The Environment Agency requires monitoring of the environmental conditions at shale gas sites before operations can start in accordance with the environmental permit granted. This provides a valuable evidence base to compare against monitoring results taken during and after operations. The type and period of monitoring required after decommissioning is determined on a site by site basis. It will depend on the risks associated with the type and scale of activities at a particular site, together with the local environmental setting.
The Environment Agency will not allow an operator to surrender their permit until it is satisfied that the well has been decommissioned in line with the Health and Safety Executive's requirements and either no pollution has occurred at a site, or if it has, that the site has been returned to its original condition.