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01/29/2004 16:53 20952 GEOLOGICAL TEq&S PAGE 05 Geoprobe®Groundwater N ,Wring Page 1 of 2 a a • be a ;K HOME ar ',tf)prn e^ Tcot�k I Sampling: kit-Groundwater-Soil Gas_Manuel I.QW,M,gnitp.,jng I Hydraulic Conductivity Geotechnical I Dirac[Sensing 0 Goo Rodwater Monitodfig Weis Advo nta,jes There's lot of excitement in the Environmental Industry about Geoprobe®Prepacked Screen Sizes Well Scr ens designed for setting Small Diameter Monitoring Wells. Prepacked screens Installation consist a standard, slotted PVC well screen pipe aur unded by a stainless steel mesh. Prepacked scraonsehown wt. Sampling Sand is acked between the slotted PVC andAie Ac+:essor!es the stain ss steel mesh.Since the sand ispacked ound the slotted PVC before the well ASIM screen i installed, using prepacks guarantees Standards that san will be located directly around the well scr n. This makes well installtion quicker Publl;hecf and mor efficient than traditional methods. Research Read m re about Geoprobe®Prepack Advantages... Prepack Yell screens are available in two outside diameters... 1.4 inches OD (0.5 in. or 0.75 in. I )and 2.5 inches OD (1.0 in. or 1.5 in. ID). To install a monitoring well with these stage prepacks, probe rods are first driven to depth with a Geoprobe®brand percussion probing machine. The well assembly is then lowered into the probe rod !' 3 string with threaded PVC riser pipe.The small diameter prepack well screen assembly uses 0.5- ."':F ,, y inch Schedule g0 PVC riser pipe and is installed with 2.125-inch OD probe rods. The larger diameter -Z"' prepack well assembly uses 1.0-inch Schedule 40 PVC riser pipe and is installed with 3.25-inch OD probe rods. Close-t p of the annular seal at 9 feet b9s.Th re are no voids in the grout Once the well assembly is lowered to the bottom of and tho well casing remains cen- the probe rod string, the probe rods are retracted to tered u the annular space.(Blue a point above the screen. A sand barrier, installed scale fir inches) directly above the well screen, prevents grout from entering the screens.This barrier can be created either by natural formation collapse (occurring during t initial probe rod retraction) or by gravity installation of fine-grade sand through the rod a inulus. With the barrier in place,granular bentonite or bentonite slurry is then installed n the annulus to form a well seal. Geoprobe®Small Diameter Monitoring Well Benefits include: Q flok and simple installation. • Pi specked Screen designed with 20/40 grade environmental sand. http://www.geoprobe.conV roducts/tools/gw_nonitoring/well_-Xmenu.httn 1/29/2004