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Roadways, footpaths and hard standings on site should be adequately drained to prevent the build-up of standing water. Drainage should be by gullies or drainage channels. All gratings and channel units should be of appropriate load bearing capacity for the location in which they are set. Connections for surface run-off from roads, hardstandings etc into drainage systems may have to include interception facilities in the case of oil or chemical contamination. Surface run-off will include fire-fighting water.


The maximum longitudinal gradient should be 1 in 12 and the minimum channel gradient should be 1 in 125. A camber of 1 in 40 provides adequate drainage. If minimum gradients are not provided, surface water will tend to pond, which will be hazardous in freezing conditions. Standing water can also obscure road markings and lead to an increased likelihood of accidents.