Fortnightly Water Quality Report

Transcription

1 0 Fortnightly Water Quality Report Ichthys Nearshore Environmental Monitoring Program Weeks 85/86: April 2014 to 20 April 2014 Weeks 85/86: 7 April 2014 to 20 April 2014 Prepared for INPEX October 2014

2 Document Information Prepared for Project Name File Reference INPEX 52_L384-AW-REP-10182_0_52_Water Quality Fortnightly Report Weeks 85_86.docm Job Reference Weeks 85/86: 7 April 2014 to 20 April 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 30/04/2014 Chris Beadle CB Isabel Jimenez IJ 0 01/05/2014 Chris Beadle CB Andrew Bradford AB 1 20/10/2014 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 2 2 Wind, Rainfall and Tidal Conditions 3 3 Turbidity 5 Tables Table 1-1 Water Quality summary period 1 Table 1-2 Level 1 wet season trigger exceedance summary (7 April 2014 to 20 April 2014) 1 Table 1-3 Summary of East Arm Dredge Operations (data provided by INPEX) 2 Table 3-1 Summary notes on turbidity plots for the period 7 April 2014 to 20 April 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 20 April Darwin predicted tide for the fortnight to 20 April 2014, based on harmonic constituents for Darwin defined by the Australian Hydrographic Service ( 4 BoM AUSWAVE Model significant wave height for the output location 11 km north-north-east of Charles Point for the fortnight to 20 April Water Quality monitoring sites 6 Channel Island (reactive coral site) 8 Channel Island 2 (contingency reactive coral site) 9 Weed Reef 1 (reactive coral site) 10 Weed Reef 2 (reactive coral site) 11 Fannie Bay (reactive seagrass site) 12 Fannie Bay 2 (contingency reactive seagrass site) 13 Lee Point (reactive seagrass site) 14 Lee Point 2 (contingency reactive seagrass site) 15 Woods Inlet (reactive seagrass site) 16 Woods Inlet 2 (contingency reactive seagrass site) 17 Casuarina Beach (seagrass site) 18 East Point (seagrass site) 19 Charles Point 2 (seagrass and coral site) 20 Mandorah (coral site) 21 Northeast Wickham Point (coral site) 22 South Shell Island (coral site) 23 Spoil Ground (spoil ground disposal site) 24 Upper East Arm 1 (harbour dredging site) 25 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 85 and 86 (7 April 2014 to 20 April 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 spring-neap 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, wave, 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, 7 April 2014 Sunday, 20 April Trigger Exceedance Summary No exceedances of the wet season trigger levels were recorded at any reactive site during this reporting period. Figures showing Darwin metocean information and all turbidity logging sites for the reporting period are included in Sections 2 and 3, respectively. 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 (7 April 2014 to 20 April 2014) Wet Season Coral Triggers for Channel Island Intensity Frequency Duration >44 NTU >26 NTU > 3 days per 7-day rolling period >26 NTU over 7 consecutive days Channel Island 1 None None None 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 None None None Weed Reef 2 None None None Wet Season Seagrass Triggers >63 NTU >52 NTU > 5 days per 7-day rolling period >52 NTU over 5 consecutive days Fannie Bay None None None Lee Point None None None Woods Inlet None None None Prepared for INPEX Cardno Page 1

5 1.3 Summary of Dredge Operations East Arm dredging progress as of 20 April 2014 is approximately 82% complete. Table 1-3 provides a summary of East Arm dredge operations undertaken during the reporting period. Gas Export Pipeline (GEP) Backhoe Dredgers (BHD) Simson and Baldur, continued to target hard high spots along the GEP route within Darwin Harbour throughout the reporting period. The BHD Baldur also conducted shoreline crossing dredging during spring high tides only, due to vessel draft restrictions. Table 1-3 Summary of East Arm Dredge Operations (data provided by INPEX) East Arm Activities Undertaken Volume Material Dredged (Reporting Period) During the reporting period, the Cutter Suction Dredger (CSD) Athena was operational in Separable Portion (SP) 4 (Approach Channel) loading Trailer Suction Hopper Dredgers (TSHDs) Vox Maxima and Queen of the Netherlands. The TSHD Rotterdam also conducted direct trailer works in SP2 (Berth Pocket) and SP3 (Berth Area) during the reporting period. ~407,300 m 3 Prepared for INPEX Cardno Page 2

6 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. From 7 April 2014 to 13 April 2014 winds were characterised by a diurnal pattern with moderate (in the range of 15 km/hr to 25 km/hr) breezes in the afternoon decreasing overnight. From 14 April 2014 to 17 April 2014 winds were moderate and generally from the north-east to north-west sectors. From 18 April 2014 to 20 April 2014 winds were moderate to fresh (in the range of 15 km/hr to 30 km/hr) and predominantly from the east. Some notable rainfall events occurred during the reporting period, with 17.6 mm, 18.4 mm, and 26.2 mm of rainfall recorded in the 24 hours to 9am on 10 April 2014, 11 April 2014 and 18 April 2014, respectively. Cumulative rainfall from 1 April 2014 to 20 April 2014 was mm, which is more than the April monthly average of mm. The total number of rain days exceeding 1 mm rainfall from 1 April 2014 to 20 April 2014 was 13 days, which is also more than the April average of 7.2 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 20 April BoM Climate Statistics for Australian Locations ( Prepared for INPEX Cardno Page 3

7 The largest predicted maximum tidal range for the reporting period was 6.6 m on 18 April The minimum tidal range for the reporting period was 0.6 m on 8 April 2014 (Figure 2-2). Figure 2-3 shows significant wave height output from the BoM AUSWAVE model located approximately 11 km north-north-east of Charles Point (Latitude 12.3 º S, Longitude º E). This figure shows that from 7 April 2014 to 18 April 2014 significant wave heights were less than 0.3 m. From 19 April 2014 to 20 April 2014 significant wave heights were moderately elevated, and in the range of 0.3 m to 0.8 m as a result of moderate to fresh easterly winds (Section 2). Darwin predicted tide for the fortnight to 20 April 2014, based on harmonic constituents for Darwin defined by the Australian Hydrographic Service ( BoM AUSWAVE Model significant wave height for the output location 11 km north-northeast of Charles Point for the fortnight to 20 April 2014 Prepared for INPEX Cardno Page 4

8 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 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 7 April 2014 to 20 April 2014 Notes During the reporting period, turbidity was generally greater during spring tides across the majority of the monitoring sites. Turbidity at the Darwin Outer sites was low to moderate (<35 NTU). Whilst wave conditions in the Beagle Gulf were moderately elevated from 19 April 2014 to 20 April 2014, waves during this period were generally from an easterly direction, and consequently most of the Darwin Outer sites (except Charles Point 2 and the Spoil Ground site) were less exposed to these waves. Of the Darwin Outer sites, the Spoil Ground site experienced the highest turbidity, peaking at a daily average of 32.1 NTU on 19 April Turbidity at the Darwin Harbour Inner sites was also generally low to moderate during the reporting period, with most sites recording daily average turbidity less than 25 NTU. The only exception to this was Northeast Wickham Point, which experienced the highest turbidity during the reporting period. Daily average turbidity at this site reached a maximum of 26.2 NTU on 16 April The largest predicted maximum tidal range for the reporting period occurred on 18 April 2014 (6.6 m). No data were transmitted from the Channel Island contingency logger from 7 April 2014 to 11 April 2014 due to a battery drain in the bottom logger. The Channel Island primary logger was recording and transmitting data during this period. Data quality at the Fannie Bay contingency logger deteriorated from 9 April 2014 to 10 April 2014 due to turbidity sensor drift. The Fannie Bay primary logger was recording and transmitting data during this period. No data were transmitted from the Woods Inlet contingency logger from 18 April 2014 to 20 April 2014 due to a severed cable and mooring line. The Woods Inlet primary logger was recording and transmitting data during this period. Data quality at Mandorah deteriorated from 7 April 2014 to 10 April 2014, and then from 17 April 2014 to 20 April 2014 due to turbidity sensor wiper jams. Whilst turbidity data was predominantly of good quality, some turbidity spikes were recorded at the Fannie Bay contingency logger and East Point during the reporting period due to soft biological growth in the vicinity of the turbidity sensor. Prepared for INPEX Cardno Page 5

9 Water Quality monitoring sites Prepared for INPEX Cardno Page 6

10 Prepared for INPEX Cardno Page 7

11 Channel Island (reactive coral site) Prepared for INPEX Cardno Page 8

12 Channel Island 2 (contingency reactive coral site) Prepared for INPEX Cardno Page 9

13 Weed Reef 1 (reactive coral site) Prepared for INPEX Cardno Page 10

14 Weed Reef 2 (reactive coral site) Prepared for INPEX Cardno Page 11

15 Fannie Bay (reactive seagrass site) Prepared for INPEX Cardno Page 12

16 Fannie Bay 2 (contingency reactive seagrass site) Prepared for INPEX Cardno Page 13

17 Lee Point (reactive seagrass site) Prepared for INPEX Cardno Page 14

18 Lee Point 2 (contingency reactive seagrass site) Prepared for INPEX Cardno Page 15

19 Woods Inlet (reactive seagrass site) Prepared for INPEX Cardno Page 16

20 Woods Inlet 2 (contingency reactive seagrass site) Prepared for INPEX Cardno Page 17

21 Casuarina Beach (seagrass site) Prepared for INPEX Cardno Page 18

22 East Point (seagrass site) Prepared for INPEX Cardno Page 19

23 Charles Point 2 (seagrass and coral site) Prepared for INPEX Cardno Page 20

24 Mandorah (coral site) Prepared for INPEX Cardno Page 21

25 Northeast Wickham Point (coral site) Prepared for INPEX Cardno Page 22

26 South Shell Island (coral site) Prepared for INPEX Cardno Page 23

27 Spoil Ground (spoil ground disposal site) Prepared for INPEX Cardno Page 24

28 Upper East Arm 1 (harbour dredging site) Prepared for INPEX Cardno Page 25