ARCHIVED REPORTS_XR0007388 CASE 1

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KLEINFELDER • The screen length is reduced if an aquitard with a minimum thickness of 5 feet is encountered If an apparent aquitard is encountered, athe well is usually cross iInf-i confined aquifer into the aquitard Effort is made not to screencross two aquifers conditions or high vadose zone contamination dwaterountere , the well screen is Wells are usually not set unuareas of ally not set above the depth of first encountered group suspected significant soil contamination • The PVC pipe and end caps are steam cleaned prior to installation The annular space between the screen and the wall of the boring is backfilled with the appropriate clean sand to approximately 2 feet above the top of the perforated sections Based on soil logs or a sieve test, modifications may be made tremm ed,iugingnl an watersize of to be used Installation of the sand may require that the s A 3- to 5-foot bentonite plug is placed above the sand pack ttopnfilt ate into lheagainst watersurface water infiltration and to reduce the potential for cement grout The remaining annular space is filled to the surface with cement/bentonite grout The wells are secured in an aboveground or underground set locking fl�sh tostovepipe ground surface wehen ads may be enclosed in a water tight cement utility located in a traffic area A-3.2 Monitoring Well Develo merit The wells are developed to reduce the effects of drilling on the formation and to increase the effective hydraulic radius of the wells Monitoring wells are generally developed 24 to 48 hours after installation to allow the grout to set Each well is first sampled with a clear disposable bailer to visually inspect for a hydrocarbon layer or sheen If no product layer or sheen is observed on the water, the well is developed by surging, pumping, or bailing Surging along the filter screened and the well,tared to he well sand pack performed to draw the sediment from the formation into the filt p Development continues until the discharge runs relatively clear of fines Approximately 5 to 10 well volumes are generally removed from each monitoring well Discharge water is stored in 55- gallon drums and left on site for later discharge ordisposal number and he iancontactdepending per on andophone ratory results The drums are labeled with the date, w number A-3.3 Equipment Decontamination To reduce the potential for cross-contamination betweendeveloping rinsed enudis lled water or ipment is washed in a trisodium phosphate or non-phosphate detergent solution and steam cleaned prior to use in the next monitoring well Page A-4 28209 T061ST05R717/LTV 1v June 23,2005 IQ 2005,Kleinfelder, Inc