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Revised Work Plan For Soil and Groundwater Assessment 9 <br /> Ranch Market 23569 South Santa Fe Road Riverbank California April 25,2000 <br /> Phase 2- Drilling and Installation of Groundwater Monitoring Wells <br /> SECOR will supervise the drilling of the soil borings using a truck-mounted drilling rig <br /> equipped with 8-inch-diameter hollow-stem augers. Well MW-5D will be drilled to a depth of <br /> 85 feet bgs to accommodate installation of a groundwater monitoring wells with a discrete <br /> screen interval. Soil borings MW-6, MW-7, MW-8, and MW-9 will be drilled to a depth of <br /> approximately 40 feet below ground surface(bgs) to accommodate groundwater monitoring <br /> well installation. Soil samples will be collected at 5 feet bgs, and at 5-foot intervals thereafter, <br /> or lithologic changes, using a split spoon sampler lined with 2-inch diameter by 6-inch-long <br /> brass sample tubes. Samples will be collected at 10 foot intervals from MW-5D. Downhole <br /> drilling equipment will be steam cleaned before drilling each borehole, and sampling equipment <br /> will be cleaned between each sampling interval. Each soil sample will be screened for <br /> hydrocarbon vapors using a portable photoionization detector(PID). Soils encountered during <br /> drilling will be logged using the Unified Soil Classification System by a SECOR field <br /> geologist,working under the supervision of a California registered geologist. One sample tube <br /> from each sampling interval will be sealed with Teflon pads and plastic caps, then labeled and <br /> placed on ice in an insulated container for delivery to Kiff Analytical located in Davis, <br /> California. <br /> All soil generated through drilling will be placed on and covered with plastic on the Site <br /> pending characterization and disposal. Water generated by steam cleaning will be contained in <br /> a steam-clean trailer and temporarily stored on Site in DOT approved 55-gallon drums. <br /> Based on field observations(PID readings, lithology, odors,etc.), a minimum of seven soil <br /> samples collected from soil boring MW-5D and four soil samples per boring collected from <br /> MW-6, MW-7,MW-8, and MW-9 will be retained for analyses. The 23 soil samples will be <br /> analyzed for BTEX, TPHg, and MtBE using EPA method 8260 B. <br /> Deep Groundwater Monitoring Well Completion <br /> In order to minimize the risk of cross contamination of the deeper soil and groundwater, the <br /> deep groundwater monitoring well will be installed using an 8 5/8 inch-diameter steel outer <br /> casing that will be cemented in place at 60 feet bgs (Figure 3). The boring will be drilled to 60 <br /> feet using 8-inch-diameter hollow-stem augers and then enlarged using 16-inch-diameter <br /> hollow-stem augers. The conductor casing will be installed through the augers and grouted in <br /> place as the augers are pulled. A neat cement plug will also be set in the steel casing from 55 to <br /> Re:RB-GwPw WeHmI U <br />