Potential Impacts of Effluent Re-Use on Groundwater at Tamworth

Client: Tamworth Regional Council
Year: 1999-2006
Project Reference: 05096
WRL Technical Reports: Potential Impacts of Effluent Re-Use on Groundwater at Tamworth (1999/05); Potential Impacts of Effluent Re-use on Groundwater at Tamworth - Desktop and Field Investigations (1999/60); Tamworth Sewerage Augmentation and 100% Effluent Reuse Scheme - Supplementary Groundwater Sampling (2002/07); Tamworth Effluent Reuse Scheme: Additional Monitoring Bores and Baseline Water Quality Monitoring (2006/12)

In 1999, Tamworth Regional Council commenced investigations for a possible effluent re-use scheme in the vicinity of Tamworth Airport. As effluent re-use schemes can impact groundwaters, baseline monitoring is required to assess the variability of local water quality and levels, and potential beneficial uses of waters prior to the development. Continued monitoring is essential after commissioning of the scheme to gauge performance and trigger contingency actions if required.

In February 1999, WRL completed a desktop assessment of the potential impacts of effluent re-use on groundwater in the area west of Tamworth Airport concluding that the available groundwater quality information is limited. To enable site specific information on geology and groundwater quality, 18 groundwater monitoring bores were installed in October 1999 at the site. Groundwater sampling was completed by WRL in October 1999 and March 2002 to establish baseline conditions. The effluent re-use scheme has never been commenced but further baseline monitoring was expanded in 2006 to include private bores, six surface water monitoring sites and the installation of an additional monitoring bore, resulting in a total of 25 monitoring bores at 18 locations.

The results of water quality sampling indicated that the shallow groundwater tends to be more saline, while deep groundwater is relatively fresh. Fluoride and nutrient concentrations were low, but faecal coliforms were detected at several sides. Generally, but not always, results were compliant with guidelines for drinking water (with disinfection), irrigation and stock watering.

For more information about research on surface-groundwater interactions in the Namoi catchment follow this link to the Connected Waters Initiative