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� v <br /> a <br /> A S S O C I A T E S I N C <br /> On April 23, 1998, a geologist from ATC Associates supervised the advancement of six soil <br /> borings, SBI through SBS, to 21 feet below ground surface (bgs) A site plan showing soil <br /> boring locations is included as Figure 2 Soil samples were collected at five-foot intervals and <br /> grab groundwater samples were collected from each boring Samples were analyzed for <br /> petroleum hydrocarbons and elevated concentrations of petroleum hydrocarbons were detected in <br /> soil and groundwater samples <br /> On September 21, 1998, an ATC geologist supervised the advancement of five soil borings, SB7 <br /> through SB 11, from 5 to 31 feet bgs A site plan showing soil boring locations is included as <br /> Figure 2 Soil samples were collected at five-foot intervals and grab groundwater samples were <br /> collected from each boring Samples were analyzed for petroleum hydrocarbons and elevated <br /> concentrations of petroleum hydrocarbons were detected in soil and groundwater samples <br /> On January 27, 1999, an ATC geologist supervised the advancement of two soil borings, MWI <br /> and MW3, to 35 feet bgs and one continuous core soil boring, MW2, to 45 feet bgs Analytical <br /> results for the soil samples indicated the presence of petroleum hydrocarbons in boring MW2 <br /> located in the center of the former UST location The groundwater wells were developed and <br /> sampled and the groundwater samples from wells MWI and MW2 contained detectable <br /> concentrations of petroleum hydrocarbons Results are summarized in ATC's Summary Report <br /> of Additional Subsurface Investigation, dated April 7, 1999 <br /> 2.0 METHODS AND PROCEDURES <br /> To evaluate the extent of impacted groundwater and determine the <br /> roundwater gradient at the <br /> g <br /> site, two soil borings were advanced at the locations shown on Figure 2 and completed as <br /> groundwater monitoring wells All field activities were performed in accordance with ATC's <br /> Workplan for Additional Subsurface Investigation at Ripon Unified School District, 304 North <br /> Acacia Avenue, Ripon, California, dated July 9, 1999 This workplan was approved by <br /> PHS/EHD on July 12, 1999 with minor modifications <br /> 2_1 Soil-Boring Advancement and Sampling <br /> Drilling was conducted on July 15, 1999 by V & W Drilling (State C57 license no 720904) <br /> utilizing a hollow stem auger drill rig Soil borings MW4 and MW5 were advanced to 36 5 feet <br /> bgs Soil samples were collected at five-foot intervals or significant changes in lithology using a <br /> 2-inch diameter split-spoon sampler containing three brass tubes Soil borings MW4 and MW5 <br /> were advanced and completed as groundwater monitoring wells A field geologist logged drill <br /> cuttings and soil samples utilizing the Unified Soil Classification System Descriptions of soil <br /> types encountered and sample collection intervals are included on the boring/well construction <br /> logs contained in Appendix A A photoionization detection meter (PID) was used as a field <br /> screening device for the detection of petroleum hydrocarbon vapors in drill cuttings Drill <br /> cuttings were temporarily stored on site in 55-gallon DOT approved steel drums <br /> w 1130991reportslsumwe]t doc 2 <br />