Tel: 01539 620227 or 07825 510553

Treatment train remediation of hydrocarbon contaminated groundwater in Ireland

We were commissioned by Nova Consulting to assist them in the remediation of a plume of hydrocarbon impacted groundwater that had migrated from a nearby fuel station and impacted the local drinking water supply. The contaminated water was 5m below ground level in jointed limestone. Geoenvironmental’s initial task was to develop the remediation strategy and gain agreement from the local authority. The strategy included:

  • Free product recovery
  • Dissolved phase treatment by pump and treat
  • Residual contamination treatment by chemical oxidation
  • Sampling and analysis of groundwater to demonstrate that natural attenuation was occurring

A treatment train strategy was chosen as the initial removal of the free product and reduction of hydrocarbon concentrations in the dissolved phase meant that less chemicals would be required in the chemical oxidation phase. This was chosen as a more cost effective option than using chemical oxidation alone. The downside is that the remediation process can take longer and will not suit all sites.

We chose to use Peroxychem’s Klozur® CR as the chemical oxidant and this was activated with a strong alkaline, sodium hydroxide. The chemicals were combined as they were pumped into the boreholes. During the works groundwater analysis showed that there was considerable reduction in contaminant concentrations to the satisfaction of the client. The contour plots below show the reduction in benzene concentrations over the project and the residual benzene concentration will naturally attenuate over time.