Independent Expert Study of 42,000 Km2 Namoi Catchment And

CASE STUDY

42,000 km2 Region Assessed for Water Resource Impacts from Potential Coal and Gas Developments Expert approach with stakeholder engagement achieves consensus and sets standard for future water resources studies

CHALLENGE Large, complex risk assessment needed for agricultural area Assess potential impact of coal seam The Namoi catchment is located in northern New South Wales (NSW), Australia. The gas development and coal mining on catchment is characterised by large volumes of groundwater abstraction used for agricultural surface and groundwater resources in irrigation, and coal has been mined within the catchment on a relatively small scale for at least a catchment with intensive agricultural a century. The NSW Government was aware of stakeholder concerns regarding coal and gas activity. exploration and possible development and the potential effects of these activities on aquifers and agriculture in the Liverpool Plains region. SOLUTION Create a database to manage large To strategically assess the likelihood of potential impact from coal and gas development on datasets, construct a geological model the quantity and quality of surface and groundwater resources in the catchment, the NSW with the Petrel* software platform, Government commissioned the Namoi Catchment Water Study. The project presented a develop and calibrate dynamic integrated number of challenges: surface and groundwater models, ■■ simulate diverse future development Comprehensive scope of work—The Study needed to consider issues ranging from scenarios and conditions, and local and short-term impacts on ecologically sensitive springs, to the whole area of the communicate the process and results catchment and long-term impacts of climate change on water resources. effectively with many stakeholders. ■■ Catchment size—The Study needed to include the entire catchment, an area of more than 42,000 km2 (roughly the size of Denmark). Previous studies and models examined only a few RESULTS small areas within the catchment. Predicted and quantified long-term ■■ Data type, quality, and quantity—More than 22 million surface water records, 25,000 effects of hypothetical coal seam gas and borehole records, and 6.5 million daily rainfall records had to be collected, organised, and coal mine development scenarios within analysed. Derived from a large number of public and private (industry partners) sources, the Namoi catchment and identified at-risk the data was immense and sometimes commercially sensitive and confidential. Secure data zones, enabling attention to be focused on storage was essential, with some data unable to be• represented on Study reports and in areas of highest concern. Moree public presentations.

•Inverell N 0 25 50 •Walgett Km •Burren Junction

•Wee Waa

•Pilliga •Narrabri GW elevation •Barraba Armidale High: 699 • (mAHD) Manilla Low: 117 •

. Bore site •Gunnedah 100 m intervals •Tamworth 25 m intervals

Drainage •Werris Creek Major roads •Quirindi Active numerical model domain Namoi catchment boundary Map Projection: Geographical Coordinate System WGS84 and Transverse Mercator, GDA94, MGA Zone 55 •Scone Non-alluvial groundwater contours.

Water Services CASE STUDY: Expert approach with stakeholder engagement achieves consensus and sets standard for future studies

Groundwater model cross section.

■■ Coal resource model—An integrated assessment of the location These included possible future open-pit and underground coal mines, of coal resources didn’t exist, so it was necessary to complete this as well as extensive areas where coal seam gas extraction might catchment-wide geological model prior to evaluating in what form, occur. The Model was required to assess the potential impact of each and where, and where coal resource development might occur. of these scenarios until the year 2100.

■■ Stakeholder engagement—Highly technical information had to be To address the need for communication with stakeholders, conveyed to the public and more than 30 stakeholders in a manner Schlumberger released interim Study reports at key milestones. Each understandable by all including local residents, landholders, milestone was presented to the various stakeholders at two separate farmers’ groups, coal industry representatives, and government community presentation and discussion forums. departments. Potential impacts quantified and areas of concern identified Database and combined modelling packages applied by The comprehensive data management, analyses, and model expert team construction enabled prediction of the potential short- and long-term The NSW government chose Schlumberger Water Services as the cumulative effects of mining and coal seam gas developments on Independent Expert to manage and complete the Study. To take on the water resources for the entire Namoi catchment. The Schlumberger complex project and meet the challenge, Schlumberger first created project team identified sub-regional areas where water resources a custom relational database to manage the datasets collected from were most at risk and quantified the potential magnitude of impact for federal, state, and local governments; industry partners; and others. different coal resource development options. They also evaluated the The final database contained more than 30 million records. sensitivity of the results to different inputs and the level of confidence The Petrel* software platform was then used to construct a 19-layer in predictions. 3D geological model representing all strata from ground level to Areas of the catchment were identified where water resources were 2,000-m depth over the catchment. Several coal seams were mapped at high, medium, or low risk to coal and gas developments. With this as individual layers, enabling a higher degree of interpretation and information, stakeholders, industry, and the government can focus 3D visualisation for these areas. Based on the Petrel model, the on specific and much smaller areas of concern rather than spreading team created linked dynamic numerical models for both the surface resources across the whole of the catchment. Stakeholders were also water and groundwater systems using LASCAM and MODFLOW made more aware of the quantitative risks associated with each type software—collectively known as “the Model.” of coal resource development.

The Model, calibrated to historical records, is able to incorporate and Furthermore, in the course of the Study, Schlumberger identified assess a wide range of potential future coal-resource-development a number of data gaps and evaluated their relative importance. A activities. It is a robust predictive tool that can be updated with new future investigation and monitoring program was proposed to provide data, recalibrated as necessary, and used to assess alternative robust catchment-specific data inputs that can be used to reduce the scenarios and the effects of changing other inputs and assumptions uncertainties and enhance confidence in predictions. such as climate change.

Based on the position of the coal seams identified, seven different scenarios were conceived for future coal resource development. www.water.slb.com