May 7, 2009 — EnSafe Inc.’s novel combination of routinely standalone treatment technologies to sustainably remediate chlorinated solvents at a site in South Carolina recently was featured at Battelle’s Tenth In Situ and On-Site Bioremediation Symposium in Baltimore, Maryland. This sustainable remedy uses environmentally preferable products and requires minimal operations and maintenance.

David Warren, PG, manager of EnSafe’s Charleston, South Carolina, office, delivered the case study “A Pilot-Scale EZVI and ZVI Treatment of Unsaturated and Saturated Soil for TCE Reduction” on May 6, 2009.

EnSafe implemented two technologies to treat chlorinated volatile organic compounds (CVOCs) at a former manufacturing facility:

• Micro-scale zero-valent iron (ZVI), hydrocarbon substrates, and nutrients
• Emulsified oil zero-valent iron (EZVI) injections

Substrate and ZVI injections — until recently typically implemented as standalone technologies — were combined to achieve synergistic reductions of tetrachloroethene (PCE), trichloroethene (TCE), and their reaction products. Thirty-eight injections were made over two days in both unsaturated and saturated zones. The groundwater results from three shallow monitoring wells inside the injection area showed a 30% reduction in dissolved concentrations of PCE and TCE within a year and 80% within two years.

Daughter products such as cis-1,2-dichloroethene increased, indicating the enhancement of reductive dechlorination. Monitoring also shows reducing conditions persist in the injection area. Analytical results from unsaturated soil sampled after the injections showed all CVOC contaminants reduced below the South Carolina industrial soil cleanup standards.

The presentation on this sustainable treatment technology was developed by Warren and EnSafe Remediation Services Vice President Craig Wise, PE, of Memphis, Tennessee (EnSafe’s headquarters), along with Elizabeth Bishop and Michael Scalzi of Innovative Environmental Technology, Inc., of Pipersville, Pennsylvania. IET, an environmental contractor and technology vendor, provides a wide variety of remedial services.