Stabilisation of shallow coal workings and mineshafts beneath a 68,800m² site at Eastlands, Manchester, has required some careful drilling and grouting works.
Bradford Colliery had been operational since Tudor times and was still producing significant amounts of coal well into the 20th century.
Despite there still being substantial coal reserves left in the area, subsidence caused by the mines became a major problem in the surrounding Bradford and Miles Platting area. The mines were finally closed in 1968, leaving a disused demolition site in their wake.
The site is situated next to the City of Manchester Stadium. Originally built to host the 2002 Commonwealth Games, it is now home to Manchester City FC and is a major regeneration focal point for Manchester.
The main £8M project is being undertaken by remediation specialists Buckingham Group Contracting and is part of the enabling works to provide a platform suitable for future commercial and leisure development on the land, which was also formerly occupied by gas and steel works alongside the centuries-old Bradford Colliery.
The project is being delivered by urban regeneration company New East Manchester, with funding from The European Regional Development Fund, the Homes & Communities Agency, the North West Regional Development Agency and Manchester City Council.
Project manager and cost consultant for the project is Turner & Townsend, with the client’s engineering design services and contract administration provided by Arup.
Stabilising the former mineworks is essential for the future viability of the land for commercial and residential use.
Despite there still being substantial coal reserves left in the area, subsidence caused by the mines became a major problem
The seams being dealt with are the Openshaw, Bradford 4ft, Bradford ¾ and Charlotte coals, down to depths of around 35m. Mine investgation and
stabilisation specialist M&J Drilling is carrying out this stage of the work.
The value of the drilling and pressure grouting work is in the region of £500,000 and has been undertaken with five Klemm 802-2 rigs.
BWB Consulting is acting as Buckingham’s engineering and environmental specialist, supervising this phase of stabilisation, which along with the drilling and grouting works comprises the capping of disused mine shafts and the verification of works undertaken on previous occasions.
The consolidation grouting works will involve the drilling of some 700 treatment and validation boreholes, totalling some 20,000m in length. This entails
using 101mm diameter steel casing through superficial deposits, penetrating the mine workings at 70mm diameter.
The stabilisation of collapsed coal seams is expected to involve the injection of around 1,500t of PFA/cement grout, pumped from a dedicated central mixing compound.
Drilling work started in early October and completion is planned for January 2011.