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rr McDowell & Davis Towing <br /> Phase 11 Groundwater Monitoring Well Installation Report <br /> Benzene) and MTBE by method 8021B with confirmation, if present, by method <br /> 8260. <br /> 2.5 Groundwater Sampling <br /> A travel blank provided by the laboratory accompanied the sample vials from the <br /> time they were picked up from the lab to the time they were delivered back to the <br /> lab. This travel blank was not analyzed since all samples did not contain <br /> detectable contamination. <br /> All sampling equipment including the pump, bailer, and cables, used by sampling <br /> personnel, were disassembled, and steam-cleaned prior to commencement of <br /> `r sampling. These procedures were also followed between each well, sampling <br /> point, and at the end of the sampling day. De-ionized or organic-free water (also <br /> provided by the laboratory) was then introduced into the bailer as a final stage of <br /> cleaning. This water was then poured into sample vials to be used as a bailer <br /> • blank. <br /> Immediately prior to sampling, water levels and well depth measurements were <br /> taken in all wells at the site. Each well was evacuated using a stainless steel <br /> �. bladder pump, which does not introduce air into the water column. The pH, <br /> temperature, and electrical conductivity of the water were monitored as the well <br /> was evacuated. A field log of well monitoring information was maintained (see <br /> Appendix B - Well Monitoring Data Sheets). Instruments calibrated to known <br /> standards were used to monitor these parameters. At least 5 well volumes were <br /> evacuated from each well, and more, if necessary, until the above parameters <br /> stabilized. The wells or other sampling points were sampled in order of the least <br /> to the most contaminated, as best known or estimated. The samples were <br /> ` carefully poured from a Teflon bailer into clean glass vials with Teflon-lined <br /> +.. screw caps. Care was taken to ensure that no air space existed in the vials by <br /> inverting to check for bubbles and re-sampling if necessary. <br /> ti- The groundwater samples were analyzed or extracted within 14 days according to <br /> their EPA methods. The samples were analyzed for Total Petroleum <br /> Hydrocarbons (gasoline), BTX&E (Benzene, Toluene, Xylene, and Ethyl <br /> �- Benzene) and the Oxygenated Compounds, including EDB and 1,2-DCA, by <br /> Method 8260B. Analysis was conducted by GeoAnalytical Laboratories; a state <br /> certified analytical laboratory. <br /> 3.0 SOIL CONDITIONS <br /> 3.1 Site Geology & Stratigraphy <br /> ' Sands of the Pliestocene Modesto Formation dominate soils geology at the site. <br /> . 1 The sands vary in color from red-brown to grey and in USCS classification from <br /> SP - poorly graded to SM - silty sands. The dominant grain size is fine to very <br /> fine; some units include sparse coarse grains, these units are skip-graded. Sand <br /> 6 <br /> L <br />