Paragraph 12 Treatment of mine shafts and depths of excavationI1

No excavation or dewatering may take place below 48 metres Above Ordnance Datum (AOD) without prior approval by the county planning authority (such approval only to be given where necessary to create a basal sub-grade suitable for the construction of the basal lining system). This permitted depth of excavation is to include the excavation of any sumps for drainage or dewatering and the capping of any mine shafts beneath the proposed waste containment facility.

Below a level of 65 metres AOD, no abstraction of water or mineral excavation may take place within an agreed stand-off horizontal distance of any mine shaft until or unless those shafts have been adequately sealed in accordance with details approved by the county planning authority in consultation with the Environment Agency and Coal Authority. The stand-off distance must be approved by the county planning authority in consultation with the Environment Agency and Coal Authority.

The sealing methods must prevent against the transmission of water between any mined voids below a depth of 48 metres AOD and the proposed mineral excavation and landfill formation.

The restriction on excavation and dewatering does not apply to the drilling of boreholes for ground investigation, monitoring or grouting. The restriction on abstraction of water does not preclude the taking of samples for water quality analysis or the execution of permeability tests where the latter are limited in scope and agreed by the Environment Agency in advance.