Soakaways are used to collect surface runoff prior to being discharged into the surrounding soil. They are usually employed in areas where the surface run-off cannot be disposed into existing streams or ditches.
A conventional soakaway comprises a shallow, partially perforated cylindrical chamber or excavation and backfilling with soakage crates, which allows the drainage of water into the surrounding soil.
Where the soakage must take place at depth a deep bored liner is used. Here the water is transported from a sealed storage chamber to the soakage medium by a small diameter plastic or steel pipe, again perforated in part.
There are a number of site investigation permeability tests for determining whether soakaways may work effectively. These range from small to large scale. Small-scale tests are only applicable to draining relatively small areas. We can offer the following test methods:
- NHBC: Chapter 5.3; Percolation Test for Surface Water Soakaways
- BS 6297: 2007; Percolation Test for Septic Tank Insulations
- BS 5930: 1999; Falling Head Test in Boreholes
- BRE Digest 365: 1991; Falling Head Test in Trial Pits
- BS 5930; 1999; Constant Head Test in Boreholes