Industrial Facility Voluntary Program
In 2015, Tioga installed four monitoring wells as part of a Supplemental Phase II Environmental Site Assessment. The monitoring wells were sampled and the results presented. Tioga recommended that the site be entered into the TDEC voluntary program. In 2019, Tioga was requested to provide remediation services for the property.
During the interim years, a different consultant entered the property into the TDEC voluntary program and performed a concurrent sub-slab vapor and indoor ambient air assessment. Results from the assessment identified a risk at the facility. It was the recommendation of the consultant that an active sub-slab vapor mitigation system be installed. Based on the recommendation, Tioga was asked to review the data for the Property and determine if active vapor mitigation was the best course of action.
After review of the previous reports, Tioga suggested that removal of the soil source of the contamination would mitigate the risk from vapor intrusion without the need to install, monitor, and maintain an active mitigation system. All data from previous assessments suggested that the source of vapor contamination was a sump located within a former maintenance shop. In April 2019, Tioga supervised the excavation of the sump and approximately 90 tons of contaminated soil from inside the maintenance shop.
After excavation, Tioga performed two sub-slab vapor assessments and identified a substantial decrease in the concentration of constituents of concern. It was the opinion of Tioga that the remediation via excavation was successful and the remaining concentrations would naturally attenuate. TDEC agreed with Tioga’s conclusions and a Brownfield Voluntary Agreement was drafted. Tioga will monitor the natural attenuation of the sub-slab vapor concentrations in quarterly monitoring events for at least two years.