P20 Groundwater Risk Assessment Demonstrates No Remediation Required
At a former engineering works near Exeter, elevated levels of polyaromatic hydrocarbons (PAH) and total petroleum hydrocarbons (TPH) were recorded in both the soil and groundwater beneath the site.
As screening criteria had been exceeded in the groundwater beneath the site for these contaminants, further assessment was required to ascertain whether the recorded levels of contaminants beneath the site could migrate to off-site receptors, e.g. to a nearby river, and cause unacceptable levels of pollution to the water environment.
Remedial targets were calculated using the Environment Agency’s Remedial Targets Worksheet (P20 assessment). In this instance, the recorded values were below the calculated remedial targets and the risk assessment demonstrated that unacceptable pollution was unlikely to occur to controlled waters, as the levels of contaminants on-site were modelled to have diluted by natural attenuation and dispersion processes before reaching the receptor.
No further assessment or remedial works were considered to be necessary. This was agreed with and accepted by the Environment Agency.