Monitoring of Injection of Hydrogen Release Compounds in a Contaminated Site

We present the set-up and results of a pilot-scale field test concerning the remediation of a site polluted by chlorinated solvents. The hydogeological setting is mainly compound by a first aquifer in silty and sandy material and a second fissured aquifer made of fractured grey marl and gypsum/sulphur formations. A preliminary characterisation of the area have pointed out the groundwater contamination by chlorinated solvents, at a depth of about 15–20 m b.g.l. Vinyl chloride was identified as the secondary pollutant, proving the occurrence of natural degradation phenomena. Hydrogen Release Compound (HRC-X, Regenesis) was selected to support the on-site biological activity. In a selected test site, we injected about 250 kg of reagent in three injection points at the depth of about 15–18 m.

The chemical and physical monitoring of the clean up activity was performed for about 6 month after the injection by groundwater sampling in the three observation boreholes (downstream with respect the injection points) and by time lapse cross-hole resistivity tomography.

The enhancement of natural attenuation phenomena is testified by the decrease of halogenated pollutants with higher number of chlorines, and by an enhancement of the amount of the reductive dechlorination secondary products.