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i <br /> I� <br /> !h 1 <br /> 26 April 2011 <br /> AGE-NC Project No. 95-0104 <br /> Page 3 of 12 <br /> �I <br /> moderately well drained soils formed in mixed alluvium; Vignolo soils are on low fan <br /> terraces. <br /> Based on quarterly ground water monitoring events condpucted at the site between January <br /> .1993 and August 2010, ground water has been encountered between approximately <br /> a 52 feet and 92 feet below surface grade (bsg)and the flow direction has consistently been I <br /> towards the northeast. Currently,ground water is encountered at approximately 72 feet bsg <br /> and flows towards the northeast. Ground water is consitlered to be of beneficial use and <br /> is used for domestic, industrial and commercial purposes. Ground water elevation data is <br /> presented in Table 1. Figure 3 illustrates the most recent contoured ground water <br /> 'f elevations measured on 10 August 2010. N! <br /> ' 2.2. UNDERGROUND STORAGE TANK REMOVALI <br /> On 04 January 1988, one 550-gallon gasoline UST was removed from 4696 East Waterloo <br /> Road (formerly 4648 East Waterloo Road), Stockton, California. The UST was removed <br /> from the site by Ramcon, Inc. with evidence of a petroleum release. In March 1988, two <br /> soil samples were collected at the base of the tank excavation at depths of approximately <br /> 17 feet bsg. Total volatile hydrocarbons (TVH), benzene, toluene, ethylbenzene, and <br /> xylenes (BTEX) were detected in both samples at m'aximu'm concentrations of 2,200 <br /> ` milligram per kilogram (mg/kg), 160 mg/kg, 710 mglk'g, 22.0 mg/kg, and 1,100 mg/kg, <br /> { respectively. Analytical results of UST soil samples ar6tsummarized in Table 2. <br /> ;. Approximately 45 cubic yards of soil was stockpiled on the site'. On 12 October 1988, three <br /> soil samples were collected from the stockpile and composited for analysis. Total <br /> petroleum hydrocarbons as gasoline (TPH-g), BTEX compounds, and organic lead were <br /> + not detected above laboratory reporting limits in the composite soil sample. <br /> 2.3. SITE INVESTIGATIONS <br /> .lr <br /> The following is a brief summary of the site assessment investigations conducted at the <br /> site to date: 0 <br /> • On 07 July 1988, one soil boring (B-1) was advanced northwest of the former UST <br /> area to 34 feet bsg and one ground water monitoring well (B-2/MW-1)was installed <br /> to 80 feet bsg southwest of the former UST location. Petroleum hydrocarbons were <br /> not detected in soil samples collected from B-1;11however, TPH-g was detected in <br /> both soil and ground water samples collected from MW-1. Analytical results of soil <br /> and ground water samples are summarized in ables 2 and 3. Boring logs are <br /> presented in Appendix C. A report of findings (Prehmrnary Report Evaluation of Soil <br /> !j Advanced CeoEnvironmental,Inc. <br /> �� I <br />