SITE INFORMATION AND CORRESPONDENCE

Home Browse Search

PUBLIC F',"'EALTH SERVItES SAN JOAQUIN COUNTY ENVIRONMENTAL HEALTH DIVISION Karen Furst, M.D., M.P.H., Health Officer 304 East Weber Avenue, Third Floor • Stockton, CA 95202 "'�9tFd' 'Al 2091468-3420 , W H COLBERG OCT 13 1997 COLBERG INC PO BOX 1288 STOCKTON CA 95201 RE: Colberg Inc. Site Code: 2005 848 W Fremont St Stockton CA 95203 San Joaquin County Public Health Services, Environmental Health Division (PHSIEHD) has reviewed the August 21, 1997 "Results of Subsurface Investigation" prepared by Apex Envirotech, Inc. for the above referenced site. The results of analyses of groundwater samples from MW4, MW5 and MW6 indicate the presence of light fraction hydrocarbons in the diesel range. PHSIEHD recommends that you identify the unknown contaminant, which was found in the three wells, during the next sampling. The boring log for MW-4 records the presence of diesel odor at 10 and 15 feet. The analytical results of soil samples do not confirm this observation. Please submit the chromatograms from these analyses to PHSIEHD for evaluation.Additional investigation may be required to determine the lateral extent of soil contamination from the UST. Due to the lack of analytical evidence of contamination, and the observed presence of same, PHSIEHD recommends the installation of a monitoring well near P-4 which is the only location where observed contamination was confirmed by laboratory analysis. During the monitoring well installation, data should be gathered to determine the vertical extent of soil contamination beneath the former UST. MTBE was distinguished during the BTEX 8020 analysis for the groundwater sample from MW-3. PHSIEHD recommends that you run an 8260 analysis to confirm the presence of MTBE as well as the additional fuel oxygenates listed in the enclosed letter. Current gradient information indicates that MW-3 is on the same contour as the UST and that MW 1 is upgradient and MW-2 is downgradient but off center. Contamination was detected in P-1 which is between MW-1 and the UST. MW-1 is non detect this indicates that MW-1 shows the upgradient extent of the groundwater plume. Contamination was detected in P3 but MW-2 was non detect. PHSIEHD recommends the installation of an additional monitoring well east of P3 directly downgradient of the UST on the south side of the large building and also possibly east of MW-3 on the north side of the building. There is some question as to the validity of the south eastern gradient calculated for this site. The calculated gradient direction differs from gradient calculated at nearby sites by 180 degrees. PHSIEHD recommends that the wells be surveyed by a licensed surveyor. Please include the survey certification with the next monitoring report. Also monthly groundwater measurements may be required until a dominant gradient direction can be established. A Division of San Joaquin County Health Care Services