Maintenance Dredging and Spoil Disposal Management Plan
Total Page：16
File Type：pdf, Size：1020Kb
Maintenance Dredging and Spoil Disposal Management Plan Document distribution Copy Name Hard Electronic no. copy copy 00 Document control 01 Department of Infrastructure, Planning and Logistics 02 Northern Territory Environment Protection Authority 03 Department of the Environment and Energy 04 Conor Walker 05 Atsushi Sakamoto 06 Craig Haymes 07 Bruce Macgregor 08 Thijs van Berkel 09 Sandy Griffin 10 Jamie Carle 11 Sean Kildare 12 David Gwyther 13 Bruce Anderson 14 Maris Steele 15 Rebecca Cass 16 Mark Wilson 17 Glen Bajars 18 Dave Dann 19 Lance Kenny 20 Jake Tobin Document no.: L060-AH-PLN-60010 ii Security Classification: Restricted Revision: 1 Date: 16 March 2018 Maintenance Dredging and Spoil Disposal Management Plan Notice All information contained with this document has been classified by INPEX as Restricted and must only be used in accordance with that classification. Any use contrary to this document's classification may expose the recipient and subsequent user(s) to legal action. If you are unsure of restrictions on use imposed by the classification of this document you must refer to the INPEX Sensitive Information Protection Standard or seek clarification from INPEX. Uncontrolled when printed. Document no.: L060-AH-PLN-60010 iii Security Classification: Restricted Revision: 1 Date: 16 March 2018 Maintenance Dredging and Spoil Disposal Management Plan Table of contents 1 INTRODUCTION 1 1.1 Purpose 1 1.2 Scope 2 1.3 Proponent 2 1.4 Independent expert review 3 1.5 Interface other INPEX and Dredging Contractor documents 3 1.6 Review and revision of this Plan 4 2 LEGISLATIVE FRAMEWORK 5 2.1 Ichthys Project environmental approval 5 2.2 Maintenance dredging approvals 5 2.3 Relevant conventions, legislation, standards and guidelines 6 2.3.1 International conventions, agreements and guidelines 6 2.3.2 Commonwealth and Northern Territory legislation, standards and guidelines 6 3 MAINTENANCE DREDGING AND SPOIL DISPOSAL ACTIVITY 10 3.1 Maintenance dredging campaigns 10 3.2 Work locations 10 3.2.1 Dredge area 10 3.2.2 Dredge spoil disposal area 11 3.3 Work method and rationale 12 3.3.1 Equipment selection 13 3.3.2 Dredging method 14 3.3.3 Spoil disposal method 15 3.4 Seabed leveller 16 4 DESCRIPTION OF THE ENVIRONMENT 17 4.1 Physical environment 17 4.1.1 Climate 17 4.1.2 Bathymetry and seafloor geology 19 4.1.3 Oceanography 19 4.1.4 Water quality 21 4.1.5 Sediment quality 24 4.1.6 Underwater noise 26 4.2 Marine benthic habitats 27 4.2.1 Mangroves 29 4.2.2 Coral 30 4.2.3 Seagrass 32 4.2.4 Macroalgae 33 4.2.5 Soft-bottom benthos 33 4.3 Pelagic environment 34 4.3.1 Marine mammals 34 Document no.: L060-AH-PLN-60010 iv Security Classification: Restricted Revision: 1 Date: 16 March 2018 Maintenance Dredging and Spoil Disposal Management Plan 4.3.2 Marine reptiles 35 4.3.3 Fish and sharks 36 4.3.4 Phytoplankton 37 4.4 Parks and reserves 38 4.5 Cultural environment 39 4.5.1 Aboriginal sacred sites 39 4.5.2 Non-Aboriginal heritage sites 39 4.6 Social and economic environment 40 4.6.1 Beneficial uses 40 4.6.2 Darwin Port operations 41 4.6.3 Tourism 41 4.6.4 Commercial fishing and aquaculture 41 4.6.5 Recreational and traditional fishing 41 5 ENVIRONMENTAL RISK ASSESSMENT 43 5.1 Conceptual site model 43 5.2 Summary of risk assessment outcomes 46 5.3 ALARP Justification 53 5.3.1 Sediment-related impacts 53 5.3.2 Underwater noise 57 5.3.3 Unexploded ordnance (UXO) and heritage objects 59 5.4 Assessment of potential for cumulative impacts 59 5.4.1 Sequential Project-related maintenance dredging campaigns 59 5.4.2 Concurrent Harbour-wide dredging campaigns 61 5.4.3 Long-term effects on East Arm sediment balance 61 6 SEDIMENT PLUME MODELLING AND IMPACT ASSESSMENT 63 6.1 Maintenance dredging scenario 63 6.2 Synthesis of modelling assessment approach 64 6.3 Hydrodynamic model 64 6.3.1 General description 64 6.3.2 Data inputs 66 6.4 Sediment transport model 66 6.4.1 General description 66 6.4.2 Data inputs 66 6.5 Model outputs 68 6.5.1 Excess SSC maps 68 6.5.2 Sediment deposition maps 73 6.6 Tolerance limits for habitats 75 6.6.1 SSC tolerance limits 75 6.6.2 Sedimentation tolerance limits 76 6.7 Habitat impact assessment analysis 77 Document no.: L060-AH-PLN-60010 v Security Classification: Restricted Revision: 1 Date: 16 March 2018 Maintenance Dredging and Spoil Disposal Management Plan 6.8 Habitat impact assessment outcomes 78 7 ENVIRONMENTAL MANAGEMENT 83 7.1 Management of sediment-related effects 83 7.1.1 Sediment-related effects management framework 85 7.1.2 Development of reactive management triggers 87 7.1.3 Attributability investigation 88 7.1.4 Responsive management 89 7.1.5 Contingency management 90 7.2 Management of other dredging aspects 90 7.2.1 Introduced marine pests management framework 91 7.2.2 Dredge materials management framework 94 7.2.3 Protected marine megafauna management frameworks 95 7.2.4 Heritage and sacred site management framework 100 7.2.5 Waste and liquid discharges management framework 103 7.2.6 Hydrocarbon and chemical management and spill response framework 105 8 WATER QUALITY MONITORING 108 8.1 Objectives 108 8.2 Development of risk-based water quality monitoring program 108 8.3 Monitoring sites 109 8.4 Methods 111 8.4.1 Data collection 111 8.4.2 Parameters 112 8.4.3 Quality control and assurance 112 8.4.4 Data analysis 113 8.5 Remote sensing 114 9 STAKEHOLDER ENGAGEMENT AND COMMUNICATIONS 115 9.1 Timing 115 9.2 Stakeholders 115 9.3 Engagement tools 115 10 ENVIRONMENTAL MANAGEMENT IMPLEMENTATION STRATEGY 116 10.1 INPEX HSEQ-MS 116 10.2 Dredging contractor HSEQ-MS 117 10.3 Emergency response 117 10.4 Roles and responsibilities 117 10.5 Inductions and training 119 10.5.1 HSEQ inductions 119 10.5.2 MMO training 119 10.6 Inspections and audits 119 10.6.1 Internal audits 119 10.6.2 External audits 120 Document no.: L060-AH-PLN-60010 vi Security Classification: Restricted Revision: 1 Date: 16 March 2018 Maintenance Dredging and Spoil Disposal Management Plan 10.7 Internal reporting 120 10.7.1 Routine reporting 121 10.7.2 Environmental event reporting and investigation 121 10.8 External reporting 121 10.8.1 Exceedance reporting 121 10.8.2 Routine monitoring reporting 122 10.8.3 Environmental incident and non-compliance reporting 122 10.8.4 Other external reporting/notification requirements 123 10.9 Data and records management 123 10.10 Management of change 124 11 REFERENCES 125 List of Tables Table 1-1: Independent experts consulted in the development of this Maintenance DSDMP 3 Table 2-1: International conventions, agreements and guidelines 6 Table 2-2: Commonwealth legislation, standards and guidelines 7 Table 2-3: Northern Territory legislation, standards, plans and guidelines 8 Table 4-1: Average monthly rainfall for Darwin (measured as mm) 17 Table 4-2: Hard coral composition (%) in the final post dredging survey (Cardno 2015c)31 Table 4-3: Conservation status of marine mammals, which may occur within the Darwin region 35 Table 4-4: Conservation status of marine reptiles, which may occur within the Darwin region 36 Table 4-5: Protected marine sharks which may be present in Darwin Harbour 37 Table 4-6: Darwin Harbour parks and reserves 38 Table 4-7: AAPA Authority Certificates relevant to maintenance dredging activities 39 Table 5-1: Summary of risk assessment outcomes 49 Table 5-2: Overview of anthropogenic noise sources 57 Table 6-1: Overview of modelling aspects for the worst-case credible scenario 63 Table 6-2: Assumed primary and secondary losses of fines during dredging, loading and disposal 67 Table 6-3: Tolerance limits for excess SSC and sedimentation 75 Table 6-4: Simulated areas of impact based on highest intensity period (SN2; days 15 to 29) of the worst-case credible scenario 78 Table 7-1: Environmental objectives, targets and indicators template 83 Table 7-2: Environmental management framework template 83 Table 7-3: Sediment-related effects management framework 85 Table 7-4: Level 1 and 2 turbidity management trigger criteria for sediment-related effects 87 Table 7-5: Responsive management practices as adapted from the PIANC 100 Report (Netzband et al. 2009) 89 Table 7-6: Contingency management practices as adapted from the PIANC 100 Report (Netzband et al. 2009) 90 Document no.: L060-AH-PLN-60010 vii Security Classification: Restricted Revision: 1 Date: 16 March 2018 Maintenance Dredging and Spoil Disposal Management Plan Table 7-7: Introduced marine pest objectives, targets and indicators 91 Table 7-8: Introduced marine pest management framework 91 Table 7-9: Dredge materials objectives, targets and indicators 94 Table 7-10: Dredge materials management framework 95 Table 7-11: Protected marine megafauna—whale, dolphin, dugong and turtle interaction objectives, targets and indicators 96 Table 7-12: Protected marine megafauna—whale, dolphin, dugong and turtle interaction management framework 96 Table 7-13: Protected marine megafauna—marine turtle and sawfish entrainment objectives, targets and indicators 99 Table 7-14: Protected marine megafauna—marine turtle and sawfish entrainment management framework 99 Table 7-15: Heritage and sacred site objectives, targets and indicators 100 Table 7-16: Heritage and sacred site management framework 100 Table 7-17: Waste and liquid discharges objectives, targets and indicators 103 Table 7-18: Waste and liquid discharges management framework 103 Table 7-19: Hydrocarbon and chemical management and spill response objectives, targets and indicators 105 Table 7-20: Hydrocarbon and chemicals management and spill response framework 106 Table 8-1: Decision tree water quality locations.