Pile: long heavy section of timber, concrete or metal, driven into the earth or seabed as support for another structure.

UNESCO: L O S S A R Y

"The controls we had put in place were inadequate due to the unusually high rainfall, which resulted in surface water flowing onto a track that was being used by heavy machinery to extract timber from the forest, " added Mr Garson.

BBC: Forestry Commission fined ?24,000 for Powys pollution