Mine Water Monitoring Borehole

Location / access Pelton Fell is a residential area in County Durham, located near Chester-le-Street. The proposed drilling site (image 1) is situated within Pelton Colliery Park, which is an open public space on a gentle slope. There is currently no dropped kerb at the location. Access to the proposed site would need to be taken via Pelton Fell Road, images 2 & 3. 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 October / early November 2026 Methodology: To be selected by the contractor to meet the target requirements. Borehole depth: 65-75m Final internal diameter: 100 mm Borehole deviation: 3 degrees Design life: Minimum of 20 years Headwork: To be completed under a square split lockable manhole cover at surface, minimum of 1000mm x 1000mm with D400 rating. Minimum of 200 mm between base of cover and top of casing Chamber must be between 0.5 and 1.0 m total depth. Indicative Geology The planed borehole is situated on the Pennine Middle Coal measures (PMCM). The Coal Measures strata are overlain by made ground and superficial deposits, likely comprised of colliery spoil and weathered bedrock. The borehole is to be drilled to intersect coal mine workings in the Low Main (K) Seam. (the 'target') of the former Pelton Fell Colliery. Permits / Land Agreements The proposed borehole will be drilled within a managed, open space park owned and maintained by Durham County Council. To proceed, the Mining Remediation Authority must agree on Heads of Terms and secure a licence from the council. This licence will be formally executed and available prior to site mobilisation. The project qualifies as permitted development; therefore, formal planning permission is not required. As the works involve only below-ground infrastructure, no additional rights or permits are required from the local council. Programme The current Programme is estimated to run to the following timescales, with an ambition to complete the Borehole by FY 26 /27. 1. Tender Publish / Advert June 2026 2. Evaluation July 2026 3. Award Early August 2026 4. Mobilisation on site Early September 2026 5. Drilling & Construction Mid-September 2026 6. Completion October / Early November 2026 Engagement Opportunities The Mining Remediation Authority is committed to continuous improvement in project delivery and risk management. Based on previous experience, one effective method has been to drill a pilot hole using a wireline coring system to maintain borehole verticality. This approach provides an opportunity to confirm geological conditions before committing to full-scale drilling. The pilot hole method mitigates this risk by offering flexibility to adjust and re-drill to an alternative target with minimal additional cost. We welcome your feedback on this proposed methodology or any alternative strategies that could further reduce risk and optimize cost efficiency for borehole construction. Site Visit Date and time of the Visit: Tuesday 31st March 2026 at 11.00am Site address: Pelton Fell, Chester-le-Street, DH2 2BN (nearest post code) Please confirm your interest in attending the site visit to email: satty.malhi@miningremediation.gov.uk Mining Remediation Authority contacts: • Satty Malhi Project Manager 07827 473955 • Sean Burke Senior Hydrogeologist 07826 908730