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y <br /> �� � • <br /> San Joaquin County DIREcraR <br /> Donna Heran,RENS <br /> pP� !" ;•.C, Environmental Health Department ASSISTANT DIRECTOR <br /> OG Laurie Cotulla,REHS <br /> 600 East Main Street <br /> Stockton, California 95202-3029 PROGRAM COORDINATORS <br /> .. µ Carl Borgman,REHS <br /> Mike Huggins,REHS,RCI <br /> c •: � =. �P Website: www.slgov.org/ehd Margaret Lagorio,REHS <br /> F o R� Phone: (209) 468-3420 Robert McCleilon,REHS <br /> Fax: (209) 464-0138 Jeff Carruesco, REHS,RCI <br /> Kasey Foley, REHS <br /> AUG 222007 <br /> CRAIG OGATA <br /> DIRECTOR OF FACILITIES MANAGEMENT <br /> 212 N SAN JOAQUIN STREET SUITE A <br /> STOCKTON CA 95202 <br /> RE: San Joaquin County Courthouse SITE CODE: 1285 <br /> 222 East Weber Avenue RO: I 1 <br /> Stockton, CA 95202 <br /> San Joaquin County Environmental Health Department (EHD) has reviewed Work Plan <br /> Vapor Intrusion Assessment dated July 27, 2007, prepared and submitted by Ramage <br /> Environmental, Inc. (Ramage Environmental) on your behalf The work plan was <br /> submitted in response to EHD's letter dated July 3, 2007, requesting an evaluation of the <br /> threat of vapor intrusion inside the buildings located onsite. Included in the work plan <br /> are results from the first quarter 2007 groundwater monitoring event that indicate the <br /> groundwater plume is stable and concentrations for chemicals of concern are decreasing <br /> slightly. <br /> Ramage Environmental completed a Tier 1 Environmental Screening Levels (ESL) <br /> assessment and determined that concentrations for benzene in soil and groundwater <br /> exceed the ESL for vapor emissions to indoor air. To evaluate the potential threat of soil <br /> vapor petroleum hydrocarbon concentrations, Ramage Environmental proposes to collect <br /> soil gas samples in Suma' canisters by advancing five borings to approximately five feet <br /> below ground surface (bgs) at the following locations: <br /> • One boring approximately seven feet west of monitoring well MW-1; <br /> • One boring approximately thirty-five feet west/southwest of MW-1 and adjacent <br /> to the courthouse; <br /> • One boring approximately eighty-five feet southwest of MW-1 and adjacent to <br /> the courthouse; <br /> • One boring approximately ninety feet northwest of MW-1 and adjacent to the <br /> courthouse; and <br /> • One boring approximately seven feet northeast of MW-3. <br /> Soil gas samples will be analyzed for total petroleum hydrocarbons quantified as gasoline <br /> (TPH-g); benzene,toluene, ethyl benzene, and total xylenes (BTEX); and methyl tertiary- <br /> butyl ether (MTBE). Analytical results will be evaluated using the Risk Integrated <br /> Software for Clean-ups (RISC4) software program. <br />