Soakaway Assessment: Drain it down (where you can!)
As part of Sustainable Drainage Systems (SuDS) assessments, the first stage on the drainage hierarchy is to mimic how water could naturally drain away; into the ground. This is commonly done using ‘soakaways’ where water is collected and then allow to drain into the underlying strata beneath a site.
At feasibility stage there are lots of things that can determine if soakaways are likely to be suitable or not. Because soakaways need to be at least 5m away from any existing or proposed structures, one of the biggest consideration can be if there’s enough space for soakaways to be viable.
For sites that are either on a hillside or next to one, soakaways are not often recommend because any water introduced into the ground might seep out lower down the hillside and cause problems for other land owners or other areas. When water is put into the ground it’s important to think about where it’s going and where it might end up!
Perhaps the main consideration is what the anticipated geological conditions are, including groundwater levels. The permeability of the underlying strata determines how fast (or not!) water passes through the strata. This is often dependent on fracturing within a rock mass or layering within superficial soils, and if the strata is already saturated this can reduce the storage potential meaning, even if the permeability of the strata is good.
At Abbeydale Geoscience we readily carry out geological assessments and soakaway assessments to look at whether soakaways might be a suitable drainage option or not.
Where the geological conditions are favourable and soakaways might be feasible, the next step is to carry out a Soakaway Investigation, either as part of a wider Ground Investigation, or as a standalone investigation, to assess the permeability of the ground at the location(s) of proposed soakaways. This is important because the permeability of the ground can vary across a site, so it’s important to do any soakaway tests where they are likely or proposed to be installed.
Whether you need a soakaway assessment as a standalone assessment for drainage design purposes, or we include it as a standard item with our Phase 1 Desk Study reports, we’re here to help you from the very outset when weighing up the potential for using soakaways as a drainage option.
