Groundwater Risk Assessment and Monitoring Program Rationalisation – Surat Basin, Queensland

Producers of coal seam gas in Queensland are required to develop and implement groundwater monitoring programs associated with the storage of produced water and process water at upstream gas production facilities. Environmental permits require groundwater monitoring to be conducted to provide a means to detect changes in groundwater quality that could arise in the event of leakage from a storage pond. The specific requirements vary depending on the permit, but generally, monitoring is required to be undertaken on a quarterly or semi-annual basis. The monitoring programs have generally evolved to include an extensive list of analysis parameters. This places a significant cost and time burden on operators.

For each of these two projects, EHS Support conducted comprehensive reviews across each client’s portfolio of upstream assets to identify opportunities for groundwater monitoring optimisation. In each case, a groundwater risk assessment report was developed detailing site-specific risks to groundwater and rationalising site-specific monitoring requirements. Using these deliverables as supporting documents, both clients successfully applied for changes to the monitoring requirements in their environmental permit conditions, including a reduction in the mandatory monitoring frequency (in one case to annual and the other to biennial). This has resulted in significant cost reductions and has freed up personnel resources for each client.

Much of the success of these projects is attributed to the novel approach used by EHS Support. This included the development of a fit-for-purpose risk-based framework, and a simplified format for presenting the information, without a loss of the necessary resolution to effectively rationalise the risk based monitoring approach. In addition, trigger concentrations were derived using an intra-bore analysis approach rather than the more typically used method of derivation based on results from a limited number of “background” bores.

The risk framework that EHS Support developed considers relevant groundwater risk factors such as site-specific background groundwater quality, constituents of potential concern, local hydrogeological and geological conditions, locations of sensitive environmental receptors, groundwater travel times, facility construction and controls and other factors. The presentation format employs simple statistical summaries of pond and water quality data, tabular presentation of key operational and conceptual information and graphical display of trends. The format allows the user to easily understand the linkages between contaminant source, environmental setting, potential receptors, fate and transport considerations and risks, and the logic of the proposed monitoring for each site.

The advantage of the intra-bore approach is that it provides for trigger concentrations that better reflect natural-occurring spatial and temporal variability, and allows for sufficient sensitivity to detect potential impacts, whilst reducing the potential for false non-compliances. This minimises the amount of time and costs associated with investigation of recurring false non-compliances.

Our approach to these projects was fit-for-purpose and effective, as well as providing a good return on investment for our clients. We provided a product that will minimise the potential for future issues, whilst being enduring and easy to update (to accommodate new data). We have recently commenced a third project of this nature and aim to achieve the same for this new client.


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