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San Joaquin County <br /> OF0 <br /> Environmental Health Department DIRECTOR <br /> Donna Heran, REHS <br /> 600 East Main Street <br /> PROGRAM COORDINATORS <br /> Stockton, California 95202-3029 <br /> Robert McClellon,REHS <br /> Jeff Carruesco, REHS,RDI <br /> Website: www.sjgov.org/ehdKasey Foley, REHS <br /> Phone: (209)468-3420 <br /> Fax: (209) 464-0138 <br /> February 23, 2010 <br /> Ava Langston-Kenney <br /> City of Stockton Redevelopment Agency <br /> 425 North EI Dorado Street, Room 317 <br /> Stockton, CA 95202-2317 <br /> Subject: 216 North California Street <br /> Stockton, CA 95202 <br /> The San Joaquin County Environmental Health Department (EHD) has reviewed <br /> Monitoring Well Installation & Additional Delineation Sampling Work Plan (Work Plan) <br /> dated February 2, 2010, submitted on your behalf by Condor Earth Technologies, Inc. <br /> (Condor) and has the following comments. <br /> In the Work Plan Condor proposes to install one groundwater monitoring well, followed by <br /> either the installation of two additional groundwater monitoring wells or two cone <br /> penetrometor test (CPT) borings, depending on the laboratory analytical results from <br /> groundwater samples collected from the proposed monitoring well (MW-1). <br /> Two previous scopes of work have been completed at this site; both involved the <br /> collection of grab soil and groundwater samples, first by Geoprobe and then by CPT <br /> borings. Analytical results from both scopes of work indicate the groundwater beneath the <br /> site is heavily impacted with petroleum hydrocarbons. A grab groundwater sample <br /> collected from boring CPT-2, located approximately 25 feet down-gradient from the former <br /> tank pit area, was reported to contain 5,800 pg/I TPHd. The highest concentration of <br /> sorbed phase diesel contamination was reported from this boring as well. <br /> In Section 3.0 it is proposed that if groundwater samples collected from proposed well <br /> MW-1 contain total petroleum hydrocarbons as diesel (TPHd) at a concentration of 2,500 <br /> micrograms per liter (pg/1) or greater, then two additional groundwater monitoring wells will <br /> be installed rather than two CPT borings. Condor referenced this concentration from the <br /> California Regional Water Quality Control Board's Groundwater Environmental Screening <br /> Levels for TPH middle distillates (Table F-1 a), November 2007. Please note that the <br /> 2,500 pg/I screening level is actually from Table F-1 b, which screens for groundwater that <br /> is not a potential drinking water resource. Since the Basin Plan designates all waters of <br /> the State of California to be potentially beneficial, the Table F-1a screening level, which is <br /> actually 100 pg/I must be applied at this site. The reported concentrations of <br /> contamination in the groundwater at this site are well above 100 pg/I TPHd. <br />