SITE INFORMATION AND CORRESPONDENCE

Home Browse Search

' Chevron/UPRR - 3 - 16 January 2007 Review - TAOC Tracy Pump Dion HHRA • Ecological Risk Assessment, Item #12 Pape 10 According to the HHRA regarding risk to ecosystems...it is expected that human health concerns will override ecological concern...and... consideration of potential effects to ecological receptors was not performed... Free product has not been observed on or near the surface and evaluation of the human health concerns addressed in the HHRA provides information to adequately address the potential risk to non-human receptors. Summary/Conclusions, page 10 The OEHHA report concluded: " The performed recalculation demonstrated that no significant risk/hazard is expected to occur due to the PAH soil contamination down to 10 ft bgs. Soil contamination below 10 ft bgs and groundwater contamination were not addressed in this risk assessment." GENERAL CONCLUSIONS Regional Water Board staff concurs that OEHHA's determination following its review of the HHRA has demonstrated that no significant risk/hazard is expected to occur due to PAH soil contamination to 10 feet below grade. Based on OEHHA comments to the HHRA and the discussion outlined above, Regional Water Board staff has the following comments: • Chevron/UPRR's consultant should collect soil-gas samples or use the NAPL version of the US EPA Johnson and Ettinger model-based spreadsheet to estimate the concentrations of TPH vapors potentially originating from groundwater as a pathway for inhalation by commercial/industrial and/or construction workers. • The removal of crude oil-affected soil piles may reduce/eliminate potential health risk concerns at those locations. • A well survey should be conducted to obtain information of groundwater production wells used for municipal, domestic, agricultural, industrial, and/or other uses on or within 2,000-feet of the property.