Fortnightly
Quality
Fortnightly Water
Water Quality
Report
Report
Ichthys
Ichthys Nearshore
Nearshore Environmental
Environmental
Monitoring
Program
Monitoring Program
Weeks 60/61: 14 October 2013 to 27 October 2013
Weeks 60/61: 14 October 2013 to 27 October 2013
Prepared for
INPEX
November 2013
Fortnightly Water Quality Report
Ichthys Nearshore Environmental Monitoring Program
Document Information
Prepared for
INPEX
Project Name
Ichthys Nearshore Environmental Monitoring Program
File Reference
L384-AW-REP-10163_0_39_Water Quality Fortnightly Report Weeks 60_61.docm
Job Reference
Weeks 60/61: 14 October 2013 to 27 October 2013
Date
November 2013
Contact Information
Cardno (NSW/ACT) Pty Ltd
Level 9, The Forum
203 Pacific Highway
St Leonards NSW 2065
Cardno (WA) Pty Ltd
11 Harvest Terrace
West Perth WA 6005
Cardno (NT) Pty Ltd
Level 6, 93 Mitchell Street
Darwin NT 0800
Telephone: 02 9496 7700
Facsimile: 02 9499 3902
International: +61 2 9496 7700
www.cardno.com.au
Telephone: 08 9273 3888
Facsimile: 08 9486 8664
International: +61 8 9273 3888
www.cardno.com.au
Telephone: 08 8942 8200
Facsimile: 08 8942 8211
International: +61 8 8942 8211
www.cardno.com.au
Document Control
Version
Date
Author
Author
Initials
Reviewer
Reviewer
Initials
A
06/11/2013
Chris Beadle
CB
Christopher Holloway
CGH
0
07/11/2013
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.
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Fortnightly Water Quality Report
Ichthys Nearshore Environmental Monitoring Program
Table of Contents
1
Summary
1
1.1
1.2
1.3
Reporting Period
Trigger Exceedance Summary
Summary of Dredge Operations
1
1
1
2
Wind, Rainfall and Tidal Conditions
2
3
Turbidity
4
Tables
Table 1-1
Water Quality summary period
1
Table 1-2
Dry season trigger exceedance summary (14 October 2013 to 27 October 2013)
1
Table 3-1
Summary notes on turbidity plots for the period 14 October 2013 to 27 October 2013
4
Figures
Figure 2-1
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 27 October 2013
2
Figure 2-2
Darwin predicted tide for the fortnight to 27 October 2013, based on harmonic constituents for
Darwin defined by the Australian Hydrographic Service (http://www.hydro.gov.au/)
3
Figure 2-3
Significant wave height measured at the IMOS station located 5 km northeast of Charles Point
for the fortnight to 27 October 2013
3
Figure 3-1
Water Quality monitoring sites
5
Figure 3-2
Channel Island (coral impact site)
6
Figure 3-3
Fannie Bay (seagrass impact site)
7
Figure 3-4
Lee Point (seagrass impact site)
8
Figure 3-5
Woods Inlet (seagrass impact site)
9
Figure 3-6
Casuarina Beach (seagrass contingency site)
10
Figure 3-7
Charles Point 1 (seagrass control site)
11
Figure 3-8
Charles Point 2 (seagrass control site and coral contingency control site)
12
Figure 3-9
East Point (seagrass contingency site)
13
Figure 3-10 Gunn Point (seagrass control site and coral contingency control site)
14
Figure 3-11 Mandorah (coral contingency control site)
15
Figure 3-12 Northeast Wickham Point (coral impact site, no trigger)
16
Figure 3-13 South Shell Island (coral impact site, no trigger)
17
Figure 3-14 Upper East Arm 1 (harbour dredging control site)
18
Figure 3-15 Weed Reef 1 (coral control site)
19
Figure 3-16 Weed Reef 2 (coral control site)
20
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Fortnightly Water Quality Report
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1
Summary
This fortnightly report covers weeks 60 and 61 since the commencement of dredging operations for the
Ichthys Project and the telemetered water quality data collected as part of the Water Quality and Subtidal
Sedimentation Monitoring Program (14 October 2013 to 27 October 2013). 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 15 different telemetered Water Quality
monitoring sites selected to assess the turbidity without dredging and spoil disposal activities, which ceased
for the dry season on 30 April 2013. Duplicate monitoring systems have been deployed at the four reactive
seagrass and coral monitoring locations to provide backup data collection at these critical sites. Dredging for
the Gas Export Pipeline (GEP) commenced during the reporting period on 23 October 2013, with East Arm
dredging scheduled to commence on 1 November 2013.
1.1
Reporting Period
This Fortnightly Water Quality Report 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
Water Quality summary period
Period Start
Period End
Monday, 14 October 2013
Sunday, 27 October 2013
1.2
Trigger Exceedance Summary
No exceedances of the Dry Season trigger levels were recorded 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
Dry season trigger exceedance summary (14 October 2013 to 27 October 2013)
Intensity
Frequency
Duration
>23 NTU
>20 NTU > 4 days
per 7-day rolling period
>26 NTU over 4
consecutive days
None
None
None
>17 NTU
>13 NTU > 3 days
per 7-day rolling period
>13 NTU over 4
consecutive days
Fannie Bay
None
None
None
Lee Point
None
None
None
Woods Inlet
None
None
None
Dry Season Coral Triggers
Channel Island
Dry Season Seagrass
Triggers
1.3
Summary of Dredge Operations
Dredging for the GEP commenced at approximately 15:45 hours on 23 October 2013 with direct Trailer
Suction Hopper Dredger (TSHD), Queen of the Netherlands. During the reporting period TSHD operations
of high spots and pipeline channel dredging occurred along the GEP route between Mandorah and Weed
Reef (Kilometre Post (KP) 861 and 871, respectively).
No East Arm dredging operations were undertaken during the reporting period. East Arm dredging
operations ceased prior to midnight on 30 April 2013 representing the end of the first wet season phase of
dredging. Dredging progress as of 30 April 2013 for East Arm was approximately 43% complete. East Arm
dredging is scheduled to recommence on 1 November 2013 at Walker Shoal (Separable Portion (SP) 5).
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Fortnightly Water Quality Report
Ichthys Nearshore Environmental Monitoring Program
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 is
characterised by north-westerly winds of up to 30 km/hr. Several notable rainfall events occurred during the
reporting period, with 14.0 mm and 26.6 mm of rainfall recorded on 15 October 2013 and 24 October 2013,
respectively. Wind gusts of over 70 km/hr and 17.4 mm of rainfall were recorded on 26 October 2013.
Cumulative rainfall for October up to 27 October 2013 was 98.0 mm, which is above the October monthly
average of 70.7 mm. The total number of rain days exceeding 1 mm for October up to 27 October 2013 was
1
9 days, compared to the October average of 5.0 days .
Figure 2-1 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 27 October 2013
1
BoM Climate Statistics for Australian Locations (www.bom.gov.au/climate/averages/tables/cw_014015.shtml)
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Ichthys Nearshore Environmental Monitoring Program
The maximum tidal range for the reporting period was 6.8 m on 20 October 2013, with a minimum of 1.2 m
on 27 October 2013 (Figure 2-2). Significant wave height recorded at the Australian Institute of Marine
Science (AIMS) Integrated Marine Observation System (IMOS) station in Beagle Gulf 5 km northeast of
Charles Point shows significant wave height was less than 0.20 m (Figure 2-3), although data records
through this period appear spurious. To avoid future periods of spurious data that occasionally affect the
AIMS IMOS station, reported wave height will be based on BoM AUSWAVE model outputs.
Figure 2-2 Darwin predicted tide for the fortnight to 27 October 2013, based on harmonic
constituents for Darwin defined by the Australian Hydrographic Service
(http://www.hydro.gov.au/)
Figure 2-3 Significant wave height measured at the IMOS station located 5 km northeast of Charles
Point for the fortnight to 27 October 2013
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Fortnightly Water Quality Report
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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 is 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 has 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 3-16, the raw (half hourly) turbidity data are presented as a grey line and the daily
average by the solid black line. The daily average 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 3-16 in accordance with the International
Oceanographic Data and Information Exchange (IODE) procedure. Level 1 Dry season trigger values for the
reactive sites Channel Island, Fannie Bay, Lee Point and Woods Inlet are shown in Figure 3-2 to Figure 3-5.
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 14 October 2013 to 27 October 2013
Notes
The maximum tidal range for the reporting period occurred on 20 October 2013 (6.8 m).
Turbidity was generally greater during spring tides across the majority of the sites.
No discernible increase in turbidity was recorded on 26 October 2013 following 17.4 mm of rainfall and wind gusts of
over 70 km/hr.
No data was transmitted at Mandorah from 14 October 2013 until service on 15 October 2013 due to battery failure in the
bottom logger.
Upper East Arm experienced spurious turbidity readings from 18 October 2013 until 27 October 2013 due to a suspected
wiper jam.
Weed Reef 2 data quality deteriorated between 14 October 2013 and 15 October 2013 due to shorting of a cable
connection.
Full complement of water quality monitoring sites were reinstalled during the reporting period with Gunn Point and East
Point redeployed on 16 October 2013, prior to the recommencement of Project dredging operations
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Fortnightly Water Quality Report
Ichthys Nearshore Environmental Monitoring Program
Figure 3-1 Water Quality monitoring sites
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Ichthys Nearshore Environmental Monitoring Program
Figure 3-2 Channel Island (coral impact site)
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Ichthys Nearshore Environmental Monitoring Program
Figure 3-3 Fannie Bay (seagrass impact site)
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Ichthys Nearshore Environmental Monitoring Program
Figure 3-4 Lee Point (seagrass impact site)
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Fortnightly Water Quality Report
Ichthys Nearshore Environmental Monitoring Program
Figure 3-5 Woods Inlet (seagrass impact site)
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Fortnightly Water Quality Report
Ichthys Nearshore Environmental Monitoring Program
Figure 3-6 Casuarina Beach (seagrass contingency site)
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Fortnightly Water Quality Report
Ichthys Nearshore Environmental Monitoring Program
Figure 3-7 Charles Point 1 (seagrass control site)
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Fortnightly Water Quality Report
Ichthys Nearshore Environmental Monitoring Program
Figure 3-8 Charles Point 2 (seagrass control site and coral contingency control site)
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Fortnightly Water Quality Report
Ichthys Nearshore Environmental Monitoring Program
Figure 3-9 East Point (seagrass contingency site)
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Fortnightly Water Quality Report
Ichthys Nearshore Environmental Monitoring Program
Figure 3-10 Gunn Point (seagrass control site and coral contingency control site)
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Fortnightly Water Quality Report
Ichthys Nearshore Environmental Monitoring Program
Figure 3-11 Mandorah (coral contingency control site)
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Fortnightly Water Quality Report
Ichthys Nearshore Environmental Monitoring Program
Figure 3-12 Northeast Wickham Point (coral impact site, no trigger)
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Ichthys Nearshore Environmental Monitoring Program
Figure 3-13 South Shell Island (coral impact site, no trigger)
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Ichthys Nearshore Environmental Monitoring Program
Figure 3-14 Upper East Arm 1 (harbour dredging control site)
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Figure 3-15 Weed Reef 1 (coral control site)
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Fortnightly Water Quality Report
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Figure 3-16 Weed Reef 2 (coral control site)
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