Pioneer conducted environmental assessment activities at an operating dry cleaning facility, and identified high levels of tetrachloroethene (PCE) and certain associated breakdown products on portions of the site. The purpose of the required remedial actions was to reduce concentrations of certain volatile organic compounds (VOCs) and achieve a site-specific Tier 3 Soil Remediation Objective (SRO) of 4.1 mg/kg that is protective of surface water in an adjacent stream. After considering several remediation options, Pioneer determined that in-situ chemical oxidation with enhanced biodegradation (a process known as BIOX®) was the most cost-effective approach to remediation.
The treatment zone consisted of an irregularly shaped volumetric area comprising approximately 1,720 cubic yards (CY). The area was treated by injecting 4,749 gallons of BIOX® fluids into 361 injection points over a period of 21 days. Pioneer conducted confirmation sampling at three and nine months following completion of injections. The results obtained in three different areas of the project site indicated a 90% reduction in PCE concentration in Area 1, a 99% reduction in PCE concentration in Area 2 and a 33% reduction in PCE concentration in Area 3. The total volume of impacted soils was reduced by approximately 66%. A second injection event has been scheduled to be completed by Pioneer in the summer of 2014. Based on the results of the first injection, Pioneer anticipates achieving the remediation goals and obtaining site closure from the state regulatory agency approximately 6 to 9 months following injection.
PCE Concentrations in mg/kg