Project:
Service Station
Bottom Line: Using in situ bioremediation and coordinating remediation activities with station improvements to minimize disruption to business operations.
Summary of Project
The site contains an active automobile service station. Three fuel and one waste oil USTs were removed in the late 1980’s; three dispenser islands and associated piping were removed in the late 1990’s. TPHg and other gasoline constituents were detected in soil samples during the equipment removal. Groundwater is present at 5 to 10 feet below grade.
- Conducted a Phase II environmental investigation, which included drilling multiple soil borings and installing groundwater monitoring wells. Encountered impacted soil in a saturated zone 30 feet below grade and beneath a neighboring commercial building.
- Performed historical review of nearby properties and retained a fuel fingerprinting expert to allocate responsibility for downgradient impacts. Determined that hydrocarbons downgradient of the site did not originate from client’s operations and obtained concurrence from RWQCB.
- Conducted a bioventing pilot test to assess the applicability of the technology for remediating vadose zone soil. Collected site-specific data to establish design parameters for a full-scale system after pilot test results indicated that bioventing was a viable technology.
- Evaluated remedial options for groundwater including monitored natural attenuation and biostimulation. Performed a biostimulation pilot test to establish design parameters for full-scale remediation.
- Compared performance of oxygen diffusion versus oxygen injection equipment. Saved client 80 percent in equipment costs by deploying more cost-effective product while still achieving biostimulation goals.
- Installed a full-scale oxygen injection system. Expanded oxygen injection system and added a nutrient injection program to enhance aerobic biodegradation of petroleum hydrocarbons in groundwater.
- Teamed with a university and microbiological laboratory to assess the requirements for bioremediation of hydrocarbons and fuel oxygenates. Used molecular biological tools including quantitative polymerase chain reaction (qPCR) to monitor gene expression. The molecular results combined with traditional groundwater monitoring conclusively demonstrated that oxygen injection promoted BTEX and MTBE biodegradation.
- Coordinated with site owner to facilitate site improvement effort that included removing and replacing three double-walled USTs and three dispenser islands. Excavated 2,800 tons of unsaturated and saturated soil to accelerate groundwater remediation.