The environmental risks posed by landfill sites continue for a significant period of time after waste acceptance has ceased. These risks can be posed by:
leachate, a liquid formed by rainwater and decomposing waste, is likely to contaminate groundwater, stormwater or surface waters if not managed appropriately
landfill gas, formed during the decomposition of waste, if not managed is likely to migrate into the surrounding ground and atmosphere, creating an environmental hazard and causing odours
inappropriate or incomplete capping will cause the infiltration of rainwater to generate large volumes of leachate and allow landfill gas to escape to the atmosphere, and
a lack of appropriate ongoing aftercare management, maintenance, monitoring and reporting, which prevents the appropriate assessment of risk.
In order to ensure that the risks are appropriately quantified and managed, occupiers of closed landfill sites are issued with pollution abatement notices that require the closed landfill to be managed so there are no unacceptable risks to the environment. These are referred to as post closure pollution abatement notices (PC PANs) for licensed landfills.
Although the use of PC PANs as the statutory tool to manage the risks from closed landfills is not a new tool – they have been used for over 25 years – EPA has made some changes to the key requirements used in this tool. The most important changes have been to the assurance provided by the role of EPA-appointed environmental auditors independently verifying the various plans, monitoring programs and the undertaking of regular environmental audits. There have also been changes to the types of plans and reports to be provided to EPA before a PC PAN is issued – including hydrogeological assessments.
The process of issuing a PC PAN commences with preparation of various plans and assessments for the landfill, some of which may have already been prepared through EPA licence conditions. EPA requires the landfill owner to develop rehabilitation plans, aftercare management and monitoring programs. A hydrogeological assessment is also required, if one has not already been completed or updated within the last four years. Following the completion or updating of these plans and documents, PC PANs are issued that require the implementation of these specific plans and programs, along with regular reporting to EPA and the independent environmental auditing of the closed landfill at a frequency appropriate to the risks posed by the site.
The implementation of PC PANs for licensed landfills across Victoria is continuing to be undertaken in stages. Owners of recently closed landfills wishing to surrender their licence are included in the first stage along with other higher risk sites. Landfills that are already closed and have an existing PC PAN will require re-assessment of their environmental risks to determine if the new PC PANs are required to manage their ongoing environmental risks.
EPA’s Closed landfill guidelines (publication 1490) provides further information on this process.