A soakaway is constructed in one of two basic forms.
A Conventional Soakaway comprises a partially perforated cylindrical chamber, which allows the drainage of water into the surrounding soil.
In cases where impermeable soils overlie the permeable strata, the soakage must take place at depth and so a deep bored liner is used. This is known as a Borehole Soakaway. 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.
Borehole Soakaways are also often used in areas of cambered or fissured strata, such as the Hythe Beds in Kent, to reduce the risk of subsidence. Subsidence can occur around shallow soakaways if loose infilling within fissures is inundated with seepage from a soakaway. By discharging the runoff into fissures at depth the risk of inducing shallow subsidence is reduced.
We have considerable experience in undertaking site investigation soakage testing, both for conventional soakaway design, as well as the drilling, testing and installation for borehole soakaways.