Groundwater Q&A with the EPA

During 2021 as Santos applied to vary their Environmental Protection Licence 20350 to downsize monitoring of groundwater in the Pilliga Forest we contacted a hydrogeologist at the EPA for answers to some of our questions.

The EPA could not explain why the pH of Monitoring Point 13 rapidly dropped by 5 points (see Question 1). To date we have been given no explanation for this worrying downwards trend from alkaline to acid within a formation that Santos characterised as alkaline. The EPA state: “The neutralizing trend of pH observed at Monitoring Point 13 is not clearly conclusive.”

The latest Water Monitoring Report on the Santos Water Portal shows that the pH rose to 7.12 in the Quarter 1 – AUG 2022 – OCT 2022 reporting period. Has connectivity occurred with a different formation?

We asked for an update on Monitoring Points 47. 48 & 49 in Question 2, these points are also known as Bibblewindi 28A, 28B and 28C. These points have been out of action for several years and we have been advised that repairs are being investigated. These repairs have been promised but have not been completed despite Santos having a workover rig in the same well set in October 2022.

The EPA state: “Faults and errors are not uncommon with water or barometric logging equipment used in continuous groundwater monitoring due to the corrosive operating environment. The EPA is currently liaising with Santos about the implications of this fault and its proposed repairs.”

This fault triggered a Non-Compliance on the Santos Annual Returns 2021-2022.

Below is the full Question and Answer set with the EPA. Download here:


This Post Has One Comment

  1. McKenzie Don Reply

    From personal experience the shallow waters in the sandstone belt are acidic and the deeper waters are alkaline

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