CARSINGTON AQUEDUCT - MAN AGAINST NATURE.

Britain's biggest current tunnelling contract outside the field of coal mining has run into severe and unexpected geological difficulties, and completion of tunnelling to hole-through may be as much as two years behind the originally planned date. The tunnelling contract, awarded by the Severn Trent Water Authority to contractor John Mowlem, calls for two main tunnels through hills, one 3. 6 km and the other 4. 8km long, connected by a 1. 6km long pipeline (1. 6m in diameter) which runs across the valley between the hills. There is also a shorter 140m long tunnel at the downstream end. With only one sixth of the 10 1/2km of tunnelling completed, harder rock and more water than expected have forced three out of the four drives to give up their roadheaders and turn to hand mining or drill and blast. The remaining face, which kept its rodheader, is being driven under compressed air to keep unexpectedly large amounts of water under control.