WATER SHARING PLAN FOR THE NSW GREAT ARTESIAN BASIN
GROUNDWATER SOURCES
Groundwater Resource Description
NSW Great Artesian Basin
February 2020

Executive Summary This report and field study was produced as a result of the comments in the Santos 2016 Environmental Impact Statement that “no stygofauna were collected during the sampling regime by Eco Logical” and therefore “there is an uncertainty regarding the presence of stygofauna at the project areas, especially Leewood”. The aim of this report is to provide certainty by demonstrating via a more extensive survey of bores across the Pilliga that stygofauna do indeed exist in the shallow aquifers of the Pilliga Forest, are at risk from the current and proposed future development of Coal Seam Gas production and therefore need to be considered and included in the environmental management program.

Andrea Broughton, Groundwater Solutions International

I am a Senior Hydrogeologist trading under the name Groundwater Solutions International as part of Gradient Limited. I worked for the formerly named Department of Water Resources, NSW, from 1992 until 1995 as a Project Hydrogeologist and was located in Gunnedah/Sydney. As a result of my work I obtained a good understanding of the hydrogeological processes that occur within, and between, the southern Surat Basin and Gunnedah Basin geological units, having undertaken an intense property-by-property three year study of bores. Data collected and reviewed included bore and well hydrographic and water quality records; geological records from both the bores, wells and mining exploratory bores; hydrological data from creeks and rivers; and climatic data. I ran educational workshops for property owners and government employees working in the area. Since leaving Australia I have reviewed groundwater impacts of mining operations at the request of community groups. I maintain a keen interest in respect to any hydrogeological investigations, and other relevant scientific studies, undertaken in the Namoi Valley Catchment.

Introduction

I was briefed by EDO NSW on behalf of the North West Alliance to provide expert advice on the Narrabri Gas Project. The following report outlines my opinions regarding the environmental impact statement (EIS) that has been prepared for Santos’ Narrabri Gas Project, particularly regarding issues related to groundwater and surface water quality. I have prepared this report in accordance with the Expert Witness Code of Conduct.

Stuart Khan Associate Professor, School of Civil & Environmental Engineering. 

According to the EIS, around 37.5 gigalitres of water would be extracted from the target coal seams over the life of the project. Water production is generally not consistent over the life of a CSG well, but much greater volumes are extracted during the first few years, with significant declines thereafter.
The EIS describes the quality and management of produced water in Chapter 7. Somewhat unhelpfully, the salinity of the produced water is described in terms of electrical conductivity (in units of microSiemens per centimetre), rather than an actual salt concentration (in units of mg/L). It is stated that the average salinity is around 14,000 microSiemens per centimetre. The EIS states that “this level of salinity is approximately 30 percent of the salinity of seawater, which is around 50,000 microSiemens per centimetre”. 

1. Introduction

I confirm that in preparing this report I have read the Expert Witness Code of Conduct under the Uniform Civil Procedure Rules 2005 and I agree to be bound by it. The documents I have utilised in preparing this report are listed under the references section at the end of the report.

1 Executive Summary

This report is the result of independent review of the numerical groundwater modelling component of the Narrabri Gas Project (the Project) Environmental Impact Statement (EIS). Construction of the numerical groundwater model is deemed to be based on sound reasoning and consideration of background information, and is consistent with standard industry practice and relevant guidelines.

There is a lack of observation data used to calibrate the model parameters with the exception of the net flux to groundwater over the Naomi Alluvium aquifer. As a result, the selected model parameters are based on expert review of background information and as such, have greater uncertainty than model parameters calibrated to observation data. The key model parameters and predictive model stresses influencing predictions of groundwater impact, have a large level of uncertainty, which results in high uncertainty in the model predictions.

A REPORT COMMISSIONED BY THE AUSTRALIAN GOVERNMENT AND GREAT ARTESIAN BASIN JURISDICTIONS BASED ON ADVICE FROM THE GREAT ARTESIAN BASIN COORDINATING COMMITTEE