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. 25 January 2001 <br /> AGE-NC Project No 99-0559 <br /> Page 12 of 14 <br /> with a peristaltic pump consisting of polyethylene tubing and a ball check valve to finish the removal <br /> of fine-grained sediment Developmental purging activities will be continued until field parameter <br /> (pH, electrical conductivity, and temperature) readings have stabilized and purged water is visually <br /> sediment-free <br /> 65 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 each boring <br /> 6 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 Division Well Standards) and <br /> CRWQCB guidelines (Tri-Regional Water Quality Control Board Recommendations for <br /> Preliminary Investigations and Evaluation of Underground Storage Tanks) sampling protocols <br /> 6 6 1 Static Water Level Measurements <br /> Prior 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-toot from <br /> a reference point marked on the top of each Teflon well casing Before and after each use, the <br /> measurement device will be rinsed with clean water <br /> 6 6 2 Well Evacuation <br /> Subsequent to measurement of depth to water and prior to sampling, each well will be purged by <br /> inserting a 3/s-inch outer diameter polyethylene hose equipped with a ball-valve water tip (lift bailer) <br /> through the selected well chamber into the specific water-charged screened interval and oscillating <br /> the tube vertically to lift the water The well will be purged until 1) a minimum of three casing- <br /> water volumes is removed from the well, and/or 2) the field-measured ground water parameters have <br /> stabilized However, if the well is purged dry prior to evacuating three casing-water volumes, a <br /> ground water sample will be collected following 80 percent recovery of ground water within the wel I <br /> or within 8 hours of well evacuation <br /> Advanced Gec&Fivironmental,Ine <br />