A WA parliamentary question addresses community concerns about effluent overflows at the Walpole Waste Water Treatment Plant, seeking information on environmental damage, preventative measures, and the impact of a seasonally active aquifer. The Minister acknowledges potential issues and outlines steps taken, including planned decommissioning of the trench.

AnsweredQoN 748Legislative Assembly
Asked
25 February 2003
Portfolio
the Environment and Heritage

QuestionView source ↗

(1) Is the Minister aware of community concern regarding several effluent overflow events over a three-month period in 2002 at the Walpole Waste Water Treatment Plant (WWTP)?
(2) Will the Minister advise what environmental damage was caused from the effluent overflow events at the Walpole WWTP?
(3) Will the Minister advise what steps have been taken to ensure there will be no further effluent overflow events at the Walpole WWTP?
(4) Will the Minister advise what impact a seasonally active aquifer would have on the effectiveness and efficiency of the effluent trenches at the Walpole WWTP?
(5) Will the Minister confirm whether a seasonally active aquifer exists under the effluent trenches at the Walpole WWTP?

AnswerView source ↗

Answered
20 March 2003
Responded by
Minister for the Environment and Heritage
Response time
23 days
(2) There may have been excess weed growth, but there was no other evidence of an adverse impact on vegetation or groundwater quality. (3) I have been advised that the Water Corporation has refurbished the infiltration trench, added process controls at the treatment plant, and implemented daily inspections. Also, a leakage of groundwater into the sewerage reticulation system was detected and repaired, which will decrease the inflow into the treatment plant. (4) It is possible that a seasonally active aquifer may cause the trench to overflow. The Water Corporation is planning to decommission the trench by February 2004. (5) It is possible that seasonally high groundwater levels may occur in Winter depending on rainfall. When the Water Corporation investigated the hydrogeological aspects of the area of the trench, it reported that there was no evidence of a seasonally active aquifer zone other than the potential for perched groundwater levels during Winter rain in the superficial aquifer.
(4) It is possible that a seasonally active aquifer may cause the trench to overflow. The Water Corporation is planning to decommission the trench by February 2004. (5) It is possible that seasonally high groundwater levels may occur in Winter depending on rainfall. When the Water Corporation investigated the hydrogeological aspects of the area of the trench, it reported that there was no evidence of a seasonally active aquifer zone other than the potential for perched groundwater levels during Winter rain in the superficial aquifer.
(5) It is possible that seasonally high groundwater levels may occur in Winter depending on rainfall. When the Water Corporation investigated the hydrogeological aspects of the area of the trench, it reported that there was no evidence of a seasonally active aquifer zone other than the potential for perched groundwater levels during Winter rain in the superficial aquifer.

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