Westleigh Mine Water Pumping Borehole

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

Parameter Requirement

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.

3. Engagement Opportunities The CA are always looking for ways to improve and streamline projects. Due to the defined verticality requirements, it is envisaged that the most robust and reliable method of completing the mine water monitoring boreholes is by drilling a pilot hole using a wireline coring system, followed by reaming to the required diameter(s).

The CA would welcome your feedback on this.

Please register your response, interest & feedback to adambeckett@coal.gov.uk

Additional information: The Coal Authority (Client) was established by Parliament to undertake specific statutory duties, set out in the Coal Industry Act 1994, associated with licensing coal mining operations; managing property and the historic legacy arising from the ownership of the coal reserves and underground workings; settling subsidence damage claims not falling on coal mine operators and providing access to coal mining information. Coal Authority tenders are now being undertaken by the Authority's eTender portal InBye, details of how to register are attached to this notice.

Should you wish to participate in any electronic tender exercise you will need to register your company details, which will require the provision of some company information and agreement to terms and conditions to access the system.

Use of the system is free of charge.

In order to register please log on to https://inbye.coal.gov.uk/s2c/