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JJ, <br /> f� <br /> I <br /> THRIFTY OIL CO. <br /> October 30, 1992 �at <br /> I V <br /> Mr Mike Infurna <br /> NOV 21802 <br /> Public Health Services/Environmental Health Division sal T {_ r + l <br /> County of San Joaquin I '`jf��'! I* <br /> P O Box 2009 (1601 E Hazelton Ave ) <br /> Stockton, California 95201 <br /> RE 77infty Oil Co, Station #1172 <br /> 7647 Pacific Ave <br /> Stockton, CA 95207 <br /> Quarterly Monitoring Report <br /> 3rd Quarter 1992 <br /> Dear Mr Infurna, <br /> This letter serves as a quarterly monitoring report for the above mentioned service station This status report <br /> presents site monitoring efforts during the months of July, August and September Thrifty Oil Co has retained <br /> Earth Management Co (EMC) to conduct quarterly monitoring and sampling activities at the site The data is <br /> reported by Thrifty in-house environmental staff <br /> SITE REMEDIATION <br /> To date, no remediation of soil and groundwater has been conducted at the site As requested by PHSIEHD, a <br /> workplan for additional investigation at the site with regard to definition of the vertical and lateral extent of soil and <br /> groundwater contamination was submitted by Thnfty Oil Co in-house staff on April 14, 1992 This workplan will <br /> be evaluated after more data is collected from the wells <br /> A survey of the wells within a 112 mile of the site was conducted by SSB Environmental Consultants in July, 1991 <br /> Their findings were included in the initial site investigation report titled "Preliminary Assessment of Soil and <br /> Groundwater Quality at Thnfty Oil Company Station No 172, 7647 Pacific Avenue, Stockton, California", dated <br /> July 17, 1991 <br /> GROUNDWATER MONTCORIN <br /> On August 5, 1992, The site was visited by an Earth Management Co (EMC) technician The EMC technician <br /> obtained depth to groundwater data and observed wells for the presence of free product Groundwater depth <br /> measurements were taken from the top of PVC well casing using an Oil Recovery Systems interface probe capable <br /> of measurements to within 0 01 feet Using the depth to groundwater and survey data for the site, a groundwater <br /> contour map was developed The contour map is presented as Figure 2 The contour map suggests that the <br /> potentiometnc surface of the shallow groundwater is generally flat across the site with a slight southward trend <br /> The groundwater elevation has risen about a foot since the hast reporting, June 5, 1991 <br /> Groundwater samples were collected from the on-site wells by EMC personnel Prior to sample collection, at least <br /> three well volumes of groundwater were removed from each well by a portable submersible pump or bailer During <br /> the purging of groundwater, pH, conductivity, temperature and turbidity were monitored at selected intervals This <br /> data is included in Appendix A along with the gauging data for the reporting period All equipment was cleaned <br /> using a solution of Alconox and water followed by two tap water rinses The actual groundwater samples were <br /> collected with a teflon bailer equipped with a bottom emptying device before being transferred into the laboratory <br /> supplied 40m1 VOA vials pending analyses The chain-of-custody documentation is presented m Appendix B. 1 <br /> QO <br /> 10000 Lakewood Boulevard, Downey, California 90240 (310) 923-9876 <br />