The EPA Research Report No. 161 has just recently been published. It relates to “Assessment of disposal options for treated waste water from single houses in low permeability subsoils”.
The potential impacts of incorrectly situated or poorly constructed domestic waste water treatment systems (DWWTSs) include the pollution of either groundwater and/or surface water and places a risk on human health particularly via private wells.
This research has demonstrated with field trials a range of systems that may be a solution for on-site wastewater treatment and disposal in low permeability soils, although changes in current policy and legislation would be required to facilitate their use. EPA staff will review the report and liaise with DECLG in relation to the relevant recommendations/findings highlighted by the authors and incorporate the findings into national guidelines as appropriate
A decision support tool, also produced by this study, has been developed for strategic assessment at a Local Authority level to inform policy. This has highlighted that surface water discharge may need to be reconsidered in areas where the discharge to ground is very problematic. It has also shown that the concept of clustered decentralised systems could target a significant proportion of potentially poor sites in low permeability areas and therefore lower the burden of monitoring associated with individual discharge consents.