Pioneer conducted environmental site assessment services for the redevelopment of a former printing facility for the purpose of obtaining closure from the state regulatory agency. Petroleum-stained soils were identified in the vicinity of two on-site abandoned-in-place USTs that formerly contained heating oil. Total Petroleum Hydrocarbons (TPH) were identified at levels above soil attenuation capacity. Thus, remediation was necessary to reduce the concentrations of TPH in order to obtain closure. Because the area of impacted soil was located underneath the building and adjacent to the building foundation, the abandoned USTs could not be removed to allow access to the soils. Based upon Pioneer’s recommendation, the property owner elected to conduct in-situ chemical oxidation with enhanced biodegradation using the BIOX® Process.
The treatment zone consisted of an irregularly shaped area of approximately 2,856 square feet and extended to 12 feet below surface grade (BSG). The area was treated by injecting 4,760 gallons of treatment solution into 180 injection points over 9 days. Although the remedial design specified 90 days following injection to achieve the remediation goals, and at the request of the client, confirmation samples were collected in three sampling rounds at approximate one-month intervals after completion of the treatment.
Although the 30-day results indicated progress, the property owner discussed the possibility of an additional injection to expedite the in-situ remediation process. Pioneer recommended that the client wait the remaining 60 days to allow the process to reach its full design potential. By the end of the three-month monitoring period, no identified TPH concentrations remained at levels above the default soil attenuation capacity. By recommending against an unnecessary supplemental injection, the property owner was spared unnecessary costs. The facility has been redeveloped as a USPS facility, and a No Further Remediation letter has been obtained for the site.
Summary of TPH Reductions (mg/kg)