ACE responded to a release of #2 heating oil due to an overfill during delivery to a home owner oil tank. The spill resulted in oil being released to the ground surface of the yard, sprayed onto the side of the residence structure, patio, driveway and adjacent vehicle.
In addition to surficial clean-up activities, approximately 55 tons of impacted soil was excavated and removed.
Based on the continued presence of vapors in the home, indoor air sampling was conducted, a subsurface investigation was initiated and a vapor extraction system consisting of a one-horsepower (HP) blower was installed to remove vapors from the residence.
Further MDE directives resulted in a work plan to conduct a microbe injection, post-injection soil sampling, and sump water sampling. The results indicated the following:
- Sump sampling activities indicate concentrations above residential MDE GNCS for TPH-DRO; however, TPH-DRO concentrations significantly declined between the two sampling events.
- The post injection soil sampling indicated that concentrations are basically below MDE GNCS concentrations with the exception of one soil sample had a concentration of 235 milligrams per kilogram (mg/kg) which is only slightly above the MDE GNCS for residential soil of 230 mg/kg.
- Air samples from the vapor extraction system indicate that concentrations of TPH-DRO have continued to decline and have not been detected since September 2015.
- Indoor air samples indicate one compound, naphthalene, exceeds applicable standards.
The vapor extraction system continues to operate.