City of Santa Rosa Garage 9 UST Investigation & Remediation
Santa Rosa, CA

EBA was contracted by the City of Santa Rosa to perform an in-situ remediation of the petroleum hydrocarbon impacts associated with leaking underground storage tanks formerly located within the Garage 9 parking structure.

EBA oversaw the installation of three dual phase extraction (DPE) wells followed by the performance of a 5-day DPE pilot test. Based on the successful removal of contaminant mass during the pilot test, EBA prepared a Remedial Action Plan (RAP) proposing an additional 30-day DPE event which was approved by the North Coast Regional Water Quality Control Board (NCRWQCB) and subsequently performed by EBA.

Additionally, EBA oversaw the installation of monitoring well MW-7 to define the lateral extent of the contaminant plume. Following the 30-day DPE event EBA performed routine post-remedial groundwater monitoring as well as performance of a soil vapor survey to evaluate the soil vapor to indoor air pathway.

Post-remedial monitoring results have shown a significant decline in contaminant concentrations.  In September 2024, EBA prepared a technical report which included a recommendation for case closure with no further action required. The NCRWQCB concurred with case closure which is anticipated to occur during the 2025/2026 fiscal year following completion of requisite site closure activities.