A roof that incorporates a substrate (laid over a waterproof membrane) that is allowed to colonise naturally. Sometimes referred to as an alternative roof.

A depressed landscaping area that is allowed to collect runoff so it percolates through the soil below the area into an underdrain, thereby promoting pollutant removal.

Decomposition of organic matter by micro-organisms and other living things.

Flow control or water treatment structure that is normally dry.

Redevelopment of a site often associated with pollution issues.

Structural and non-structural measures used to store or treat urban surface water runoff to reduce flooding, remove pollution and provide other amenities.

Sustained or dry weather flows not directly generated by rainfall. It commonly constitutes flows generated by domestic and industrial discharge and also infiltration.

A pond designed to attenuate flows by storing runoff during the peak flow and releasing it at a controlled rate during and after the peak flow has passed. The pond always contains water. Also known as wet detention pond.