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SETTING A GOAL FOR TPH THAT ELIMINATES FREE PRODUCT IN WELLS
Citation:
WILSON, J. T., M. OKELLEY, AND T. LAINS. SETTING A GOAL FOR TPH THAT ELIMINATES FREE PRODUCT IN WELLS. Presented at 17th Annual UST/LUST National Conference, Seattle, WA, March 14 - 16, 2005.
Impact/Purpose:
To inform the public.
Description:
The U.S. EPA expects that remedial action at UST sites will reduce free product in monitoring wells to the maximum extent practicable. How much active treatment is necessary to ensure that free product will not accumulate in a monitoring well? The concentration of TPH that will produce free product can vary widely, depending on the texture of the geological materials, the properties of the fuel that is spilled, and the location of the spill with respect to the water table. This variation from site to site makes it difficult to set a single clean up goal for the concentration of residual gasoline (TPH mg/kg). However, to negotiate a pay-for-performance contract, a cleanup goal is necessary. The technical staff of the Petroleum Storage Tank Division of the Oklahoma Corporation Commission, in collaboration with U.S. EPA scientists, has developed an alternative approach to set a site-specific cleanup goal for TPH. Basically, we let the site tell us how much cleanup is necessary. Core samples are collected and analyzed for TPH when monitoring wells are installed. We compare the concentrations of TPH in the core samples to the presence or absence of free product in the well. The highest concentration of TPH that did not allow accumulation of free product is taken to be the site-specific cleanup goal for the site.