FREMANTLE PORT INNER HARBOUR AND CHANNEL DEEPENING ...
FREMANTLE PORT INNER HARBOUR AND CHANNEL DEEPENING – RECLAMATION AT ROUS HEAD AND OFFSHORE PLACEMENT OF DREDGED MATERIAL WATER QUALITY MONITORING PROGRAM DATA REPORT: 8/10/2010 Summary for Period 27th September to 3rd October 2010 Inclusive This report covers the eighth week of „Phase 2‟ dredging works, and any data from prior sampling that has been released following laboratory analyses. Monitoring Results for Public Health Concentrations of toxicants were of the same magnitude within sentinel mussels and adjacent natural mussels collected around the Inner Harbour, and did not exceed trigger levels relevant to the protection of fishing and aquaculture values. Monitoring Results for Aesthetics and Human Amenity Water clarity at Point Preston Beach within the Lower Swan River Estuary and at all coastal beaches met water clarity guidelines during this monitoring period. Monitoring Results for Ecosystem Health Dissolved oxygen levels within the bottom waters of the Inner Harbour dredge plume and Offshore Disposal plume met the relevant ecosystem health protection levels during the present monitoring period. Light levels at seagrass monitoring sites adjacent to the Offshore Disposal Area determined: o within the zone of influence were above the Level 1 management trigger for the entire 28-day monitoring period - this duration equates to an exceedance of the Level 3 management trigger; and o within the zone of effect exceeded the Level 4 management trigger on some occasions between 5th and 24th September 2010, but not thereafter. Light levels at seagrass monitoring sites adjacent to the Deep Water Channel: o determined within the zone of influence were above the Level 1 management trigger between 22nd and 24th September 2010, but not thereafter; and o could not be determined within the zone of effect due to missing loggers (likely from vessel disturbance); however, it is noted that dredging within the Deep Water Channel only occurred for 8 days over the monitoring period and the risk of reduced light impacts on seagrass from resultant plumes is low.
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Disclaimer This report has been prepared on behalf of and for the exclusive use of Fremantle Ports and the Office of the EPA, and is subject to and issued in accordance with the agreed terms and scope between Fremantle Ports and Oceanica Consulting Pty Ltd (Oceanica). All results presented will be subject to further review and Quality Assurance checks during preparation of the final Compliance Assessment Report in accordance with Ministerial Statement 801. Oceanica accepts no liability or responsibility whatsoever in respect of any use of or reliance upon this report by any third party. Copying this report without the permission of Fremantle Ports or Oceanica Consulting Pty Ltd is not permitted.
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WATER QUALITY MONITORING PROGRAM DATA REPORT: 8/10/2010 This report considers environmental values addressed by the document “Fremantle Port Inner Harbour and Channel Deepening-Reclamation at Rous Head and Offshore Placement of Dredged Material: Water Quality Monitoring Program, January 2010” (WQMP), providing monitoring results for: public health values (i.e. primary contact recreation and fishing values) (Section 1); aesthetics and human amenity values (i.e. water clarity and aesthetics of primary and secondary contact areas) (Section 2); and ecosystem health values (in terms of acceptable toxicant thresholds and light requirements for seagrass and coral) (Section 3). Please refer to the WQMP for a full description of management trigger levels, reporting limits and contingency management actions. In summary, reporting requirements are based on Tables 4.4 (pg.15) to 4.7 (pg.18) of the WQMP, which outline the water, seafood and sediment quality indicators and trigger levels for all monitoring site locations based on the relevant areas of application. Definitions of monitoring terms frequently used are provided in Appendix 1. As shown in Figure 1.1, areas of application relevant to this report are: Recreation and Aesthetics water quality monitoring sites (swimming beaches); Inner Harbour Dredge Plume water quality monitoring sites; Offshore Dredge and Disposal Plume water quality monitoring sites; Seagrass and Coral water quality monitoring sites; and Water, Mussel and Sediment Quality monitoring sites. This area of application includes water quality data routinely collected and made available by the Department of Water (DoW), as well as mussel and sediment quality data collected as part of the WQMP. Structured in order of those environmental values described above, Sections 1 to 3 of this report detail monitoring data obtained from each relevant area of application for the period of 27th September to 3rd October inclusive.
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Figure 1.1
Water Quality Monitoring Program site locations for period 27th September to 3rd October 2010. Note: The location of natural mussel sampling site „RH2‟ is approximate (GPS datum was not obtained).
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1.
Public Health
1.1.
Toxicants at Primary Contact Areas
As defined within Section 5.1.2 of the WQMP, toxicants including metals, organotins, pesticides and polycyclic aromatic hydrocarbons (PAHs) within water at primary contact areas (i.e. swimming beaches – “Recreation & Aesthetic” sites RA1 to RA6; Figure 1.1) shall be monitored prior to dredging, and thereafter only if toxicants within the Inner Harbour dredge plume exceed triggers for high protection of ecosystem health. The rationale for this conservative approach is that high protection ecosystem health trigger levels for toxicants in water are either similar to, or more typically orders of magnitude lower than, primary contact recreation trigger levels (see Table 4.5 of the WQMP); such that non-exceedance of toxicant triggers for the high protection of ecosystem health near the source of release (i.e. within the Inner Harbour) indicates that dredging activities are not significantly contributing to toxicant concentrations at more distant swimming beaches. On the other hand, exceedance of toxicant triggers relevant to the high protection of ecosystem health “near source” does not imply that toxicant concentrations at those more distant beaches will be above primary contact triggers, but rather that further investigation of toxicant concentrations at primary contact areas shall be initiated1. Monitoring of toxicants at public beaches has not been triggered to date; and toxicant concentrations at Inner Harbour sites will be monitored on one further occasion, i.e. within one week after dredging has ceased (further see Section 3.1).
1.2.
Fishing and Aquaculture Values surrounding the Inner Harbour and Rous Head
1.2.1. Toxicants in Sentinel Mussels In accordance with Section 5.2.1 of the WQMP, sentinel mussels are deployed and collected every six weeks at “Water, Mussel & Sediment Quality” locations (see Figure 1.1 - sites RB1, FP1, FP7, RH2 & RH3, plus the reference site MR1). Sentinel mussels are then analysed for concentrations of toxicants in their tissue (metals, organotins, pesticides, PAHs and Polychlorinated Biphenyls [PCBs]), to provide an indication of whether seafood are within the relevant guideline limits for toxicants. Sentinel mussels filter the water column continuously, retaining bioaccumulative toxicants within their tissue, and as such mussels are often used as an integrated measure of toxicant exposure over time (in this case, six weeks). Concentrations of toxicants in sentinel mussels did not exceed trigger levels relevant to the protection of fishing and aquaculture values 2 within the six-weekly deployment of mussels prior to the commencement of Phase 2 dredging (from 16 th June to 28th July 2010; see WQMP Report: 27/8/2010). Sentinel mussels were next collected on 10th September 2010 after a six week deployment encompassing the commencement of Phase 2 dredging. Resultant toxicant concentration data are provided in Figure 1.2, Figure 1.3 and Appendix 2. 1
Note that toxicant concentrations in the Inner Harbour are actually compared to relevant management triggers for the moderate protection of ecosystem health. While moderate protection ecosystem health triggers are typically greater than high protection ecosystem health triggers, they are still either similar to, or less than, primary contact recreation trigger levels. As such, non-exceedance of toxicant triggers for the moderate protection of ecosystem health near the source of release (i.e. within the Inner Harbour) similarly indicates that dredging activities are not substantially contributing to toxicant concentrations at more distant swimming beaches. 2
Please note that the Department of Health recommends only eating commercially harvested shellfish and not shellfish collected from the wild (further see http://www.health.wa.gov.au/docreg/Education/Risk/ Environmental Health/Safe Food Handling/HP010646 wild shellfish collection.pdf). P:\FremantlePorts\816_InnerHarbourDredgeMonitoring\007_ImplementWQMP\Reports\Water Report_20101008\IHR Water Quality report_20101008_RevA.docx 8 October 2010 10:23 AM
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Mussel concentrations of metals, organotins, pesticides, PAHs and PCBs did not exceed trigger levels relevant to the protection of fishing and aquaculture values (Figure 1.2 and Figure 1.3), and were below detection limits for pesticides, PAHs and PCBs (Appendix 2). Sentinel mussels were redeployed on 10th September 2010, for another six week period.
1.2
2.5
Arsenic (inorganic)
Concentration (mg/kg)
1
2
0.8
1.5
0.6 1 0.4 0.5
0.2
0
0 RB1
FP7
35
FP1
RH2
RH3
Concentration (mg/kg)
RB1
MR1
FP7
2.5
Copper
30
FP1
RH2
RH3
MR1
Lead
2
25
20
1.5
15
1
10 0.5
5
0
0
RB1
FP7
0.6
Concentration (mg/kg)
Cadmium
FP1
RH2
RH3
MR1
RB1
FP7
FP1
350
Mercury
RH2
RH3
MR1
Zinc
300
0.5
250
0.4
200 0.3
150 0.2
100
0.1
50
0
0
RB1
Figure 1.2
FP7
FP1
RH2
RH3
MR1
RB1
FP7
FP1
RH2
RH3
MR1
Concentrations of metals in sentinel mussels deployed in triplicate for 6-weeks at monitoring sites surrounding the Inner Harbour (RB1, FP7, FP1, RH2, RH3) and at an offshore reference site (MR1), compared to guideline fishing and aquaculture trigger levels. Where data are not shown, metal concentrations are below the analytical detection limit.
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140
Tributyltin
Concentration (ng Sn/g)
120 100 80 60 40
20 0 RB1
Figure 1.3
FP7
FP1
RH2
RH3
MR1
Concentrations of tributyltin in sentinel mussels deployed in triplicate for 6weeks at monitoring sites surrounding the Inner Harbour (RB1, FP7, FP1, RH2, RH3) and at an offshore reference site (MR1), compared to guideline fishing and aquaculture trigger levels (dashed line). Where data are not shown, tributyltin concentration is below the analytical detection limit.
1.2.2. Toxicants in Natural Mussels In addition to WQMP requirements, adult natural mussels were collected from pylons adjacent to the five sentinel mussel monitoring locations surrounding the Inner Harbour on 14th September (see Figure 1.1 – “Natural mussel” sites RB1, FP7, FP1, RH2, RH3). Natural mussels were then analysed for concentrations of toxicants in their tissue (metals, organotins, pesticides, PAHs and Polychlorinated Biphenyls [PCBs]), to provide an indication of whether naturally occurring seafood are within the relevant guideline limits for toxicants. In the same way as sentinel mussels, natural mussels filter the water column continuously and retain bioaccumulative toxicants within their tissue; however, the duration of time that adult natural mussels are exposed to the water column is equivalent to their lifespan (>1 year) which in this case will have included the Phase 1 and 2 dredging periods and likely many prior months to years. Concentrations of metals, organotins, pesticides, PAHs and PCBs within natural mussels (Figure 1.4, Figure 1.5, Appendix 3) were of the same order of magnitude as those determined within sentinel mussels (Figure 1.2, Figure 1.3, Appendix 2), did not exceed trigger levels relevant to the protection of fishing and aquaculture values, and were below detection limits for pesticides, PAHs and PCBs (Appendix 3).
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1.2
2.5
Arsenic (inorganic)
2
Concentration (mg/kg)
Concentration (mg/kg)
1 0.8
0.6 0.4 0.2
1.5 1 0.5
0
0 RB1
FP7
35
FP1
RH2
RH3_M
RB1
25 20
15 10
5
FP1
RH2
RH3_M
RH2
RH3_M
RH2
RH3_M
Lead
2
Concentration (mg/kg)
Concentration (mg/kg)
FP7
2.5
Copper
30
1.5
1 0.5
0
0 RB1
FP7
0.6
FP1
RH2
RH3_M
RB1
FP7
350
Mercury
FP1
Zinc
300
Concentration (mg/kg)
0.5
Concentration (mg/kg)
Cadmium
0.4 0.3
0.2 0.1
250
200 150
100 50
0
0 RB1
Figure 1.4
FP7
FP1
RH2
RH3_M
RB1
FP7
FP1
Concentrations of metals in natural mussels collected from sites within and surrounding the Inner Harbour (see Figure 1.1), compared to guideline fishing and aquaculture trigger levels. Where data are not shown, metal concentrations are below the analytical detection limit.
Tributyltin
120
Concentration (mg/kg)
100 80
60 40
20 0 RB1
Figure 1.5
FP7
FP1
RH2
RH3_M
Concentrations of tributyltin in natural mussels collected from sites within and surrounding the Inner Harbour (see Figure 1.1), compared to guideline fishing and aquaculture trigger levels (dashed line). Where data are not shown, tributyltin concentration is below the analytical detection limit.
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2.
Aesthetics and Human Amenity
2.1.
Water Clarity and Aesthetics of Primary Contact Areas
Secchi depth is monitored at one river beach and five coastal swimming beaches (respectively, “Recreation and Aesthetic” sites RA1 and RA2 to RA6; Figure 1.1) for comparison with the relevant management trigger level for primary contact recreation and aesthetics, as per Section 5.1.2 of the WQMP (i.e. Secchi depth should be greater than 1.6 m)3. Measures of water clarity were undertaken on 30th September 2010 during the eighth week of Phase 2 dredging. Secchi depth data for “Recreational and Aesthetic” sites for the present and previous monitoring periods are provided in Figure 2.1. The management trigger for Secchi depth was not exceeded at any beach during the present monitoring period (see Appendix 4 for raw data). The water column concentration of total suspended solids (TSS) and percentage of organic matter in suspended solids (Loss on ignition at 550˚C – LOI) at all “Recreation and Aesthetic” sites determined during the present and previous monitoring periods are also provided for contextual purposes (Figure 2.2).
3
Note that this Secchi depth management trigger was developed for application in coastal marine areas and its use in riverine or estuarine environments is highly conservative as these waters are often naturally more turbid than marine waters. P:\FremantlePorts\816_InnerHarbourDredgeMonitoring\007_ImplementWQMP\Reports\Water Report_20101008\IHR Water Quality report_20101008_RevA.docx 8 October 2010 10:23 AM
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0
1
1
2
2
3
3
Secchi depth (m)
Secchi depth (m)
0
4
5
6
7
5
6
7
Preston Point - RA1
8
0
1
1
2
2
Secchi depth (m)
3
4
3
4
5
5
6
6
7
7 Fremantle SLSC - RA3
0
1
1
2
2
3
3
Secchi depth (m)
Secchi depth (m)
0
4
5
Figure 2.1
4
5
6
6
8
Cottesloe Beach - RA4
8
8
7
Port Beach - RA2
8
0
Secchi depth (m)
4
7 Bather's Beach - RA5
South Beach - RA6
8
Secchi depth measured at public beaches (sites RA1 to RA6) compared to the guideline trigger for primary contact recreation and aesthetics (dashed line; i.e. Secchi depth should be greater than 1.6 m).
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90.0
12.0 Preston Point - RA1
Port Beach - RA2
80.0 10.0
60.0
TSS concentration mg/L
TSS concentration mg/L
70.0
50.0 40.0
30.0
8.0
6.0
4.0
20.0 2.0 10.0 0.0
10.0
8.0
8.0
TSS concentration mg/L
10.0
6.0
4.0
4.0
2.0
0.0
0.0
10.0
8.0
6.0
4.0
Bather's Beach - RA5
12.0
South Beach - RA6
10.0
8.0
6.0
4.0
2.0
2.0
0.0
0.0
Figure 2.2
Cottesloe Beach - RA4
6.0
2.0
12.0
TSS concentration mg/L
12.0
Fremantle SLSC - RA3
TSS concentration mg/L
TSS concentration mg/L
12.0
0.0
Concentration of total suspended solids (TSS) measured at public beaches (sites RA1 to RA6; the organic fraction of TSS determined by loss on ignition at 550˚C is shaded black). Note difference in vertical scale for Preston Point – RA1.
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3.
Ecosystem Health
3.1.
Toxicants within Inner Harbour Dredge Plume
In accordance with Section 5.1.1 of the WQMP, monitoring of toxicants within the Inner Harbour dredge plume was required “weekly for the duration of dredging of the 300,000 m3 potentially contaminated sediment within the Inner Harbour and then one sampling occasion one week after dredging of the potentially contaminated sediment”. This dredging of potentially contaminated (unconsolidated) sediment was undertaken during the first few weeks of Phase 1 works in January 2010, without exceedance of relevant management triggers for moderate ecosystem health protection. In addition to WQMP requirements, Fremantle Ports continued to weekly monitor toxicant concentrations within the Inner Harbour dredge plume during Phase 1 works, and also committed to weekly monitoring during the week preceding and first fortnight of Phase 2 dredging of consolidated limestone. On all monitoring occasions toxicant concentrations were below relevant ecosystem health management levels (see WQMP Report: 3/09/2010 for results of Phase 2 monitoring). Toxicant concentrations at Inner Harbour sites will be monitored on one further occasion within one week after dredging has ceased.
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3.2.
Toxicants in Sediments Outside of Dredge Areas
Sediments are sampled monthly at five “Water, Mussel & Sediment Quality” monitoring sites surrounding the Inner Harbour (sites RB1, FP1, FP7, RH2 & RH3; Figure 1.1) on one baseline occasion prior to dredging and then during active dredging (as per Section 5.3.1 of the WQMP). Sediments are analysed for toxicant concentrations (metals, organotins, pesticides, PAHs and PCBs) for comparison with: 1. ecosystem health levels defined by the WQMP and EPA (2005); and, 2. the re-sampling levels defined by EPA (2005). Levels are applicable to the toxicant concentration determined at each site; in this case, represented by the mean of triplicate samples4. As per ANZECC/ARMCANZ (2000; Chapter 8, Section 4), exceeding the ecosystem health trigger level does not necessarily mean that adverse biological effects occur. At toxicant concentrations below ecosystem health trigger levels the frequency of adverse biological effects is expected to be very low (CSIRO 2005). Similarly, the presence of toxicant concentrations above re-sampling levels does not mean that adverse biological effects will occur; however, they could be expected to occur more frequently and further investigation (e.g. additional sampling) should be undertaken to determine this (EPA 2005; CSIRO 2005). Sediments were sampled on 24th August 2010 during the first month of Phase 2 dredging works, with toxicant results previously reported in WQMP Report: 10/09/2010. Sediments were sampled on 28th September following the second month of dredging operations, with results to be provided in a subsequent report following release of final results by the laboratory.
4
Triplicate sediment samples taken at monitoring sites surrounding the Inner Harbour and Rous Head (RB1, FP1, FP7, RH2 and RH3) are physically combined for laboratory analyses, with one mean concentration result reported for each toxicant at each site. When the mean concentration of triplicate sediment samples include one or more values less than the detection limit ( 80% in MEPA, > 90% in HEPA (dashed lines) and never < 60% saturation (solid line). Note: * Dissolved oxygen saturation data at site DH500 were not collected due to monitoring equipment (YSI) malfunction.
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Table 3.1
Location
Temperature and turbidity at 0.5 m below sea surface and 0.5 m above sediment surface, plus Secchi depth and integrated TSS, including the organic fraction of TSS determined by loss on ignition (LOI) at 550˚C, at monitoring sites within the Inner Harbour dredge plume and Offshore Disposal Area plume. Site
Date
DH10
1/10/2010
DH50
1/10/2010
DH100
1/10/2010
DH500*
1/10/2010
DS10
1/10/2010
DS50
1/10/2010
DS100
1/10/2010
DS500
1/10/2010
Inner Harbour
Offshore Disposal Area
Time
Depth (m)
Temp. (oC)
Turbidity (NTU)
9:47:41
0.51
18.45
7.4
9:48:32
13.60
18.18
402.1
10:06:02
0.35
18.58
5.8
10:06:52
13.32
18.22
29.0
10:16:50
0.25
18.56
6.0
10:17:49
13.37
18.19
13.7
-
-
-
-
-
-
-
-
12:09:16
0.49
18.51
6.8
12:10:17
18.53
18.47
33.5
12:24:20
0.26
18.69
2.5
12:25:25
18.87
18.52
9.6
12:36:51
0.95
18.64
4.6
12:37:53
19.02
18.51
12.2
12:48:22
0.97
18.96
2.1
12:49:02
19.19
18.50
2.1
TSS (mg/L)
LOI (%)
Secchi depth (m)
16
22
1.5
18
21
1.6
16
23
1.5
15
24
1.5
38
15
1.0
17
26
1.5
16
17
1.5
15
19
3.1
Notes:No management triggers are relevant to temperature, turbidity, TSS, LOI or Secchi depth. Data are presented for contextual information only. * Temperature and turbidity data at site DH500 were not collected due to monitoring equipment (YSI) malfunction.
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3.4.
Light Attenuation Coefficient (LAC) Monitoring for Seagrass and Coral Health
3.4.1. LAC data The Light Attenuation Coefficient (LAC) of the water column is continuously recorded by light loggers deployed at sites overlying seagrass and coral habitats. LAC is a measure of the attenuation of light with depth through the water column – the higher the LAC, the less light that can penetrate the water column to reach photosynthesising benthic primary producers, such as seagrass and corals. Monitoring is targeted and focussed on data collection at those sites within proximity of the visible plume/s (as based on field observation and aerial imagery), plus associated reference sites. That is, not all sites will be sampled for the full duration of the dredge program and when dredging, only those sites within the proximity of the visible dredge and/or disposal plumes will be sampled, plus associated reference sites. Recorded light data are downloaded from loggers each fortnight, and processed to rolling 14-day median LAC values for assessment against management trigger values that are specific to depth, habitat (seagrass or corals) and BPPH management zones (further see Sections 4.1.1 and 5.1.1 of the WQMP). It is noted that “nearshore” light loggers (in proximity to the Inner Harbour dredge plume and Hall Bank coral sites) and “offshore” light loggers (in proximity to the offshore dredge and disposal plumes) are collected in alternate weeks of the fortnight, such that any given weekly WQMP data report will only present LAC data for either nearshore sites or offshore sites. This WQMP data report presents LAC data resultant from the most recent collection of offshore light loggers. For contextual purposes TSS concentrations, including determination of the organic component via loss on ignition (LOI) and water turbidity (NTU) are also determined at each seagrass monitoring site (see Appendix 6). Offshore light loggers were retrieved and redeployed on 30/09/2010. The cumulative period of LAC data collected at each seagrass health monitoring site is provided in Table 3.2. As relevant to the definition of LAC management triggers (defined by Section 4.1.1 of the WQMP), Table 3.2 further provides monitoring site water depths and information regarding where each site is located in terms of predicted zones of potential influence, effect or loss of BPPH due to dredging. LAC data for sites located within the predicted zones of potential influence (ZoI) and potential effect (ZoE) are compared against management triggers. For the period of disposal to the Offshore Disposal Area from 21/08/2010 to 30/09/2010, median LAC data and applicable management triggers are shown for adjacent monitoring sites (SH49B, SH50B, SH51, SH7; Figure 3.2 and Figure 3.3) and reference sites (SH32, SH33, SH34, SH35; Figure 3.6) from 3/09/2010, i.e. the first possible day of rolling 14day median data. Dredging of the Deep Water Channel commenced on 9/9/2010, and 14day median LAC data for adjacent sites (SH2, SH5, SH46, SH47) are shown from 22/09/2010 (Figure 3.4 and Figure 3.5). For seagrass health monitoring sites adjacent to the Offshore Disposal Area, median LAC values at site SH51within the ZoI were above the Level 1 management trigger for the duration of the 28-day period (Figure 3.2). This duration of exceedance equates to an exceedance of the Level 3 management trigger at site SH51. At the other site within the ZoI (SH7) the bottom light logger malfunctioned for the current period and both loggers were missing during the previous period such that 14-day median LAC data are not available. Median LAC values within the ZoE at site SH49B were above the Level 4 management trigger on 5/09/2010 and from 10–24/09/2010, but dropped below the Level 3 management trigger on 25/09/2010 and below the Level 2 management trigger from 26–30/09/2010 (Figure 3.3). At the other site within the ZoE (SH50B), loggers were missing for the current period such that 14-day median LAC datum is only available for 13/09/2010 and was above the Level 4 management trigger (Figure 3.3). A survey of P:\FremantlePorts\816_InnerHarbourDredgeMonitoring\007_ImplementWQMP\Reports\Water Report_20101008\IHR Water Quality report_20101008_RevA.docx 8 October 2010 10:23 AM
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seagrass health at sites in both the ZoE and ZoI adjacent to the Offshore Disposal Area is scheduled for 6-7/10/2010 (in accordance with Section 5.1.1 of the WQMP). For seagrass health monitoring sites adjacent to the Deep Water Channel, median LAC values at sites SH2 and SH5 within the ZoI exceeded the applicable Level 1 management triggers between 22-24/9/2010 but dropped below the triggers between 25-30/9/2010 (Figure 3.4). Rolling 14-day median LAC values at sites SH46 and SH47 within the ZoE could not be determined due to loss of data resulting from missing loggers (likely due to disturbance from dredge or other vessels). It is noted that over the period of LAC monitoring at sites adjacent to the Deep Water Channel (9-30/09/2010), active dredging has only occurred on 8 days, such that the risk of significant impacts on seagrass from light reduction associated with dredge plumes is low.
Table 3.2
Region
Offshore Disposal Area
Offshore light logger monitoring site details and LAC data (rolling 14-day median LAC). Habitat
Site
Zone
Depth (m)
Period
LAC Trigger Exceeded
Seagrass
SH51
Influence
17.0
21/08/2010 – 30/09/2010
Level 3 trigger exceeded
Seagrass
SH7
Influence
19.3
21/08/2010 – 30/08/2010*
No data
Seagrass
SH49B
Effect
20.0
21/08/2010 – 30/09/2010
Level 4 trigger exceeded
Seagrass
SH50B
Effect
16.4
31/08/2010 – 13/09/2010*
Level 4 trigger exceeded
SH2
Influence
15.6
9/09/2010 – 30/09/2010
Level 1 trigger exceeded
SH5
Influence
14.2
9/09/2010 – 30/09/2010
Level 1 trigger exceeded
Seagrass
SH46
Effect
17.6
9/09/2010 – 13/09/2010*
No data
Seagrass
SH47
Effect
16.1
No data*
No data
Seagrass
SH32
Reference
16.1
21/08/2010 – 30/09/2010
N/A
Seagrass
SH33
Reference
15.1
21/08/2010 – 13/09/2010*
N/A
Seagrass
SH34
Reference
15.1
21/08/2010 – 30/09/2010
N/A
Seagrass
SH35
Reference
13.6
21/08/2010 – 30/09/2010
N/A
Seagrass Deep Water Channel
Offshore Reference Sites Note: * N/A
Seagrass
Missing data resultant from logger loss or malfunction. New loggers were redeployed in the same location. Not applicable.
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Offshore Disposal Area – Zone of Potential Influence
SH7 Loggers Missing (N.B. Rolling 10-day median LAC from 21st to 30th August 2010 = 0.068 m-1; Rolling 14-day median LAC Trigger for Level 1 Management = 0.050 m-1)
SH51 0.30
Light Attenuation Coefficient (m-1)
0.25
0.20
0.15
0.10
0.05
0.00
Date Median
Figure 3.2
Level 1 Trigger
Rolling 14-day median LAC at seagrass health monitoring sites located adjacent to the Offshore Disposal Area, within the predicted zone of potential influence (SH7 – top; SH51 – bottom). LAC thresholds pertaining to Level 1 management triggers are also presented.
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Offshore Disposal Area – Zone of Potential Effect SH49B 0.30
Light Attenuation Coefficient (m-1)
0.25
0.20
0.15
0.10
0.05
0.00
Median
Level 1 Trigger
Date Level 2 Trigger
Level 3 Trigger
Level 4 Trigger
SH50B 0.3
Light Attenuation Coefficient (m-1)
0.25
0.2
0.15
0.1
0.05
0
Median
Figure 3.3
Level 1 Trigger
Date Level 2 Trigger
Level 3 Trigger
Level 4 Trigger
Rolling 14-day median LAC at seagrass health monitoring sites located adjacent to the Offshore Disposal Area, within the predicted zone of potential effect (SH49B – top; SH50B – bottom). LAC thresholds pertaining to Level 1, 2, 3 & 4 management triggers are also presented.
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Deep Water Channel – Zone of Potential Influence SH2 0.30
Light Attenuation Coefficient (m-1)
0.25
0.20
0.15
0.10
0.05
0.00
Date Median
Level 1 Trigger
SH5 0.3
Light Attenuation Coefficient (m-1)
0.25
0.2
0.15
0.1
0.05
0
Date Median
Figure 3.4
Level 1 Trigger
Rolling 14-day median LAC at seagrass health monitoring sites located adjacent to the Deep Water Channel, within the predicted zone of potential influence (SH2 – top; SH5 – bottom). LAC thresholds pertaining to Level 1 management triggers are also presented.
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Deep Water Channel – Zone of Potential Effect
SH46 Loggers Missing (N.B. Rolling 5-day median LAC from 9th to 13th September 2010 = 0.065 m-1; Rolling 14-day median LAC Triggers for Level 1 & 2 Management = 0.056 m-1 & 0.072 m-1)
SH47 Loggers Missing (N.B. no data)
Figure 3.5
Rolling 14-day median LAC at seagrass health monitoring sites located adjacent to the Deep Water Channel, within the predicted zone of potential effect (SH46 - top; SH47 – bottom).
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Offshore – Reference Sites SH32 0.3
Light Attenuation Coefficient (m-1)
0.25
0.2
0.15
0.1
0.05
0
Date Median
SH33 0.3
Light Attenuation Coefficient (m-1)
0.25
0.2
0.15
0.1
0.05
0
Date Median
Figure 3.6(a)
Rolling 14-day median LAC at offshore reference seagrass health monitoring sites, outside the predicted zone of potential influence (SH32 – top; SH33 – bottom). Management triggers are not applicable to reference sites.
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SH34 0.3
Light Attenuation Coefficient (m-1)
0.25
0.2
0.15
0.1
0.05
0
Median
Date
SH35 0.30
Light Attenuation Coefficient (m-1)
0.25
0.20
0.15
0.10
0.05
0.00
Median
Figure 3.6(b)
Date
Rolling 14-day median LAC at offshore reference seagrass health monitoring sites, outside the predicted zone of potential influence (SH34 – top; SH35 – bottom). Management triggers are not applicable to reference sites.
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4.
References
ANZECC/ARMCANZ (2000) National Water Quality Management Strategy: Paper No 4 Australian and New Zealand Guidelines for Fresh and Marine Water Quality. Volume 2 - Aquatic Ecosystems - Rationale and Background Information (Chapter 8). Australian and New Zealand Environment and Conservation Council / Agriculture and Resource Management Council of Australia and New Zealand, October 200. Commonwealth Australia (2009). National Assessment Guidelines for Dredging. Canberra, ACT. CSIRO (2005). Handbook for Sediment Quality Assessment. Commonwealth Scientific and Industrial Research Organisation, Bangor, NSW. EPA (2005). Environmental Quality Criteria Reference Document for Cockburn Sound (2003-2004): A supporting document to the State Environmental (Cockburn Sound) Policy 2005. Environmental Protection Authority, Report 20, January 2005. Oceanica (2010). Fremantle Port Inner Harbour and Channel Deepening – Reclamation at Rous Head and Offshore Placement of Dredged Material: Water Quality Monitoring Program, Prepared for Fremantle Ports by Oceanica Consulting, January 2010.
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Appendix 1 Definitions of Monitoring Terms Used DO (%): the amount of oxygen dissolved in water, expressed relative to the amount of oxygen the water can hold when „saturated‟ with oxygen. LOI % (550°C): Loss On Ignition, the % of TSS which is lost when heated to 550°C. This provides an indication of the % of TSS which is organic matter. pH: A measure of how acidic or alkaline water is. The ocean is typically slightly alkaline: seawater typically has a pH between 8.0 and 8.4, and estuaries such as the Swan River typically have a pH of 7.5-8.5. Rainwater is slightly acidic, with a pH of 5.6. Salinity: The total dissolved salts in the water measured as parts per thousand (ppt). Secchi depth: A standard measure of water clarity using a Secchi disc, which is circular plate 0.3 m in diameter with alternating black and white quadrants. The Secchi depth is the water depth at which the human eye can no longer distinguish between the black and white quadrants. TSS: Total Suspended Solids, a measure of the amount of fine particles suspended in the water. TSS is measured by filtering a known volume of water, and then drying and weighing the material left on the filter. Turbidity (NTU): a measure of water clarity using an instrument called a nephelometer that measures how much the suspended particles in water scatter a light beam focused on them. The units of turbidity from a calibrated nephelometer are called Nephelometric Turbidity Units (NTU).
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Appendix 2 Sentinel Mussel Toxicant Concentrations: Raw Data
Toxicant
Trigger level (to protect fishing & aquaculture values)
RB1
RB1
RB1
FP7
FP7
FP7
FP1
FP1
FP1
RH2
RH2
RH2
RH3
RH3
RH3
MR1
MR1
MR1
Metals
mg/kg wet weight (ww) mussel tissue
Rep-A
Rep-B
Rep-C
Rep-A
Rep-B
Rep-C
Rep-A
Rep-B
Rep-C
Rep-A
Rep-B
Rep-C
Rep-A
Rep-B
Rep-C
Rep-A
Rep-B
Rep-C
Arsenic inorganic
1
0.027
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Disclaimer This report has been prepared on behalf of and for the exclusive use of Fremantle Ports and the Office of the EPA, and is subject to and issued in accordance with the agreed terms and scope between Fremantle Ports and Oceanica Consulting Pty Ltd (Oceanica). All results presented will be subject to further review and Quality Assurance checks during preparation of the final Compliance Assessment Report in accordance with Ministerial Statement 801. Oceanica accepts no liability or responsibility whatsoever in respect of any use of or reliance upon this report by any third party. Copying this report without the permission of Fremantle Ports or Oceanica Consulting Pty Ltd is not permitted.
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WATER QUALITY MONITORING PROGRAM DATA REPORT: 8/10/2010 This report considers environmental values addressed by the document “Fremantle Port Inner Harbour and Channel Deepening-Reclamation at Rous Head and Offshore Placement of Dredged Material: Water Quality Monitoring Program, January 2010” (WQMP), providing monitoring results for: public health values (i.e. primary contact recreation and fishing values) (Section 1); aesthetics and human amenity values (i.e. water clarity and aesthetics of primary and secondary contact areas) (Section 2); and ecosystem health values (in terms of acceptable toxicant thresholds and light requirements for seagrass and coral) (Section 3). Please refer to the WQMP for a full description of management trigger levels, reporting limits and contingency management actions. In summary, reporting requirements are based on Tables 4.4 (pg.15) to 4.7 (pg.18) of the WQMP, which outline the water, seafood and sediment quality indicators and trigger levels for all monitoring site locations based on the relevant areas of application. Definitions of monitoring terms frequently used are provided in Appendix 1. As shown in Figure 1.1, areas of application relevant to this report are: Recreation and Aesthetics water quality monitoring sites (swimming beaches); Inner Harbour Dredge Plume water quality monitoring sites; Offshore Dredge and Disposal Plume water quality monitoring sites; Seagrass and Coral water quality monitoring sites; and Water, Mussel and Sediment Quality monitoring sites. This area of application includes water quality data routinely collected and made available by the Department of Water (DoW), as well as mussel and sediment quality data collected as part of the WQMP. Structured in order of those environmental values described above, Sections 1 to 3 of this report detail monitoring data obtained from each relevant area of application for the period of 27th September to 3rd October inclusive.
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Figure 1.1
Water Quality Monitoring Program site locations for period 27th September to 3rd October 2010. Note: The location of natural mussel sampling site „RH2‟ is approximate (GPS datum was not obtained).
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1.
Public Health
1.1.
Toxicants at Primary Contact Areas
As defined within Section 5.1.2 of the WQMP, toxicants including metals, organotins, pesticides and polycyclic aromatic hydrocarbons (PAHs) within water at primary contact areas (i.e. swimming beaches – “Recreation & Aesthetic” sites RA1 to RA6; Figure 1.1) shall be monitored prior to dredging, and thereafter only if toxicants within the Inner Harbour dredge plume exceed triggers for high protection of ecosystem health. The rationale for this conservative approach is that high protection ecosystem health trigger levels for toxicants in water are either similar to, or more typically orders of magnitude lower than, primary contact recreation trigger levels (see Table 4.5 of the WQMP); such that non-exceedance of toxicant triggers for the high protection of ecosystem health near the source of release (i.e. within the Inner Harbour) indicates that dredging activities are not significantly contributing to toxicant concentrations at more distant swimming beaches. On the other hand, exceedance of toxicant triggers relevant to the high protection of ecosystem health “near source” does not imply that toxicant concentrations at those more distant beaches will be above primary contact triggers, but rather that further investigation of toxicant concentrations at primary contact areas shall be initiated1. Monitoring of toxicants at public beaches has not been triggered to date; and toxicant concentrations at Inner Harbour sites will be monitored on one further occasion, i.e. within one week after dredging has ceased (further see Section 3.1).
1.2.
Fishing and Aquaculture Values surrounding the Inner Harbour and Rous Head
1.2.1. Toxicants in Sentinel Mussels In accordance with Section 5.2.1 of the WQMP, sentinel mussels are deployed and collected every six weeks at “Water, Mussel & Sediment Quality” locations (see Figure 1.1 - sites RB1, FP1, FP7, RH2 & RH3, plus the reference site MR1). Sentinel mussels are then analysed for concentrations of toxicants in their tissue (metals, organotins, pesticides, PAHs and Polychlorinated Biphenyls [PCBs]), to provide an indication of whether seafood are within the relevant guideline limits for toxicants. Sentinel mussels filter the water column continuously, retaining bioaccumulative toxicants within their tissue, and as such mussels are often used as an integrated measure of toxicant exposure over time (in this case, six weeks). Concentrations of toxicants in sentinel mussels did not exceed trigger levels relevant to the protection of fishing and aquaculture values 2 within the six-weekly deployment of mussels prior to the commencement of Phase 2 dredging (from 16 th June to 28th July 2010; see WQMP Report: 27/8/2010). Sentinel mussels were next collected on 10th September 2010 after a six week deployment encompassing the commencement of Phase 2 dredging. Resultant toxicant concentration data are provided in Figure 1.2, Figure 1.3 and Appendix 2. 1
Note that toxicant concentrations in the Inner Harbour are actually compared to relevant management triggers for the moderate protection of ecosystem health. While moderate protection ecosystem health triggers are typically greater than high protection ecosystem health triggers, they are still either similar to, or less than, primary contact recreation trigger levels. As such, non-exceedance of toxicant triggers for the moderate protection of ecosystem health near the source of release (i.e. within the Inner Harbour) similarly indicates that dredging activities are not substantially contributing to toxicant concentrations at more distant swimming beaches. 2
Please note that the Department of Health recommends only eating commercially harvested shellfish and not shellfish collected from the wild (further see http://www.health.wa.gov.au/docreg/Education/Risk/ Environmental Health/Safe Food Handling/HP010646 wild shellfish collection.pdf). P:\FremantlePorts\816_InnerHarbourDredgeMonitoring\007_ImplementWQMP\Reports\Water Report_20101008\IHR Water Quality report_20101008_RevA.docx 8 October 2010 10:23 AM
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Mussel concentrations of metals, organotins, pesticides, PAHs and PCBs did not exceed trigger levels relevant to the protection of fishing and aquaculture values (Figure 1.2 and Figure 1.3), and were below detection limits for pesticides, PAHs and PCBs (Appendix 2). Sentinel mussels were redeployed on 10th September 2010, for another six week period.
1.2
2.5
Arsenic (inorganic)
Concentration (mg/kg)
1
2
0.8
1.5
0.6 1 0.4 0.5
0.2
0
0 RB1
FP7
35
FP1
RH2
RH3
Concentration (mg/kg)
RB1
MR1
FP7
2.5
Copper
30
FP1
RH2
RH3
MR1
Lead
2
25
20
1.5
15
1
10 0.5
5
0
0
RB1
FP7
0.6
Concentration (mg/kg)
Cadmium
FP1
RH2
RH3
MR1
RB1
FP7
FP1
350
Mercury
RH2
RH3
MR1
Zinc
300
0.5
250
0.4
200 0.3
150 0.2
100
0.1
50
0
0
RB1
Figure 1.2
FP7
FP1
RH2
RH3
MR1
RB1
FP7
FP1
RH2
RH3
MR1
Concentrations of metals in sentinel mussels deployed in triplicate for 6-weeks at monitoring sites surrounding the Inner Harbour (RB1, FP7, FP1, RH2, RH3) and at an offshore reference site (MR1), compared to guideline fishing and aquaculture trigger levels. Where data are not shown, metal concentrations are below the analytical detection limit.
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140
Tributyltin
Concentration (ng Sn/g)
120 100 80 60 40
20 0 RB1
Figure 1.3
FP7
FP1
RH2
RH3
MR1
Concentrations of tributyltin in sentinel mussels deployed in triplicate for 6weeks at monitoring sites surrounding the Inner Harbour (RB1, FP7, FP1, RH2, RH3) and at an offshore reference site (MR1), compared to guideline fishing and aquaculture trigger levels (dashed line). Where data are not shown, tributyltin concentration is below the analytical detection limit.
1.2.2. Toxicants in Natural Mussels In addition to WQMP requirements, adult natural mussels were collected from pylons adjacent to the five sentinel mussel monitoring locations surrounding the Inner Harbour on 14th September (see Figure 1.1 – “Natural mussel” sites RB1, FP7, FP1, RH2, RH3). Natural mussels were then analysed for concentrations of toxicants in their tissue (metals, organotins, pesticides, PAHs and Polychlorinated Biphenyls [PCBs]), to provide an indication of whether naturally occurring seafood are within the relevant guideline limits for toxicants. In the same way as sentinel mussels, natural mussels filter the water column continuously and retain bioaccumulative toxicants within their tissue; however, the duration of time that adult natural mussels are exposed to the water column is equivalent to their lifespan (>1 year) which in this case will have included the Phase 1 and 2 dredging periods and likely many prior months to years. Concentrations of metals, organotins, pesticides, PAHs and PCBs within natural mussels (Figure 1.4, Figure 1.5, Appendix 3) were of the same order of magnitude as those determined within sentinel mussels (Figure 1.2, Figure 1.3, Appendix 2), did not exceed trigger levels relevant to the protection of fishing and aquaculture values, and were below detection limits for pesticides, PAHs and PCBs (Appendix 3).
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1.2
2.5
Arsenic (inorganic)
2
Concentration (mg/kg)
Concentration (mg/kg)
1 0.8
0.6 0.4 0.2
1.5 1 0.5
0
0 RB1
FP7
35
FP1
RH2
RH3_M
RB1
25 20
15 10
5
FP1
RH2
RH3_M
RH2
RH3_M
RH2
RH3_M
Lead
2
Concentration (mg/kg)
Concentration (mg/kg)
FP7
2.5
Copper
30
1.5
1 0.5
0
0 RB1
FP7
0.6
FP1
RH2
RH3_M
RB1
FP7
350
Mercury
FP1
Zinc
300
Concentration (mg/kg)
0.5
Concentration (mg/kg)
Cadmium
0.4 0.3
0.2 0.1
250
200 150
100 50
0
0 RB1
Figure 1.4
FP7
FP1
RH2
RH3_M
RB1
FP7
FP1
Concentrations of metals in natural mussels collected from sites within and surrounding the Inner Harbour (see Figure 1.1), compared to guideline fishing and aquaculture trigger levels. Where data are not shown, metal concentrations are below the analytical detection limit.
Tributyltin
120
Concentration (mg/kg)
100 80
60 40
20 0 RB1
Figure 1.5
FP7
FP1
RH2
RH3_M
Concentrations of tributyltin in natural mussels collected from sites within and surrounding the Inner Harbour (see Figure 1.1), compared to guideline fishing and aquaculture trigger levels (dashed line). Where data are not shown, tributyltin concentration is below the analytical detection limit.
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2.
Aesthetics and Human Amenity
2.1.
Water Clarity and Aesthetics of Primary Contact Areas
Secchi depth is monitored at one river beach and five coastal swimming beaches (respectively, “Recreation and Aesthetic” sites RA1 and RA2 to RA6; Figure 1.1) for comparison with the relevant management trigger level for primary contact recreation and aesthetics, as per Section 5.1.2 of the WQMP (i.e. Secchi depth should be greater than 1.6 m)3. Measures of water clarity were undertaken on 30th September 2010 during the eighth week of Phase 2 dredging. Secchi depth data for “Recreational and Aesthetic” sites for the present and previous monitoring periods are provided in Figure 2.1. The management trigger for Secchi depth was not exceeded at any beach during the present monitoring period (see Appendix 4 for raw data). The water column concentration of total suspended solids (TSS) and percentage of organic matter in suspended solids (Loss on ignition at 550˚C – LOI) at all “Recreation and Aesthetic” sites determined during the present and previous monitoring periods are also provided for contextual purposes (Figure 2.2).
3
Note that this Secchi depth management trigger was developed for application in coastal marine areas and its use in riverine or estuarine environments is highly conservative as these waters are often naturally more turbid than marine waters. P:\FremantlePorts\816_InnerHarbourDredgeMonitoring\007_ImplementWQMP\Reports\Water Report_20101008\IHR Water Quality report_20101008_RevA.docx 8 October 2010 10:23 AM
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0
1
1
2
2
3
3
Secchi depth (m)
Secchi depth (m)
0
4
5
6
7
5
6
7
Preston Point - RA1
8
0
1
1
2
2
Secchi depth (m)
3
4
3
4
5
5
6
6
7
7 Fremantle SLSC - RA3
0
1
1
2
2
3
3
Secchi depth (m)
Secchi depth (m)
0
4
5
Figure 2.1
4
5
6
6
8
Cottesloe Beach - RA4
8
8
7
Port Beach - RA2
8
0
Secchi depth (m)
4
7 Bather's Beach - RA5
South Beach - RA6
8
Secchi depth measured at public beaches (sites RA1 to RA6) compared to the guideline trigger for primary contact recreation and aesthetics (dashed line; i.e. Secchi depth should be greater than 1.6 m).
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90.0
12.0 Preston Point - RA1
Port Beach - RA2
80.0 10.0
60.0
TSS concentration mg/L
TSS concentration mg/L
70.0
50.0 40.0
30.0
8.0
6.0
4.0
20.0 2.0 10.0 0.0
10.0
8.0
8.0
TSS concentration mg/L
10.0
6.0
4.0
4.0
2.0
0.0
0.0
10.0
8.0
6.0
4.0
Bather's Beach - RA5
12.0
South Beach - RA6
10.0
8.0
6.0
4.0
2.0
2.0
0.0
0.0
Figure 2.2
Cottesloe Beach - RA4
6.0
2.0
12.0
TSS concentration mg/L
12.0
Fremantle SLSC - RA3
TSS concentration mg/L
TSS concentration mg/L
12.0
0.0
Concentration of total suspended solids (TSS) measured at public beaches (sites RA1 to RA6; the organic fraction of TSS determined by loss on ignition at 550˚C is shaded black). Note difference in vertical scale for Preston Point – RA1.
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3.
Ecosystem Health
3.1.
Toxicants within Inner Harbour Dredge Plume
In accordance with Section 5.1.1 of the WQMP, monitoring of toxicants within the Inner Harbour dredge plume was required “weekly for the duration of dredging of the 300,000 m3 potentially contaminated sediment within the Inner Harbour and then one sampling occasion one week after dredging of the potentially contaminated sediment”. This dredging of potentially contaminated (unconsolidated) sediment was undertaken during the first few weeks of Phase 1 works in January 2010, without exceedance of relevant management triggers for moderate ecosystem health protection. In addition to WQMP requirements, Fremantle Ports continued to weekly monitor toxicant concentrations within the Inner Harbour dredge plume during Phase 1 works, and also committed to weekly monitoring during the week preceding and first fortnight of Phase 2 dredging of consolidated limestone. On all monitoring occasions toxicant concentrations were below relevant ecosystem health management levels (see WQMP Report: 3/09/2010 for results of Phase 2 monitoring). Toxicant concentrations at Inner Harbour sites will be monitored on one further occasion within one week after dredging has ceased.
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3.2.
Toxicants in Sediments Outside of Dredge Areas
Sediments are sampled monthly at five “Water, Mussel & Sediment Quality” monitoring sites surrounding the Inner Harbour (sites RB1, FP1, FP7, RH2 & RH3; Figure 1.1) on one baseline occasion prior to dredging and then during active dredging (as per Section 5.3.1 of the WQMP). Sediments are analysed for toxicant concentrations (metals, organotins, pesticides, PAHs and PCBs) for comparison with: 1. ecosystem health levels defined by the WQMP and EPA (2005); and, 2. the re-sampling levels defined by EPA (2005). Levels are applicable to the toxicant concentration determined at each site; in this case, represented by the mean of triplicate samples4. As per ANZECC/ARMCANZ (2000; Chapter 8, Section 4), exceeding the ecosystem health trigger level does not necessarily mean that adverse biological effects occur. At toxicant concentrations below ecosystem health trigger levels the frequency of adverse biological effects is expected to be very low (CSIRO 2005). Similarly, the presence of toxicant concentrations above re-sampling levels does not mean that adverse biological effects will occur; however, they could be expected to occur more frequently and further investigation (e.g. additional sampling) should be undertaken to determine this (EPA 2005; CSIRO 2005). Sediments were sampled on 24th August 2010 during the first month of Phase 2 dredging works, with toxicant results previously reported in WQMP Report: 10/09/2010. Sediments were sampled on 28th September following the second month of dredging operations, with results to be provided in a subsequent report following release of final results by the laboratory.
4
Triplicate sediment samples taken at monitoring sites surrounding the Inner Harbour and Rous Head (RB1, FP1, FP7, RH2 and RH3) are physically combined for laboratory analyses, with one mean concentration result reported for each toxicant at each site. When the mean concentration of triplicate sediment samples include one or more values less than the detection limit ( 80% in MEPA, > 90% in HEPA (dashed lines) and never < 60% saturation (solid line). Note: * Dissolved oxygen saturation data at site DH500 were not collected due to monitoring equipment (YSI) malfunction.
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Table 3.1
Location
Temperature and turbidity at 0.5 m below sea surface and 0.5 m above sediment surface, plus Secchi depth and integrated TSS, including the organic fraction of TSS determined by loss on ignition (LOI) at 550˚C, at monitoring sites within the Inner Harbour dredge plume and Offshore Disposal Area plume. Site
Date
DH10
1/10/2010
DH50
1/10/2010
DH100
1/10/2010
DH500*
1/10/2010
DS10
1/10/2010
DS50
1/10/2010
DS100
1/10/2010
DS500
1/10/2010
Inner Harbour
Offshore Disposal Area
Time
Depth (m)
Temp. (oC)
Turbidity (NTU)
9:47:41
0.51
18.45
7.4
9:48:32
13.60
18.18
402.1
10:06:02
0.35
18.58
5.8
10:06:52
13.32
18.22
29.0
10:16:50
0.25
18.56
6.0
10:17:49
13.37
18.19
13.7
-
-
-
-
-
-
-
-
12:09:16
0.49
18.51
6.8
12:10:17
18.53
18.47
33.5
12:24:20
0.26
18.69
2.5
12:25:25
18.87
18.52
9.6
12:36:51
0.95
18.64
4.6
12:37:53
19.02
18.51
12.2
12:48:22
0.97
18.96
2.1
12:49:02
19.19
18.50
2.1
TSS (mg/L)
LOI (%)
Secchi depth (m)
16
22
1.5
18
21
1.6
16
23
1.5
15
24
1.5
38
15
1.0
17
26
1.5
16
17
1.5
15
19
3.1
Notes:No management triggers are relevant to temperature, turbidity, TSS, LOI or Secchi depth. Data are presented for contextual information only. * Temperature and turbidity data at site DH500 were not collected due to monitoring equipment (YSI) malfunction.
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3.4.
Light Attenuation Coefficient (LAC) Monitoring for Seagrass and Coral Health
3.4.1. LAC data The Light Attenuation Coefficient (LAC) of the water column is continuously recorded by light loggers deployed at sites overlying seagrass and coral habitats. LAC is a measure of the attenuation of light with depth through the water column – the higher the LAC, the less light that can penetrate the water column to reach photosynthesising benthic primary producers, such as seagrass and corals. Monitoring is targeted and focussed on data collection at those sites within proximity of the visible plume/s (as based on field observation and aerial imagery), plus associated reference sites. That is, not all sites will be sampled for the full duration of the dredge program and when dredging, only those sites within the proximity of the visible dredge and/or disposal plumes will be sampled, plus associated reference sites. Recorded light data are downloaded from loggers each fortnight, and processed to rolling 14-day median LAC values for assessment against management trigger values that are specific to depth, habitat (seagrass or corals) and BPPH management zones (further see Sections 4.1.1 and 5.1.1 of the WQMP). It is noted that “nearshore” light loggers (in proximity to the Inner Harbour dredge plume and Hall Bank coral sites) and “offshore” light loggers (in proximity to the offshore dredge and disposal plumes) are collected in alternate weeks of the fortnight, such that any given weekly WQMP data report will only present LAC data for either nearshore sites or offshore sites. This WQMP data report presents LAC data resultant from the most recent collection of offshore light loggers. For contextual purposes TSS concentrations, including determination of the organic component via loss on ignition (LOI) and water turbidity (NTU) are also determined at each seagrass monitoring site (see Appendix 6). Offshore light loggers were retrieved and redeployed on 30/09/2010. The cumulative period of LAC data collected at each seagrass health monitoring site is provided in Table 3.2. As relevant to the definition of LAC management triggers (defined by Section 4.1.1 of the WQMP), Table 3.2 further provides monitoring site water depths and information regarding where each site is located in terms of predicted zones of potential influence, effect or loss of BPPH due to dredging. LAC data for sites located within the predicted zones of potential influence (ZoI) and potential effect (ZoE) are compared against management triggers. For the period of disposal to the Offshore Disposal Area from 21/08/2010 to 30/09/2010, median LAC data and applicable management triggers are shown for adjacent monitoring sites (SH49B, SH50B, SH51, SH7; Figure 3.2 and Figure 3.3) and reference sites (SH32, SH33, SH34, SH35; Figure 3.6) from 3/09/2010, i.e. the first possible day of rolling 14day median data. Dredging of the Deep Water Channel commenced on 9/9/2010, and 14day median LAC data for adjacent sites (SH2, SH5, SH46, SH47) are shown from 22/09/2010 (Figure 3.4 and Figure 3.5). For seagrass health monitoring sites adjacent to the Offshore Disposal Area, median LAC values at site SH51within the ZoI were above the Level 1 management trigger for the duration of the 28-day period (Figure 3.2). This duration of exceedance equates to an exceedance of the Level 3 management trigger at site SH51. At the other site within the ZoI (SH7) the bottom light logger malfunctioned for the current period and both loggers were missing during the previous period such that 14-day median LAC data are not available. Median LAC values within the ZoE at site SH49B were above the Level 4 management trigger on 5/09/2010 and from 10–24/09/2010, but dropped below the Level 3 management trigger on 25/09/2010 and below the Level 2 management trigger from 26–30/09/2010 (Figure 3.3). At the other site within the ZoE (SH50B), loggers were missing for the current period such that 14-day median LAC datum is only available for 13/09/2010 and was above the Level 4 management trigger (Figure 3.3). A survey of P:\FremantlePorts\816_InnerHarbourDredgeMonitoring\007_ImplementWQMP\Reports\Water Report_20101008\IHR Water Quality report_20101008_RevA.docx 8 October 2010 10:23 AM
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seagrass health at sites in both the ZoE and ZoI adjacent to the Offshore Disposal Area is scheduled for 6-7/10/2010 (in accordance with Section 5.1.1 of the WQMP). For seagrass health monitoring sites adjacent to the Deep Water Channel, median LAC values at sites SH2 and SH5 within the ZoI exceeded the applicable Level 1 management triggers between 22-24/9/2010 but dropped below the triggers between 25-30/9/2010 (Figure 3.4). Rolling 14-day median LAC values at sites SH46 and SH47 within the ZoE could not be determined due to loss of data resulting from missing loggers (likely due to disturbance from dredge or other vessels). It is noted that over the period of LAC monitoring at sites adjacent to the Deep Water Channel (9-30/09/2010), active dredging has only occurred on 8 days, such that the risk of significant impacts on seagrass from light reduction associated with dredge plumes is low.
Table 3.2
Region
Offshore Disposal Area
Offshore light logger monitoring site details and LAC data (rolling 14-day median LAC). Habitat
Site
Zone
Depth (m)
Period
LAC Trigger Exceeded
Seagrass
SH51
Influence
17.0
21/08/2010 – 30/09/2010
Level 3 trigger exceeded
Seagrass
SH7
Influence
19.3
21/08/2010 – 30/08/2010*
No data
Seagrass
SH49B
Effect
20.0
21/08/2010 – 30/09/2010
Level 4 trigger exceeded
Seagrass
SH50B
Effect
16.4
31/08/2010 – 13/09/2010*
Level 4 trigger exceeded
SH2
Influence
15.6
9/09/2010 – 30/09/2010
Level 1 trigger exceeded
SH5
Influence
14.2
9/09/2010 – 30/09/2010
Level 1 trigger exceeded
Seagrass
SH46
Effect
17.6
9/09/2010 – 13/09/2010*
No data
Seagrass
SH47
Effect
16.1
No data*
No data
Seagrass
SH32
Reference
16.1
21/08/2010 – 30/09/2010
N/A
Seagrass
SH33
Reference
15.1
21/08/2010 – 13/09/2010*
N/A
Seagrass
SH34
Reference
15.1
21/08/2010 – 30/09/2010
N/A
Seagrass
SH35
Reference
13.6
21/08/2010 – 30/09/2010
N/A
Seagrass Deep Water Channel
Offshore Reference Sites Note: * N/A
Seagrass
Missing data resultant from logger loss or malfunction. New loggers were redeployed in the same location. Not applicable.
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Offshore Disposal Area – Zone of Potential Influence
SH7 Loggers Missing (N.B. Rolling 10-day median LAC from 21st to 30th August 2010 = 0.068 m-1; Rolling 14-day median LAC Trigger for Level 1 Management = 0.050 m-1)
SH51 0.30
Light Attenuation Coefficient (m-1)
0.25
0.20
0.15
0.10
0.05
0.00
Date Median
Figure 3.2
Level 1 Trigger
Rolling 14-day median LAC at seagrass health monitoring sites located adjacent to the Offshore Disposal Area, within the predicted zone of potential influence (SH7 – top; SH51 – bottom). LAC thresholds pertaining to Level 1 management triggers are also presented.
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Offshore Disposal Area – Zone of Potential Effect SH49B 0.30
Light Attenuation Coefficient (m-1)
0.25
0.20
0.15
0.10
0.05
0.00
Median
Level 1 Trigger
Date Level 2 Trigger
Level 3 Trigger
Level 4 Trigger
SH50B 0.3
Light Attenuation Coefficient (m-1)
0.25
0.2
0.15
0.1
0.05
0
Median
Figure 3.3
Level 1 Trigger
Date Level 2 Trigger
Level 3 Trigger
Level 4 Trigger
Rolling 14-day median LAC at seagrass health monitoring sites located adjacent to the Offshore Disposal Area, within the predicted zone of potential effect (SH49B – top; SH50B – bottom). LAC thresholds pertaining to Level 1, 2, 3 & 4 management triggers are also presented.
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Deep Water Channel – Zone of Potential Influence SH2 0.30
Light Attenuation Coefficient (m-1)
0.25
0.20
0.15
0.10
0.05
0.00
Date Median
Level 1 Trigger
SH5 0.3
Light Attenuation Coefficient (m-1)
0.25
0.2
0.15
0.1
0.05
0
Date Median
Figure 3.4
Level 1 Trigger
Rolling 14-day median LAC at seagrass health monitoring sites located adjacent to the Deep Water Channel, within the predicted zone of potential influence (SH2 – top; SH5 – bottom). LAC thresholds pertaining to Level 1 management triggers are also presented.
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Deep Water Channel – Zone of Potential Effect
SH46 Loggers Missing (N.B. Rolling 5-day median LAC from 9th to 13th September 2010 = 0.065 m-1; Rolling 14-day median LAC Triggers for Level 1 & 2 Management = 0.056 m-1 & 0.072 m-1)
SH47 Loggers Missing (N.B. no data)
Figure 3.5
Rolling 14-day median LAC at seagrass health monitoring sites located adjacent to the Deep Water Channel, within the predicted zone of potential effect (SH46 - top; SH47 – bottom).
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Offshore – Reference Sites SH32 0.3
Light Attenuation Coefficient (m-1)
0.25
0.2
0.15
0.1
0.05
0
Date Median
SH33 0.3
Light Attenuation Coefficient (m-1)
0.25
0.2
0.15
0.1
0.05
0
Date Median
Figure 3.6(a)
Rolling 14-day median LAC at offshore reference seagrass health monitoring sites, outside the predicted zone of potential influence (SH32 – top; SH33 – bottom). Management triggers are not applicable to reference sites.
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SH34 0.3
Light Attenuation Coefficient (m-1)
0.25
0.2
0.15
0.1
0.05
0
Median
Date
SH35 0.30
Light Attenuation Coefficient (m-1)
0.25
0.20
0.15
0.10
0.05
0.00
Median
Figure 3.6(b)
Date
Rolling 14-day median LAC at offshore reference seagrass health monitoring sites, outside the predicted zone of potential influence (SH34 – top; SH35 – bottom). Management triggers are not applicable to reference sites.
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4.
References
ANZECC/ARMCANZ (2000) National Water Quality Management Strategy: Paper No 4 Australian and New Zealand Guidelines for Fresh and Marine Water Quality. Volume 2 - Aquatic Ecosystems - Rationale and Background Information (Chapter 8). Australian and New Zealand Environment and Conservation Council / Agriculture and Resource Management Council of Australia and New Zealand, October 200. Commonwealth Australia (2009). National Assessment Guidelines for Dredging. Canberra, ACT. CSIRO (2005). Handbook for Sediment Quality Assessment. Commonwealth Scientific and Industrial Research Organisation, Bangor, NSW. EPA (2005). Environmental Quality Criteria Reference Document for Cockburn Sound (2003-2004): A supporting document to the State Environmental (Cockburn Sound) Policy 2005. Environmental Protection Authority, Report 20, January 2005. Oceanica (2010). Fremantle Port Inner Harbour and Channel Deepening – Reclamation at Rous Head and Offshore Placement of Dredged Material: Water Quality Monitoring Program, Prepared for Fremantle Ports by Oceanica Consulting, January 2010.
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Appendix 1 Definitions of Monitoring Terms Used DO (%): the amount of oxygen dissolved in water, expressed relative to the amount of oxygen the water can hold when „saturated‟ with oxygen. LOI % (550°C): Loss On Ignition, the % of TSS which is lost when heated to 550°C. This provides an indication of the % of TSS which is organic matter. pH: A measure of how acidic or alkaline water is. The ocean is typically slightly alkaline: seawater typically has a pH between 8.0 and 8.4, and estuaries such as the Swan River typically have a pH of 7.5-8.5. Rainwater is slightly acidic, with a pH of 5.6. Salinity: The total dissolved salts in the water measured as parts per thousand (ppt). Secchi depth: A standard measure of water clarity using a Secchi disc, which is circular plate 0.3 m in diameter with alternating black and white quadrants. The Secchi depth is the water depth at which the human eye can no longer distinguish between the black and white quadrants. TSS: Total Suspended Solids, a measure of the amount of fine particles suspended in the water. TSS is measured by filtering a known volume of water, and then drying and weighing the material left on the filter. Turbidity (NTU): a measure of water clarity using an instrument called a nephelometer that measures how much the suspended particles in water scatter a light beam focused on them. The units of turbidity from a calibrated nephelometer are called Nephelometric Turbidity Units (NTU).
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Appendix 2 Sentinel Mussel Toxicant Concentrations: Raw Data
Toxicant
Trigger level (to protect fishing & aquaculture values)
RB1
RB1
RB1
FP7
FP7
FP7
FP1
FP1
FP1
RH2
RH2
RH2
RH3
RH3
RH3
MR1
MR1
MR1
Metals
mg/kg wet weight (ww) mussel tissue
Rep-A
Rep-B
Rep-C
Rep-A
Rep-B
Rep-C
Rep-A
Rep-B
Rep-C
Rep-A
Rep-B
Rep-C
Rep-A
Rep-B
Rep-C
Rep-A
Rep-B
Rep-C
Arsenic inorganic
1
0.027
