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California Foional Water Quality Cor of Board
<br /> Central Valley Regione
<br /> Katherine Hart., Chair �.::--.
<br /> Arnold
<br /> Linda S. Adams 11020 Sun Center Drive#200, Rancho Cordova,Califor aSchwarzenegger
<br /> Secretary for Phone(916)464-3291 •FAX(94 Govemor
<br /> Environmental http1//www.waterboards.ca.gov/ I�u
<br /> Protection
<br /> Russell F. Chapin Sr. N?:�q 1 �' 2�1t7 17 March 2010
<br /> Chapin Bros., Inc. Et�V RONI.411ZW N A►TH
<br /> 1203 N. Charlton Avenue F'ERPv�ITI�ERVlCt�
<br /> Stockton, CA 95203
<br /> DOCUMENT REVIEW, CHAPIN BROTHERS INC., 1766 MONTE DIABLO AVE., STOCKTON,
<br /> SAN JOAQUIN COUNTY, REGIONAL BOARD CASE NO. 390577
<br /> 1 reviewed the Soil Vapor Survey and Human Health Risk Assessment Work Plan (Workplan) received
<br /> 15 March 2010 from your consultant Closure Solutions, Inc. The Workplan describes the methodology
<br /> in the California Regional Water Quality Control Board - Los Angeles Region / Department of Toxic
<br /> Substances Control Advisory- Active Soii Gas Investigation (January 20031 guidance, and proposes
<br /> advancing one soil vapor sampling point to 5' below ground surface, approximately 60' from the former
<br /> underground storage tanks (USTs) in the rear of the automotive repair shop (building). One soil gas
<br /> sample will be collected in a Summa Canister, and analyzed for benzene, toluene, ethylbenze e, and
<br /> gasoline
<br /> (BTEX) by Method T03, total petroleum hydrocarbons as TPHg) by
<br /> Methodand oxygen, carbon dioxide, and methane by ASTM-1946. A second Summa Canister will collect an
<br /> ambient air sample outside of the automotive repair shop. The soil gas data will be evaluated for vapor
<br /> intrusion in a risk assessment, which will also evaluate a dermal contact pathway. A report will be
<br /> submitted 60 days after receipt of the soil gas analytical data. Additional soil samples will be collected
<br /> from the direct push boring, and analyzed for TPHg, BTEX, methyl tert-butyl ether (MTBE), lead (for
<br /> waste disposal), soil density, organic carbon content, soil moisture, effective permeability, porosity and
<br /> grain size distribution analysis.
<br /> All known constituents of concern, including MTBE, will be analyzed and reported in the soil gas
<br /> analyses. While the one soil gas sample collected inside of the automotive repair shop is adequate to
<br /> evaluate soil vapor intrusion from residual soil contamination detected in soil samples taken under the
<br /> building, a minimum of two additional soil gas samples are necessary to complete the soil gas
<br /> investigation. You are to add a second soil gas sample location outside on the north side of the building
<br /> and south of the former USTs, and a third soil gas sample location outside on the east side of the
<br /> building, for a minimum of three soil gas samples for the proposed risk assessment. All three soil gas
<br /> results will be compared to the San Francisco Bay Regional Water Quality Control Board Residential
<br /> Environmental Screening Levels (ESLs), which may be downloaded from the Internet at
<br /> http�//vwvw waterboards ca qov/sanfran ciscob htrolle the
<br /> revised Figure 2,exceeded,
<br /> howing all three so Irisk
<br /> assessment will be submitted with the report Please pvida
<br /> gas sampling locations, as an attachment in an email to me by 15 April 2010. If you have any
<br /> ) 464-4615, or by e-mail at Ibarton(c�waterboards.ca.gov.
<br /> qu stions, you can contact me at (916
<br /> rte\
<br /> ,James L.L. Barton, P.G.
<br /> >% Engineering Geologist
<br /> cc: Nuel Henderson, San Joaquin County Environmental Health Department, Stockton
<br /> Kathleen Waldo, Closure Solutions, Inc., 2151 Salvio St., Ste. 301, Concord 94520
<br /> California Environmental Protection Agency
<br /> *p�Recycled Paper
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