Environment

Our comprehensive range of programs meet government regulations and evaluate the mine's performance.

Results from the programs help us improve environmental management strategies and identify emerging or potential impacts.

We compare monitoring results against baseline information along with national guidelines for water and soil quality set by the Australian and New Zealand Environment Conservation Council (ANZECC), and the National Environment Protection Measures (NEPM).

Environmental monitoring activities form part of our commitment to the Australian and Northern Territory regulatory authorities.

We operate a comprehensive air quality-monitoring network in accordance with our Air Quality Management Plan, developed in consultation with the Northern Territory Government and independent air quality experts.

The monitoring network allows for a better understanding of air quality surrounding the operation and identifies any exceedances of management trigger and compliance values.

We undertake continuous air quality monitoring between the mine and Borroloola and Goolminyini (Devil Springs). Real time sulphur dioxide (SO₂) monitoring data and monthly consultant reports are available on our online portal.

The monitoring program checks for any changes in the population of birds in the area surrounding the mine both up and downstream and compared with other local sites. The program provides information on the range of birds found in the local area.

The banding of birds is undertaken on indicator species like the purple crowned fairy wren and buff sided robin.

We conduct annual migratory bird surveys around Port McArthur across an area that exceeds 100,000 hectares of shorebird and wetland bird habitat. The study area has been recognised as an important bird area for species listed under the Environment Protection and Biodiversity Conservation (EPBC) Act 1999.

Many of these species migrate to the Northern Hemisphere on the East Asian-Australasian migratory bird flyway.

The annual migratory bird program reports are provided to the Australian Government.

Monthly dust and annual soil samples are taken from sites around both the mine and our Bing Bong Loading Facility.

These check for any potential contamination from dust generated by the operations.

Soil samples are taken at the same locations and are checked for zinc, lead, cadmium and copper.

The McArthur River is home to a range of native fish, including the Freshwater Sawfish (Pristis pristis) listed as vulnerable and matters of national environmental significance under the  Environment Protection and Biodiversity Conservation (EPBC) Act 1999.

Conducted by specialist consultants, our program monitors the abundance and diversity of fish, molluscs and crustaceans in the McArthur River and local tributaries around the mine. A tagging program we use to track fish movements is supported by the local fishing community.

Our action plan for the freshwater sawfish includes:

• the ecology and biology of the freshwater sawfish
• a description of the existing environment
• management actions to ensure the longevity of the freshwater sawfish populations
• ongoing monitoring of the freshwater sawfish populations for the life of the mine
• a community awareness and education program.

Specific monitoring of metals in fish has found that fish from the McArthur River are safe to eat as long as residents follow guidelines standardised across Australia for eating fish. An ongoing metals in fish monitoring program was developed in consultation with the local community.

The revegetation of the constructed channels is a high priority for our operation, necessary for the early establishment of aquatic and riparian ecosystem function.

Our Rehabilitation Monitoring Program is designed to meet three key objectives:

• Scientific assessment: to provide indicator data from rehabilitated sites across the McArthur River Mine lease area, and a comparison against undisturbed reference sites
• Continuous improvement: to provide results which allow refinement of rehabilitation techniques and an assessment of specific management options
• Evaluation of ecosystem development: to quantify the condition of sites.

These objectives are designed to restore mined land to self-sustaining riparian and aquatic ecosystems, similar to those that existed prior to rechannelling works.

Our long-term monitoring of the Barney Creek and McArthur River channels is important to check their stability. Vegetation abundance and diversity will be based on species highlighted through previous baseline surveys prior to rechannelling.

We complete a seagrass monitoring program annually. This is important because seagrass is an essential part of the diet of the Dugongs in the Gulf region.

The program aims to determine whether any observed change in seagrass distribution or composition has occurred in the marine waters adjacent the Bing Bong Loading Facility.

Monitoring identifies whether change is naturally occurring or related to the loading facility operations.

An annual marine monitoring program involves the collection of marine water, sediment and biota samples for analysis of metals and metalloids.

Samples are collected from areas adjacent the Bing Bong Loading Facility, as well as sites in the Gulf of Carpentaria to the northwest and southeast of the loading facility.

The program monitors metal concentrations in select commonly consumed species, such as Barramundi (Lates calcarifer), oysters (Saccostrea spp.) and mud crab (Scylla serrata). Marine water and sediment metal concentrations are compared to relevant Australian quality guidelines.

We carry out a regular and extensive range of tests to determine the content of the tailings, assess any incidence of seepage and to ensure the embankment wall, pipe and all infrastructure are in working order.

We have an extensive water quality monitoring program around the mine that includes monitoring of groundwater, natural surface water, artificial waters and potable waters.

The program characterises the quality of these waters and assesses the effectiveness of our risk management controls. It includes:

• over 250 groundwater monitoring sites used for water quality and water level measurements
• approximately 30 natural surface water quality monitoring sites, which are located in local creeks and rivers, including the McArthur River, Barney Creek, Surprise Creek and Emu Creek
• over 50 artificial water monitoring sites, which track the water quality in our onsite dams and storages
• a number of gauging stations, level monitors and flow meters that measure water height and flow in creeks and rivers, water height and volumes in dams and storages and volumes of water transferred around the operational site
• potable water monitoring sites, which are located throughout the operation, with water quality results compared to the Australian Drinking Water Guidelines.

To access the ore, our open pit development required 5.5 kilometres of the McArthur River and 2.5 kilometres of Barney Creek to be rechannelled. The new channels were completed in 2008.

Stream flows throughout the creek and river change depending on time of year. During the dry season, the McArthur River is slow-flowing. Flow during the wet season is highly variable due to the monsoonal rainfall and potential for cyclones.

Most years the channel overflows during the wet season which can be up to 21 metres deep, and regularly inundates the flood plain up to five metres deep. Water level rises of up to seven metres over a 24-hour period are not uncommon.

The new channels were planned in great detail to ensure they:

• remain stable for all flood events and throughout the mine life and beyond
• will not be subject to higher than natural levels of erosion and sedimentation
• enable the river to continue to flood in parts naturally into the plain without affecting the mine facilities
• re-establish the river vegetation so there is no fragmentation of fauna habitats
• allow fish to continue to naturally pass through the channels.

The channel design for both McArthur River and Barney Creek copies the natural environmental conditions where possible.

The main differences are in the use of bedrock and artificial rock riffles in some locations on the riverbed to help prevent eroded sediment flowing downstream.

Riffles are 'U'-shaped rocky structures that mimic the existing bedrock outcrops, reducing the speed of water flow, and in doing so, help revegetation along the channel banks.

These rock riffles are similar to already naturally-occurring rock bars and will not disrupt fish passage.

Our rehabilitation program also plays an important part in ensuring the stability of the new channels to prevent erosion.

A major upgrade to our onsite nursery has led to a dramatic improvement in the number of tubestock available for rehabilitation planting.

In 2019, our team planted more than 120,000 trees, shrubs and grasses on the river channel, bringing the total since rehabilitation began to more than 650,000 plants.

Our aim is to return the environment to its natural state by using key plants native to each area and habitat type. To achieve this goal, ecological studies were conducted to identify the structure, including the number of species and density of existing plant communities.

The rehabilitation of the new McArthur River and Barney Creek channels was designed to provide a suitable environment for fish passage and to establish a functioning riverine ecosystem by:

• including large woody debris along the channel bed and creating shallow pools to provide micro-habitats for fish
• revegetating the banks using seeds and seedlings from local species already growing along the river bank, using appropriate soils and fine sediments on the channel banks to promote root development, recreating rocky crevices and banks
• maintaining, monitoring and replacing plants and weeds as necessary.

Results of ongoing monitoring programs have indicated that:

• the mine is having no adverse impacts on the McArthur River
• fish passage throughout the McArthur River diversion channel has been maintained with fish able to travel along its entire length
• aquatic habitats are moving towards that of natural upstream and downstream sites
• riparian bird assemblages are trending towards natural levels in parts of the channel
• the Northern Territory Environment Protection Authority (EPA) stated that monitoring has indicated that the McArthur River is in good condition.