Maintenance Dredging 2015 Environmental Monitoring Report

Transcription

1 Maintenance Dredging 2015 Environmental Monitoring Report 1208_001/1_Rev0 July 2015

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3 P:\SouthernPorts\1208_PortAlbanyMaintDredging\001_OriginalScope\Reports\ReportFolder_EnvironmentalMonitoring\AlbanyPorts20 15MaintDredging_EnvMon_1208_Rev0_ docm Maintenance Dredging 2015 Environmental Monitoring Report Prepared for Southern Ports Authority Prepared by BMT Oceanica Pty Ltd July 2015 Report No. 1208_001/1_Rev0

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5 Client: Southern Ports Authority Document history Distribution Revision Author Recipients Organisation No. copies & format A J. Anderson L. Twomey BMT Oceanica 1 x docm 21/07/2015 B J. Anderson L. Twomey BMT Oceanica 1 x docm 22/07/2015 C J. Anderson R. Hillman BMT Oceanica 1 x docm 23/07/2015 D J. Anderson R. Goetze Southern Ports Authority 1 x pdf 23/07/ J. Anderson R. Goetze Southern Ports Authority 1 x pdf 29/07/2015 Date Review Revision Reviewer Intent Date A L. Twomey Technical review 21/07/2015 B L. Twomey Editorial review 22/07/2015 C R. Hillman Administrative review 23/07/2015 D R. Goetze Client review 24/07/2015 Quality Assurance BMT Oceanica Pty Ltd has prepared this report in accordance with our Health Safety Environment Quality Management System, certified to ISO 9001: Status This report is 'Draft' until approved for final release, as indicated below by inclusion of signatures from: (i) the author and (ii) a Director of BMT Oceanica Pty Ltd or their authorised delegate. A Draft report may be issued for review with intent to generate a 'Final' version, but must not be used for any other purpose. Approved for final release: Author Director (or delegate) Date: 29/07/15 Date: 29/07/15

6 Disclaimer This report has been prepared on behalf of and for the exclusive use of Southern Ports Authority, and is subject to and issued in accordance with the agreed terms and scope between Southern Ports Authority and BMT Oceanica Pty Ltd. BMT Oceanica Pty Ltd accepts no liability or responsibility for it in respect of any use of or reliance upon this report by any third party. Copying this report without prior written consent of Southern Ports Authority or BMT Oceanica Pty Ltd is not permitted. Copyright 2015 BMT Oceanica Pty Ltd

7 Contents Acronyms... iii Executive Summary... v 1. Introduction Environmental approvals Potential environmental impacts Purpose of document Objectives Methods Turbidity plumes Secchi disc monitoring Visual record of turbidity plumes Seagrass epiphyte monitoring Marine fauna Trained observers Introduced marine species Results Turbidity monitoring Remote imagery units Seagrass epiphyte monitoring Marine fauna Summary and discussion References BMT Oceanica: Southern Ports Authority: Maintenance Dredging 2015 Environmental Monitoring Report i

8 List of Figures Figure 1.1 Albany Port harbour basin, entrance channel and disposal area... 2 Figure 2.1 Turbidity and seagrass monitoring sites for the 2015 maintenance dredging campaign... 6 List of Tables Table 2.1 Secchi disc depth and seagrass epiphyte loading monitoring sites... 5 Table 3.1 Dates of completed environmental monitoring during dredging campaign... 7 Table 3.2 Water clarity monitoring (secchi disc depth) as part of the 2015 maintenance dredging campaign... 7 Table 3.3 Seagrass epiphyte loading monitoring as part of the 2015 maintenance dredging campaign... 8 Table 3.4 Observations of marine mammals during dredging operations... 9 List of Appendices Appendix A Appendix B Appendix C Remote imagery photo examples Seagrass epiphyte loading photo examples Marine mammal observation logs ii BMT Oceanica: Southern Ports Authority: Maintenance Dredging 2015 Environmental Monitoring Report

9 Acronyms APA AQIS CS DoE DoF DoW EIA EPA EPBC IMS IS LoR MMO OEPA OS QA/QC SAP SPA WA Albany Port Authority, now part of SPA Australian Quarantine Inspection Service Control Site Commonwealth Department of the Environment Western Australian Department of Fisheries Western Australian Department of Water Environmental impact assessment Environmental Protection Authority Environment Protection and Biodiversity Conservation Introduced Marine Species Inner Site Limit of reporting Marine mammal observer Western Australian Office of the Environmental Protection Authority Outer Site Quality assurance and quality control Sampling and Analysis Plan Southern Ports Authority Western Australia BMT Oceanica: Southern Ports Authority: Maintenance Dredging 2015 Environmental Monitoring Report iii

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11 Executive Summary Southern Ports Authority commissioned maintenance dredging within the Port of Albany in June 2015 to remove high spots in the entrance channel and harbour basin to reinstate the declared navigation depths. BMT Oceanica undertook environmental monitoring during the maintenance dredging program to fulfil the environmental commitments made by the Southern Ports Authority. The monitoring program included the following components: 1. Monitoring of the dredging turbidity plumes through: i. Measuring water clarity with a Secchi disc ii. Capturing a visual record of turbidity plumes within the harbour basin to record the distribution of plume movement over time to assist with planning for future dredging campaigns iii. Visually assessing any change on epiphyte loading in seagrass meadows. 2. Mitigation of potential vessel impact with whales and other protected marine fauna by completing marine mammal observer training of the maintenance dredging vessels crew for cetacean impact avoidance measures 3. Reducing the potential for introduced marine species from dredging operations by consulting with Western Australian Department of Fisheries (DoF) on appropriate steps to risk assess potential pest vectors 4. Reporting on Secchi disc depth (i.e. water clarity) and seagrass epiphyte loading monitoring results (this report). All of the environmental commitments outlined in the EIA (BMT Oceanica 2014) were satisfied by the Albany Port 2015 maintenance dredging environmental monitoring, which included: There were no exceedances of turbidity. Monitoring of water clarity through secchi disc depth measurements found short lived decreases in water clarity and these were limited to harbour and near the harbour entrance sites (IS1-4 and OS1). Minor differences occurred in seagrass epiphyte loading at sites CS1 (decreased) and OS7 and OS8 (increased), while sites OS5 and OS6 had no change. Three remote imagery units were deployed for a period of up to 28 days, which resulted in collection of over 3,000 photos of the maintenance dredging operation. The information may be useful to inform decision making for future dredging campaigns. The potential impacts to marine fauna from vessels were managed through comprehensive marine mammal observation training. A total of 53 Humpback whale adults and nine calves were observed by the dredge vessel crew during the dredging operations. Approximately seven hours of shutdown time was required for impact avoidance procedures, but no impacts to marine mammal were recorded. The risk of IMS incursion was determined to be low by Department of Fisheries due to the recent dry docking of the dredge vessel and associated support vessels. BMT Oceanica: Southern Ports Authority: Maintenance Dredging 2015 Environmental Monitoring Report v

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13 1. Introduction The Port of Albany is located on the southern coast of Western Australia with infrastructure in Princess Royal Harbour and King George Sound (Figure 1.1). Southern Ports Authority (SPA) was required to undertake maintenance dredging to remove high spots within the Port of Albany entrance channel and harbour basin, to reinstate the declared navigation depths. Dredging commenced on 31 May at 1400 and works were completed on 15 June Additional sweep bar works continued until 19 June Dredging works were completed with a Trailer Suction Hopper Dredge, the River Bee, operated by WA Dredging. Southern Ports Authority was authorised to dispose of 82,400 m 3 of dredged material to an offshore disposal area (G7 Figure 1.1), in accordance with sea dumping permit SD2014/2902. The total volume dredged during the campaign was calculated to be 52,482 m 3, which was significantly less than the amount approved. 1.1 Environmental approvals Environmental approvals for the 2015 maintenance dredging works consisted of: EPBC referral Licence to Dredge and Reclaim Sea Dumping permit The maintenance dredging works were not considered to be a controlled action and EPBC approval was provided by Department of Environment (DoE) on 17 July 2014 (EPBC 2014/7246). An application for a Licence to Dredge and Reclaim was submitted to Western Australia (WA) Department of Water on 17 June The works were directly referred to the OEPA and the outcome was Not Assessed Public Advice Given (Dated 8 Sept 2014). The Western Australia Department of Water issued a Licence to Dredge and Reclaim on 14 November Sea Dumping permit (No. SD2014/2902) was granted by DoE on 2 December 2014 for up to 82,400 m 3 of dredging materials for disposed at site (G7) in King George Sound (Figure 1.1). Potential environmental impacts were assessed in the Albany Port Authority Maintenance Dredging Program Environmental Impacts Assessment (EIA) report (BMT Oceanica 2014a). These potential impacts were assessed based on data presented in the Albany Port Authority Maintenance Dredging Program Sediment Sampling and Analysis Implementation report (BMT Oceanica 2014b). BMT Oceanica: Southern Ports Authority: Maintenance Dredging 2015 Environmental Monitoring Report 1

14 Figure 1.1 Albany Port harbour basin, entrance channel and disposal area 2 BMT Oceanica: Southern Ports Authority: Maintenance Dredging 2015 Environmental Monitoring Report

15 1.2 Potential environmental impacts A number of key potential impacts for the 2015 maintenance dredging campaign were identified in the EIA which included: turbidity mobilisation of contaminants and nutrients hydrocarbon spills noise vessel movements threatened or migratory species introduced marine species waste management impacts to other users exposure to contaminants. The potential impacts were risk assessed and management actions were developed to mitigate the risks. The risk assessment identified three environmental issues for monitoring during the dredging campaign, including: turbidity migratory species (marine mammals) introduced marine species. 1.3 Purpose of document This document presents the results of the environmental monitoring requirements of the Albany Port Authority Maintenance Dredging Program Environmental Impacts Assessment report. 1.4 Objectives Requirements of the Albany Port Authority Maintenance Dredging Program Environmental Impacts Assessment (BMT Oceanica 2014a) were: 1. Monitoring of the dredging turbidity plumes through: i. Measuring water clarity with a secchi disc ii. Capturing a visual record of turbidity plumes within the harbour basin to record the distribution of plume movement over time to assist with planning for future dredging campaigns iii. Visually assessing any change on epiphyte loading in seagrass meadows. 2. Mitigating potential of vessel to impact with whales and other protected marine fauna by completing marine mammal observer training for vessel crew for cetacean impact avoidance measures 3. Reducing the potential for introduced marine species from dredging operations by consulting with Western Australian Department of Fisheries (DoF) on appropriate steps to risk assess potential pest vectors 4. Reporting on secchi disc depth (i.e. water clarity) and seagrass epiphyte loading monitoring results (this report). BMT Oceanica: Southern Ports Authority: Maintenance Dredging 2015 Environmental Monitoring Report 3

16 2. Methods 2.1 Turbidity plumes Turbidity of the dredging plumes were monitored with the following methods: 1. Measurement of water clarity with a secchi disc 2. Capture of a visual record of turbidity plumes within the harbour basin using remote imagery units to record the distribution of plume movement over time to assist with planning for future dredging campaigns 3. Visual assessment of any change on epiphyte loading in seagrass meadows Secchi disc monitoring Dredging was completed within two weeks and turbidity was monitored in case there was an unexpected extension of the dredging program. Turbidity was monitored using Secchi depth as a proxy for water quality (i.e. water clarity) at five inner sites, eight outer sites and one control site (Table 2.1 and Figure 2.1). Monitoring was undertaken by recording the Secchi depth, which was conducted by lowering the Secchi disc through the water column and estimating the depth that the white and black quarters of the Secchi disc were still distinguishable. Secchi depths were monitored pre-dredging and after dredging for contextual information. During dredging a staged trigger and action approach was employed, as follows: 1. Secchi disc monitoring was carried out twice weekly at all sites during dredging 2. If the Secchi depth at one or more of the outer sites was below 4 m (8 m for sites OS7 and OS8) while the Secchi depth at site CS1 remained above 4 m, monitoring increase to daily 3. If Secchi depths remained below 4 m (8 m for sites OS7 and OS8) at one or more outer sites on three consecutive days while site CS1 remained above 4 m then dredging will cease until Secchi depths were greater than 4 m at all outer sites (8 m for sites OS7 and OS8) Visual record of turbidity plumes A visual record of turbidity plumes was recorded within the harbour basin using two remote imagery units (i.e. time lapse cameras). Harbour camera 1 faced east and collected images of the entrance channel. Harbour camera 2 faced southwest and collected images of the inner harbour basin area. An additional time lapse camera was mounted on the stern of the dredge vessel to collect further information on the turbidity plumes during the campaign. Images were taken every 15 minutes from sunrise to sunset each day Seagrass epiphyte monitoring Seagrass epiphyte loading was monitored to document any potential effect of nutrient release on epiphyte growth. Photographs of the seagrass meadows were taken in ten randomly placed 20 x 20 cm quadrats, one week prior to, once during, and one week after dredging at the control sites and each of the outer sites with seagrass (CS1, OS5, OS6, OS7 and OS8) (Table 2.1 and Figure 2.1). Epiphyte cover was visually assessed from photographs and qualitatively classified as low, medium or high density by a local seagrass expert. 4 BMT Oceanica: Southern Ports Authority: Maintenance Dredging 2015 Environmental Monitoring Report

17 Table 2.1 Secchi disc depth and seagrass epiphyte loading monitoring sites Site Description Type Location (GDA94 UTM 50) Easting Northing IS1 Inner Site Secchi disc IS2 Inner Site Secchi disc IS3 Inner Site Secchi disc IS4 Inner Site Secchi disc IS5 Inner Site Secchi disc OS1 Outer Site Secchi disc OS2 Outer Site Secchi disc OS3 Outer Site Secchi disc OS4 Outer Site Secchi disc OS5 Outer Site Secchi disc Seagrass epiphyte OS6 Outer Site Secchi disc Seagrass epiphyte OS7 Outer Site Secchi disc Seagrass epiphyte OS8 Outer Site Secchi disc Seagrass epiphyte CS1 Control Site Secchi disc Seagrass epiphyte Marine fauna Risks to marine fauna from vessel impacts were managed by mitigating potential of vessel to impact with whales and other protected marine fauna by the vessel crew completing marine mammal observer training for cetacean impact avoidance measures Trained observers The River Bee vessel crew attended a one day marine mammal observer (MMO) course on 27 May This course was taught by Rochelle Desmond of BMT Oceanica who has extensive experience in marine mammal observation work. The course included regulatory and operational aspects of interactions with marine fauna at sea. Learning aids were provided and included a training manual and marine fauna field guide. Training also included examples of: vessel pre-start checklists, observation recording forms, MMO summary sheets, reporting chain, and auditing procedures. 2.3 Introduced marine species Risks of marine pest introductions were managed by reducing the potential for introduced marine species (IMS), from dredging operations; by consulting with DoF on appropriate steps to risk assess potential pest vectors. Due to the recent dry dock history (May 2015) of the River Bee, an IMS low risk approval application was submitted to the Marine Biosecurity branch of DoF on 20 May Further to this, additional IMS low risk approval applications were submitted for the dredging support vessels (Flinders Bay, Total Assist and Total Response) on 25 May DoF approved the designation of low risk for the vessels on 27 May 2015 and no further actions were required for IMS relating to the vessels hulls. BMT Oceanica: Southern Ports Authority: Maintenance Dredging 2015 Environmental Monitoring Report 5

18 Figure 2.1 Turbidity and seagrass monitoring sites for the 2015 maintenance dredging campaign 6 BMT Oceanica: Southern Ports Authority: Maintenance Dredging 2015 Environmental Monitoring Report

19 3. Results Field survey monitoring of secchi depths and seagrass epiphytes was completed by Bastyan & Associates. Survey dates for each secchi depth and seagrass epiphyte monitoring event are listed in Table 3.1. Table 3.1 Dates of completed environmental monitoring during dredging campaign Date Campaign stage Monitoring action Sites 25 May 2015 Pre-dredging Secchi disc All Seagrass epiphytes CS1, OS5, OS6, OS7 and OS8 4 June 2015 Week 1 dredging Secchi disc All 7 June 2015 Week 1 dredging Secchi disc All 8 June 2015 Week 1 dredging Seagrass epiphytes CS1, OS5, OS6, OS7 and OS8 10 June 2015 Week 2 dredging Secchi disc All 12 June 2015 Week 2 dredging Secchi disc All 24 June 2015 Post dredging Secchi disc All Seagrass epiphytes CS1, OS5, OS6, OS7 and OS8 Remote imagery units were installed on port infrastructure within the inner harbour and on the dredge vessel on 27 May Units were removed from the dredge vessel on 22 June and from the harbour infrastructure on 25 June Turbidity monitoring Water clarity was monitored once prior to dredging, four times during dredging and once after dredging as part of the environmental monitoring of the dredging campaign (Table 3.2). No additional monitoring was required as minimal visual depth triggers were never reached or exceeded. Site OS2 was recorded as >3.9 m on 4 June, but this measurement represented the secchi disc on the seabed and thus visibility had not been reduced. Table 3.2 Water clarity monitoring (secchi disc depth) as part of the 2015 maintenance dredging campaign Site Description Minimum depth trigger (m) Secchi disc depth (m) 25 May 4 June 7 June 10 June 12 June 24 June IS1 Inner Site 4 > IS2 Inner Site 4 >10.5 > IS3 Inner Site 4 > IS4 Inner Site 4 > IS5 Inner Site 4 > >10.8 >11.0 >11.3 >11.0 OS1 Outer Site 4 >7.3 > >7.5 >7.5 OS2 Outer Site 4 >4.0 >3.9 >4.1 >4.1 >4.2 >4.1 OS3 Outer Site 4 >6.0 >5.7 >5.6 >6.0 >6.3 >5.7 OS4 Outer Site 4 >6.2 >6.0 >6.0 >5.8 >6.4 >5.8 OS5 Outer Site 4 >5.6 >5.4 >5.4 >5.4 >5.9 >5.8 OS6 Outer Site 4 >6.2 >5.6 >5.6 >5.6 >6.4 >6.1 OS7 Outer Site 8 >12.4 >12.2 >12.4 >12.5 >12.8 >12.1 OS8 Outer Site 8 >13.0 >13.2 >13.0 >12.6 > CS1 Control Site >4 > Note: 1. Data with > indicates secchi disc was visible on seabed BMT Oceanica: Southern Ports Authority: Maintenance Dredging 2015 Environmental Monitoring Report 7

20 3.1.1 Remote imagery units The remote imagery units captured more than 3,000 photos throughout the dredging campaign. Although photo quality varied due to weather conditions, refraction from sea surface and limitations of available light, hundreds of photos were collected. The photos have provided valuable information on plume distribution and dispersion within the harbour basin, which may be useful to inform decisions for future dredging campaigns. The images revealed surface plumes of sediments with proximity to dredging and disposal. In general, the photos revealed relatively small turbidity plumes which were short lived, particularly in the entrance channel. The harbour turbidity plumes were a darker colour and appeared to remain slightly longer. Example photos are found in (Appendix A) Seagrass epiphyte monitoring Seagrass epiphyte monitoring was completed three times as part of the dredging campaign (Table 3.3). Some slight differences in seagrass epiphyte loading were noted amongst surveys. Representative photos of sites during each survey are provided in Appendix B. Changes include a decrease of epiphytes at the control site during the post dredging survey, and a slight increase in epiphytes at OS7 and OS8. No noticeable change occurred at sites OS5 and OS6. Table 3.3 Seagrass epiphyte loading monitoring as part of the 2015 maintenance dredging campaign Site Description Depth (m) Seagrass epiphyte loading (density) 25 May 8 June 24 June CS1 Control Site 4.0 High High Medium OS5 Outer Site 5.5 Low Low Low OS6 Outer Site 6.0 Low Low Low OS7 Outer Site 12.5 Low Low Medium OS8 Outer Site 12.5 Low Low Medium Marine fauna Marine mammal observations were completed by the River Bee vessel crew during hours of dredging operations (see Appendix C for logs). Marine mammal observers continually monitored for marine mammals during dredging operations and marine mammal sightings were recorded on an hourly basis. Additionally, a minimum of five minutes of visual observation for marine mammals was completed prior to operations daily start up and a 20 minute observation period (with the aid of binoculars) prior to the commencement of dumping activities. A total of 53 Humpback whale adults, nine Humpback calves and two seals were observed by the vessel crew during dredging operations (Table 3.4). Although most marine mammals were not within the 300 m operations exclusion zone, approximately seven hours of shut down time was required during the campaign as part of the cetacean impact avoidance stop work and continuation procedures. 8 BMT Oceanica: Southern Ports Authority: Maintenance Dredging 2015 Environmental Monitoring Report

21 Table 3.4 Observations of marine mammals during dredging operations Date Humpback whale adult Humpback whale calves Other mammal Required shutdown time (hr) 31 May June June June seals 0 4 June June June June June June June June June June June June Total BMT Oceanica: Southern Ports Authority: Maintenance Dredging 2015 Environmental Monitoring Report 9

22 4. Summary and discussion All of the environmental commitments outlined in the EIA (BMT Oceanica 2014) were satisfied by the Albany Port 2015 maintenance dredging environmental monitoring. The key results included: There were no exceedances of turbidity. Monitoring of water clarity through secchi disc depth measurements and seagrass epiphyte loading resulted in no exceedances. Secchi disc depth measurements found short lived decreases in water clarity and these were limited to the harbour and near the harbour entrance sites (IS1-4 and OS1). Slight differences occurred in seagrass epiphyte loading at sites CS1 (decreased) and OS7 and OS8 (increased) but no change was noted at sites OS5 and OS6. Three remote imagery units were deployed for a period of up to 28 days, which resulted in collection of over 3,000 photos of the maintenance dredging operation. The information may be useful to inform decision making for future dredging campaigns. The risk of IMS incursion was determined to be low by Department of Fisheries due to the recent dry docking of the dredge vessel and associated support vessels. The potential impacts to marine fauna from vessels were managed through comprehensive marine mammal observation training supplied by BMT Oceanica. A total of 53 Humpback whale adults and nine calves were observed during the dredging operations. Approximately seven hours of shutdown time was required due to impact avoidance procedures, but no impacts to marine mammals were recorded. 10 BMT Oceanica: Southern Ports Authority: Maintenance Dredging 2015 Environmental Monitoring Report

23 5. References BMT Oceanica (2014a) Albany Port Authority Maintenance Dredging Program: Environmental Impact Assessment. Prepared for Albany Port Authority by BMT Oceanica Pty Ltd, Report No. 812_01_002/2_Rev1, Perth, Western Australia, August 2014 BMT Oceanica (2014b) Albany Port Authority Maintenance Dredging Program Sediment Sampling and Analysis Implementation. Prepared for Albany Port Authority by BMT Oceanica Pty Ltd, Report No. 812_01_002/1_Rev0, Perth, Western Australia, May 2014 BMT Oceanica: Southern Ports Authority: Maintenance Dredging 2015 Environmental Monitoring Report 11

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25 Appendix A Remote imagery photo examples

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27 Appendix B Seagrass epiphyte loading photo examples

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29 Appendix C Marine mammal observation logs

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32 BMT Oceanica Pty Ltd PO Box 462 Wembley WA 6913 Australia Tel: Fax: bmtoceanica@bmtoceanica.com.au