Fate and Transport Analysis to Achieve Regulatory Closure at a Chemical Processing Plant

Fate and Transport Analysis to Achieve Regulatory Closure at a Chemical Processing Plant

Project Highlights:
  • Operated a large soil vapor extraction system (SVE) for the remediation of chlorinated solvents above a regional groundwater aquifer
  • Provided technical evaluation of contaminant fate and transport, demonstrating client was not responsible for negative impact to water production well
  • Successfully isolated client’s exposure from those shown as potentially responsible parties (PRPs) by a water district
  • Provided a stepwise closure process, whereby soil closure was achieved, followed by groundwater closure; closure process freed millions of dollars set aside in reserve
  • Negotiated closure with the California Regional Water Quality Control Board (RWQCB)

EEC Environmental (EEC) was retained by a chemical processing plant to complete a fate and transport analysis in order to achieve regulatory closure. Environmental site investigations indicated the presence of solvents and solvent degradation products in the soil and groundwater beneath and downgradient of the site. A groundwater production well located nearly 3 miles downgradient of the Subject Property was found to contain elevated concentrations of tetrachloroethene (PCE), one of the constituents concern (COCs) emanating from the site.

As a result of the detection of PCE in the drinking water production well, EEC was retained to define the extent of the dissolved contaminant plume at the client’s property, remediate that plume, and determine if the client was a contributor to the degradation of groundwater in the drinking water well.  EEC successfully utilized a variety of methods including the evaluation of parent/daughter product ratios, contaminant fingerprinting, and contaminant transport modeling to demonstrate that the client was not a contributor to the contamination in the well.

This demonstration relieved the client of any liability associated with the groundwater issue and resulted in the closure of the client’s groundwater issues. EEC later obtained closure of the site soil issue; to gain complete site closure. Closure of the site resulted in the release of millions of dollars of reserves set aside by the client for environmental issues.

In addition to the groundwater concerns, and prior to obtaining groundwater closure, a soil vapor extraction system was installed consisting of 40 SVE wells to remove volatile organic compounds (VOCs) in the soil at the site. EEC was retained to provide professional consulting services associated with the operation of the SVE system and, upon retention by the client, evaluated the system and upgraded the system’s motors, blowers, and heat exchangers. Additionally, the enhancement included installation of four 2,000-pound vapor phase carbon vessels.

EEC performed weekly operation and maintenance to optimize and enhance remedial progress, pursuant to the system’s Air Quality Management District (AQMD) permit. Quarterly progress reports were prepared and submitted to the RWQCB describing the system operation, flow rates, vacuums, and mass removal rates. EEC also performed quarterly groundwater monitoring and sampling services of on-site and off-site wells, and prepared quarterly groundwater monitoring reports detailing groundwater flow direction, gradient, and VOC concentrations detected from the groundwater samples collected. Based on successful soil remediation and fate and transport modeling, EEC submitted a closure request to the RWQCB and was granted a “No Further Action” letter in April 2005.

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