Residential Remediation

SCOPE OF WORK: Environmental consulting services, assessment, and remediation at a residence

Omni Environmental Group provided environmental consulting services under an insured loss to address a release of #2 fuel oil to the basement of a residence that resulted from an overfill and over-pressurization of a fuel oil tank. Our scope of services included identifying the extent of impact to soil and groundwater; preparing a suitable remedial action plan; providing daily oversight and direction of field activities; collection of characterization and confirmatory media samples for laboratory analysis; project management and project-related correspondence with the Rhode Island Department of Environmental Management (RIDEM); and regulatory closure in accordance with the states Remediation Regulations.

Through assessment activities, #2 fuel oil impacts were confirmed to include ~75% of the basement footprint, extending to the exterior beneath an attached deck and into the rear yard. Free phase #2 fuel oil was identified within open excavations within the basement and in a monitoring well in the rear yard. Our staff installed and maintained an oil recovery and groundwater dewatering system to remove free phase oil and impacted groundwater to mitigate the potential for further migration via groundwater.

Excavation activities were conducted within the basement using a soil vactor to remove petroleum contaminated soils (PCS) from beneath the floor slab. In order to maintain the structural integrity of the residence and allow for excavation beneath the foundation walls, we utilized a Structural Excavation Plan (SEP) including resistance piers and concrete underpins beneath affected portions of the foundation and crib towers, and beams supporting the wood framing of the residence.

Excavation and dewatering efforts removed a substantial portion of interior and exterior petroleum-contamination resulting from the release. However, residual impacts exceeding RIDEM standards remained in select locations of the Site, inaccessible from an excavation standpoint. These locations were selected for an in-situ remedial program.

Omni Environmental Group specified the installation of a vapor intrusion (VI) barrier and soil vapor extraction (SVE) system. Operation of the SVE system and VI barrier were utilized as interim mitigation measures. In order to reduce residual soil and groundwater impacts to levels below RIDEM standards, we designed and implemented a successful in-situ remedial program utilizing a combined approach of enhanced aerobic bioremediation and sodium percarbonate based alkaline oxidant.

The post remedial soil gas, soil, and groundwater sampling conducted by Omni Environmental Group supported Site closure under the RIDEM Remediation Regulations.