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clay layers greater than 5 feet that are below the shallow water table. Factory-slotted casing is used thio Shout and extends at least 2 feet above the permeable water-bearing zone. The top of the well is solid casing. 'rhe annular spas;; ,.f the borehole is backfi led with washed, kiln-dried sand to a point at least i foot above the slotted screen. A seal above the Ater pack is formed by placing a 1- to 2-foot Jayer of bentoatite pellets on top of the sand. The bentonite Pellets are moistened by pouring clean tap water down the hole so that they can expand and seal the annulus. A neat cement grout is placed above the bentonite seal and brought to the ground surface. Well casings are protected from surface contamination,accidental entry or tampering with water-tight locking caps on the well e c and unauthorized surrounded by a concrete vault. Wells are clearly identified vita mete� or therare devices where the following information is recorded:well number, depth to water,depth of welt �. .^ sing data including location of screened intervaL The well seal in newly developed wells must set up for 48 to 72 hours prior to development. Since development of the well can volatilize contaminants present,the we 11 must also settle for at least 4!S tea 72 hours between development and the first purging/samp ling incident. Ail mOmtt'TW wells are initially developed to clean the well and stabdize sand,gravel, and _.. disturbed aquifer materials around the screened internal perforations. Wells are ciev. :oped by Pumping dor baling)and until water some cas�,As,where woclls an� �and specific conductance stabilize. In Installed in low permeability formations and the wells the well is allowed to ret�ver and is purge dry, P dry wee tints. Clean tap water is introduced into the well dam not recover rapidly enough. Pendiag Y'l r�Y laboratory analis,purge water from well development ar:d samplingis - plaid into DO'T-approved drums,labeled�+ith the na,_.:a of the and left at the site. Uncon ,well number, �mmaEed water may disposed of by the client. Water found to contain levels of contaminants above local or state action levels rMPAres that the client dispose of it in accordance with hazardous waste requireme= At the client's request,we can assist with the disposal of contaminated purge water. .