LINK — DEWATERING
1312. Hon Dr STEVE THOMAS to the minister representing the
Minister for Water:
My question without notice, of which
considerable notice has been given, is to the minister representing the
Minister for Water. Sorry, Minister for Environment, you miss out today.
I refer to the Forrestfield–Airport
Link project and my question without notice 1157, asked on 16 October, which
identified that 656 million litres of water has been dewatered from the FAL
project and reinjected into the extraction sites.
(1) Can water reinjected
into soil or aquifers on the route of the FAL project connect or mix with water
in the area's underground aquifers, watertables or surface waterways?
(2) What prevents
the reinjected water from mixing with the area's underground aquifers,
watertables or surface waterways?
(3) Is there any
way the reinjected water could carry PFAS chemicals into the area's
underground aquifers, watertables or surface waterways?
(4) Could any of this reinjected
water find its way into the Swan River system?
(5) What monitoring has been conducted to assess
whether PFAS from the FAL project dewatering has reached the area's
underground aquifers, watertables or surface waterways, and please provide the
ALANNAH MacTIERNAN replied:
I thank the member for the question.
The following information has been provided by the Minister for Water.
(1)–(3) The Department of Water and Environmental
Regulation does not regulate the reinjection of dewatered water. However,
the project managers have advised the department that as part of the
Forrestfield–Airport Link construction, dewatering is required to allow
for the construction of underground structures such as stations and tunnel portals. Dewatering involves removing groundwater to
temporarily lower the watertable within the work area to allow soil to
be evacuated. The watertable is the top surface of the superficial aquifer. The
department advises that the dewatered water from the FAL project is reinjected
back into the superficial aquifer from which it was removed. Therefore,
dewatered water and the superficial aquifer water are from the same source and,
when mixed, would have a similar base chemistry. The natural pathways of the
superficial aquifer in the area would continue.
(4) Groundwater in the superficial
aquifers in the area flows to the Swan River.