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Results of Limited Subsurface Investigation Former P.E.O'Hair Site, 1102 South Aurora Street,Stockton,San Joaquin County,California Page 2 BACKGROUND In November 1988,two underground storage tanks(UST)were removed from the subject property. Two additional USTs were removed in February 1994. During the removal process,no soil staining was observed in the vicinity of three of the former UST locations. However,County of San Joaquin Environmental Health Division (County) personnel noted that soil staining and petroleum hydrocarbon odor was present beneath one of the former USTs. Confirmation soil samples were collected from beneath each of the former USTs. None of the confirmation soil samples contained detectable levels of gasoline or gasoline-related constituents. The soil samples were not analyzed for methyl t-butyl ether(MTBE)or the other fuel oxygenates. MTBE and the other fuel oxygenates were not required by the state of California to be analyzed at that time. In April of 1997,the County issued a letter stating that they would not support closure for the site. Apex was contracted by Rexel on December 10,2001 to prepare a workplan and bring the site into compliance with all regulatory agencies, regarding the former USTs. In Apex's Workplan for Additional Subsurface Investigation,dated January 3,2002,Apex proposed advancing five Geoprobe®soil borings to groundwater and collecting soil and groundwater samples from each boring. In a letter, dated January 11,2002 (Appendix A),the CVRWQCB approved the workplan. INSTALLATION OF GEOPROBE®SOIL BORINGS On March 26, 2002,Apex personnel supervised the installation of five Geoprobe® soil borings (GP-1 through GP-5)that were advanced to 39 feet bgs (Figure 3)by Enprobe Environmental, of Oroville, California,with the exception of GP-2,which was advanced to 36 feet bgs. Depth to groundwater at the site ranged from approximately 32 feet bgs to 36 feet bgs. Soil samples were collected from each boring at five-foot intervals and screened in the field with a photo ionization device (PID) for sample selection purposes. Two soil samples (collected just above groundwater) and one groundwater sample,from each of the five borings, were selected and submitted, under chain-of-custody,to California Laboratory Services (CLS), a state certified analytical laboratory, for analysis. Four soil samples were collected and submitted for analysis from GP-3, due to slightly elevated PID detections noted during field screening in samples collected at 20.and 25 feet bgs.