The Environmental Protection Authority (EPA) has recommended conditional approval for the second stage of the Water Corporation’s proposed Perth Groundwater Replenishment Scheme.
The proposal is to build an advanced water recycling plant at the Corporation’s Beenyup wastewater treatment plant in Craigie to transport highly treated recycled water that meets potable water standards by pipeline to recharge facilities in Wanneroo and Neerabup. The Corporation aims to annually recharge an additional 14GL into the deep Leederville and Yarragadee aquifers.
As a result of this proposal, the proponent would then abstract the same amount of groundwater from other areas for Perth’s drinking supply.
Groundwater replenishment has been identified as a key component of the proponent’s 50-year water source plan. The process involves advanced treatment of secondary treated wastewater for re-injection into aquifers.
The proposal includes construction and operation of an advanced water recycling plant at Beenyup, located about 25km north of Perth, a 12.8km recharge pipeline, and two recharge facilities.
The pipeline would mostly be constructed using conventional open-trench excavation. Other sections would use trenchless technologies to reduce the need for vegetation clearing.
EPA Chairman, Dr Tom Hatton, said that for the proposal, including across the 12.8km route, only 2.19ha of native vegetation is required to be cleared and the proponent would use tunnelling techniques to minimise impacts.
“Some sections of the pipeline would be constructed using technologies such as microtunnelling or horizontal directional drilling to avoid the clearing of native vegetation in sensitive Banksia woodland,” Dr Hatton said.
The Corporation would also be required to ensure there are no indirect impacts to Banksia woodlands within five years post construction.
Recommended conditions include implementing hygiene protocols, undertaking weed control, treating and managing acid sulfate soils, and minimising impacts to terrestrial fauna during construction.
The proposal to ‘top up’ the city’s groundwater supplies is part of a plan to help ensure climate resilience in the city’s integrated water supply scheme in a drying climate.
The EPA did not assess Stage 1 of the proposal as it considered it was unlikely to have a significant impact on the environment. It concluded that Stage 2 was environmentally acceptable provided conditions were met.