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w - <br /> San Joaquin County DIRECTOR <br /> Ronna Heran, REHS <br /> o?au�N .c Environmental Health Department <br /> ASSISTANT DIRECTOR <br /> 600 East Main Street Laurie Cotulla,REHS <br /> . < Stockton, California 95202-3029 PROGRAM COORDINATORS <br /> .. Carl Borgman,REHS <br /> Mike Huggins, REHS,RDI <br /> c' .-�•��° Website: www.sjgov.org/ehd Margaret Lagorio, REHS <br /> 0Z Phone: (209)468-3420 Robert MoVellon, REHS <br /> Fax: (209) 464-0138 .teff Carruesco,REHS,RDI <br /> Duly 25,zoos Kasey Foley,REHS <br /> Ms. Beverly Garcia <br /> Raymond Investment Corporation <br /> Post Office Box 567 <br /> Stockton, California 95201 <br /> Subject: Raymond Investment Corporation <br /> 730 Channel Street <br /> Stockton, California 95202 <br /> The San Joaquin County Environmental Health Department (EHD) has reviewed historical <br /> analytical data collected from soil borings SB-1 through SB-11, hydropunch borings HP-1 through <br /> HP-3, and monitoring wells MW-1 through MW-4, prepared and submitted by Condor Earth <br /> Technologies, Inc. (Condor) on your behalf for the above-referenced site. Groundwater results <br /> from the 2007 quarterly sampling events indicate high concentrations of benzene, total petroleum <br /> hydrocarbons quantified as gasoline (TPH-g), and total extractable petroleum hydrocarbons <br /> quantified as diesel (TEPH-d) are present in groundwater samples collected from monitoring well <br /> MW-4. Also, although it appears that contaminants of concern are delineated vertically in soil, as <br /> indicated by non-detect results for soil samples collected from S13-7, it does not appear that <br /> groundwater is delineated vertically since grab groundwater samples collected at seventy-two feet <br /> below surface grade (bsg) from SB-7 have been reported with 1,600 micrograms per liter(pg/L) of <br /> TPH-g and 220 pg/L TEPH-d. For these reasons, the EHD does not believe this site is ready for <br /> closure consideration at this time. Of concern are the data gaps that exist largely due to onsite <br /> structures. These data gaps should be presented in the context of a preliminary site conceptual <br /> model (SCM) to determine whether additional investigation is needed and address appropriate <br /> remediation methods for removing the petroleum hydrocarbon contaminants. <br /> An SCM that incorporates findings from the last five years of site characterization is needed to <br /> evaluate present site conditions. The general purposes of an SCM are to demonstrate where the <br /> contaminants came from, where they are at the present time, how they move through the <br /> subsurface, how they will respond to changes in the groundwater flow characteristics or to potential <br /> remediation efforts, what the contaminants' ultimate environmental fate will be, and to help <br /> evaluate the risk posed by the contaminants to groundwater supplies and sensitive receptors. To be <br /> sure that the SCM will adequately address the assessment, remediation and, ultimately, final closure <br /> requirements for this site, please include the following in the SCM: <br /> Local and regional plan view maps showing locations of sources, boring and monitoring <br /> well locations, lines of cross section, extent of contaminants in each media (i.e., an <br /> interpretive drawing — not merely a plot of laboratory results), direction and rate of <br /> groundwater flow, and receptor locations, including water supply wells within 2,000 feet of <br /> the site; <br /> t <br />