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clay layers greater than 5 feet that are below the shallow water table 1 aL;tory-slotted casing Ls isLsed throughout and extends at least 2 feet above the permeable water-beanng zone The top of the well is solidi rasing. The annular space of the borehole is backfilled with washed, kiln-fined sand to a point at least s foot above the slotted screen. A seal above the filter pack is formed by placing a 1- to 2-foot layer of bentonite 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 Heat cement grout is placed above the bentonite seal anis brought to the ground surface. Well casings are protected from surface contamination, accidental damage, and unauthorized entry or tampering with water-tight locking caps on the well casings. The caps are usually surrounded by a concrete vault. Wells are clearly identified with a metal tag or other device where the foilowing information is recorded well number, depth to water,depth of well, casing data including location of screened interval. REU 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 well must also settle for at least 48 to 72 hours between development and the fust pwWag/sampling incident. All monitoring wells are irunally developed to clean the well and stabilize sand,gravel, and disturbed aquifer materials around the screened internal perforations. Wells are developed by primping(or bailing)and surging imhl water ttirbxaty and specific condueta...,.e stabiltze. In some cams,where wells are Installed m low permeability formation and the wells purge dry, the well is alloaad to recoviiw and is pinged dry three tames. Clean tap water is introduced lino the weD dws not recover rapidly enough. P water from well deve nt and sampling is e�8 ��7 Y F� �F� F� placed into DOT-approved dnims,labeled with the nanic of the mte,address,well number, and left at the site. Uncontamiaated water may be disposed of by the client. Water found to eontam levels of contaminants above local or state action Jewels requires that the cheat dispose of it in accordance with hazardous waste requirements. At the client's inquest,we can assist with the drsposal of contaminated purge water.