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• Collect two in-situ groundwater samples, downgradient from the areas suspected <br /> to contain elevated levels of mercury in soil, to assess the potential lateral <br /> r migration of mercury in groundwater. These groundwater samples will be <br /> collected approximately 50 feet downgradient from the suspected impact areas. <br /> • One duplicate sample will be collected from one of the locations directly below <br /> the soil impacted areas for quality control purposes. Groundwater samples will <br /> be analyzed for total dissolved mercury by EPA Method 7470. <br /> Groundwater samples will be analyzed by MBT Environmental Laboratories in Rancho <br /> Cordova, California. <br /> 3.4 TASK 4 - REPORT PREPARATION <br /> At the conclusion of the tasks described above, a letter report will be prepared presenting <br /> the findings of the investigation. The letter report will include a description of the work <br /> performed and the results of the soil and groundwater sampling and analysis. Conclusions and <br /> any applicable recommendations will also be included in the report. <br /> 4.0 FIELD PROCEDURES AND PROTOCOL <br /> All field procedures will be overseen by a Dames & Moore representative under the <br /> supervision of a California Registered Geologist. Procedures for soil borings, soil sampling, <br /> groundwater sampling, equipment decontamination, and sample shipment and documentation <br /> are outlined below. Site specific health and safety procedures will be overseen by the Dames <br /> & Moore Site Safety Officer and are described in Appendix A. <br /> f 4.1 SOIL BORINGS <br /> Soil borings will be advanced by Geoprobe' direct-push penetration and hand auger <br /> techniques,which either method is more effective. Soil borings will be push penetrated utilizing <br /> Kvilhaug Well Drilling and Pump Company, Inc., of Concord, California (License No. C57- <br /> 482390) as the soil boring subcontractor. The Geoprobe"" rig advances soil borings using a <br /> hydraulic or pneumatic hammer with 1-inch diameter steel piston rods to drive 1 3/8-inch <br /> diameter soil and groundwater sampling tools to specified depths. <br /> SAC167.14 4 <br /> S D:�,\aLs & MOORE <br />