In situ chemical oxidation (ISCO) is being used to remediate petroleum-related contaminants at a former gasoline station in Delaware County, New York. Underground storage tanks and contaminated soils reportedly were removed in the 1970s; however, ground-water impacts in the sandy aquifer remain. RegenOx(r) is a product manufactured by Regenesis for chemical oxidation of a range of contaminants, including petroleum compounds. The product rapidly desorbs contaminants from the soil into the ground water where the compound facilitates oxidation of the contaminant. A pilot study was performed to evaluate the effectiveness of chemical oxidation at the former gasoline station. The pilot treatment area was approximately 30 feet by 30 feet with a contaminated zone 4 ft thick at a depth of 25 ft below ground surface. The total petroleum volatile organic compound (VOC) concentration at well MW-5 in the center of the pilot study area was 14,490 ug/L in April 2007. A total of 1,500 pounds of RegenOx(r) was injected during two events between October 15 and November 12, 2007, using a direct-push drill rig around the monitoring well. The total petroleum VOC concentration was reduced to 7,730 ug/L at MW-5 based on ground-water samples collected on December 12, 2007, a decrease of 38%. Naphthalene, n-propylbenzene, isopropylbenzene, and o-xylene decreased to less than detectable concentrations in the injection area. The radius of influence from the injection in the vicinity of MW-5 appears to extend a distance of at least 30 feet, as evidenced by the decrease in concentrations to non-detectable levels 25 feet away and reductions in VOCs 50 feet away. The potential indirect effects of injection due to changes in the chemical equilibrium may extend beyond 30 feet. The results of the pilot study confirm that RegenOx(r) likely can be used successfully to reduce petroleum hydrocarbons in the ground water at this site. Full-scale remediation has been scheduled to reduce the concentrations in ground water to acceptable levels and achieve site closure.
Authors:Hulseapple, S.M., 2008
Subsurface Remediation Symposium, April 29, 2008; Central New York Association of Professional Geologists