Hat Head Effluent Groundwater Monitoring Program
Client: Macleay Water
Year: 2002-Ongoing
Project Reference: 00684
WRL Technical Reports: Hat Head Dune Effluent Disposal Site - Baseline Groundwater Monitoring (2002/45); Hat Head Dune Effluent Disposal Site Post Commissioning Monitoring (2004/27); Hat Head Effluent Disposal Scheme - Ongoing Monitoring Results (2008/07)
With pressure from tourism, population and increasing concerns about the impact of septic tanks on the local environment, investigations into the sewering of Hat Head commenced in 2000. Sewage exfiltration into the sand dunes directly north of the town was selected as the most appropriate and economical means of disposing of the sewage. WRL was commissioned by Macleay Water to design a groundwater monitoring program to allow early detection should sewage impacts from the exfiltration occur, and thereby prevent degradation of sensitive environmental areas surrounding the site and pollution of Hat Head village.
In 2002-2003, WRL designed the monitoring program, oversaw installation of monitoring piezometers, and collected and analysed baseline groundwater quality and level data for the site at multiple sampling events. This field work required strict quality control for the calibration of water quality meters, disinfection of equipment between samples, and collection and handling of groundwater samples. Submersible groundwater pumps were use to develop the piezometers prior to sampling and for subsequent collection of samples.
Using this data, WRL set trigger levels for the detection of effluent impacts at the site. After commissioning of the exfiltration site, WRL continued to collect and assess the groundwater quality and level data at Hat Head and subsequently review and revise the groundwater monitoring program. Investigations at this site have led to review into the formerly accepted methods of setting trigger levels for groundwater and WRL continues to work at the forefront of this area. WRL is still actively involved in the ongoing groundwater monitoring program at Hat Head.
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