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ll(VJV %TC <br /> ASSOCIATES I NC <br /> F1__On July 13, 1998, a geologist from ATC Associates supervised the advancement of four soil <br /> borings to 26 to 31 feet bgs Analytical results of soil samples indicated the presence of <br /> ' petroleum hydrocarbons One groundwater sample was collected from each boring at the depth <br /> groundwater was first encountered Groundwater samples indicated the presence of petroleum <br /> hydrocarbons Results are summarized in ATC's Summary Report of Additional Subsurface <br /> ' Investigation, dated September 9, 1998 <br /> 2.0 METHODS AND PROCEDURES <br /> ' <br /> To evaluate the extent of impacted groundwater and determine the groundwater gradient at the <br /> site, three soil borings were advanced in the vicinity of the former USTs and completed as <br /> groundwater monitoring wells All field activities were performed in accordance with ATC's <br /> Workplan for Additional Subsurface Investigation at N&S Irrigation, 215 West Main Street, <br /> Ripon, California, dated December 29, 1998 This workplan was approved by PHS/EHD on <br /> January 27, 1999 with minor modifications <br /> 2.1 Soil Boring Advancement and Sampling <br /> Drilling was conducted on February 18, 1999 by V & W Drilling (State C57 license no 720904) <br /> utilizing a hollow stem auger drill rig The soil samples from soil borings MW1, MW2, and <br /> MW3, advanced to depths between 39 and 41 feet bgs, were collected at five-foot intervals using <br /> a 2-inch diameter split-spoon sampler containing three brass tubes A field geologist logged drill <br /> ' cuttings and soil samples utilizing the Unified Soil Classification System <br /> The drill cuttings were characterized for soil type, moisture content, and visual evidence of <br /> ' petroleum hydrocarbons A photoionization detection meter (PID) was used as a field screening <br /> device for the detection of petroleum hydrocarbon vapors in drill cuttings and cored samples <br /> ' Drill cuttings were temporarily stored on site in 55-gallon DOT approved steel drums <br /> Descriptions of soil types encountered and sample collection intervals are included on the <br /> boring/well construction logs contained in Appendix A Soil borings MW1, MW2, and MW3 <br /> were advanced and completed as groundwater monitoring wells <br /> 2.2 Soil Sample Analysis <br /> ' Selected soil p <br /> were samples laced on ice, and transported under chain-of-custody to Sequoia <br /> p <br /> Analytical (ELAP #1210) of Redwood City, California for analysis All soil samples were <br /> analyzed for total petroleum hydrocarbons as gasoline (T_PHg) and benzene, toluene, <br /> ethylbenzene, and xylenes (BTEX) utilizing EPA 8015 and 8020 methodologies, and oxygenate <br /> fuel additives utilizing EPA 8260 methodology The analytical results for soil samples are <br /> ' summarized in Table 1 Laboratory data sheets and chain-of-custody documentation are included <br /> in Appendix B <br /> w 1149811reponslsumwel doc 2 <br />