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' Jerry Lile <br /> t December 10, 2003 <br /> Page 6 <br /> a. For non-carcinogenic effects, the following hierarchy of sources is to be used for <br /> ' selecting toxicity criteria. CaIEPA values (Air Toxics Hot Spots Program, Risk <br /> Assessment Guidelines, Part III, Technical Support Document for the Determination of <br /> Noncancer Chronic Reference Exposure Levels (RELs)(CaIEPA, February 2000) <br /> t are to be used preferentially followed by U.S. EPA's IRIS, U.S. EPA's National Center <br /> for Environmental Assessment (NCEA) (liftp://www.epa.gov/nceawwwl/), and U.S. <br /> EPA's HEAST. <br /> b. The scientific data sources from which the toxicity criteria were obtained need to be <br /> included for each chemical. <br /> ' -• c.-Justification is-needed for the use of each surrogate toxicity criterion employed. <br /> 5. Calculations: Some calculations are not reproducible,for example the Soil/Air Partition <br /> ' Coefficient (Kas) in Table A-8. <br /> 6. The analytical data for naphthalene and phenanthrene in grab groundwater were not <br /> ' included in and carried through the screening risk evaluation. <br /> 7. Metals were not included in the screening risk evaluation. No metals data were <br /> collected from the petroleum impacted soil or groundwater. <br /> SPECIFIC COMMENTS— Ecological Screening Risk Evaluation: <br /> ' The Surland Homes area is a residential development, thus poor wildlife habitat. As <br /> such, ecological receptors are not expected to come in contact with the underlying area <br /> impacted by petroleum products. Nevertheless, the human health screening risk <br /> t evaluation cannot be extrapolated to ecological receptors; ecological receptors are not <br /> limited to mammals, dose on a body weight basis is dependant on exposure <br /> assumptions, and toxicity criteria are available for non-mammalian species. A Scoping <br /> Assessment consistent with DTSC Guidance (1996) is expected; in essence this <br /> ' consists of documenting whether any complete exposure pathways exist for ecological <br /> receptors. If no complete exposure pathways exist for ecological receptors, the <br /> ecological risk evaluation is concluded. If complete exposure pathways do exist for <br /> ' ecological receptors, the next step in DTSC's tiered approach to ecological risk <br /> evaluation is a Phase I Predictive Ecological Risk Assessment. <br /> tCONCLUSIONS <br /> HERD evaluated the August 2002, `Health Risk Screening Evaluation, Surland Homes <br /> Property, Tracy, California" and the August 1998 `Soil and Groundwater Investigation <br /> ' and Site Status Report, Surland Homes Property, Tracy, California." The scope of our <br /> review was limited to assessment of releases from the OVP and APL. Potential risks <br />