Delays have prevented Clarence Valley Council (CVC) from commencing remediation works at three former sewerage treatment plants (STP) at Maclean, Townsend and Ilarwill, apart from stockpiling soil at the former Maclean STP.
“We had an opportunity to obtain at least 7,000 tonnes of excess spoil from the former South Grafton STP site that was classified as ‘Virgin Excavated Natural Material’ (VENM) and therefore suitable for use in rehabilitation,” Clarence Valley Council’s water cycle manager, Greg Mashiah, said in a statement to the Independent.
“Council would otherwise have to obtain quarried material at significant additional cost.”
Councillors awarded a $1,595,388 contract to Ledonne Constructions to rehabilitate the three STPs at the November 15, 2016 council meeting.
The council also engaged Public Works Advisory to undertake project management services of the contract.
However, additional costs could be incurred if the Environmental Protection Authority (EPA) does not approve the reuse of residual bio-solids at the sites.
The council’s tender documents invited estimates “on the basis that most of the [onsite] material met the EPA’s guidelines for the use and disposal of bio-solids products”.
The report to yesterday’s Corporate, Governance & Works Committee meeting stated that “additional sampling and groundwater investigation was scheduled to be undertaken in May but was deferred pending a response from EPA regarding its requirements”.
Subsequently, samples were taken in July and, after analysis, the results will be included in the Remediation Action Plan (RAP) submitted to the EPA for approval, after which rehabilitation of the sites can commence.
Mr Mashiah said the 7,000 tonnes of fill from South Grafton was stockpiled at the McPhee Street, Maclean site.
“Subject to EPA approval of the RAP, we are hoping existing site material [in addition to the stockpile] , including all the remaining bio-solids, can be reused at Maclean as part of the rehabilitation,” he said.
The material transported from the troublesome former South Grafton STP and site of the new depot – where CVC spent $6.976million on transporting asbestos and bio-solid contaminated material from South Grafton to a landfill near Ipswich in Queensland – has been certified as VENM by consultants GHD and the EPA accredited contaminated site auditor.
The Protection of the Environment Operations Act defines VENM as: “natural material (such as clay, gravel, sand, soil or rock fines): (a) that has been excavated or quarried from areas that are not contaminated with manufactured chemicals, or with process residues, as a result of industrial, commercial, mining or agricultural activities; and, (b) that does not contain any sulfidic ores or soils or any other waste.”
The revised budget, as adopted in November 2016, is $1.95million, the report to last week’s committee meeting stated, “which included a 15% allowance for variations”.
“To date two variations have been approved in the amount of $89,719.20 (ex GST) being for additional work required in order to produce a RAP that will allow the level of remediation agreed with the Site Auditor.
“Expenditure and commitments to date total $1.735million, leaving a contingency balance of $0.215 million.
“If the EPA does not approve reuse of bio-solids at the Maclean STP site and reuse of the stockpiled material at the Townsend STP site, the material will need to be disposed off site, which may incur additional costs.”