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01 September 1999 <br /> AGE-NC Project No 97-0301 <br /> ' Page 9of10 <br /> ' 4 6 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 Ditiision 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 6 1 Static Water Level Measurements <br /> Prior to all ground water purging and sampling, static water levels in edt_h 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 6 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 surrounding 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 groundwater 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 /> follo A ing 80 percent recovery of ground water within the well or within 24-hours of well evacuation <br /> ' 4 6 ') Sample Withdrawal <br /> ' Water samples will be collected from the monitoring well using a new, pre-cleaned disposable <br /> polyethylene bailer These bailers are disposed of after one use and require no decoctaminating, <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 /> 4 6 4 Sample Handling <br /> Ground water samples will be collected into laboratory supplied containers Ground water samples <br /> ' for TPH-g, TPH-d, BTEX and fuel oxygenate (EPA 8260) analyses will be collected into 40-m1 <br /> 4dianced GcoLn%iron mental Inc <br />