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Shawna Chambers <br /> May 29, 2003 <br /> Page 2 <br /> Joaquin County(May 8, 2003) for our evaluation of this site. This document was prepared by URS <br /> Corporation on behalf of DTSC,and the Lodi Unified School District. <br /> Comments <br /> 1) Please note that the outdoor air pathway for VOCs, the indoor air pathway for non-VOCs, and <br /> dermal contact and ingestion of subsurface VOCs are not generally required for PEA type risk <br /> assessments.They can either remain or be removed from the current PEA, <br /> 2) The factors used to calculate the particulate emission factor (PEF) need to be justified or the <br /> default factors should be used_ This risk assessment used a Q/C value of 62, wind speed of 2.86 <br /> msec, and a wind speed distribution function factor(F(x)) of 3.19E-04. This resulted in a FEF <br /> of 2,41E+12, which is three orders of magnitude greater than the default value based on a <br /> hypothetical site in Fresno. This value results in an exposure concentration that is three orders of <br /> magnitude less than that obtained from using the default value, <br /> 3) DTSC's modified version of the Johnson & Ettinger screening soil gas model should be used <br /> mead of the USEPA version of the advanced soil gas model that was used in the FF-A. An <br /> electronic version of this model was provided via e-mail recently. The entries made on the <br /> Datenter worksheet should be either default values or defensible site-specific values. <br /> 4) The results from the total petroleum hydrocarbon analysis need to be incorporated into the PEA <br /> risk assessment. This Can be done using methodology developed by the Total Petroleum <br /> Hydrocarbon Criteria Working Group (TPHCWG) or the Massachusetts Department of <br /> Environmental Protection (MADEP). Guidance from other regulatory bodies may also be <br /> acceptable but HfiRD should be contacted prior to using. <br /> Conclusions and Recommendations <br /> The results of HERD's review of this PEA indicate the need for a limited number of revisions, The <br /> most significant of these is the need to change the model used for evaluating indoor air exposure, <br /> This Change has the potential to result in a substantial upward change in the risk estimate. <br /> Please call (916) 255-6628 or e-mail me (Tboo� dtsc.ra.gov) if you have questions regarding <br /> HERD's recommendations. <br /> f <br /> Reviewed by: Deborah Oudiz, Ph.D, <br /> Senior Toxicologist,HERD <br /> cc: Javier Hinojosa, Senior <br /> Schools Unit <br /> Department of Toxic Substances Control,Region 3 <br /> 1011 North Grandview Avenue <br /> Glendale, California 91202 <br /> ZO'd 6T:Zi 20OZ 6E huW ZS99-SSG'-9T6:XPJ ASId 1093 8 NUwnH OSiG <br />