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Caution. Be careful when"kneading"the screen Sudden screen slippage can pinch hands between the screen and the probe rod To prevent screen slippage, have an assistant hold onto the prepack during the ' "kneading"operation 4 Add additional five-foot prepacks to obtain the desired screened interval 0-rings can be installed between the prepack sections if desired ' 5 With the assistance of second person,attach five- foot sections of l 0-inch Schedule 40 PVC Riser to the top of the screen assembly O-nngsare re- Plastic Plug quired at each riser joint to prevent groundwater, (13227) located above the desired monitoring interval, from seeping into the well Continue to add riser 1 0-in Sch 40 PVC sections until the assembly reaches the bottom of (11�2876�� the probe rods (Fig 5 7) At least one foot (0 3 m) of riser should extend past the top probe rod Place the plastic plug into the top riser Duct tape may be used to help keep the plug in the riser 6 It is now time to pull up the probe rods from around the well screen and riser Reposition the probe unit so that the Rod Grip Puller can be attached to the rod string 7 Retract the rod string the total length of all the screens plus an additional 3 feet (1 m) While pulling the rods, observe whether the top PVC 1 0-m x 2 5-m OD riser stays in place or moves up with the rods Prepack Screen (11679) ~L a) if the riser stays in place,stable formation con- ditions.are present Continue retracting the rods to the depth specified above Go to Section 4 4 ~� b) if the riser moves up with the probe rods,have a second person hold it in place while pulling up 1 0-1n x 2 5 in OD the rods An additional section of PVC riser may 4: ~ Prepack Screen ' be helpful Once the probe rods have cleared the =`> (11679) L� lower section of screen, the screen and riser as- sembly should stop rising with the rods Con- tinue retracting to the depth specified above Go to Section 5 4 c~' c) if the risers continue to move up with the probe L'n PVC Bottom Plug rods and cannot be held in place by hand, sand (12881) heave has most likely caused the screen to bind to Expendable Pant the inside of the rods Extension rods are now 3 6-in OD ' required (Refer to Figure 5 8 for an illustration (AT3215) of extension rod accessories) FIGURE 5 7 Prepack Assembly Inside Probe Rods Standard Operating Procedure Page 14 1 Qin x 2 5-in OD Prepack Screen Monitoring Well