TV/Grant LUST Investigation and Remediation
EEC removed an underground storage tank system and performed the required assessment of soils beneath the system components at Tanque Verde Automotive in Tucson. One 12,000 gallon gasoline UST, two 10,000 gallon gasoline USTs, one 8,000 gallon diesel UST, and eight product dispensers and associated product lines were removed and a UST Closure Report was prepared and submitted to the ADEQ.
Laboratory analyses of the soil samples collected during the UST removals confirmed that there had been a release of gasoline product from the USTs. EEC subsequently performed a Leaking Underground Storage Tank (LUST) site characterization and defined the extent of impacted soils as approximately 175 feet in depth. The Site Characterization report was submitted to and approved by the ADEQ.
EEC then designed, permitted, and installed a soil vapor extraction system at the facility. The system uses a 250 cfm catalytic oxidation unit to remediate the soils of the site. Early in the remediation process, EEC employed a propane fueled soil vapor extraction system due to high contaminant concentrations in the subsurface soils. Once contaminant concentrations had been sufficiently reduced, EEC replaced the propane fire unit with an electrically fired unit to reduce energy costs.
Active remediation with the electrically fired unit is ongoing, with EEC monitoring the system and progress of soil remediation. Analytical analysis of monthly influent airstream samples into the system indicate contaminant concentrations in the subsurface soils are nearing levels that may allow LUST case closure. Confirmation soil sampling for case closure is anticipated in early to mid 2014.
Discovery of gasoline impacted soils at the time of UST removal meant additional regulatory requirements needed to be addressed and the project required completion in multiple phases. EEC mapped out the logical progression of phases and presented them to both the client and the regulatory agency and guided the project towards successful completion.
The ability to design and utilize different remediation units during different phases of the soil remediation process has reduced total remediation time while keeping energy consumption costs to a minimum. In another cost saving measure, EEC completed an exploratory soil boring drilled for soil assessment purposes as a vapor extraction well for use in the remediation phase of the project. This reduced project time and cost to the client.