EOI T2025-15 CWMS Leachate Treatment

Summary and scope

CWMC is seeking responses for leachate management options for the 8.5 megaliter (ML) leachate pond at the site. The project aim is to increase the level of freeboard within the leachate pond by 3.0 ML (3,000,000L) This will increase the level of redundancy within the pond during periods of sustained wet weather. The project will deliver positive environmental outcomes for the site by reducing the potential for leachate overflows. A non-compulsory pre-tender meeting will be held on Tuesday 14 October 2025 at 10am at theCessnock Waste Management Centre (CWMC) UPDATE FROM SITE MEETING ON 14 OCTOBER: Q= Question A = Answer Q1: If we could or wanted to meter our surface water and/or leachate flows into the LP. A1: It is not considered essential at this stage of the proposal. Further detail may be provided in Stage 2 of the process. Q2: Historical PFAS data is requested, some asked if it were possible to sample the pond at lower depths (and/or take a sludge sample) to understand the gradient of the LP’s contamination profile, rather than relying on current surface grab samples data. A2: An additional document has been added into the VendorPanel portal ‘PFAS data’. Council notes that this data is not current, however, no new inputs have been connected to the pond and therefore results are not expected to be significantly different (aside from the subsequent point below). Q3: This was noted as important to understanding the methodological and budgetary impact of lower pond stratum processing for proposals, should they be required to be treated for acceptable removal. A3: Noted – Additional samples will be collected on 15/10/25 in an attempt to gather data across the depth of the water column. Council is aiming to collect an additional surface water and “at depth” sample which will be provided with the additional provision of results. Q4:The reduced levels from the top of the adjacent northern batter and the leachate pond were requested. A4: Approximate RL’s for the leachate pond (surface) is 90m and the top levelled out surface of the active tip face is 110m. Q5: The depth of the pond was also requested. A5: Council to confirm.