Westleigh Mine Water Pumping Borehole

Description

1. Background The Coal Authority (CA) requires a mine water pumping borehole to assess rising mine water on the surrounding environment at Westleigh, Wigan. A review of the mine water block has highlighted that mine water levels in the area could be elevated in respect to the rest of the block. There is potential for elevated mine water levels which could pose a risk to the overlying drinking water aquifers and the surface water environment. Therefore, the CA requires construction of a borehole to intersect flooded underground workings and will be used to improve understanding of mine water in the Golborne-Bickershaw-Parsonage mine water sub-block of the Lancashire Coalfield, through water level monitoring, quality sampling and long-term abstraction. 2. Key Requirements The Contractor will be responsible for specific construction details to achieve the borehole requirements, as specified below. Summary of key requirements Operational time: By March 2025. * Methodology: Anticipated to require a pilot hole to be drilled by wireline coring methods to assist in maintaining verticality. * Borehole depth: Estimated 200 - 250 metres below ground level (m bgl). * Final internal diameter: Minimum of 400mm. * Borehole deviation: 2m from surface location of borehole (0.6° from vertical). * Design life: Minimum of 20 years. * Headworks: To be completed under a square split lockable manhole cover at surface, minimum of 600mm x 600mm with D400 rating.

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