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Temporary Well Installation and Groundwater Sampling SURFACE Depth to 7STEELIVE CASING Water Figure 1 III III WELL SCREEN: 0.020" III MACHINE SLOTTED 3, STAINLESS STEEL END CAP LEFT IN PLACE Groundwater samples are collected by removing the inner rod and attaching a 4-foot stainless steel screen with a drive point at the end(Figure 1). The screen and rod are then inserted in the outer barrel and driven to the desired depth where the outer rod is retracted to expose the screen. if enough water for sampling is not produced through the stainless well screen, a 1-inch PVC screen can be installed in the boring and the outer rod retracted to leave a temporary well point for collecting groundwater samples or water levels. Monitoring Well Installation and Development Permanent small-diameter monitoring wells are installed by driving the outer barrel and inner rod as described above. Upon reaching the desired depth the system is removed and 2-inch OD(1/2-inch ID)pre-packed PVC piping is installed. The well plug is created using granular bentonite. The well seal is constructed of cement and sealed at the surface with a conventional"Christy®Box"or similar vault. Monitoring wells are developed by surging the well with a small diameter bailer and removing 3 to 5 casing volumes of water until the produced water is clear. Groundwater Sample Collection and Water Level Measurement Prior to collecting groundwater from the wells the water l:vels are measured in all wells using an electronic water level gauge. Monitoring wells are prepared for sampling by purging three well bore volumes of water. Water is removed using small diameter bailers,a peristaltic pump,or manually using tubing with a check valve at the bottom. During removal of each volume, the temperature, pH and conductivity are measured and recorded on the field sampling form. Successive well volumes are removed until the parameters have stabilized or the well has gone dry. Prior to sampling,the well is allowed to recover to within 90%of the stabilized water levels. Groundwater samples are collected using small diameter bailers. The samples are decanted into laboratory supplied containers, labeled,recorded on a chain-of-custody form and placed on ice for transport to a certified laboratory. 1 Small diameter wells often produce small sample quantities and are appropriate for analysis of volatile and aromatic compounds and dissolved metals analysis using VOA vials. Obtaining liter-size samples can be difficult and time consuming. Monitoring wells installed by the direct push method are most effective at sites where the subsurface soils are more coarse than silt,gasoline components are the key contaminants of concern,and water levels are not more than 25 feet below ground surface. CLEARwATER GROUP(DIRECT PUSH) 2 revised October 5,2002