ESI Consulting Ltd

Contaminated land site investigation in Bristol


Courtesy of ESI Consulting Ltd

Client: Property Developer

Location: Bristol, UK

Services: Contaminated Land Risk Assessment, Human Health Risk Assessment, Controlled Waters and Ecological Risk Assessment.

Summary: ESI’s contaminated land assessment ensured that this former brickworks site was not registered as contaminated land under Part 2A of the Environmental Protection Act (1990)

ESI was commissioned to undertake a site investigation on disused land intended for redevelopment for commercial use following demolition of the existing buildings.  The purpose of the investigation was to acquire sufficient geo-environmental information to support a planning application for the redevelopment.

Investigations were conducted during January 2008 and involved the borehole drilling, in situ geotechnical testing, collection and analysis of soil and groundwater samples; and installation of temporary piezometers for soil gas and groundwater monitoring.

The site investigation proved that Made Ground was present across the entire site and was underlain by weathered mudstone bedrock of the Mercia Mudstone Group.

Laboratory analysis of soil samples found that metals (in particular lead, arsenic and chromium) were elevated in Made Ground compared to the Mercia Mudstone with the maximum observed concentrations tending to occur in shallow Made Ground. Petroleum hydrocarbons were widespread across the site in both Made Ground and the Mercia Mudstone.

In groundwater, metals were detected at low to moderate concentrations across the Site, with some localised areas of elevated arsenic, nickel, selenium, copper and boron.

A human health risk assessment demonstrated that only lead presented a potential risk to human health under the planned future commercial use of the site.

A controlled waters risk assessment considered a groundwater pathway from the Site to a stream and a minor aquifer to the south of the Site. Through the application of the Environment Agency’s Remedial Targets Methodology it was shown that once the effects of dilution along the groundwater pathway had been incorporated, there would be no unacceptable impact to the identified receptors.

The options to address potential human health risks from the lead contamination were highlighted as either undertaking a more detailed site specific risk assessment (in consultation with the Local Authority) or taking remedial action as part of the redevelopment of the site. Options for remediation were detailed, and included the removal of the sources of contamination or breaking the pollutant linkage with the latter deemed to offer a more proportionate and cost effective solution.

ESI is recognised as a UK centre of excellence for contaminated land assessment and remediation, and is contracted by both public and private organisations to carry out similar work.

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