Geoff Helisma |
Rehabilitating former sewer treatment plants (STP) has proved to be problematic for Clarence Valley Council, with discoveries of what lay beneath the surface costing millions of dollars.
In May this year, the Environmental Protection Authority (EPA) conducted a “state-wide bio-solids sampling event … and analysed samples for PFAS”.
Bio-solids are often recycled from sewage for use in agriculture.
All of the samples were found to contain “PFAS above the limit of reporting”.
PFAS (per- and poly-fluoroalkyl substances) are “a group of manufactured chemicals that have been used since the 1950s in a range of common household products and specialty applications, including in the manufacture of non-stick cookware; fabric, furniture and carpet stain protection applications; food packaging; some industrial processes; and in some types of fire-fighting foam”, an Australian Government Department of Health factsheet states.
An updated report on the rehabilitation of Lower Clarence STPs, to be tabled at next week’s CVC meeting, advises councillors that the EPA and the Office of Environment and Heritage (OEH) were due to complete its Human Health And Environmental Risk Assessment (HHERA), regarding PFAS contamination of bio-solids and the implications this will have on their “beneficial reuse”.
The council’s water cycle manager Greg Mashiah told the Independent that the assessment had not been received at the time of writing.
While the Biosolids Reuse Guidelines currently do not require testing for PFAS chemicals, Mr Mashiah said the contaminated land site auditor for the Lower Clarence STPs required testing for these chemicals “as part of the rehabilitation signoff”.
Once the risk assessment is completed, the EPA will “make a determination regarding beneficial reuse”, Mr Mashiah writes in his report to council.
“As well as impacting this project, the issue of managing bio-solids with PFAS is likely to impact council’s operational STPs, with potentially significant increases in management costs if the only viable option is determined to be landfill disposal.
“EPA has indicated that it would not permit burial and capping at other sites without appropriate licencing, and has advised that it would only permit interim storage at operational STPs pending resolution of the issue.”
Current estimates for rehabilitating the STPs show a cost overrun $133,311 above the approved budget of $1.950million.
As the laws stand now, if the bio-solids can be used agriculturally it will cost $637,000 to transport 10,900 cubic metres of bio-solids.
If the EPA rules this as inappropriate use, it will cost $1.489million to transport them to a Queensland landfill; however, if transportation occurs after December 2018, when the laws are due to be amended, “the cost is likely to approximately double”, the report to council states.
“There is no guarantee than an HHERA will permit reuse, so potentially up to $250,000 could be expended determining this option is not feasible,” the report to council states.
“The accredited Contaminated Site Auditor has suggested that the likely timeframe for a risk assessment would be four to sixth months, which would potentially cause some contract delay costs, even if beneficial agricultural reuse was then feasible.”
If the contractor performing the rehabilitation works is delayed beyond the approved completion date – currently November 27 – CVC would be required to pay the contractor $3,067.27 (ex GST) per day in penalties.