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1 <br /> 1 <br /> Jerry Lile <br /> 1 December 10, 2003 <br /> Page 2 <br /> 1 northwest. Petroleum sheen has been reported in grab groundwater samples. <br /> DOCUMENTS REVIEWED <br /> 1 We reviewed the August 2002, Heafth Risk Screening Evaluation, Surland Homes <br /> Property, Tracy, California"and the August 1998 `Soil and Groundwater Investigation and <br /> Site Status Report, Surfand Homes Property, Tracy, California" prepared for Chevron by <br /> 1 Geomatrix Consultants, Inc. in Oakland, CA and San Francisco, CA, respectively. <br /> SCOPE OF REVIEW <br /> 1 The-document was reviewed for technical accuracy and validity of the human health <br /> screening-level risk evaluation for releases from the OVP onto the Surland Homes <br /> property. Site characterization data was reviewed to a limited extent, to determine <br /> 1 adequacy with respect to use in a screening-level human health risk appraisal. <br /> Sampling details, analytical methodology, and technical approach were evaluated. The <br /> screening-level human health risk appraisal was evaluated for consistency with DTSC <br /> 1 guidance and technical accuracy and validity. Neither the screening-level risk <br /> assessment, nor HERD's review, is reflective of the potential risks from any other <br /> potential or actual sources of release on the Surland Homes property. Furthermore, <br /> 1 releases from the OVP that have migrated off the Surland Homes property, particularly <br /> via groundwater, were not included in the scope of the risk appraisal or HERD's review <br /> of the document. <br /> 1 GENERAL COMMENTS <br /> 1. HERD disagrees with the conclusion that no further action is required. There are not <br /> 1 sufficient data to support a risk-based no further action declaration. Soil and <br /> groundwater data demonstrate impacts by petroleum contamination; however the data <br /> are not sufficient to draw conclusions regarding potential human health risks. <br /> 1 2. The screening-level human health risk appraisal was generally conducted as per <br /> DTSC guidance. The conceptual site model, exposure pathways, exposure <br /> parameters, potentially exposed populations, exposure scenarios, toxicity criteria, <br /> 1 calculations of exposure point concentrations and intakes, and risk characterization <br /> were all evaluated and determined to be in accordance with DTSC's recommendations, <br /> except as noted below. <br /> 1 SPECIFIC COMMENTS - Site Characterization: <br /> 1 1. The location of the pipelines, or former pipelines, need to be depicted in the maps. <br /> Include in the text the information regarding the depths of the OVP and APL, whether <br /> each is in place or removed, and if removed please specify the source of backfill used. <br /> 1 <br />