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a <br /> RIPONA MARKET <br /> 223 W. Washington Street, Ripon, California <br /> Groundwater Monitoring Well Installation <br /> Report <br /> 1.0 PROJECT IDENTIFICATION <br /> The objective of this phase was to provide a scope of work that would further define the <br /> lateral and vertical extent of the hydrocarbon plume in the soil and groundwater at the <br /> Ripona Market facility The work included a well receptor survey and definition of the <br /> groundwater flow direction as requested in the San Joaquin County department of <br /> Environmental Health letter dated March 31, 2000 Three on-site groundwater monitoring <br /> wells were installed, in various locations, to obtain soil and ground water samples and for <br /> rthe calculation of the groundwater gradient <br /> I1.1 Site Description and History <br /> Two underground fuel tanks were removed on February 11, 1999 by SEMCO <br /> under permit Low levels of xylene were disclosed in laboratory soil samples <br /> collected at 13 feet to depth, primarily in the area of Tank i (TK-1) (Figure 2) <br /> Moderately high levels of specific oxygenated compounds were present to the <br /> stockpiled soil that had surrounded the tanks Since no apparent contamination <br /> was noted during the removal this soil was placed back into the excavation <br /> Table of Laboratory Sample Results (February 11, 1999) <br /> Sam le I D Gasoline Benzene Toluene E-Benzene Xylenes 8260 <br /> TK1-S l5' ND ND ND ND ND ND <br /> I TK 1-N@ 13' ND ND ND ND 47 ND <br /> TK2—SA13' ND ND ND ND ND ND <br /> TK2—N(0,15' ND ND ND ND ND ND <br /> SP-1 ND ND ND ND ND 190 urea 1200 B.d <br /> SP-2 ND ND ND ND ND ND <br /> ND=Non Detect Gasoline in mg/Kg 8260 toµi / g <br /> On January 31, 2000 M J Kloberdanz & Associates drilled a single soil boring to <br /> 30 feet in depth Groundwater was measured at 29 feet below grade surface (bgs) <br /> The former tank excavation had been filled with the previously excavated soils <br /> and topped with about eight feet of pea gravel so sampling started at ten feet in <br /> depth The boring was located near the center of the backfilled tank excavation <br /> (Figure 2 Site Map) <br />' <br /> Laboratory samples les were obtained every five feet, below the gravel layer, for <br /> P <br /> laboratory analysis since contaminated soils were placed back in the tank pit The <br /> ten and twenty foot samples were non detect for all compounds analyzed The 15 <br /> foot sample contained only 19 ltg/Kg of xylenes MTBE was present at 25 and 30 <br /> feet in depth The sample with the highest concentration of MTBE, B-1-25', was <br /> I <br />