Unreinforced concrete in foundations may be deposited in contact with but not mixed with earth. All reinforced concrete in the ground shall be adequately protected to ensure that the soil does not contaminate the concrete, and the required dimensions shown on the drawings and cover to reinforcement are maintained. The means of protection are subject to the Project Manager 's comment.The faces of reinforced concrete retaining walls and enclosing walls of basement structures must be cast against formwork. The type of formwork is subject to the Project Manager's comment.Before placing structural concrete (not blinding concrete) on hard-core or other absorbent substrates, lay 2000g polythene. Lap edges 150mm.