Fortnightly Water Quality Report

Transcription

1 0 Fortnightly Water Quality Report Ichthys Nearshore Environmental Monitoring Program Weeks 75/76: 27 January 2014 to February 2014 Weeks 75/76: 27 January 2014 to 9 February 2014 Prepared for INPEX October 2014

2 Document Information Prepared for INPEX Project Name File Reference L384-AW-REP-10177_0_47_Water Quality Fortnightly Report Weeks 75_76.docm Job Reference Weeks 75/76: 27 January 2014 to 9 February 2014 Date October 2014 Contact Information Cardno (NSW/ACT) Pty Ltd Cardno (WA) Pty Ltd Cardno (NT) Pty Ltd Level 9, The Forum 11 Harvest Terrace Level 6, 93 Mitchell Street 203 Pacific Highway West Perth WA 6005 Darwin NT 0800 St Leonards NSW 2065 Telephone: Telephone: Telephone: Facsimile: Facsimile: Facsimile: International: International: International: Document Control Version Date Author Author Initials Reviewer Reviewer Initials A 18/02/2014 Chris Beadle CB Michael Hughes Isabel Jimenez 0 20/02/2014 Chris Beadle CB Michael Hughes Isabel Jimenez MH IJ MH IJ 1 23/10/2014 Chris Beadle CB Christopher Holloway CGH This document is produced by Cardno solely for the benefit and use by the client in accordance with the terms of the engagement for the performance of the Services. Cardno does not and shall not assume any responsibility or liability whatsoever to any third party arising out of any use or reliance by any third party on the content of this document. Prepared for INPEX Cardno Page ii

3 Table of Contents 1 Summary Reporting Period Trigger Exceedance Summary Summary of Dredge Operations 3 2 Wind, Rainfall and Tidal Conditions 4 3 Turbidity 6 Tables Table 1-1 Water Quality summary period 1 Table 1-2 Level 1 wet season trigger exceedance summary (27 January 2014 to 9 February 2014) 2 Table 1-3 Summary of East Arm Dredge Operations (data provided by INPEX) 3 Table 3-1 Summary notes on turbidity plots for the period 27 January 2014 to 9 February Figures Darwin Airport (data source Bureau of Meteorology) air temperature and atmospheric pressure, wind speed and direction and half hourly rainfall (daily totals presented numerically on top of plot) for the fortnight to 9 February Darwin predicted tide for the fortnight to 9 February 2014, based on harmonic constituents for Darwin defined by the Australian Hydrographic Service ( 5 BoM AUSWAVE Model significant wave height the for output location 11 km north-north-east of Charles Point for the fortnight to 9 February Water Quality monitoring sites 8 Channel Island (reactive coral site) 9 Channel Island 2 (contingency reactive coral site) 10 Weed Reef 1 (reactive coral site) 11 Weed Reef 2 (reactive coral site) 12 Fannie Bay (reactive seagrass site) 13 Fannie Bay 2 (contingency reactive seagrass site) 14 Lee Point (reactive seagrass site) 15 Lee Point 2 (contingency reactive seagrass site) 16 Woods Inlet (reactive seagrass site) 17 Woods Inlet 2 (contingency reactive seagrass site) 18 Casuarina Beach (seagrass site surrogate reactive site from 29 January 2014 to 5 February 2014) 19 East Point (seagrass site surrogate reactive site from 6 February 2014 to 9 February 2014) 21 Charles Point 2 (seagrass and coral site) 22 Mandorah (coral site) 23 Northeast Wickham Point (coral site) 24 South Shell Island (coral site) 25 Spoil Ground (spoil ground disposal site) 26 Upper East Arm 1 (harbour dredging site) 27 Prepared for INPEX Cardno Page iii

4 1 Summary This fortnightly report presents telemetered water quality data collected as part of the Ichthys Water Quality and Subtidal Sedimentation Monitoring Program during weeks 75 and 76 (27 January 2014 to 9 February 2014) since the commencement of dredging operations. The fortnightly report provides an assessment of the water quality trigger levels for the fortnight and has been based on this period to highlight the springneap tidal cycle. This report collates information from 14 different telemetered Water Quality monitoring sites selected to assess the turbidity associated with dredging and spoil disposal activities. Duplicate monitoring systems have been deployed at four of the reactive monitoring locations to provide backup data collection at these critical sites. 1.1 Reporting Period This summarises dredging activities, metocean (wind, rainfall and tidal) conditions and water quality (turbidity) results for the period defined in Table 1-1. Table 1-1 Period Start Water Quality summary period Period End Monday, 27 January 2014 Sunday, 9 February Trigger Exceedance Summary Fifty-seven Level 1 wet season coral and seagrass triggers were exceeded during this reporting period at primary logger sites (Table 1-2 and Figure 3-2 to Figure 3-13), with 10 trigger exceedances recorded at Channel Island, 14 at Weed Reef 1, 12 at Weed Reef 2, 14 at Fannie Bay and seven at Woods Inlet. A further twenty seven trigger exceedances were also recorded by contingency loggers located at Fannie Bay (n=7), Channel Island (n=10) and Woods Inlet (n=10) (Table 1-2). During the reporting period, data were not available from the Lee Point primary logger (due to biofouling) or contingency logger (due bottom battery drain resulting from a severed cable). From 29 January 2014 to 5 February 2014, Casuarina Beach was adopted as a surrogate reactive seagrass water quality monitoring site in the absence of functioning water quality loggers at Lee Point. Surrogate threshold conditions at Casuarina Beach indicating a potential Level 1 wet season intensity trigger exceedance at Lee Point were determined based on correlation analyses of daily-averaged turbidity between the sites during periods of moderate to high wave energy. These surrogate threshold conditions were: predicted offshore significant wave heights exceeding 0.5 m, and daily-averaged turbidity measured at Casuarina Beach exceeding 50 NTU for Intensity and 40 NTU for Duration and Frequency. Twenty-three surrogate exceedances were recorded at Casuarina Beach during the reporting period (Table 1-2). From 6 February 2014 to 9 February 2014, battery drain in the Casuarina Beach bottom logger resulted in turbidity data loss. Consequently, from 6 February 2014 to 9 February 2014, East Point was adopted as a surrogate reactive seagrass water quality monitoring site in the absence of functioning water quality loggers at Lee Point (and Casuarina Beach). Surrogate threshold conditions at East Point indicating a potential Level 1 wet season intensity trigger exceedance at Lee Point were determined in the same manner as for Casuarina Beach. These surrogate threshold conditions were: predicted offshore significant wave heights exceeding 0.5 m, and daily-averaged turbidity measured at East Point exceeding 30 NTU for Intensity and 22 NTU for Duration and Frequency. Four surrogate exceedances were recorded at East Point (Table 1-2). The reported trigger exceedances occurred across a large spring tidal phase that also included heavy rainfall, strong westerly winds, large swell and waves generated by monsoon conditions over northern Australia (see Section 2). The monsoon trough resulted in the generation of Tropical Cyclone (TC) Fletcher, which began as a tropical low situated in the Gulf of Carpentaria on 2 February It briefly intensified into a Category 1 TC on 3 February 2014, before crossing the Gulf of Carpentaria coast near the Gilbert River mouth and dropping below cyclone intensity. From 3 February 2014 to 6 February 2014 the system lingered inland near the south-east Gulf of Carpentaria as an Ex-TC before dissipating. Prepared for INPEX Cardno Page 1

5 Additionally, a separate tropical low was located in the Kimberly region from 4 February 2014 to 7 February The tropical low tracked westwards and did not develop into a TC. The severe metocean conditions produced strong littoral stirring, resulting in significant regional increases in turbidity along the Western Australian and Northern Territory coastal strip, including the Beagle Gulf. Catchment runoff is also likely to have contributed to the increased turbidity recorded at both Darwin Harbour Inner and Darwin Outer sites. As such, the INPEX Exceedance Attributability and Implementation Report attributed these trigger exceedances to natural oceanic and meteorological processes associated with the monsoonal trough coupled with large spring tides. Table 1-2 provides a summary of the trigger exceedances observed during the reporting period. Table 1-2 Level 1 wet season trigger exceedance summary (27 January 2014 to 9 February 2014) Intensity Frequency Duration Wet Season Coral Triggers for Channel Island >44 NTU >26 NTU > 3 days per 7-day rolling period >26 NTU over 7 consecutive days Channel Island 1 to 5 February 2014 (n=5) 3 to 6 February 2014 (n=4) 6 February 2014 (n=1) Channel Island 2* (contingency logger) 1 to 5 February 2014 (n=5) 3 to 6 February 2014 (n=4) 6 February 2014 (n=1) Wet Season Coral Triggers for Weed Reef >65 NTU >46 NTU > 3 days per 7-day rolling period >46 NTU over 6 consecutive days Weed Reef 1 1 to 6 February 2014 (n=6) Weed Reef 2 1 to 6 February 2014 (n=6) 3 to 7 February 2014 (n=5) 3 to 6 February 2014 (n=4) 5 to 7 February 2014 (n=3) 5 to 6 February 2014 (n=2) Wet Season Seagrass Triggers >63 NTU >52 NTU > 5 days per 7-day rolling period >52 NTU over 5 consecutive days Fannie Bay 30 January 2014 to 5 February 2014 (n=7) 3 to 5 February 2014 (n=3) 2 to 5 February 2014 (n=4) Fannie Bay 2* (contingency logger) 30 January 2014 to 1 February 2014, 3 February February 2014 (n=1) 5 to 6 February 2014 (n=2) (n=4) Lee Point None (no available data) None (no available data) None (no available data) Woods Inlet 1 1 to 4 February 2014 (n=4) 5 February 2014 (n=1) 4 to 5 February 2014 (n=2) Woods Inlet 2* (contingency logger) 1 to 5 February 2014 (n=5) 5 to 6 February 2014 (n=2) 4 to 6 February 2014 (n=3) Wet Season Seagrass Triggers >50 NTU Hs > 0.5m Casuarina Beach (Lee Point surrogate) 30 January 2014 to 5 February 2014 (n=7) 29 January 2014 to 5 February 2014 (n=8) 29 January 2014 to 5 February 2014 (n=8) Wet Season Seagrass Triggers >30 NTU Hs > 0.5m East Point (Lee Point surrogate) 6 February 2014 (n=1) 6 February 2014, 8 February 2014 (n=2) *Trigger exceedance summaries for contingency loggers are provided for information only. 6 February 2014 (n=1) Prepared for INPEX Cardno Page 2

6 1.3 Summary of Dredge Operations East Arm dredging progress as of 9 February 2014 is approximately 65% complete. Table 1-3 provides a summary of East Arm dredge operations undertaken during the reporting period. No Gas Export Pipeline (GEP) dredge operations were undertaken during the reporting period. Table 1-3 Summary of East Arm Dredge Operations (data provided by INPEX) Activities Undertaken Volume Material Dredged (Reporting Period) The Cutter Suction Dredger (CSD) Athena continued dredging in Separable Portion (SP) 3 (Turning Basin) throughout the reporting period, loading Trailer Suction Hopper Dredgers (TSHDs) Vox Maxima and Queen of the Netherlands. The TSHD Rotterdam conducted direct trailer works in SP4 (Approach Channel) during the reporting period. ~574,600 m 3 Prepared for INPEX Cardno Page 3

7 2 Wind, Rainfall and Tidal Conditions Atmospheric conditions at Darwin Airport, sourced from the Bureau of Meteorology (BoM), are presented in Figure 2-1 and the predicted tides at the Port of Darwin are shown in Figure 2-2. The reporting period was characterised by strong westerly winds in the range of 20 to 45 km/hr (with gusts up to 70 km/hr) from 30 January 2014 to 7 February 2014 as a result of the influence of the monsoon trough over northern Australia. Some notable rainfall events occurred during the reporting period, with 81.4 mm, 42.0 mm, 34.4 mm and 59.4 mm of rainfall recorded on 29 January 2014, 30 January 2014, 31 January 2014 and 1 February 2014, respectively. Cumulative rainfall for January 2014 was mm, which is above the January monthly average of mm. Cumulative rainfall from 1 February 2014 to 9 February 2014 was mm, compared to the February monthly average of mm. The total number of rain days exceeding 1 mm for January 2014 was 23 days, compared to the January average of 18.9 days 1. The total number of rain days exceeding 1 mm from 1 February 2014 to 9 February 2014 was 8 days, compared to the February average of 18.1 days 1. Darwin Airport (data source Bureau of Meteorology) air temperature and atmospheric pressure, wind speed and direction and half hourly rainfall (daily totals presented numerically on top of plot) for the fortnight to 9 February BoM Climate Statistics for Australian Locations ( Prepared for INPEX Cardno Page 4

8 The largest predicted maximum tidal range for the reporting period and second largest predicted tide for 2014 was 7.5 m on 1 February 2014, with a minimum of 0.9 m on 9 February 2014 (Figure 2-2). Figure 2-3 shows significant wave height output from the BoM AUSWAVE model located approximately 11 km northnorth-east of Charles Point (Latitude 12.3 º S, Longitude º E). This figure shows that significant wave height was highly elevated during the reporting period as a result of the monsoon trough over northern Australia, reaching peaks of 2.7 m on 1 February 2014 and 2.9 m on 3 February Significant wave height decreased from 4 February 2014, and dropped below 1.0 m late on 8 February Darwin predicted tide for the fortnight to 9 February 2014, based on harmonic constituents for Darwin defined by the Australian Hydrographic Service ( BoM AUSWAVE Model significant wave height the for output location 11 km north-northeast of Charles Point for the fortnight to 9 February 2014 Prepared for INPEX Cardno Page 5

9 3 Turbidity Fortnightly turbidity time series for the reporting period are shown in the figures below for all monitoring sites (Figure 3-1). Turbidity data are telemetered half hourly and daily averages calculated from the available readings (48 records per day) between 00:00 and 23:59 on each day. The data have been subjected to an automated three step QA/QC procedure including: > Removal of negative values; > Removal of flat line sections; and > Removal of outliers by a de-spiking algorithm (Wong et al. 2012). In Figure 3-2 to Figure 3-19, the raw (half hourly) turbidity data are presented as a grey line and the daily average by the solid black line. The daily-averaged turbidity is shown and the number of data points used in the calculation of the daily average is indicated at the top of the plot. Daily averages based on less than 48 points are generally due to the removal of points due to QA/QC procedures. The times of instrument servicing (should they fall within the fortnight) are highlighted by a green square ( Service ) symbol and missing data by red squares ( Suspect ) in Figure 3-2 to Figure 3-19 in accordance with the International Oceanographic Data and Information Exchange (IODE) procedure. Level 1 wet season trigger values for the reactive sites Channel Island, Weed Reef 1, Weed Reef 2, Fannie Bay, Lee Point, and Woods Inlet, as well as the surrogate reactive sites Casuarina Beach and East Point are shown in Figure 3-2 to Figure Table 3-1 provides summary notes on the information presented in the figures below. Table 3-1 Summary notes on turbidity plots for the period 27 January 2014 to 9 February 2014 Notes Daily-averaged turbidity was elevated across both the Darwin Harbour Inner and Darwin Outer sites. Turbidity at the Darwin Outer sites peaked around 2 February 2014 to 4 February 2014, with daily-averaged turbidity in the range of 60 NTU to 100 NTU. Turbidity at the Darwin Harbour Inner sites also peaked around 2 February 2014 to 4 February 2014, with daily-averaged turbidity in the range of 60 NTU to 115 NTU. The highest recorded turbidity during the reporting period was at Weed Reef 1, which experienced a daily-averaged turbidity of NTU on 4 February Figure 2-3 indicates that offshore significant wave height was high from 28 January 2014 to 8 February Significant rainfall during the reporting period (Figure 2-1) and associated terrestrial run-off from the catchments, particularly the large Shoal Bay catchment, most likely contributed additional suspended load to the coastal zone. Increasing sea state and littoral mixing in Darwin Outer coastal waters and rainfall appear to have contributed to the increase in turbidity both in the Darwin Harbour Inner and Darwin Outer sites. Overall, 111 Level 1 wet season coral and seagrass triggers were exceeded during this reporting period. Fifty-seven Level 1 wet season coral and seagrass triggers were exceeded at primary monitoring stations (Figure 3-2 to Figure 3-13), with 10 recorded at Channel Island, 14 at Weed Reef 1, 12 at Weed Reef 2, 14 at Fannie Bay and seven at Woods Inlet. In the absence of functioning water quality loggers at Lee Point, surrogate reactive seagrass water quality monitoring sites were adopted at Casuarina Beach from 29 January 2014 to 5 February 2014 (which experienced 23trigger exceedances), and East Point from 6 February 2014 to 9 February 2014 (which experienced four trigger exceedances). A further 27 trigger exceedances were also recorded by contingency loggers located at Fannie Bay (n=7), Channel Island (n=10) and Woods Inlet (n=10). The largest predicted maximum tidal range for the reporting period and second largest for 2014 occurred on 1 February 2014 (7.5 m). Weed Reef 2 ceased transmitting data from 6 February 2014 to 9 February 2014 due to battery failure in the surface transmission logger. The bottom logger was recording data during this period. Lee Point 1 experienced spurious turbidity readings from 27 January 2014 to 9 February 2014 due to biofouling of the sensor. Lee Point 2 ceased transmitting data from 28 January 2014 to 9 February 2014 due to cable connection issues in the bottom logger and surface transmission logger. Casuarina Beach experienced turbidity data loss from 5 February 2014 to 9 February 2014 due to bottom logger battery drain. Data quality at Charles Point 2 deteriorated from 27 January 2014 to 9 February 2014 due to a cable connection issue. Data quality at Mandorah deteriorated from 30 January 2014 to 9 February 2014 due to a suspected wiper jam. Prepared for INPEX Cardno Page 6

10 Notes Data quality at Northeast Wickham Point deteriorated (suspected sensor wiper jam) from 1 February 2014 until the issue self-corrected on 3 February The Spoil Ground site ceased transmitting data from 31 January 2014 to 9 February 2014 due to battery failure in the surface transmission logger. The bottom logger was recording data during this period. Prepared for INPEX Cardno Page 7

11 Water Quality monitoring sites Prepared for INPEX Cardno Page 8

12 Channel Island (reactive coral site) Prepared for INPEX Cardno Page 9

13 Channel Island 2 (contingency reactive coral site) Prepared for INPEX Cardno Page 10

14 Weed Reef 1 (reactive coral site) Prepared for INPEX Cardno Page 11

15 Weed Reef 2 (reactive coral site) Prepared for INPEX Cardno Page 12

16 Fannie Bay (reactive seagrass site) Prepared for INPEX Cardno Page 13

17 Fannie Bay 2 (contingency reactive seagrass site) Prepared for INPEX Cardno Page 14

18 Lee Point (reactive seagrass site) Prepared for INPEX Cardno Page 15

19 Lee Point 2 (contingency reactive seagrass site) Prepared for INPEX Cardno Page 16

20 Woods Inlet (reactive seagrass site) Prepared for INPEX Cardno Page 17

21 Woods Inlet 2 (contingency reactive seagrass site) Prepared for INPEX Cardno Page 18

22 Casuarina Beach (seagrass site surrogate reactive site from 29 January 2014 to 5 February 2014) Prepared for INPEX Cardno Page 19

23 Prepared for INPEX Cardno Page 20

24 East Point (seagrass site surrogate reactive site from 6 February 2014 to 9 February 2014) Prepared for INPEX Cardno Page 21

25 Charles Point 2 (seagrass and coral site) Prepared for INPEX Cardno Page 22

26 Mandorah (coral site) Prepared for INPEX Cardno Page 23

27 Northeast Wickham Point (coral site) Prepared for INPEX Cardno Page 24

28 South Shell Island (coral site) Prepared for INPEX Cardno Page 25

29 Spoil Ground (spoil ground disposal site) Prepared for INPEX Cardno Page 26

30 Upper East Arm 1 (harbour dredging site) Prepared for INPEX Cardno Page 27