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EXPLORATION DRILLING <br /> Mobilization <br /> Prior to any drilling activities, Enviros, Inc. (Enviros)'will verify than <br /> necessary drilling permits have been secured. <br /> Utility locations will be located and drilling will be conducted so as not to <br /> disrupt activities at a project site. Enviros will obtain and review available <br /> public data on subsurface geology and if warranted, the location of wells <br /> within a half-mile of the project site will be identified. Drillers'will be <br /> notified in advance so that drilling equipment can be inspected prior to <br /> performing work. . <br /> Drillins <br /> The subsurface investigations are typically performed to assess the lateral <br /> and vertical extent of petroleum hydrocarbons present in soils and <br /> groundwater. Drilling methods will be selected to optimize field data <br /> requirements as well as be compatible with known or suspected subsurface <br /> geologic conditions. <br /> Monitoring wells are installed using as truck-mounted hollow-stem auger <br /> drill rig or mud-rotary drill rig. Typically, the hollow-stem rig is used for <br /> wells up to 100 feet, if subsurface conditions are favorable. Wells greater <br /> than 100 feet deep are typically drilled using mud-rotary techniques. When <br /> mud rotary drilling is used, an-electric log will be performed for additional <br /> lithological information. Also during�mud rotary drilling, precautions will <br /> be taken to prevent mud from circulating contaminants by using a conductor <br /> casing to seal off contaminated zones. Samples will be collected for <br /> lithologic logging by continuous chip;and where needed by drive sample or <br /> core as specified by the supervising geologist. <br /> Geo_Probe Drilling Methods <br /> The geoprobe system utilizes a percussion hammer and hydraulically- <br /> powered system to drive probes which are approximately 1.75-inches in <br /> diameter to the desired depth and retrieve soil and groundwater samples. <br /> enviroso <br /> f <br />