• Emergency Response
  • Site Characterization
  • Vapor Extraction System Design and Operation

Christian County, MO

2008 to present

Site Description

A faulty flex connector released approximately 8,000 gallons of gasoline to the subsurface. The site complexities include complex faulted Karst geology.  The site is bounded by two parallel faults which are complicated further by the presence of traverse faults.  Free phase gasoline was present within bedrock fractures.

Site Characterization Summary

A total of 44 soil borings, 3 permanent unconsolidated wells, and 35 bedrock wells were installed by Sunbelt crews in efforts to delineate the soil and groundwater contamination. In addition, private water wells have been sampled in the area. A large plume of gasoline contamination was delineated. Free phase gasoline was present in voids and fractures in the subsurface at a depth of approximately 60 feet below grade.

Pressure transducers where installed in numerous monitoring wells to better understand the rapid fluctuations of the groundwater due to precipitation. Poly diffusion bags were utilized for groundwater sampling at some monitoring well locations in an effort to document variable mass flux within the fractured bedrock. A deep Ozark aquifer well was installed to determine the potential for the deeper aquifer to be impacted.

Vapor Extraction Operation Summary

A Vapor Extraction System (VES) was installed at the site, utilizing three existing monitoring wells. The VES was designed to remove free phase gasoline mass. The VES was operated for a period of approximately 2.5 years.  Over 8,000 pounds of petroleum hydrocarbons were removed by the VE system.
The removal of LNAPL mass resulted in a significant decrease in the contaminant concentrations and the plume dimensions.

Risk Assessment Summary

Risk assessment evaluations are being completed to determine necessary controls for prevention of future potential exposures.