Management of closed landfill sites presents various long term environmental challenges. In particular, the waste stabilization process is specific to every landfill site, and the resultant risks to the surrounding environment associated with landfill gas and leachate require a tailored management approach.

Egniol has been advising a local authority in north Wales on aftercare management of a closed landfill site since 2014. The site comprises both engineered areas and older ‘dilute & disperse’ areas, and has a highly variable waste composition across the site.

The remit of Egniol’s support to the local authority is two fold, to ensure full compliance with the site’s environmental permit whilst ensuring an optimal stabilization of the waste mass; this is imperative for any future permit surrender. Egniol prepared a comprehensive Gas Management Review Plan which was agreed with Natural Resources Wales (NRW) and has been implemented with the local authority. The Plan contains a series of measures aimed to improve the gas production process, reduce fugitive emissions and downsizing of the existing landfill gas engine.

Further work included carrying out of a leachate audit for better understanding of conditions within the landfill cells. A leachate recirculation system was designed and an initial recirculation trial overseen. Further trials are to be carried out in the near future before the long term leachate management approach is finalized.

Egniol has also begun appraisal of the potential opportunities to transform the cost liabilities of the site management to a revenue-generating business. The site already benefits from the existing road access, available space, and spare grid capacity.

A number of potential energy technologies were assessed and presented to the local authority, each providing certain marked benefits in terms of revenue, cost reduction, energy security and environmental sustainability. These options are undergoing further technical and financial feasibility assessments as we continue to work closely with the local authority.

Penhesgyn Site