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tRipona Market <br /> Groundwater Monitoring Well Installation Report <br /> Page, b <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 />' 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 by Method 8260B Analysis was <br /> conducted by GeoAnalytical Laboratories, a state certified analytical laboratory <br /> 3.0 SITE CONDITIONS <br /> 3.1 Site Geology & Groundwater Occurrence <br />' 3.1a— Soils Geology The site is underlain by interbedded fine to medium grained <br /> distal facies sediments of the Pleistocene Modesto Formation The Modesto <br />' Formation in the Ripon area was deposited in the distal portion of coalescing <br /> alluvial fans derived from the Sierra Nevada mountains to the east In the distal <br /> portions of the fans, sandy sediments interfinger with silts and clays deposited at the <br /> interface of the lacustrine environment which was found in the center of the San <br /> Joaquin Basin The upper unit at the site, which is described below, represents a <br /> basinward transgression of the coarser grained alluvial fan sediments over the <br />' underlying finer grained lacustrine sediments <br /> The upper 15 feet of sediments explored at the site consist of medium dense to <br />' dense, fine to medium, angular, arkosic sands The USCS designation is SW to <br /> SM A coarser grained, fluvial channel sand is found In MW — 2 and MW— 3, from <br />' 17 to 21 feet depth This unit has a USCS designation of SW, due to its coarser <br /> grained nature, permeability and porosity can be expected to be higher in this unit, <br /> than in the sediments immediately overlying it <br /> A fine-grained unit is found from 21 to 30/35 ft in MW— 2 and MW - 3 and 17 to <br /> • 35 in MW — 1 This unit consists of predominately low plasticity, hard, clays, silts <br /> and silty sands The USCS designation for this unit ranges from SM to SC to CL <br /> r <br />