Project:
Former Service Station
Bottom Line: Implementing multiple remediation technologies cost-effectively to achieve soil and groundwater treatment goals.
Summary of Project
The site formerly contained an automobile service station. Four 12,000-gallon gasoline and diesel USTs and two fuel dispenser islands were removed. Numerous historical releases resulted in free-phase product beneath the site and dissolved-phase hydrocarbons migrating across a highway and beneath a public park almost 1,000 feet downgradient. The depth to groundwater was approximately 35 feet below grade. Multiple remedial technologies were designed, installed, and operated to treat hydrocarbons present in varying hydrogeologic conditions.
- Conducted numerous soil and groundwater investigations to evaluate the lateral and vertical extent of onsite and offsite sorbed- and dissolved-phase petroleum hydrocarbon and oxygenate impacts.
- Drilled, installed, and sampled 19 groundwater monitoring wells and 3 piezometers to monitor onsite and offsite gasoline-impacted groundwater.
- Conducted source removal activities including soil excavation and free product removal. Designed, implemented, and completed a free product removal program to the satisfaction of the RWQCB.
- Evaluated cost and performance for several in situ groundwater treatment technologies to contain and remediate the onsite and offsite impacts. Prepared remedial action plans approved by the RWQCB.
- Conducted multiple pilot tests to evaluate technologies to treat impacted soil and groundwater including SVE, DPE, oxygen release compound, and oxygen injection.
- Designed, installed, and operated a full-scale SVE system. Treated soil vapor with an 200-scfm combustion unit operated under an SCAQMD permit. Operated the SVE system until vadose zone soil was remediated to RWQCB approval.
- Designed, installed, and operated a combined full-scale DPE and pump-and-treat system including 36 DPE wells and 1 groundwater extraction well. Treated 15,000 gpd of purged groundwater using a bioreactor and discharged to the storm drain under an NPDES permit. Operated the DPE and pump-and-treat systems until source area hydrocarbon mass was effectively removed.
- Designed, installed, and operated an oxygen injection system including 7 single-casing and 27 dual-casing injection wells. Operated the oxygen injection system to enhance aerobic degradation of residual concentrations of petroleum hydrocarbons and oxygenates in groundwater.
- Performing phased equipment decommissioning and well abandonment, including the decommissioning of the SVE, DPE, and groundwater pump-and-treat systems and the abandonment of 7 SVE and 29 DPE wells.
- Negotiated with the RWQCB to have the site reclassified from priority class B1 to priority class D resulting in reduced monitoring and reporting requirements.