Reports

Prior to the commencement of capital dredging, INPEX in consultation with the NT Heritage Branch engaged with specialist maritime archaeologists to employ a range of survey methods (multi-beam echo sound, side-scan sonar, sub-bottom profiling, gradiometer, and dive inspections) to collect data to identify potential unexploded ordinance and cultural anomalies of potential heritage significance, within the dredge footprint.  This resulted in maritime archaeologists working closely with a local dive company to visually assess over 1,000 seabed anomalies throughout the latter part of 2011 and the first half of 2012. 

All identified cultural material within the dredging footprint was removed, rapidly recorded, relocated, or discarded in accordance with their level of cultural heritage significance.  A total of 6,897 artefacts were recovered from the seabed ranging in size from silver dessert spoons to vertical boilers. The majority of artefacts were associated with the WWII era including small calibre rounds, automotive parts and accessories, camp beds, tools, and stoves. The more significant finds were Consolidated PBY Catalina and Supermarine Spitfire aircraft components.  Most of this material had been dumped, presumably at the end of WWII.

Artefacts were de-concreted and individually recorded by a total of 17 archaeologists over a period covering 14 months. The cultural heritage significance of all artefacts was individually assessed and 506 objects were wrapped and reburied in underwater repositories with the intention to prevent degradation for as long as possible.  A comprehensive artefact database was created by Cosmos Archaeology which provides a detailed platform for future research into this collection. This has the potential to contribute to numerous fields of study ranging from the examination of impact damage to aircraft components to the quality and variety of equipment used by the military based in the Darwin area during WWII.

     Before                                                                                      After 

Artefacts with significant cultural heritage values were buried in long-term underwater repositories administered by the Northern Territory Government, for future study and potential display.

Prior to dredging, INPEX undertook maritime heritage baseline surveys of Catalinas 1 – 6, in order to provide a dataset for comparisons to be made during quarterly monitoring inspections. Each Catalina site had its own specific monitoring manual; with a survey methodology aligned with Appendix 10 of the Supplement Environmental Impact Statement, which broadly consisted of:

• diver circuit inspection
• video records
• seabed sediment level measurements
• comparison to previous surveys (including baseline).

Accessibility to maritime heritage sites was dependant on weather, tides, and simultaneous activities at the time. All monitoring reports were provided to NT Heritage Branch.

A total of 28 maritime heritage inspections were conducted and reported to NT Heritage Branch.

During the capital dredging campaign between August 2012 to July 2014, INPEX ensured that chance finds procedures were implemented to identify potential heritage or UXO dredged up from the seabed; resulting in rapid (four hour turn around) reporting, assessment and management protocols involving INPEX, the dredging contractor and an on-call (24/7) maritime archaeologist. A total of 52 individual artefacts were discovered, assessed, and rapidly reported using this chance heritage discovery process. Only one out of the 52 artefacts was classified by the maritime archaeologist as high significance[1] . 

More information on the Ichthys LNG dredging program here. 

[1] Object was identified as a Bendix Stromberg twin barrel, float‐type aircraft carburettor. Dimensions ‐ 320mm maximum width x 290mm maximum height x 180mm maximum thickness, with barrel flange opening of 100mm and venturi throat diameter of 79mm.

INPEX would like to acknowledge Cosmos Archaeology and Tek Ventures for their services to the Ichthys Project, and the NT Heritage Branch for their regulatory guidance.

A list of reports and associated datasets are provided in the document below, and can be accessed from the NT Heritage Branch at [email protected].

Onshore Whole Effluent Toxicity (WET) testing

Whole Effluent Toxicity (WET) testing is completed at commingled jetty outfall stream discharge pipes to assess the ecotoxicity of the commingling jetty outfall stream and to verify that once commingled the discharge can reach safe dilution within the mixing zone.

Jetty Outfall Monitoring

Jetty outfall water quality monitoring is completed to detect changes in water quality attributable to liquid discharges from the LNG jetty outfall. Results of monitoring are compared to triggers developed in consultation with the Northern Territory EPA.

Nearshore Marine Pest Monitoring

The presence/absence of invasive marine species (IMS) at the Ichthys LNG and LPG/condensate product loading jetties is monitored using artificial settlement units (ASU). The ASUs are provided by NT Department of Primary Industries and Resources (DPIR) Aquatic Biosecurity Unit and are regularly inspected for IMS presence. Suspected IMS are sent to the NT DPIR for identification.

Harbour Sediment Monitoring

INPEX's harbour sediment quality monitoring program provides an early warning of potential accumulation of contaminants in sediments surrounding the Ichthys LNG outfall, located on the condensate/LPG jetty. The key objective is to detect changes in surficial sediment quality and determine if changes are attributable to Ichthys LNG operations.

Groundwater Monitoring

Groundwater monitoring is completed to detect changes in groundwater quality and determine if these changes are attributable to Ichthys LNG operations. Note there are no planned discharges directly to groundwater, other than clean rainfall and non-contaminated water. However unplanned spills, leaks or rupture to infrastructure may result in some impacts to groundwater.

Weed Surveillance

Terrestrial weed surveillance is completed throughout the Ichthys LNG facility. The key objectives of the weed mapping program are to identify the abundance and spatial distribution of known and new emergent weed populations and inform weed management and control activities.

Vegetation Surveillance

Native vegetation surveillance is completed throughout the Ichthys LNG facility to map the distribution of vegetation communities immediately adjacent to the GEP corridor and monitor/manage the rehabilitation of cleared areas. Over time it is anticipated that the rehabilitating vegetation communities will resemble the species composition and structure of surrounding remnant vegetation.

Mangrove Health Monitoring

Mangrove health, intertidal sediments and bio-indicators are monitored to detect potential adverse changes in mangrove community health as an indirect result of Ichthys LNG operations. The objectives of annual mangrove health, intertidal sediment and bioindicator surveys are to:

• informatively monitor mangroves adjacent to the Ichthys LNG plant
• detect changes in intertidal sediment quality attributable to Ichthys LNG operations
• determine through bio-indicator monitoring if changes in seafood quality is occurring

Air Emissions Monitoring

Air quality monitoring data is collected and analysed to assess the potential impact of production activities at Ichthys LNG facility on the broader air environment. Monitoring includes both ambient air quality and point-source emissions monitoring.

Visual monitoring and closed-circuit television monitoring of flares is undertaken to detect possible dark-smoke events. If dark smoke is produced during operations, the shade (or darkness) of the smoke is estimated and recorded.

Operational & Scientific Monitoring Plan

INPEX maintains an Operational and Scientific Monitoring Plan (OSMP) to ensure that, in the unlikely event of an oil spill, combat efforts are effective and that timely and appropriate monitoring of environmental receptors at risk during a large oil spill is undertaken. The OSMP defines the operational and scientific monitoring required to be completed by INPEX in the event of a spill.

Offshore Whole Effluent Toxicity (WET) testing

Whole Effluent Toxicity (WET) testing is completed at offshore facilities discharge pipes (prior to commingling and discharge) to assess whether there are any potential environmental impacts that could occur from discharge of waste streams from the Central Processing Facility (CPF) and Floating Production Storage and Offtake (FPSO) facility into the marine environment.

Offshore Chemical Characterisation

Chemical characterisation of selected discharge streams at the end-of-pipe (prior to commingling and discharge to the receiving environment) will be undertaken in accordance with the Offshore Facilities EP. The purpose of this monitoring is to provide information to support the assessment of potential additive or synergistic effects that may result from constituents interacting within the different discharge streams as they enter the marine environment.
The key objective of chemical characterisation is to verify that the discharge constituents are as expected and provide information about the composition of the streams so that any changing conditions can be identified.

Offshore Water & Sediment Monitoring

Water and sediment quality monitoring is completed to monitor for any potential impacts associated with liquid discharges from the offshore facilities. The key objectives of the offshore water and sediment quality monitoring program are to detect changes in water quality attributable to liquid discharges from the CPF and FPSO, and sediment quality from the FPSO.

Offshore Marine Pest Observations

Project-related biosecurity aspects are managed by INPEX to minimise the potential for the introduction of pests and diseases at offshore facilities. Offshore marine pest observations are completed through opportunistic review of remotely operated vehicle (ROV) survey footage collected during inspection, monitoring and repair (IMR) activities, and in-particular during marine fouling inspections for wave‑loading purposes.