Case Study: Muir Group Housing Association
Design and supervise remediation to remove traces of benzene and ensure CO2 and methane levels were controlled at a housing estate in England for the Muir Group Housing Association.
In 2005, the unusual deaths of two toddlers from acute myeloid leukemia sparked the assessment and remediation of a housing estate in Leftwich, England (35 km southwest of Manchester).
The girls lived in houses backing onto each other. The estate was built in 1994 on 4 m of primarily inert landfill such as clay, sand, gravel, building rubble plus small amounts of vegetation, metal fragments, paint tins and other detritus.
The Health Protection Agency conducted an assessment of whether the deaths were related, noting that the cause might be viral or environmental.
The local authority (or council) performed ground investigations. While the cause of the deaths could not be linked to any one factor, traces of benzene and highly elevated methane and carbon dioxide levels were found in one garden area and at lower levels around the rest of the estate.
Muir Group (the estate’s housing association or ‘social landlord’) engaged ERM to design and supervise extensive remediation. This involved installing new gas-resistant membranes beneath the floors of all 24 houses, replacing all fill in six gardens with clean fill, providing sub-structural vents and verifying all works.
Benefits and Value
The project (which involved close liaison with residents, council staff and consultants) was successful. The Part 2A Environmental Protection Act contaminated land designation was discharged; the project won the 2007 Brownfield Briefing Innovation Award for Verification Works and resident confidence in the estate was restored.