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4 29PH FPOM P 1 <br /> PUBLIC HEALTH SERVICES <br /> SAN JOAQUIN COUNTY <br /> s ENVIRONMENTAL HEALTH DIVISION <br /> Karen Furst, M D , M PH., Health Officer <br /> 304 East Weber Avenue,Third Floor - Stockton, CA <br /> 2E1914ti8-3420 <br /> W H GOLBE RG OOT 13 9 <br /> COLBERG INC <br /> PO BOX 1288 <br /> STOCKFON CA 95201 <br /> RE Colberg Inc Site Code 2005 <br /> 848 W Fremont St <br /> Stockton CA 95243 <br /> San JoagLlrt County Public Health Services, Environmental Health Division (PHS/EHD) has <br /> reviewed the August 21, 1997'Results of Subsurface Investigation"prepared by Apex Envirotech, <br /> Inc for the above referenced Me <br /> The results of analyses of groundwater samples from MW4, MW5 and MWo indicate the presence <br /> of light fraction hydrocarbons in the diesel range PHSIEHD recommends that you identify the <br /> unknown contaminant,which was found in the three wells,during the next sampling <br /> The boring log for MW-4 records the presence of diesel odor at 10 and 15 feet The analytical <br /> results of soil samples do not confirm this observation Please submit the chromatograms from <br /> these analyses to P✓-lS/EHD for evaluation Additional investigation may be required to determine <br /> the lateral extent of soil contamination from the UST <br /> Due to the lack of analytical evidence of contamination, and the observed presence of same, <br /> PHS/EyHD recommends the irstallaton of a monitoring well near P-4 which is the only location <br /> where observed contamination was confirmed by laboratory analysis During the monitoring well <br /> installation, data should be gathered to determine the vertical extent of soil contamination beneath <br /> the former UST <br /> MTBE was distinguished dunng the BTEX 8020 analysis for the groundwater sample frim MW-3 <br /> PHS/EHD recommends that you run an 8260 analysis to confirm the presence of MTBE as well as <br /> the additional fuel oxygenates listed in the enclosed letter <br /> Current gradient information indicates that MW-3 is on the same contour as the UST and that MW- <br /> 1 is upgradient and MW-2 is downgradient but off center Contamination was detected In P-1 which <br /> is between MW-1 and the UST MW-1 is ;son detect this indicates that MW-1 shows the upgradient <br /> extent of the groundwater plume Contamination was detected in P3 but MW-2 was non detect <br /> PHS/EHD recommends the installation of an additional mondariing well east of P3 directly <br /> downgradient of the UST on the south side of the large building and also possibly east of MW-3 on <br /> the north side of the building <br /> There is some question as to the validity of the south eastem gradient calculated for this site The <br /> calculated gradient direction differs from gradeent calculated at nearby sites by 180 degrees <br /> PHS/EHD recommends that the wells be surveyed by a licensed surveyor Please include the <br /> survey certification with the next moriftonng report-Also monthly groundwater measurements may <br /> 0 be required until a dominant gradient direction can be established <br /> A 1:hvis►on of San loaquji,County Heaith CGre Servos&$ <br />