone that would maintain compliance at all WSRs. Based on the results and taking into account the potential activities of concurrent projects in the vicinity, recommendations were made on the maximum allowable dredging rates for the Project, which is summarised in Table 3-1.

Table 3-1: Recommended Maximum Allowable Dredging Rates

*Maximum allowable dredging rate (m³/day)**	Dry Season				Wet Season
*Maximum allowable dredging rate (m³/day)**	A	B	C	D	A	B	C	D
Grab Dredger	49,800	90,400	89,600	57,800	72,100	73,700	63,500	38,500
TSHD	78,900	137,600	171,900	63,300	132,500	78,800	65,100	22,200

*Values are rounded to the nearest hundred

With these recommended maximum allowable dredging rates, all WSRs would comply with the water quality criteria. No adverse water quality impacts due to sedimentation, release of contaminants from sediment and dissolved oxygen depletion were identified from the modelled and calculated results based on the recommended maximum allowable dredging rates. Nevertheless, controls to safeguard water quality during construction phase are specified in the Environmental Monitoring and Audit Manual and would be implemented as part of the environmental monitoring and audit programme for the Project.

3.1.2 Operation Phase

For this Project, the marine activities (improvement dredging) to be conducted during construction phase and the recurring improvement dredging to be conducted during operation phase are the same, though there may be differences in the dredgers and quantity of dredged sediment each time. The ‘backwards’ modelling approach adopted provides the recommended maximum allowable dredging rates which are applicable to all recurring improvement dredging operations. These recommended maximum allowable dredging rates are considered to be robust as they have taken into account the following:

§ The long term baseline marine water quality in Southern and Western Buffer WCZs (1986 to 2015).

§ The hydrodynamics for the whole of Hong Kong waters (which is covered by the water quality model).

§ Incorporated a 10% reduction in the maximum allowable dredging rates as contingency to cater for changes in the status of concurrent projects over time.

In addition, the Project area has been periodically dredged since 1990 and the approach adopted for this assessment is consistent with, and has been successfully adopted in the preceding EIA for dredging at this Project location (refer to the approved EIA report No. AEIAR-069/2003), which has demonstrated no adverse water quality impacts. With the application of the recommended maximum allowable dredging rates and mitigation measures, no adverse water quality impacts are anticipated during operation phase recurrent dredging. Further controls to safeguard water quality during operation phase recurrent improvement dredging are specified in the Environmental Monitoring and Audit Manual and would be implemented as part of the environmental monitoring and audit programme for the Project.

3.2 Marine Ecological Impact

The Marine Ecological Impact Assessment has been conducted in accordance with the requirements stipulated under Section 3.4.3 and Appendix C of the EIA Study Brief No. ESB-282/2014 as well as Annexes 8 and 16 of the EIAO-TM. The Study Area of the Project for ecological impact assessment will cover the Southern Water Control Zone (WCZ) and Western Buffer WCZ as designated under the Water Pollution Control Ordinance.

Based on literature review and field survey findings, the key habitats and recognised sites of conservation interest identifies within the Study Area are Sham Wan SSSI and Restricted Area, hard shore habitat including artificial and rocky shores, soft shore habitat (sandy shores), sub-tidal habitats including soft bottom substrates (benthos) and hard bottom substrate (with and without corals), and marine waters (potential marine park at South Lamma, Green Turtle and Finless Porpoise habitat). From the evaluation of the potential ecological impacts, the direct impact of the loss of subtidal soft bottom habitat and benthic communities is considered to be minor. Similarly, the indirect disturbance impact on benthic communities and coral communities are expected to be minor, while the indirect disturbance impact on intertidal communities is anticipated to be negligible. The potential impact on the Green Turtle and its nesting site at south-eastern Lamma is also expected to be minor. For the disturbance impact on cetaceans, dredging activities for both construction and operation phases of this Project are unlikely to cause any long-term damage to cetaceans and the potential disturbance or collision impacts of proposed dredging works on finless porpoise are considered as minor since the past dredging works had no significant effect on finless porpoise. Therefore, it is concluded that the overall marine ecological impact is expected to be minor.

Mitigation/precautionary measure is only considered to be necessary to further avoid and minimize the potential impacts on the cetacean Finless Porpoise for both construction and operation (operation dredging) phases. It is recommended to avoid dredging Zone 4 of the navigation channel (except for necessary hotspot / localised dredging) during the calving season from February to April to avoid disturbance impacts. To minimise the disturbance to Finless Porpoise habitat outside the Project Area, it is recommended that vessel movements to disposal grounds to bypass the Finless Porpoise habitat area in southwest and east Lamma, and to implement a maximum speed limit of 10 knots in south and east Lamma waters. All vessel operators working on the Project should be thoroughly briefed on the possible occurrence of Finless Porpoise within and in the vicinity of the Project Area and along routes to the Project Area, as well as rules for safe vessel operation around cetaceans and slowing down to 10 knots in the presence of cetaceans in south and east Lamma waters. With the implementation of the abovementioned mitigation measures and water quality mitigation measures, no residual impact on the marine environment is expected.

3.3 Fisheries Impact

A fisheries impact assessment has been conducted in accordance with Clause 3.4.4 and Appendix D of the EIA Study Brief No. ESB-282/2014 as well as Annexes 9 and 17 of the EIAO-TM, to include an assessment of the following:

§ Size of affected area

§ Loss of fisheries resources / production

§ Destruction and disturbance of nursery and spawning grounds

§ Impact on fishing activity

§ Impact on aquaculture activity.

The potential fisheries impacts including loss of fishing ground, loss of spawning / nursery grounds for commercial fisheries resources, loss of fisheries resources and impact on fisheries operation are considered to be minor for the improvement dredging works during construction phase and operation period due to the short-term and small-scale nature of the works. A ‘backwards’ modelling approach has been adopted, which estimates the maximum dredging rates which would ensure no unacceptable environmental impacts. The results were then verified with a ‘forwards’ model taking into account concurrent projects. The modelling result demonstrated that there would be no significant adverse indirect fisheries impact caused by the deterioration of water quality. With the implementation of water quality control measures, no fisheries specific measure is considered necessary.

3.4 Hazard to Life

A Hazard Identification workshop has been organized with various stakeholders including HK Electric to identify the hazards associated with the dredging works using the Grab Dredging method and TSHD method near the existing natural gas submarine pipeline. For each of the identified hazards, both existing and potential mitigation measures have been explored. The findings have been properly recorded in the worksheets.

The Hazard Analysis has evaluated the risk based on the risk acceptability defined in the ETWB Risk Management User Manual and has considered all the existing engineering measures and procedural controls in order to reduce the risks to acceptable level. Where the level of risk is initially assessed as high, additional safeguards have been recommended by the attendees of the workshop that will be effective in controlling the risk to an acceptable level. All the risk items will be subject to ongoing review and monitoring to ensure the level of risk will not increase throughout the dredging operation of the project.

3.5 Noise Impact

Potential noise impacts associated with the construction and operation phases of the Project have been assessed in accordance with the technical requirements stipulated in Clause 3.4.6 and Appendix E of the EIA Study Brief (ESB-282/2014), as well as Annexes 5 and 13 of the EIAO-TM.

3.5.1 Construction Phase

Quantitative assessment of the potential construction noise impact has been carried out in accordance with the EIA study brief requirements. With the optimum quantity of construction plants, the construction noise levels at all noise sensitive receivers (NSRs) are predicted to comply with the relevant noise criteria. Adverse construction noise impacts are therefore not anticipated in this project.

The proposed construction has been assessed on a 24 hours per day basis. As the construction noise impact levels at the representative NSR are predicted to comply with the noise criteria during restricted hours, it is considered feasible for the construction works to be undertaken during restricted hours. In case of any construction activities during restricted hours, it will be the Contractor’s responsibility to ensure compliance with the Noise Control Ordinance and the relevant TMs. The Contractor will be required to submit a Construction Noise Permit (CNP) application and obtain a CNP from the Noise Control Authority.

3.5.2 Operation Phase

Some operation dredging for the improvement work to maintain the required depth within the navigation channel will be required. The noise criteria for the construction phase are also applicable to the future operation dredging during operational phase of this Project.

Same plant inventory has been assumed for the operation dredging as that for the construction dredging in this Project, the noise levels at the representative NSR during operation dredging are expected to be no worse than during the construction phase and will comply with the construction noise criteria.

3.6 Waste Management Implications

3.6.1 Construction Phase

The major waste types generated by the construction activities will be marine sediment. Based on the review of the sediment quality data from the approved EIA report No. AEIAR-069/2003, previous marine site investigation studies and Sediment Quality Report (SQR), the marine sediment to be dredged is classified as Category L (for Type 1, Open Sea Disposal). The total volume of dredged sediment requiring marine disposal is estimated to be up to 3.2 million m³. Subject to the result of future bathymetric surveys, sediment sampling will be carried out at the actual dredging area prior to dredging activity in the future to confirm the classification of sediment, and to comply with the DASO permitting requirements and Marine Fill Committee’s (MFC) approval on disposal allocation. With implementation of the recommended mitigation measures and management procedures in accordance with the requirements of PNAP ADV-21, no environmental impact is anticipated.

Chemical waste will be generated from maintenance and servicing of dredging plant and equipment as well as general refuse to be generated from the workforce. Provided that all these identified wastes are handled, transported and disposed of in strict accordance with the relevant legislative and recommended requirements and that the recommended mitigation measures are properly implemented, no adverse environmental impact is expected during the construction phase.

3.6.2 Operation Phase

During the operation phase, it is anticipated that with recurrent dredging of localised high spots once every 4 years or so (with estimated dredging quantity up to 0.9 million m³ each time), full re-profiling of the Channel with a dredging quantity of up to 2.9 million m³ can be delayed to approx. once every 10+ years. The extent of dredging area within the project boundary will be subjected to the result of the future bathymetric surveys. Based on the previous site investigation studies, the marine sediment to be dredged is expected to be classified as Category L (for Type 1, Open Sea Disposal). In any case, recurring improvement dredging would require sediment sampling and testing in accordance with the requirements of the PNAP ADV-21 for proper disposal of the dredged sediment. MFC would determine the most appropriate marine disposal site on the basis of the testing results and formally allocate marine disposal space in accordance with the PNAP ADV-21. With implementation of the recommended mitigation measures and management procedures in accordance with the requirements of PNAP ADV-21, no environmental impact is anticipated.

3.7 Impact Summary

A summary of the environmental impacts for individual aspects in the EIA report is presented in Table 3-2.

Table 3-2: Summary of Environmental Impacts

Assessment Points	Results of Impact Predictions	Relevant Standards / Criteria	Extent of Exceedances Predicted	Impact Avoidance Measures Considered	Mitigation Measures Proposed	Residual Impacts
Water Quality Impact – Construction and Operation Phase
WSRs within: § Southern WCZ § Western Buffer WCZ	§ No exceedance of SS criteria § No exceedance of sedimentation criteria § No adverse water quality impact due to turbidity § No adverse water quality impact due to release of contaminants from marine sediment § No adverse water quality impact due to depletion of dissolved oxygen at WSRs § No significant changes in hydrodynamics before and after dredging	§ EIAO-TM Annex 6 & 14 § Water Pollution Control Ordinance (WPCO) § Dumping at Sea Ordinance (DASO) § Southern WCZ WQO § Western Buffer WCZ WQO § WSD’s water quality criteria for flushing water intake § Sediment Deposition and SS Criteria for Corals, “Standards and Criteria for Pollution Control in Coral Reef Areas” § European Union Environmental Quality Standards (EU EQS) § The US Environmental Protection Agency (USEPA) Criteria Maximum Concentration (CMC) § The USEPA Criteria Continuous Concentration (CCC) § Australian and New Zealand (ANZ) guidelines for aquatic ecosystems	No exceedances predicted due to the project.	§ Maximum allowable dredging rates specified in Table 3-1 for each respective working zone and for the respective dredging method. § Prohibiting use of lean mixture overboard (LMOB) system for TSHDs	§ Dredging by either closed grab dredgers and/or TSHDs. The grab dredgers and TSHDs shall not be operating at the same time. § Application of the lowest maximum dredging rate in total if dredging work is carried out in more than one working zone in any day. § Use of cage-type silt curtains for the grab dredger options. § Closed grab capacity of grab dredgers to be not less than 8 m³(except near the submarine pipeline). § Sizing of vessels to reduce undue turbidity generated by turbulence from vessel movement or propeller wash § Reducing vessel speeds to no more than 10 knots within the project site boundary	No adverse residual impacts predicted
Marine Ecological Impact – Construction and Operation Phase
Flora, fauna and other components of the ecological habitats within: § Southern WCZ § Western Buffer WCZ	§ Direct impact of temporary loss of subtidal soft bottom habitat and benthic communities due to dredging is minor § Indirect disturbance impact on benthic communities associated with sedimentation generated by dredging works is minor § Indirect disturbance impact on coral communities associated by water quality impacts is minor § Indirect disturbance impact on intertidal communities associated with potential perturbations in water quality is negligible § Disturbance impact on Green Turtles and their inter-nesting habitat is minor § No adverse disturbance impact on cetaceans’ habitat use and other indirect impacts associated with construction vessels	§ Wild Animals Protection Ordinance (Cap. 170); § Protection of Endangered Species of Animals and Plants Ordinance (Cap. 586); § Marine Parks Ordinance (Cap. 476); § Town Planning Ordinance (Cap. 131); § Environmental Impact Assessment Ordinance (Cap. 499) and the Technical Memorandum on Environmental Impact Assessment Process (EIAO-TM); § EIAO Guidance Notes No. 6/2010 Some Observations on Ecological Assessment from the Environmental Impact Assessment Ordinance Perspective; § EIAO Guidance Notes No. 7/2010 Ecological Baseline Survey for Ecological Assessment; § EIAO Guidance Note No. 11/2010 Methodologies for Marine Ecological Baseline Surveys; § The Convention on Biological Diversity (1992) and the Strategic Plan for Biodiversity 2011-2020 and Aichi Biodiversity Targets; § Convention on International Trade in Endangered Species of Wild Flora and Fauna (CITES); § The IUCN Red List of Threatened Species; and § Wild Animal Protection Law of the Peoples’ Republic of China (PRC).	N/A	§ Avoid dredging for Zone 4 of the navigation channel from February to April when it is the most sensitive period for the calves, with the exception of necessary hotspot / localised dredging of being kept under the recommended maximum allowable dredging rates which would ensure no unacceptable disturbance impacts on Finless Porpoise.	§ Vessel movements to disposal grounds are recommended to bypass the Finless Porpoise habitat area in southwest and east Lamma § Implement a maximum speed limit of 10 knots in south and east Lamma waters § All vessel operators working on the Project should be thoroughly briefed on the possible occurrence of Finless Porpoise within and in the vicinity of the Project Area and along routes to the Project Area, as well as rules for safe vessel operation around cetaceans and slowing down to 10 knots in the presence of cetaceans in south and east Lamma waters.	Residual impacts are negligible
Fisheries Impact – Construction and Operation Phase
§ Lo Tik Wan FCZ and associated artificial reefs § Sok Kwu Wan FCZ § Cheung Sha Wan FCZ § Nursery and spawning ground for fisheries § Capture fisheries activities around Lamma waters	§ Low impact on loss of fishing ground, fisheries resources and fishing operation	§ EIAO-TM Annexes 9 and 17 § Fisheries Protection Ordinance (Cap.171) § Marine Fish Culture Ordinance (Cap. 353) § Water Pollution Control Ordinance (Cap. 358)	No exceedances predicted due to the project.	§ Maximum allowable dredging rates specified in Section 3.7.1.3 for each respective working zone and for the respective dredging method. § Prohibiting use of lean mixture overboard (LMOB) system for TSHDs	§ Dredging by either closed grab dredgers and/or TSHDs. The grab dredgers and TSHDs shall not be operating at the same time. § Application of the lowest maximum dredging rate if dredging work is carried out in more than one working zone in any day. § Use of cage-type silt curtains for the grab dredger options. § Closed grab capacity of grab dredgers to be not less than 8 m³(except near the submarine pipeline). § Sizing of vessels to reduce undue turbidity generated by turbulence from vessel movement or propeller wash § Reducing vessel speeds to no more than 10 knots within the project site boundary	No adverse residual impacts predicted
Hazard to Human Life – Construction and Operation Phase
Grab Dredging Method and Trailing Suction Hopper Dredging Method (TSHD) near the existing natural gas submarine pipeline	For Grab Dredging method A total of 30 hazards have been identified, with 13 of them being ranked in High risk level while the rest are in Medium risk level. For TSHD method A total of 23 hazards have been identified, with 15 of them being ranked in High risk level while the rest are in Medium risk level	Risk Management User Manual published by the Environment Transport and Works Bureau 2005	N/A	General 1. Rock armour with 730 long is provided along the pipeline inside the Channel. 2. Shut down the pipeline in case of a large gas release. 3. Non anchor zone will be applied. 4. Navigation lights and markers on will be provided on working vessel. 5. When the visibility is low, navigational warnings will be broadcast to advise vessels to proceed with a safe speed. 6. Typhoon moorings for all marine plant shall be arranged. 7. Marine operations terminated and marine plant sent to the designated typhoon moorings when No.3 or above typhoon signal is hoisted. 8. Mariner Notice will be sent out to notify the dredging works area. 9. Coordinate marine traffic arrangement . 10. The Contractor will be requested to comply with all local requirement for safe traveling inside Hong Kong. 11. The Engineer evaluates the marine traffic arrangement. 12. Advance notice will be sent to Contractor about the berthing and unberthing of coal vessel. 13. Any vessel occupying the navigation channel shall be removed before berthing/unberthing of coal vessels. 14. Large and moveable objects on the vessel will be secured. 15. Fire-fighting equipment are provided in the working vessel. 16. Engineer will review and inspect the fire-fighting facilities and licence of the dredger. 17. The section of pipeline rising from seabed to onshore is covered by armour rocks, not being exposed. 18. The project site boundary will be marked with flags, marker buoys and lights. 19. The project site boundary is about 100m away from the seawall where the pipeline transits from onshore to seabed. 20. Floating plant shall be maintained in a satisfactory and seaworthy condition, and shall have adequate attendance by competent seamen at all times. The plant shall be fully provided with sound and satisfactory ropes, lines and moorings and shall be fully equipped with lights. 21. Chain/echo sounding will be conducted during trial run. Specific for Grab Dredging 1. An anchor exclusion zone will be established. All relevant data will be input into the GPS by surveyor. 2. During anchoring, the tugboat masters will make use of the GPS on board of tug boat. 3. A radio communications network shall be provided by the Contractor 4. A competent person will be deployed in the tug boat to oversee the anchor deployment process. 5. Positions of anchor shall be monitored regularly. 6. DGPS will be mounted on top of the dredge boom and the exact location will be displayed. 7. As-built details of the pipeline will be provided. 8. The location of the pipeline will be highlighted at the dredging grid plan and all operatives on board of the dredging team will be aware of it 9. The grab will be held by using braking system in around 100mm layer by layer approaching from existing seabed to the final design level. 10. Four anchors will be deployed. 11. Dredging works performed near to the pipeline shall be performed at day time and away from the seawall. 12. Design capacity of the hopper barge will restrict over loading. 13. Barges shall not be filled to a level exceeding its maximum capacity. 14. The split type hopper barge will have locking device. 15. Movement of dredger will be controlled by winches after anchoring. Specific for TSHD 1. The TSHD will only moor outside the Channel. 2. Navigation lights and markers will be provided in the TSHD. 3. TSHD manevours away from the pipeline in case the draghead cannot be retrieved back. 4. The dredging path will be in parallel with the pipeline alignment. 5. Electronic sensors will be installed in the dragheads and locking device will be provided in hopper. 6. TSHD is equipped with compensator.	General 1. Confirm all anchors are secured in position. 2. Avoid the working vessel traveling during berthing and unberthing of coal vessel or after sunset/low visibility. 3. Check the weather information from Marine Department. 4. Consider the preliminary coal vessel shipping plan provided by HK Electric. 5. Confirm that all large and moveable objects are secured on the dredger. 6. Use electrical appliance for cooking and smoking onboard not allowed. 7. Store dangerous goods in an explosion proof cabinet according to local requirements. 8. Check any loosen anchoring system on board regularly to avoid drifting of the working vessel. 9. Prepare a plan to cater for drifting of working vessel. 10. Provide maintenance records of the working vessel and lifting appliance and gears for dredger. 11. Request working vessel not to stay right above the pipeline unless necessary. 12. Prepare a method statement for dredging works and ensure it is followed during the operation. 13. Conduct the dredged profile measurement and the results will be immediately reviewed by Engineer. 14. The foreman will have the knowledge about dredged profile measurement. 15. Conduct underwater survey by diver at the location of pipeline after dredging. 16. Impose a safe traveling speed and provide an indicator onshore with a good visibility in the atmosphere when the dredger travels near the seawall. Specific for Grab Dredging 1. Provide buoys above pipeline alignment. 2. Deploy a guard boat to alert third party vessel not to travel inside the dredging works area. 3. Dredger maintains an enough separation distance from the seawall of Lamma Power Plant. 4. Check if the anchor dropping point is within the anchorage area. 5. Verify the accuracy of all GPS/DGPS system. 6. Tug boat travels at a low speed when anchor is placed on it. 7. Check if the length of anchor chain is sufficient for the non-anchor zone. 8. Deploy a guard boat to monitor the separation distance between the anchor chain and 3^rd party vessel. 9. Observe tidal conditions and sea current in the works area. 10. Check the depth of the seabed and maintain the bottom of the silt curtain to be above the seabed. 11. Verify if the dredger is near the pipeline when it arrives at the project site or when it needs to be relocated. 12. The grab shall be lowered slowly to the seabed when the dredging works takes place near the pipeline. 13. Conduct a trial run for the dredging works. Establish communication network among working members in the trial run. 14. Monitor pressure fluctuation in the pipeline. 15. Use a much smaller grab for dredging works with control movement near the pipeline. 16. Review the type of grab used for the dredging works near the pipeline. 17. Confirm only the correct type of grab will be installed in the dredger. 18. Dredger master observes if there is any rock being dredged from seabed. 19. Send a diver to seabed to indicate the point where the pipeline without rock armour and provide buoys right above it. 20. Retrieve the grab back to the dredger after dredging works in each day. 21. Use GPS to ensure the dredger is not carried away by sea current. 22. Monitor the draught of barge. 23. Retrieve all anchors before the vessel travels to non-anchor zone. 24. Hopper barge not to stay near the pipeline. Specific for TSHD 1. The working vessel leaves the Channel in case of fire and not to stay near the pipeline. 2. The dredging path avoids potential infringement to nearby structure. 3. Provide maintenance record for the dredger and the compensator. 4. Prepare a plan to minimize the impact to the pipeline due to failure of suction pipe gantries system or draghead is stuck with rock armour or the seabed. 5. Provide the Contractor the details of the pipeline. 6. TSHD travels in a slow speed and not to lower suction pipe when the dredging works is near the pipeline. 7. Confirm the operability of the compensator by visual check. 8. Remind the dredger master to observe if liquid flow is reduced by clogging of suction pipe.	Adverse residual impact is not anticipated.
Noise Impact – Construction Noise
The first layer of houses / school of each village located close to the site boundary have been selected as assessment points.	§ With the optimum quantity of construction plants, the construction noise levels at all NSRs are predicted to comply with the relevant noise criteria. Adverse construction noise impacts are therefore not anticipated in this project	§ Noise Control Ordinance; § EIAO-TM; relevant Guidance Notes under EIAO; and § Technical Memorandum on Noise from Construction Work other than Percussive Piling.	N/A	§ The quantity of construction plant not more than the optimum quantity as specified in Section 7.6.	N/A	No adverse residual impacts would be anticipated.
Waste Management Implication – Construction and Operation Phase
Project area	§ The total volume of dredged sediment requiring marine disposal is estimated to be up to 3.2 million m³ during construction phase. During operation phase, with recurrent dredging of localised high spots once every 4 years or so (with estimated dredging quantity up to 0.9 million m³ each time), full re-profiling of the Channel with a dredging quantity of up to 2.9 million m³ can be delayed to approx. once every 10+ years. Marine sediment to be dredged is classified as Category L (for Type 1, Open Sea Disposal) § Small quantity of chemical waste from maintenance and servicing of dredgers § General refuse of maximum daily arising of approximately 300 kg from construction workforce	§ Annexes 7 and 15 of EIAO-TM § Waste Disposal Ordinance (Cap. 354); § Waste Disposal (Chemical Waste) (General) Regulation (Cap. 354C); § Dumping at Sea Ordinance (DASO) (Cap. 466); and § Public Cleansing and Prevention of Nuisances Regulation (Cap. 132BK).	N/A	N/A	§ Distance between the barge and the dredging point should be shortened as far as possible to avoid dropping of sediment from the close grab to seawater; § During transportation and disposal of the dredged marine sediments, mitigation measures should be taken to minimise potential impacts; § Handling of chemical wastes in accordance with the Code of Practice on the Packaging, Labelling and Storage of Chemical Wastes, and disposal of chemical wastes at licensed chemical waste recycling/ treatment facilities; and § General refuse should be stored in enclosed bins or compaction units and delivered to the refuse collection point accordingly.	No adverse residual impacts would be anticipated.

[1] While the Project aims to dredge to a target depth of -16.5 mPD, some overdredge may occur due to the limited precision control of dredging depths in practice.