Previously unidentified underground storage tanks were uncovered at a former petrol filling station in West Sussex, that was due to be redeveloped by a major supermarket.
Detailed investigation encountered a plume of hydrocarbons up to 29mg/l were recorded in the groundwater. A local water body and the ground- water in the chalk aquifer were found to be at risk from the migrating plume.
Geo2 worked with an Environmental Consultant to undertake the remediation, which employed a detailed Site Investigation and Risk Assessment process to calculate suitable Remediation Targets.
The treatment programme involved:
- Injecting a solution containing a bacterial agent together with a catalysing Oxygen Release Compound into the contaminated areas of the site.
- A total of 41 injection points were treated, preventing the need to remove any soils.
- After the treatment, the site was left for the developers to start work, whilst the remediation continued in the subsurface.
A hydrocarbon concentration reduction of 97% was achieved. This was far higher than the client had experienced on previous projects (with other contractors) using similar techniques.
Avoided costly soil removal and disposal costs or costs and disruption associated with ex-situ treatment.