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San Joaquin County DIRECTOR
<br /> Pp N Donna Heran, REHS
<br /> Environmental Health Department ASSISTANT DIRECTOR
<br /> ti 2< 600 East Main Street Laurie Cotulla,RENS
<br /> Stockton, California 95202-3029 PROGRAM COORDINATORS
<br /> •` Mike Huggins,RENS, RDI
<br /> c ''•' tNW.S OV,OC eMargaret Lagorio,REHS
<br /> Website: W
<br /> j / hd
<br /> g g Robert McClellon,REHS
<br /> Phone: (209)468-3420 ,teff Carruesco,RENS,RDI
<br /> Fax: (209) 464-0138 Kasey Foley,REHS
<br /> 10 February 2009
<br /> David A Rosso
<br /> Stockton Center Site Authority
<br /> 401 Golden Shore, Second Floor
<br /> Long Beach CA 90802 4210
<br /> Subject: California State University Stanislaus
<br /> 1252 N. Stanislaus Street
<br /> Stockton, CA 9520
<br /> The San Joaquin County Environmental Health Department (EHD) has reviewed Second
<br /> Quarter(Semi-Annual) Groundwater Monitoring Report—June 2008 (the QR), dated 17 October
<br /> 2008, prepared and submitted by your consultant, Condor Earth Technologies, Inc. (Condor).
<br /> The EHD also reviewed various data from your site to evaluate its characterization status and
<br /> future assessment, monitoring or remediation requirements for obtaining site closure.
<br /> The QR reports the analytical results for monitoring wells MW-3, MW-5, MW-6, MW-7, MW-8
<br /> and MW-9; monitoring wells MW-1, MW-2, and MW-4 were not sampled, but were intended to
<br /> be sampled during the December 2008 monitoring event. Total petroleum hydrocarbons
<br /> quantified as gasoline (TPH-g) was detected in two well samples, MW-3 and MW-8,
<br /> at concentrations of 77.9 micrograms per Liter (pg/L) and 82.2 pg/L, respectively.
<br /> 1,2-Dichloroehtane (1,2-DCA) was detected in two well samples, MW-7 and MW-8, at 4.6 pg/L
<br /> and 4.7 pg/L, respectively. Total petroleum hydrocarbons quantified as kerosene (TPH-k), as
<br /> diesel (TPH-d), or as motor oil (TPH-mo), and the aromatic hydrocarbons benzene, toluene,
<br /> ethylbenzene and total xylenes (BTEX) were not detected in any of the well samples.
<br /> The recent monitoring data combined with previously obtained site investigation data show that
<br /> the plume of impacted groundwater has been adequately delineated in the shallow zone (25 to
<br /> 49 feet below surface grade [bsg]) north of the assumed source area underlying the former
<br /> underground storage tank (UST) pit by MW-1, toward the northwest by CPT-4, probably toward
<br /> the southwest by MW-2, toward the south by CPT-6, toward the southeast by MW-3 and MW-6,
<br /> and toward the east-northeast by MW-5.
<br /> The deeper zone investigated, approximately 85 to 90 feet bsg, is adequately characterized by
<br /> MW-9 and CPT-4 toward the northwest, CPT-6 toward the south, CPT-7 toward the southeast,
<br /> and CPT-5 toward the east-northeast.
<br /> The vertical extent of 1,2-DCA is delineated by CPT-8 as shallower than 96 and 128 feet bsg;
<br /> however the vertical extent of TPH-g and BTEX in the former UST area is not so clearly
<br /> delineated; the EHD suspects that deeper grab groundwater samples were cross contaminated
<br /> by more intensely impacted shallow groundwater. TPH-g and BTEX have not been detected at
<br /> Comment and Directive Letter 0209
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