Use of Risk-Based Standards for Cleanup of Petroleum Contaminated Soil

摘要

This study evaluated the TPH (total petroleum hydrocarbon) cleanup standard forpetroleum contaminated soils (PCS). Regulators from thirteen states were surveyed to characterize current standards used for PCS cleanup and regulatory viewpoints on the use of a TPH versus a BTEX (benzene, toluene, ethylbenzene, xylene) cleanup standard. BTEX was identified as the compound specific standard used most frequently by states for cleanup of PCS. The research found that the regulatory community considers BTEX the most mobile and toxic surrogates of petroleum. Regulators, however, expressed concern that the use of a compound specific standard, without an accompanying analysis for TPH, might result in residual soil contamination that may present risk. This study also evaluated the ratio of BTEX to TPH in soil against the ratio found in a pre-spilled product. Based on JP-4 contaminated soil data contained in the Air Force Installation Restoration Program Information Management System database, this study demonstrated that the ratio of BTEX to TPH is statistically less than the pre-spilled product ratio. The results indicate that the assumption used by the California Leaking Underground Storage Tank manual and Stokman and Dime's research, that the ratio of BTEX to TPH remains constant in soil over time, is not valid. A conclusion is made that the use of this assumption in deriving TPH levels, which are protective of groundwater and human health, may be overly conservative. Lastly, this research identifies potential cost savings that would result if a BTEX based standard, versus a TPH based standard, were required at all Air Force petroleum contaminated sites. This study shows that only 13% of sites requiring cleanup under a TPH standard would require cleanup under a BTEX based standard.