SITE INFORMATION AND CORRESPONDENCE

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Shell Sites Page 2 2320 El Dorado Street Stockton An SCM was submitted on November 4,2005. Shell thinks the hydrocarbons are migrating across El Dorado Street from the site at 2315 El Dorado Street. TCE and PCE have been detected in the water samples collected from the Shell site monitoring w 11s. The source of these contaminants is unknown. Shell requested that the site at 2315 El Dorado be directed to add analysis for TCE and PCE to the suite of constituents being analyzed for in that sites water samples. At this time EHD will wait for data from Shell indicating 2315 El Dorado is the source of the TCE and PCE since the current data discussed below doesn't support Shell's requ st. EHD previously completed a cursory review of the history and investigation of the former waste oil underground storage tank (UST) tank at the 2315 El Dorado Street. In April 1987,a 200-gallon waste oil UST was removed from the site. Analytical results of the soil sample collected beneath the UST were non-detect (ND) for TCE and 1.6 micrograms per kilogram (ug/kg).of PCE. In October 1993 multiple soil samples were collected from 3 soil borings to 30 feet below surface grade (bsg) and 1 soil boring to 36 feet bsg that were installed next to the former UST. Analytical results of all the samples were ND for PCE and TCE. Analytical results of a ground water sample from monitoring well MW-1 installed next to the former UST in September 1994 were also ND for PCE and TCE. EHD also reviewed our Shell station UST file ind found that Shell originally reported a 550 gallon waste oil"UST to be at the site,but when EIIE staff inspected the site in 1986 it was stated that the UST-had been removed prior to 1984 sot ere is no soil data on the Shell waste oil UST. The-file did have soil sample results from the UST system removal in July 1990 and soil samples SS-1, 5,7, 1,0, 11 and 12 all had detections of PCE,in the soil samples collected. Shell plans to request a review of our files for both sites. Shell needs to provide information showing the location of their former waste oil tank and that it was removed prior to 1984. Currently, there is no monitoring well placed dawn-gradi nt of the current UST system. Shell is to submit a work plan for installation of a monitoring well d wn-gradient of the current UST system. In addition,Shell may want to propose installation of antip-gradient well near the 2315 El Dorado site to gather additional data. 2494 Fremont Street,Stockton After a report of the most recent site work is submitted to EHD for review,EHD will provide comments on whether further investigation is necessary. 2375 Grant Line,TraU An SCM is being prepared for this site. Periodic vacuum extraction operation has been initiated and a proposal of frequency and rate of pumping is to be included in the SCM. Shell will discuss with 7- Eleven submitting a co-mingled plume application. A sampling program for analyzing for MTBE, TBA and TAME in the water samples from the monitoring wells on a quarterly basis and adding analysis for BTEX,TPH and other oxygenates annually on the water samples will be prepared. 1071 Main Street,Manteca A site closure report submitted on September 19,2005,is being reviewed by EHD. After review of the report discontinuance of quarterly monitoring will be iecided. 341 Main Street,Ripon El-ID responded to'the closure report prepared for this si e. Collection of additional soil data or preparation of a site'model should be completed to justi closure. i 7700 Moreland Street,Stockton A deep monitoring well was to be installed on November 14, 2005.