HIGHWAY DRAINAGE TO THE CHALK AQUIFER. THE MOVEMENT OF GROUNDWATER IN THE CHALK NEAR BRICKET WOOD, HERTFORDSHIRE, AND ITS POSSIBLE POLLUTION BY DRAINAGE FROM THE M25 MOTORWAY

The terms of reference of this study were to investigate the flow characteristics in the chalk in the vicinity of the M1/M25 interchange in order to determine whether or not pollutants entering the soakaways of the M25 motorway drainage system could be carried towards any source of water supply. The work was carried out in 3 stages: 1) a desk study and modelling exercise of the hydrogeology of the chalk in the vicinity of the M1/M25 and the M1/A405 interchanges; 2) a tracer study with some testing in 1986-87; and 3) a more sophisticated tracer study in 1988. The tracer tests, using fluorescent dye and bacteriophage tracers, confirmed the predictions of the modelling and desk studies, and showed that a substance entering a soakaway near the centre of the M1/M25 interchange will reach the public water supply source at Bricket Wood Pumping Station in 20 to 25 days. Interceptors provided at soakaways will not stop solvents such as organochlorine which are denser than water, nor will they stop liquids or solids that are readily soluble in water. The implications of these tracer tests are that a complete spillage of a large tanker load of completely miscible solvent could cause concentrations of about 70-80 mu g/l, although concentrations at the pumping will not be strictly in proportion to the size of the spill. These predicted concentrations are in excess of those laid down by the EC for some substances in drinking water. Significant concentrations may remain in the aquifer, dissolving slowly, for a very long time.

  • Corporate Authors:

    British Geological Survey

    Keyworth, Nottingham  United Kingdom  NG12 5GG
  • Authors:
    • Price, M
    • Atkinson, T C
    • Wheeler, D
    • Barker, J A
    • Monkhouse, R A
  • Publication Date: 1989

Language

  • English

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00609880
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Report/Paper Numbers: WD/89/3
  • Files: ITRD, TRIS
  • Created Date: Jun 30 1991 12:00AM