Thorpe Park Development, Leeds

This is a large development, just outside Leeds, which had an area of historical old mineworkings present in one area of the site. Harland were asked to put forward a proposal for prior extraction of the coal and reinstatement and recompaction of the overburden to pre-set standards determined by the Consultant.

The initial Site Investigation report indicated the remaining coal volume to be in the region of 30,000 tonnes of the Flockton Thick Coal seam, 2.5 metres thick.

Further investigations by open hole drilling identified a larger number of voids, inconsistent with the initial estimates of residual coal, which Harland estimated at 12,000 tonnes.

During the excavations, it became clear that the unrecorded workings were far greater, more in the region of 80%. This was exceptional, as normal practice is 50%, and all under 3 metres of cover.

The ingenuity and courage of the old miners is only to be admired.

The final figure of recovered coal, was 7,800 tonnes.

Had the Developer chosen to grout the old workings, the initial budget would have been far exceeded due to the unknown high degree of workings.

After our costs, the estimated savings of prior extraction versus grouting, were in the region of 3 million pounds – which would have made a substantial difference in the development costs.