I.D. Corcoran Contractors Ltd

Infilling of inlet and outlet tunnels along with steam and cable tunnels

Bentonite (Manufacturing & Supply) Ltd was approached by I.D. Corcoran Contractors Ltd for advice on the infill of decommissioned steam and cable tunnels, along with decommissioned inlet and outlet tunnels. At Dungeness (A) Power Station, our production team was pumping 100 linear metres above ground and then a further 250 linear metres on installed underground production lines.

Testing of the blended bentonite/cement/slag which was to meet the required strength and the non-porous permeability of 1×10-9 minimum were carried out at our head office, near Gravesend in Kent. We then mobilised our 16-metre batching plant along with a 40-ton vertical silo and our 55,000 litre water tank and two holding tankers. This was to ensure room for two 28-ton deliveries a day of the blended material.

Due to the sensitivity of the job, rigorous testing was conducted on each batch, along with flow and density checks as well as temperature checks on the material. These were recorded on our technical and production sheets, with printouts of densities. Ten cores were also taken each day for the testing of the blended material.

• Total volume of project: 6,102 cubic metres.