Treatment of chlorinated solvents at a complex site with sensitive receptors
Chlorinated solvents were used for a number of years at a former manufacturing facility in Italy. This has resulted in contamination of the groundwater underlying a large proportion of this 6ha site. Groundwater concentrations of up to 155,000 μg/L TCE presented an unacceptable risk to both on- and off-site receptors and it was determined that active remediation was required. A remediation approach was designed based on targeted excavation of highly impacted soils, plume treatment through Enhanced Reductive Dechlorination (ERD) and the installation of a down-gradient treatment zone to prevent further contamination of the river beyond the site boundary.
ERD of the chlorinated solvents was achieved through a grid of direct push injections, introducing a suite of REGENESIS products into the subsurface. The site was first divided into different areas based on the distribution of contamination and differing permeabilities. A tailored product mix and dosage was then created for each area. Our wide-distribution substrate (3DMe) was used in the up-gradient zones on a widely spaced injection grid, to minimise injection cost, while providing optimum treatment of the contamination. The down- gradient treatment zone required application very close to the river at the site boundary. A mixture of low volume, high viscosity (HRC) products were used here to prevent contaminant egress from the site for up to five years from a single injection while remediation of the source area is completed upgradient.
- Over 500 direct injection points were used to apply a range of substrates across 10,000 m2 of the site;
- The on-site activities were successfully completed in only 6 months. Remediation will occur over several years, with no further site attendance or operational costs beyond validation sampling;
- Remediation is intended to reach stringent clean-up targets at both the site boundary and within the property were required by the regulator;
- The wide range of REGENESIS injectable substrates allowed for a tailored design solution. Product mix and dosages were designed for each part of the site, providing the most accurate and cost effective solution.