Oral Presentation NCGRT/IAH Australasian Groundwater Conference 2019

Managed aquifer recharge feasibility assessment, City of Rockingham WA (104)

Cassie Turvey 1
  1. RPS, West Perth, WA, Australia

Increasing population, drying climate and historical over-allocation are placing groundwater resources under increased pressure within the Perth Metropolitan area. The City of Rockingham, located to the south of Perth, currently utilises ~5GL/yr of groundwater for irrigation of parks, reserves and streetscapes, with this water requirement set to increase in the coming years due to continuing urban expansion. Most of the groundwater resources in the Rockingham area are currently at or above allocation limits, thus groundwater availability is becoming increasingly limited and the feasibility of alternative water sources needs to be considered. Managed Aquifer Recharge (MAR) offers a means to recycle water into aquifers to provide licencing credits for abstraction. As part of a preliminary study, RPS and the City identified and assessed the feasibility of several potential MAR sources, following the Australian Guidelines for Water Recycling. Potential source volumes for MAR totalling over 100 GL/year were identified across the city, however key issues in assessing the viability of a MAR scheme in the Rockingham were identified. These include the shallow depth to groundwater which limits infiltration into the Superficial Aquifer, and the uncertainty of regional confining layers when considering injection to the deeper Leederville Aquifer. Based on the outcomes of the degree-of-difficulty assessment, initial focus has been placed on the harvesting and MAR of urban subsoil drainage water. This talk summarises the results of the regional MAR feasibility and details a case-study at the Rivergums residential development. The case-study has included: monitoring and analysis of several years of subsoil drainage flow volumes and quality; an assessment of the aquifer’s suitability for MAR; and the next steps towards practical implementation of a trial MAR scheme using harvested subsoil drainage water.