The Trustees of the Irish World Heritage Centre (IWHC) commissioned a Preliminary Risk Assessment (PRA) (Phase I Desk Study), Geo- environmental Investigation and Risk Assessment Report (Phase II) on the IWHC site in Manchester.
Located within the boundary of a large domestic landfill, the IWHC site occupies a small section of the landfill which was previously partially occupied by a petrol filling station.
Extensive site investigation works were carried out within the area of the former petrol station and the landfill, where up to 10.2m of the made ground material included some, but not significant volumes of domestic refuse.
Visual and olfactory evidence of hydrocarbon contamination was encountered, particularly in the area of the former petrol station. Subsequent soil and water sample analysis identified the presence of hydrocarbon contamination within the made ground and the groundwater of the underlying aquifer. This was present both within and outside of the footprint of the former petrol station.
Although, the concentrations of hydrocarbons were noted to reduce with increasing distance from the source, they were still considered to pose a potential risk to the identified receptors.
Remedial Targets (formerly P20) Groundwater Risk Assessment was undertaken for the contaminants based on very conservative parameters. The compliance points were determined as the River Irk and the underlying aquifer.
Due to the congealed nature of the hydrocarbons encountered on the IWHC site, the modelled data generated compliance criteria which were similar to the concentrations encountered on site. This showed that the compliance points were not at risk and modelled data closely followed the actual site data.