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1 28 August 2000 <br /> 1 AGE-NC Project No 97-0249 <br /> Page 9of10 <br /> 1 4 6 EQUIPMENT DECONTAMINATION <br /> All sampling tools used for sample collection will be thoroughly rinsed with clean water after being <br />' washed with a solution of Alconox All down-hole drilling and sampling equipment will be pressure <br /> washed prior to starting the boring <br />' 4 7 GROUND WATER MONITORING PROCEDURES <br />' Groundwater sample collection will be performed in accordance with PHS-EHD guidelines (San <br /> Joaquin County Public Health Services Environmental Health Division Well Standards) and <br /> CVRWQCB guidelines (Tri-Regional Water Quality Control Board Recommendations for <br />' Preliminary Investigations and Evaluation of Underground Storage Tanks) sampling protocols <br />' 4 7 1 Static Water Level Measurements <br /> Pnor to all ground water purging and sampling, static water levels in each well will be measured <br /> using an electric water level indicator Water level data will be recorded to the nearest 0 01 foot from <br /> a reference point marked on the top of each PVC well casing Before and after each use, the <br /> measurement device will be rinsed with clean tap water <br /> 4 7 2 Well Evacuation <br /> Subsequent to measurement of depth to water and prior to sampling, each well will be purged using <br /> a bailer or submersible pump to ensure that the sample is representative of the surroundmg aquifer <br /> ground water The well will be purged until 1)a minimum of three casing volumes is removed from <br /> the well,and/or 2)the field-measured ground water parameters have stabilized However,if the well <br /> is purged dry prior to evacuating three casing volumes, a ground water sample will be collected. <br /> following 80 percent recovery of ground water within the well or within 24-hours ofwell evacuation <br />' 4 7 3 Sample Withdrawal <br /> Water samples will be collected from the momtornng well using a new, pre-cleaned disposable <br /> polyethylene bailer These bailers are disposed of after one use and require no decontaminating, <br /> thereby minimizing cross contamination due to sampling devices Samples will be drawn and <br /> collected in such a manner that agitation and exposure of the groundwater to the atmosphere is <br /> minimal Sample containers will be filled using the appropriate disposable sampling attachment <br /> which allows controlled flow out of the bottom of the bailer by lifting the check valve <br /> Advanced GeoEnviroamental,Inc <br />