Highways Agency Reports

The construction of a road runway or other paved surface on the outcrop of an aquifer introduceds an impermeable area into an otherwise permeable environment. Srface water must be drained from these areas and the most conenient and inexpensive way of disposing of this water is usually to lead into soakaways in the saturated zone of the aquifer. This approach is acceptable in that it can provide valuable recharge to aquifers in times of low rainfall. However it carries the risk that pollutants from the surface can alsi be carried into the aquifer. These pollutants can be generated from (a) normal abrasion, (b) maintenance opertaions such as de-icing and defoliation and (c) accidental spillages. Although there is evidence that such drainage can carry a pollutant load and that drainage entering soakaways can reach a public supply well there does not seem to be any evidence available at present of any public supply in the UK being seriously affected by such drainage.