Case Study - High Volume Groundwater Treatment
Background
During gardening works a plant support stake was driven into the ground and through a buried heating oil line. The estate manager first noted an odour of kerosene two days later and identified kerosene in a series of ponds at the property. It is estimated that up to 3,500 litres of kerosene was lost into the ground as a result of the damaged oil line.
The property is Grade II listed and the tiered spring fed ponds are designated as a scheduled monument.
Initial spill response works were undertaken by another contractor and OEE were instructed to continue works on behalf of the owners insurer.
LNAPL Recovery
Additional spill containment measures were deployed by Oracle into the ponds to prevent further migration into the nearby river.
An interception trench excavated by the estate maintenance team was extended and groundwater recovery sumps installed to target shallow perched water.
A groundwater recovery and treatment system was installed to prevent further migration of kerosene into the ponds.
Remediation
A source excavation was completed at the point of loss and the groundwater treatment system was successful in preventing any further migration of kerosene contamination into the ponds on site and also the remediation of the shallow perched groundwater. The treatment system processed a total of 985 cubmic metres of kerosene contaminated groundwater at the site.
The excavation works removed 39 tonnes of kerosene contaminated soils from the site, which were treated at a soil treatment facility, and verification sampling confirmed the hydrocarbon concentration within the affected ponds had been reduced to <0.01 mg/l following the initial identification of free phase kerosene.