Permeable paving instead of impermeable surfaces

Where hard surfacing is necessary, permeable paving should be used rather than conventional hard surfaces (e.g. impermeable concrete and tarmacadam) which allow rain and storm water to flow across such surfaces to gullies that collect and direct water into underground pipes and drains. This can increase the speed and volume of flows downstream and the risk of flooding elsewhere. It is important, however, that any surfacing submitted for adoption is acceptable to DfI Roads.