Old Station and Tar Works Contamination Assessment

A multi-phase contamination investigation was undertaken by Ruddlesden geotechnical ltd, as part of a proposed residential redevelopment of a former Railway Station and Bitumen Emulsion Works. The investigation comprised a combination of trial pits, windowless sample boreholes with gas and groundwater monitoring installations, multi-system comacchio boreholes and cable percussive boreholes. Extensive soil and groundwater contamination laboratory testing was also carried out.

Both soil and groundwater were shown to be heavily contaminated with residual and free-phase hydrocarbons, as a result of the site's previous usage. Much of the recorded contamination was attributed to previous on site storage and leakage of diesel fuel. In addition, a former below ground bitumen/ tar emulsion pit was uncovered, filled with considerable quantities of free-phase tar and barrels of unidentified aqueous contaminants. Elevated levels of methane were also recorded during ongoing ground gas monitoring (~80% volume).

A detailed Contamination Investigation & Environmental Assessment Report was produced, comprising a detailed quantitative risk assessment (DQRA) for human health and controlled waters. The hydrogeological risk assessment was undertaken using the Environment Agency's Remedial Target's Methodology, which identified considerable free-phase hydrocarbon product within groundwater beneath the site. Working closely with a specialist contamination remediation contractor, a programme of contamination remediation was devised, comprising a combination of 'hot-spot' removal, in-situ and ex-situ treatment of contaminated soil and 'pump and treat' of contaminated groundwater.

Ruddlesden geotechnical also supervised and validated the subsequent remediation works.

 

 

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Old Station and Tar Works Contamination Assessment image

Old Station and Tar Works Contamination Assessment image