ORIN has completed work at a former gas station in western Nebraska utilizing in-situ chemical oxidation with vacuum extraction. A dual phase extraction system was previously in place, but was not sufficient in meeting the site clean-up goals. The contaminants of concern at this site were benzene, toluene, ethylbenzene, and xylene (BTEX). The treatment chemistry utilized on this project was catalyzed sodium persulfate combined with calcium peroxide. Delivery of this chemistry was performed using direct push technology (DPT) where geoprobe rods with expendable tips are driven to depth and then raised upward through the contaminated interval while simultaneously injecting the treatment chemistry. Thirteen DPT points were spaced around monitoring wells that had shown some of the highest concentrations of BTEX. A vacuum extraction truck was also on site to remove contaminated groundwater and maintain hydraulic control.
The thirteen injection points received a combined total of 1,125 gallons of treatment chemistry. Original concentrations of the BTEX compounds were 6.4, 21.1, 1.9, and 11.9ppm, respectively. Four weeks after injection activities were completed a sampling event occurred and total BTEX concentrations showed a 98% decrease. The site will be eligible for closure after one year of below standard sampling results.
This site was the second project in one week in Nebraska enabling ORIN to reduce mobilization charges for both clients. This shows how ORIN is able to efficiently complete two separate projects in a narrow period of time and yield successful results following sampling events.