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F. Amador <br /> March 1, 1993 <br /> Page 6 <br /> Since riparian habitat is located in such close proximity to <br /> the site, it is important that a DTSC geologist verify the <br /> assertion that local groundwater is not hydraulically <br /> connected to Mormon Slough, and that surface water runoff <br /> will not flow to the slough. The potential for future <br /> migration or transport, for example as a result of a rising <br /> water table, should also be evaluated by a DTSC geologist. <br /> Appendix J, Toxicological Profiles <br /> Although no references are cited, the narrative toxicity <br /> information listed in four tables appears adequate and accurate, <br /> and the chemical listings in the tables are well-organized and <br /> easy to follow. Inclusion of RfD and CSF values for the <br /> chemicals in these tables would be beneficial . <br /> Appendix K, Human Health Risk Assessment Methodology <br /> Equations from USEPA ( 1989) are cited, although this <br /> reference is not listed in the Appendix K Bibliography. The <br /> equations shown are correct. <br /> Appendix L, Risk Calculations <br /> Footnote "c" in Table L-2 states that the highest <br /> concentration in air from Tables K-1 through K-3 was used to <br /> estimate risk from inhalation of organic vapors. However, Table <br /> K-3 notes a calculated air concentration for benzene of 3 . 97 E-5 <br /> ug/L, which is greater than the air concentration used in Table <br /> L-2 . Also, there appears to be an error in conversion of <br /> concentration in air in ug/L to ug/m3, resulting in a six order <br /> of magnitude error in the estimated excess lifetime cancer risk. <br /> Other calculations spot-checked appear to be correct. <br /> CONCLUSIONS <br /> Based on our review of the submitted document a)id the scope <br /> defined in Page 1 of this memorandum, the human health and <br /> environmental risk assessments for this site are not adequate. <br /> Major deficiencies of the analysis include exclusion of <br /> chemicals, potential receptors, and exposure pathways without <br /> acceptable justification. Further, risks for the Hazelton Avenue <br /> Strip were not characterized. We will evaluate the revised <br /> document when these deficiencies are corrected. <br />