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California Ref/tonal Water Quality Ciktrol Board <br />Central Valley Region Ai. HEAL 1} <br />FRKE <br />Terry Tamminen <br />Secretary for Sacramento Main Office 04 JUN - I PM 3: 27 Environmental Internet Address: http://www.swrcb.ca.gov/rwqcb5 <br />Protection 11020 Sun Center Drive #200 Rancho Cordova, CA 95670-6114 <br />Phone (916) 464-3291 Fax (916) 464-4797 <br />1 Tune 2004 <br />Ms. Frances Schmiedt <br />20696 South Main Street <br />Manteca, CA 9533 <br />REVIEW OF LIMITED SOIL AND GROUNDWATER INVESTIGATION REPORT, SCHMIEDT <br />SOIL SERVICE, 20696 SOUTH MAIN STREET, MANTECA, SAN JOAQUIN COUNTY <br />Staff of the Central Valley Regional Water Quality Control Board (Regional Board) have reviewed the <br />13 February 2004 Report Limited Soil and Groundwater Investigation (Report) submitted by Kleinfelder <br />on your behalf for the former Schmiedt Soil Service Incorporated property at 20696 South Main Street in <br />Manteca (site). The Report discusses the soil and groundwater sampling results from three newly <br />installed monitoring wells, the on-site domestic well, and eight borings, summarizes the results of the <br />geophysical survey to determine if there are any underground storage tanks at the site, and recommends <br />limited use of the domestic well and a limited soil excavation in the southwest corner of the <br />warehouse/shed. The Department of Toxic Substances Control (DTSC) has also reviewed the Report. <br />Regional Board and DTSC staff have the following comments on the Report: <br />The table on Page 14 of the Report lists the Residential Preliminary Remediation Goal (PRG) for <br />oryzalin as 3.1E+06. The residential PRG for oryzalin is 3.1E+03 <br />The Report states that the concentrations of pesticides and other constituents detected in soil <br />samples are below residential PRGs, which are useful as a screening tool to determine if <br />additional investigation may be required. However, a screening level risk assessment should be <br />conducted for soils, as outlined in DTSC's Preliminary Endangerment Assessment Guidance <br />Manual (DTSC 1994), for all constituents that were analyzed for and exceed site-specific <br />background concentrations. Site-specific background samples will need to be collected for <br />metals unless the highest concentration of each metal detected is used for the evaluation of risk <br />and hazard. The purpose of the screening level risk and hazard evaluation is to document the <br />cumulative potential risk and hazard for these constituents and make a determination on the need <br />for further investigation or remediation of soils. The screening level evaluation should be <br />conducted based on an unrestricted land use, and possibly a commercial/industrial land use if a <br />deed restriction is an alternative that is considered for the site. Lead concentrations should be <br />evaluated against site-specific background concentrations and using DTSC's Lead Spread <br />spreadsheet, which allows calculation of potential blood lead levels that may occur in children <br />and adults. Information should be provided in tables within the text of the report that identify the <br />background concentrations detected and the concentrations used in the screening level risk <br />California Environmental Protection Agency <br />Robert Schneider, Chair <br />Arnold Schwarzenegger <br />Governor <br />r 3 Recycled Paper