EIA

Improvement Dredging for Lamma Power Station Navigation Channel

Environmental Impact Assessment Report

May 2017

The Hongkong Electric Company Limited

Contents

Chapter Title

1 Introduction

1.1_______ Project Background______________________________________________________________

1.1.1______ Project History_________________________________________________________________

1.2_______ Purpose and Objectives of the Project_______________________________________________

1.3_______ Location and Scale of the Project___________________________________________________

1.4_______ EIA Study Brief Requirements______________________________________________________

1.4.1______ Designated Project under the EIA Ordinance__________________________________________

1.4.2______ Purpose of the EIA Study_________________________________________________________

1.4.3______ Objectives of the EIA Study_______________________________________________________

1.4.4______ Scope of the EIA Study___________________________________________________________

1.5_______ Structure of this EIA Study Report___________________________________________________

2 Project Description

2.1_______ Project Overview_______________________________________________________________

2.2_______ The Need for the Project__________________________________________________________

2.3_______ Scenario With the Project_________________________________________________________

2.4_______ Scenario Without the Project_______________________________________________________

2.5_______ Consideration of Alternative Options, Construction Methods and Work Sequences_______________

2.5.1______ Channel Alignment Options________________________________________________________

2.5.2______ Dredging Methods_______________________________________________________________

2.5.3______ Phased Implementation___________________________________________________________

2.5.4______ Use of Smaller Vessels___________________________________________________________

2.5.5______ Need for Operation Dredging_______________________________________________________

2.5.6______ Summary of Options Evaluation and Selection of Preferred Option__________________________

2.6_______ Work Programme______________________________________________________________

2.7_______ Potential Concurrent Projects_____________________________________________________

3 Water Quality Impact Assessment

3.1_______ Introduction____________________________________________________________________

3.2_______ Environmental Legislation, Standards, Guidelines and Criteria______________________________

3.2.1______ Environmental Impact Assessment Ordinance (EIAO)____________________________________

3.2.2______ Water Pollution Control Ordinance (WPCO)____________________________________________

3.2.3______ Dumping at Sea Ordinance (DASO)_________________________________________________

3.2.4______ Water Services Department Standards for Seawater Intakes_______________________________

3.3_______ Baseline Conditions_____________________________________________________________

3.3.1______ Study Area and Water Sensitive Receivers____________________________________________

3.3.2______ Baseline Water Quality___________________________________________________________

3.3.3______ Baseline Sediment Quality_______________________________________________________

3.4_______ Assessment Criteria____________________________________________________________

3.4.1______ Suspended Solids______________________________________________________________

3.4.2______ Dissolved Oxygen______________________________________________________________

3.4.3______ Unionised Ammonia and Total Inorganic Nitrogen______________________________________

3.4.4______ Metals and Other Contaminants___________________________________________________

3.4.5______ Sedimentation_________________________________________________________________

3.5_______ Identification of Pollution Sources__________________________________________________

3.5.1______ Construction Phase Water Quality Impact____________________________________________

3.5.2______ Operation Phase Water Quality Impact______________________________________________

3.5.3______ Concurrent Projects____________________________________________________________

3.6_______ Water Quality Assessment Methodology_____________________________________________

3.6.1______ Hydrodynamic Model___________________________________________________________

3.6.2______ Suspended Sediment___________________________________________________________

3.6.3______ Release of Contaminants from Sediment_____________________________________________

3.6.4______ Impacts on Dissolved Oxygen_____________________________________________________

3.6.5______ Recurrent Improvement Dredging__________________________________________________

3.7_______ Evaluation and Assessment of Water Quality Impacts___________________________________

3.7.1______ Suspended Sediment___________________________________________________________

3.7.2______ Sedimentation_________________________________________________________________

3.7.3______ Release of Contaminants from Sediment_____________________________________________

3.7.4______ Impact on Dissolved Oxygen______________________________________________________

3.7.5______ Recurrent Improvement Dredging__________________________________________________

3.8_______ Mitigation Measures____________________________________________________________

3.9_______ Evaluation of Residual Impacts____________________________________________________

3.10______ Environmental Monitoring and Audit Requirements_____________________________________

3.11______ Conclusion___________________________________________________________________

4 Marine Ecological Impact

4.1_______ Introduction____________________________________________________________________

4.2_______ Environmental Legislation, Standards, Guidelines and Criteria______________________________

4.3_______ Study Area and Methodology______________________________________________________

4.3.1______ Study Area____________________________________________________________________

4.3.2______ Desktop Review________________________________________________________________

4.3.3______ Ecological Field Surveys__________________________________________________________

4.4_______ Baseline Conditions and Marine Ecological Sensitive Receivers_____________________________

4.4.1______ Marine Waters_________________________________________________________________

4.4.2______ Recognized Sites of Conservation Importance__________________________________________

4.4.3______ Coral Communities and Sub-tidal Hard Bottom Habitat___________________________________

4.4.4______ Benthic Infauna and Sub-tidal Soft Bottom Habitat______________________________________

4.4.5______ Intertidal Habitats and Communities________________________________________________

4.5_______ Evaluation of Ecological Importance________________________________________________

4.5.1______ Habitat Evaluation______________________________________________________________

4.5.2______ Species of Conservation Interest___________________________________________________

4.6_______ Identification and Evaluation of Potential Marine Ecological Impacts_________________________

4.6.1______ Assessment Methodology________________________________________________________

4.6.2______ Identification of Potential Ecological Impacts__________________________________________

4.6.3______ Evaluation of Potential Ecological Impacts____________________________________________

4.7_______ Mitigation/Precautionary Measures_________________________________________________

4.8_______ Evaluation of Residual Impacts____________________________________________________

4.9_______ Ecological Monitoring and Audit Requirements________________________________________

4.10______ Conclusion___________________________________________________________________

4.11______ References___________________________________________________________________

5 Fisheries Impact Assessment

5.1_______ Introduction____________________________________________________________________

5.2_______ Environmental Legislation, Standards, Guidelines and Criteria_____________________________

5.3_______ Baseline Conditions_____________________________________________________________

5.3.1______ Study Area____________________________________________________________________

5.3.2______ Physical Environmental Background_________________________________________________

5.3.3______ Fisheries Baseline_______________________________________________________________

5.4_______ Identification and Evaluation of Potential Fisheries Impacts________________________________

5.4.1______ Construction Phase______________________________________________________________

5.4.2______ Operation Phase________________________________________________________________

5.5_______ Mitigation of Adverse Environmental Impacts__________________________________________

5.6_______ Cumulative Impacts_____________________________________________________________

5.7_______ Evaluation of Residual Impacts____________________________________________________

5.8_______ Ecological Monitoring and Audit Requirements________________________________________

5.9_______ Conclusion___________________________________________________________________

5.10______ References___________________________________________________________________

6 Hazard to Life Assessment

6.1_______ Introduction____________________________________________________________________

6.1.1______ Project Background______________________________________________________________

6.1.2______ Objectives____________________________________________________________________

6.1.3______ Scope of Work_________________________________________________________________

6.2_______ Description of Existing Submarine Natural Gas Pipeline___________________________________

6.2.1______ Submarine Natural Gas Pipeline____________________________________________________

6.2.2______ Physical Properties of Natural Gas__________________________________________________

6.3_______ Description of Dredging Methods____________________________________________________

6.3.1______ Grab Dredging_________________________________________________________________

6.3.2______ Trailing Suction Hopper Dredging___________________________________________________

6.4_______ Risk Assessment Methodology____________________________________________________

6.4.1______ Qualitative Risk Assessment Approach______________________________________________

6.4.2______ Hazard Identification____________________________________________________________

6.4.3______ Risk Analysis_________________________________________________________________

6.4.4______ Risk Evaluation________________________________________________________________

6.4.5______ Risk Treatment________________________________________________________________

6.5_______ Review of Previous Risk Assessment for the Submarine Pipeline of the Hongkong Electric_______

6.5.1______ Background of Previous Risk Assessments for the Submarine Pipeline______________________

6.5.2______ Potential Causes of Failure of the Submarine Pipeline___________________________________

6.5.3______ Recommended Mitigation Measures from Previous Assessments__________________________

6.6_______ Hazard Identification Workshop____________________________________________________

6.6.1______ Results______________________________________________________________________

6.6.2______ Recommendations of Risk Mitigation Measures________________________________________

6.7_______ Environmental Monitoring and Audit________________________________________________

6.8_______ Conclusions__________________________________________________________________

6.9_______ References___________________________________________________________________

7 Noise Impact Assessment

7.1_______ Introduction____________________________________________________________________

7.2_______ Environmental Legislation, Standards, Guidelines and Criteria_____________________________

7.2.1______ Construction Phase______________________________________________________________

7.2.2______ Operation Phase________________________________________________________________

7.3_______ Description of the Environment_____________________________________________________

7.3.1______ Study Area____________________________________________________________________

7.3.2______ Baseline Conditions_____________________________________________________________

7.3.3______ Noise Sensitive Receivers_________________________________________________________

7.4_______ Identification of Noise Emission Sources______________________________________________

7.4.1______ Construction Phase Noise Impact___________________________________________________

7.4.2______ Operation Phase Noise Impact_____________________________________________________

7.4.3______ Concurrent Projects_____________________________________________________________

7.5_______ Noise Impact Assessment Methodology______________________________________________

7.5.1______ Dredging Working Zones__________________________________________________________

7.6_______ Construction Noise Impact Assessment_______________________________________________

7.6.1______ Noise Impact during Normal Working Hours (i.e. Non-Restricted Hours)_____________________

7.6.2______ Noise Impact during Evening and Holiday Day-time Periods_______________________________

7.6.3______ Noise Impact during Night-time Period________________________________________________

7.7_______ Operation Phase Noise Impact Assessment___________________________________________

7.8_______ Mitigation Measures____________________________________________________________

7.9_______ Evaluation of Residual Impacts____________________________________________________

7.10______ Environmental Monitoring and Audit Requirements_____________________________________

7.11______ Conclusion___________________________________________________________________

8 Waste Management Impact Assessment

8.1_______ Introduction____________________________________________________________________

8.2_______ Environmental Legislation, Standards and Guidelines___________________________________

8.2.1______ Environmental Impact Assessment Ordinance________________________________________

8.2.2______ Waste Disposal Ordinance_______________________________________________________

8.2.3______ Waste Disposal (Chemical Waste) (General) Regulation________________________________

8.2.4______ Dumping at Sea Ordinance_______________________________________________________

8.2.5______ Public Cleansing and Prevention of Nuisances Regulation_______________________________

8.3_______ Assessment Methodology_________________________________________________________

8.3.1______ Analysis of Activities and Waste Generation__________________________________________

8.3.2______ Dredging and Dumping__________________________________________________________

8.4_______ Identification, Prediction and Evaluation of Environmental Impact__________________________

8.4.1______ Construction Phase_____________________________________________________________

8.4.2______ Operation Phase_______________________________________________________________

8.5_______ Mitigation Measures_____________________________________________________________

8.5.1______ Marine Sediment_______________________________________________________________

8.5.2______ Chemical Waste_______________________________________________________________

8.5.3______ General Refuse________________________________________________________________

8.6_______ Evaluation of Residual Impacts____________________________________________________

8.7_______ Environmental Monitoring and Audit Requirements_____________________________________

8.8_______ Conclusion____________________________________________________________________

8.8.1______ Construction Phase_____________________________________________________________

8.8.2______ Operation Phase_______________________________________________________________

9 Conclusion

9.1_______ General______________________________________________________________________

9.2_______ Summary of Environmental Outcomes______________________________________________

9.2.1______ Environmentally Friendly Options Considered and Incorporated in the Preferred Option_______

9.2.2______ Environmental Designs Recommended_____________________________________________

9.2.3______ Estimated Population and Environmentally Sensitive Areas Protected_____________________

9.2.4______ Key Environmental Problems Avoided and Compensation Areas Included__________________

9.2.5______ Environmental Benefits of Environmental Protection Measures Recommended______________

9.3_______ Key Assessment Assumptions and Limitations of Assessment Methodologies_______________

9.4_______ Summary of Environmental Impacts_________________________________________________

9.4.1______ Water Quality Impact_____________________________________________________________

9.4.2______ Marine Ecological Impact_________________________________________________________

9.4.3______ Fisheries Impact________________________________________________________________

9.4.4______ Hazard to Life__________________________________________________________________

9.4.5______ Noise Impact___________________________________________________________________

9.4.6______ Waste Management Implications___________________________________________________

10 Environmental Monitoring and Audit

10.1______ General_____________________________________________________________________

10.2______ Water Pollution________________________________________________________________

10.3______ Marine Ecology________________________________________________________________

10.4______ Fisheries_____________________________________________________________________

10.5______ Hazard to Life_________________________________________________________________

10.6______ Noise_______________________________________________________________________

10.7______ Waste Management____________________________________________________________

11 Implementation Schedule

11.1______ Project Implementation Schedule__________________________________________________

Tables

Table 2-1:__ Summary of Environmental Benefits and Dis-Benefits of Alignment Options_________________

Table 2-2:__ Summary of Dredging Technology_________________________________________________

Table 2-3:__ Siltation Rates Based on Past Bathymetry Records____________________________________

Table 2-4:__ Summary of Options Evaluation and the Preferred Option_______________________________

Table 2-5:__ Summary of Concurrent Projects Considered for Cumulative Impact Assessment____________

Table 3 1:__ Water Quality Objectives for Western Buffer WCZ_____________________________________

Table 3 2:__ Water Quality Objectives for Southern WCZ__________________________________________

Table 3 3:__ Sediment Quality Criteria under ETWB TCW No. 34/2002_______________________________

Table 3 4:__ WSD’s Water Quality Criteria for Flushing Water at Sea Water Intakes_____________________

Table 3-5:__ Water Sensitive Receivers_______________________________________________________

Table 3 6:__ Baseline Marine Water Quality in Western Buffer WCZ (1986 to 2015)_____________________

Table 3 7:__ Baseline Marine Water Quality in Southern WCZ (1986 to 2015)__________________________

Table 3 8:__ Summary of Past Sediment Quality Testing Results within the Channel_____________________

Table 3-9:__ Summary of Sediment Sampling and Elutriation Test Results_____________________________

Table 3-10:_ Assessment Criteria for Suspended Solids___________________________________________

Table 3-11:_ Assessment Criteria for Suspended Solids (WSD Seawater Intakes)_______________________

Table 3 12:_ 10th Percentile Dissolved Oxygen Levels from EPD’s Monitoring Stations___________________

Table 3 13:_ Water Quality Criteria for Metals and Other Contaminants________________________________

Table 3 14:_ Summary of Concurrent Projects for Cumulative Water Quality Impact Assessment___________

Table 3-15:_ Summary of Assumptions for Dredgers______________________________________________

Table 3 16:_ Comparison of Elutriation Test Results against Criteria Limits_____________________________

Table 3-17:_ WSRs and Sediment Sampling Locations Assessed using the Gaussian Dispersion Model______

Table 3-18:_ Predicted Worst Affected WSRs and Maximum Allowable SS Release Rates_________________

Table 3-19:_ Predicted Maximum Allowable Dredging Rates________________________________________

Table 3-20:_ Summary of SS Contributions to Allowable Elevations due to Concurrent Projects_____________

Table 3-21:_ Predicted Worst Affected WSRs and Maximum Allowable SS Release Rates (Cumulative)_______

Table 3-22:_ Recommended Maximum Allowable SS Release Rates and Maximum Allowable Dredging Rates_

Table 3.23:_ Predicted Cumulative Maximum SS Elevation at WSRs based on the Recommended Maximum Allowable Release Rates (Grab Dredger)

Table 3.24:_ Predicted Cumulative Maximum SS Elevation at WSRs based on the Recommended Maximum Allowable Release Rates (TSHD)

Table 3.25:_ Maximum Sedimentation Rate at WSRs Representing Corals (g/m²/day) due to Grab Dredging____

Table 3.26:_ Maximum Sedimentation Rate at WSRs Representing Corals (g/m²/day) due to TSHD___________

Table 3.27:_ Summary of Results for TIN and UIA at the Representative Nearest WSRs during Flood and Ebb Tide

Table 3.28:_ Calculated Changes to DO Concentration at WSRs due to the Project_______________________

Table 3.29:_ Factors Affecting Operation Phase Recurrent Dredging__________________________________

Table 3.30:_ Wet and Dry Season Tidal Discharges (m³/s)__________________________________________

Table 4 1: __ Ecological Evaluation of Sham Wan SSSI and Restricted Area____________________________

Table 4 2: __ Ecological Evaluation of Intertidal Habitat – Artificial Seawall of Lamma Power Station Extension__

Table 4 3: __ Ecological Evaluation of Intertidal Habitat – Rocky Shores________________________________

Table 4 4: __ Ecological Evaluation of Intertidal Habitat – Sandy Shores________________________________

Table 4 5: __ Ecological Evaluation of Sub-tidal Soft Bottom Habitat___________________________________

Table 4 6: __ Ecological Evaluation of Sub-tidal Hard Bottom Habitat__________________________________

Table 4 7: __ Ecological Evaluation of Marine Waters______________________________________________

Table 4 8: __ Evaluation of Fauna Species of Conservation Interest within the Study Area__________________

Table 5-1:__ Fishing Operations within the Project area_____________________________________________

Table 5-2:__ Summary of Hong Kong Capture Fisheries Industry over the past 8 years____________________

Table 5-3:__ Predicted Cumulative Depth Average Maximum SS Elevation at Fish Culture Zones____________

Table 5-4:__ Calculated Changes to Depth Average DO Concentration at WSRs due to the Project___________

Table 5-5:__ Evaluation of Potential Fisheries Impacts during Construction Phase_________________________

Table 5-6:__ Evaluation of Potential Fisheries Impacts during Operation Phase___________________________

Table 6 1: __ Likelihood Criteria for the Cause of Incident___________________________________________

Table 6 2: __ Consequence Criteria for the Cause of Incident________________________________________

Table 6 3: __ Risk Analysis Matrix____________________________________________________________

Table 6 4: __ Risk Evaluation Criteria__________________________________________________________

Table 6 5: __ Risk Ranking for SWIFT Log Sheets – Grab Dredging Method____________________________

Table 6 6: __ Risk Ranking for SWIFT Log Sheets – TSHD Method___________________________________

Table 6 7: __ Summary of Hazards in High Risk Level – Grab Dredging Method_________________________

Table 6 8: __ Summary of Hazards in High Risk Level – TSHD Method________________________________

Table 7 1:__ Noise Standards for Daytime Construction Activities____________________________________

Table 7 2:__ Acceptable Noise Level for Construction Noise during Restricted Hours_____________________

Table 7 3:__ Representative Noise Sensitive Receivers Identified for the Assessment____________________

Table 7 4:__ PME Adopted in Previous Approved EIA Study________________________________________

Table 7 5:__ Summary of Potential Concurrent Projects for Cumulative Noise Impact Assessment__________

Table 7 6:__ Construction Noise Impact during Normal Working Hours________________________________

Table 7 7:__ Construction Noise Impact during Evening and Holiday Day-time Periods___________________

Table 7 8:__ Construction Noise Impact during Night-time Period____________________________________

Table 8.1:__ Summary of Previous Sediment Sampling Works______________________________________

Table 8.2:__ Summary of Laboratory Testing Results of Sediment Samples Collected in April 2014_________

Table 9.1:__ Key Assessment Assumptions, Limitations of Assessment Methodologies___________________

Table 9.2:__ Summary of Environmental Impacts_________________________________________________

Table 11.1:_ Implementation Schedule of Recommended Mitigation Measures__________________________

Figures

Figure 1.1: _ Project Area

Figure 3.1__ Water Sensitive Receivers

Figure 3.2__ Sediment Sampling Locations for Elutriation Test

Figure 3.3__ Dredging Locations for Water Quality Modelling

Figure 4.1__ Locations of Coral Dive Survey

Figure 4.2__ Marine Benthic Sampling Stations

Figure 4.3__ Locations of Intertidal Survey

Figure 4.4__ Locations of Marine Ecological Sensitive Receivers

Figure 4.5__ Density of Finless Porpoises in Southern Waters of Hong Kong During Wet and Dry Seasons

Figure 5.1 _ Fisheries Sensitive Receivers

Figure 5.2 _ Overall Distribution of Fishing Operations

Figure 5.3 _ Distribution of Fishing Operations Vessel Exceeding 15M in Length

Figure 5.4 __ Distribution of Fishing Operations Vessel Not Exceeding 15M in Length

Figure 5.5 _ Distribution of Adult Fish Production

Figure 5.6 _ Distribution of Fisheries Production (Fish Fry)

Figure 6-1: _ Location of the Lamma Power Station Navigation Channel

Figure 6-2: _ Alignment of the Submarine Pipeline

Figure 6-3: _ Submarine Pipeline across Lamma Power Station Navigation Channel

Figure 6-4: _ Clamshell Grab Dredger

Figure 6-5: _ Cage Type Silt Curtain

Figure 6-6: _ Cross-section of Cage Type Silt Curtain Arrangement

Figure 6-7: _ Clamshell installed in Grab Dredger

Figure 6-8: _ Trailing Suction Hopper Dredger

Figure 6-9: _ Draghead and Suction Pipe

Figure 6-10: Swell Compensator

Figure 7.1__ Noise Impact Study Area and Locations of Representative Noise Sensitive Receivers

Figure 8.1__ Grab Sampling Location

Maps

Map 2-1:___ Possible Alternatives for Channel Alignment and Approach

Appendices

Appendix 1.1____ Extracts of Past Bathymetry Surveys and Dredging Extents

Appendix 3.1____ Model Grid Refinement and Validation Results

Appendix 3.2____ Modelling Assumptions for Concurrent Projects

Appendix 3.3____ Dilution Results and Calculated Maximum Allowable SS Release (Project Only)

Appendix 3.4____ Predicted Maximum SS at WSRs (Concurrent Projects Only)

Appendix 3.5____ Contour plots of SS due to Concurrent Projects Only

Appendix 3.6____ Predicted Maximum SS and Sedimentation Rate at WSRs (Cumulative)

Appendix 3.7____ Contour plots of SS based on the Recommended Maximum Allowable SS Release (Project Only)

Appendix 3.8____ (not used)

Appendix 3.9____ (not used)

Appendix 3.10___ Calculated DO Concentrations at WSRs

Appendix 3.11___ Operation Phase Hydrodynamic Results (Before and After Dredging)

Appendix 4.1____ Coral Dive Survey Results

Appendix 4.2 ____ Benthic Field Surveys Results

Appendix 4.3 ____ Intertidal Field Survey Results

Appendix 4.4____ Inter-nesting Locations of the Green Turtle in Hong Kong in 2003, 2008 and 2012

Appendix 6.1____ SWIFT Workshop Attendance List

Appendix 6.2____ SWIFT Log Sheet

Appendix 7.1____ Construction Plant Inventory and Noise Impact Assessment

Appendix 8.1____ Relevant EPD Sediment Monitoring Results

Appendix 8.2 ____ Approved Sediment Quality Report