Manchester Tank shut down its Dinwiddie County manufacturing facility Thursday and laid off 66 employees. The Franklin, Tenn.-based company cited a drop in demand and the poor economy as reasons. Cost-cutting through consolidation also played a part and Virginia lost out, the company said. Employees at a Manchester Tank facility in Quincy, Ill., will take on additional production duties to make up for the closure, said Mickie Coggin, communications director for McWane Inc., which owns Manchester Tank.