Human Health Contamination Risk Assessments
Human health contamination risk assessments are undertaken to demonstrate that the site is suitable for the proposed end use, often to satisfy a planning condition and/ or warranty provider (e.g. NHBC) land quality condition.
Following the preliminary risk assessment (Phase 1 Contamination Risk Assessment), these will typically take the form of a Generic Qualitative Risk Assessment (GQRA), where the results of the contamination laboratory testing are compared to Generic Assessment Criteria (GAC) to aid the evaluation of the extent of contamination at the site. If any of the GAC are exceeded, this may be indicative of an unacceptable risk to the health of site users and that further investigation, assessment and/ or remediation is required.
Residential Redevelopment of Former Garage
A human health risk assessment at a proposed residential development site in North Devon was undertaken as part of a wider scope of works comprising a Phase 1 and Phase 2 contamination assessment, followed by the production of a remediation strategy and subsequent validation testing.
The Phase 1 assessment indicated that the site was a former garage, part of a larger historical coach depot.
The Phase 2 contamination investigation, which comprised windowless sample boreholes and contamination laboratory testing, recorded elevated levels of total petroleum hydrocarbons (TPH)and lead within both made ground and underlying natural soils, associated with a remnant underground storage tank (UST), fuel lines and an off-site tank, within the confines of the former coachworks.
The contamination risk assessment indicated the recorded levels of contamination to potentially be harmful to human health, given the proposed residential land use.
To protect end users, Ruddlesden recommended that all of the tanks and associated fuel lines be remove, and that all proposed garden/ soft-landscaped areas be capped with a minimum thickness of 600mm topsoil and subsoil underlain by a geotextile membrane.
All of Ruddlesden’s reports were approved by the local authority’s environmental health officer and the contaminated land planning condition was satisfied.