Before placing concrete, the formwork and reinforcement should be checked to make sure that they are clean and free of any detritis, such as ends of tying wire. The fresh concrete should be deposited as close as possible to its final position. Care should be taken when discharging concrete from skips to avoid dislodging the reinforcement or over filling the formwork. When filling columns and walls, care should be taken that the concrete does not strike the face of the formwork, which might affect the surface finish of the hardened concrete. For deep sections the concrete should be placed in uniform layers, typically not more than about 500 mm thick, each layer being fully compacted.