TPH Envirotreat was engaged by Thomas Vale to undertake source and groundwater remediation at the ERA site for the manufacture of locks and ironmongery.
The site was being developed by Midland Heart for a residential development comprising of 33 houses.
The main contamination sources were identified in the central area of the site, beneath the floor slab of the former building.
The prime contaminants of concern were total petroleum hydrocarbons [TPH]. The nature of the contamination was consistent with historical activities on site. Lubricating oils would have been widely utilised in the manufacture of locks and associated ironmongery products.
Three distinct TPH contamination areas were identified. These areas coincided with the historical location of machine sumps, oil storage areas, drainage runs. The source areas were delineated based on a TPH remediation target criteria.
The source contamination extended to depths in excess of 3.5m bgl . Significant TPH concentrations were recorded within these areas (greater than 30,000 mg/kg).
The site investigation identified the presence of chlorinated hydrocarbon contamination (TCE) within the groundwater. These would have originated from the usage of degreasing agents (typically chlorinated hydrocarbons). These chlorinated hydrocarbons were shown to be impacting the groundwater.
A remediation strategy of in-situ / ex-situ E-Clay (to address TPH) and StabOx (to address TCE) stabilisation was used to address the source contamination. A StabOx permeable reactive barrier was installed to intercept and treat the contaminated groundwater leaving site.