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04/23/2003 15:41 209832511, WRIGHT EWIRONMEN `"? PAGE 08 <br /> Conductor casing will be used oat•the rnonitoriflg well advanced to 119 feet. ,A, steel eor:ductor <br /> casing will first be drilled into position to a depth of abou=t 65 feet-- The conductor will help <br /> prevent leakage from the upper to lower aquif6 zones. The steel conductor will use a -„2-iunch <br />' diameter boring and tett-inch conductor. The conductor will be lowered into the borehole and <br /> pressed about one foot into the undisturbed seta. .The annWus on the outside of the casing will <br /> be grouted into place using cement grout, and the drilling muck and water in3ide the cor:ductor <br /> will be bailed out. After 2�4 hours, a.seal check of the conductor will be made to ascertain <br /> whether leakage has occurred. The borehole will then telescope to air eigk-ingh diatmetr;:r hole <br /> and advanced to the ultimate depth. <br /> Once the aquifer strata, have been define,. the casing will be lowered to the `bottom of the <br /> s borehole_ The sand pack will be placed to a point about two feet above the slots. A end grout <br /> seal will be placed atop the.placed.,atop the san pack using a trexnie line, filling from the bottom to <br /> top of the borehole. A traffic-rated wellhead 'access box and security device will Gompl to the <br /> E wellhead. <br /> Montto Well SamVWad o ent All rnonitoring wells will be developed to rannove <br /> the drilling truck and drilling fluids in the shallo�v borehole wall, grade the sand pack and F rovide <br /> a wort complete hydraulic connection to the aquifer. A weU development log will be kept,of the <br /> well volumes removed until the water becomes c1=and the amount of sand pumped is minimal. <br /> The well will be allowed to recover for at least"72 hours prcot to sampling. The-well casr'V will <br /> I <br /> be surveyedto a known datum to accurmtel measure ground4rater elevation contours. <br /> The monitoring well casing elevations will be suiveyed to the same known elevation datum as the <br /> vda ing wells so accurate groundwater elevations and flow giadieat can be measured. <br /> Groundwater Satnnitna i <br /> The monitoring wells will be purged using calculated well volumes based upon the depth tc:water <br /> in the casing. Depth to groundwater measurements will be trade to tho nearest o.u�-one <br /> hundredth of one foot, and also checked for the presence of separate phase product. The w'll will <br /> be purged to remove stagnant water in the well casing. !As each purge.volume is rer.aaved, <br /> measurements of pH, electrical conductivity and temperature;will be taken until these para,neters <br /> stabilize over two purge volumeremovals, which is mterpMed to be aquifer water erAeri rig the <br /> casing. The well will be aEowed.to recover to%about M of the initially measured watea:level, <br /> after which the sample will be collected. <br /> j3 <br /> The water samples will be carefully collected,:with a clean bailer or pump discharge Brie and <br /> poured into the appropriate laboratory prepared container with n*imum cavitation. The water <br /> sample will be labeled, logged oito a drain-of custody forih, and placed.in a chilled ice chest. <br /> ked. <br /> Upon completion of well sampliatg, the well will'be closed and lot <br /> E <br /> Fag*6 of 6 <br /> • <br />