Laserfiche WebLink
v <br /> 0 <br /> A S S 0 C I A T E S I N C <br /> 2.0 METHODS AND PROCEDURES <br />' To investigate the extent of residual soil and groundwater contamination at the site, a total of five <br /> soil borings were advanced south and east of the former USTs and the fuel dispenser All field <br /> activities were performed in accordance with ATC's Workplan for Additional Subsurface <br /> Investigation at Ripon Unified School District, 304 North Acacia Avenue, Ripon, California, <br /> dated September 18, 1998 This workplan was approved by PHS/EHD on September 18, 1998 <br />' with minor modifications <br />' 2_1 Drilling Activities <br /> On September 21, 1998, an ATC geologist supervised the advancement of five soil borings from 5 <br /> to 31 feet below ground surface (bgs) Soil borings SB7 through SB I 1 were placed south and <br /> east of boring SB6 which was completed in April 1998 and contained detectable concentrations of <br /> petroleum hydrocarbons Borings SBI through SB5 which were also completed in April 1998 <br /> defined the impacted soil and groundwater to the north and west of SB6 A site plan with soil <br /> boring locations is shown on Figure 2 Fisch Environmental, California License C57 683865, <br /> advanced the borings using a truck mounted GeoprobeO narrow diameter rig employing direct <br /> push technology Soil samples were collected from borings SB7 through SB I 1 at five-foot <br /> intervals in acetate sampling tubes and were described according to the Unified Soil Classification <br /> System Descriptions of soil types encountered and sample collection intervals are presented on <br />' the boring logs contained in Appendix A <br /> 2,_2 Soil Sampling and Analysis <br />' Each soil sample was field screened with a Photoionization Detector (PID) for the presence of <br /> volatile organic compounds Sample tubes were then sealed at each end using Teflon tape and <br /> plastic end caps, labeled, and placed on ice Selected soil samples were kept on ice and delivered <br /> under chain-of-custody documentation to a State-certified Sequoia Analytical (ELAP #12 10) for <br /> chemical analysis Selected soil samples were analyzed by Sequoia for total petroleum <br /> hydrocarbons as gasoline (TPHg) and diesel (TPHd) by EPA method 8015 modified, benzene, <br /> toluene, ethylbenzene, and xylenes (BTEX) by EPA method 8020, oxygenate fuel additives by <br />' EPA method 8260 <br /> 2.3 Groundwater Sampling find Analysis <br /> One groundwater sample was collected from borings S137, S138, SB 10, and SB I I at the depth <br /> groundwater was first encountered, approximately 20 feet bgs A Geoprobe0 Screen Point 15 <br />' Groundwater Sampler was threaded onto the leading end of the Geoprobe after groundwater had <br /> been encountered When the sampler was advanced, O-ring seals and an expendable drive point <br /> provided a watertight system to ensure sample integrity <br /> w 1134991repoM\sum2 doe 2 <br />