RemedX were tasked with undertaking a pilot test within a residential area located in Rennes, France. The site was previously used as a petrol service station that experienced a loss of 13,000 – 15,000L of gasoline into the surrounding soil and groundwater, over an area of circa 700m2
Site investigations indicated the existence of hydrocarbon impact in the groundwater, soil gas, and the presence of low mobility/residual NAPL in the bedrock fractures that could be released in the future. The bedrock fracturing on site also had the potential to create preferential pathways for groundwater, increasing the risk of off-site migration.
A pilot test was mobilised to understand the likely success of different in-situ remediation techniques and help inform the selection of the preferred remedial approach for the site. The tests conducted on site during the pilot test works were; a Hydraulic Conductivity test and Multi-phase extraction (MPE).
The test demonstrated the benefits of extended dewatering, with volatile organic compound recovery rates trending upwards over the course of the test. The data gathered from the pilot test provided valuable information on well spacing and equipment specification for potentialfull-scale works. Overall the tests confirmed that MPE was a feasible remedial option for the site and gave further clarity on full scale remediation costs.