Enhanced Reductive Dechlorination Used to Treat Former Dry Cleaner in South Carolina Coastal Plain

Project Highlights

  • Small groundwater recovery system in place to provide hydraulic control.
  • Enhanced Reductive Dechlorination (ERD) treatment selected to achieve site closure more quickly.
  • High PCE concentrations reduced by more than 100x within 6 months and remain
  • Follow-up treatments enhanced initial injection and contributed to continued dechlorination.

Project Summary

The site, located in the Coastal Plain of South Carolina, was impacted from former dry cleaning operations. A small groundwater recovery system had historically been used to provide hydraulic control, but the site owner wanted to move the site toward closure more quickly. Enhanced Reductive Dechlorination (ERD) with 3-D Microemulsion® was selected based on cost, ease-of-use and expected remediation performance. After the initial injection, PCE concentrations decreased by more than 100x within 6 months of application and remain below 5 ug/L two years after the initial injection.

Remediation Approach

The core of the plume was characterized by concentrations of 14-18 mg/L PCE at baseline plus the full suite of chlorinated ethene daughter products. An initial application of 3-D Microemulsion occurred in June 2011 over a 7,750-square-foot area in the surficial aquifer from 3-25 feet below ground surface. The injections were completed using direct-push equipment into temporary borings on 13-20 foot centers. Based on the success of the initial injection, a follow-up injection was completed in September 2013 over a much smaller footprint (2,200 square feet) to fill in treatment gaps near the upgradient edge of the initial treatment area and to supplement the 3-D Microemulsion in the core of the plume. The follow-up treatment has built on the initial treatment and is contributing to continued depletion of the chlorinated solvents.

Technology Description

3-D Microemulsion is an engineered electron donor material that offers a novel 3-stage electron donor release profile, pH neutral chemistry and is delivered on-site as a factory-emulsified product.