Soakaway Drainage Feasibility Assessment, Cornwall
Soakaway drainage, combined with sustainable drainage systems (SuDS), was proposed as a means of surface water drainage at a proposed residential development site in Cornwall.
Soakaway testing and assessment was as a pre-commencement planning requirement.
In order to provide soil infiltration rates for preliminary design, in-situ soakaway testing was undertaken in accordance with BRE DG 365. Close liaison with the consulting engineer ensured that the test locations were targeted at key locations and depths across the site.
In addition to considering the infiltration characteristics at the site, as parts the site were relatively steeply sloping, a slope stability assessment was undertaken, to assess how soakaway drainage might affect slope instability; soakaways had to be carefully sited as a result of this.
Long-term groundwater level monitoring was also undertaken to demonstrate that the seasonal high groundwater table would not rise above the base of the soakaway.