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.,. <br /> 18 November 1999 <br /> AGE-NC Project No. 97-0327 <br /> Page 8 of 9 <br /> 4.4. WELL DEVELOPMENT <br /> Development of the proposed wells will consist of a combination of bailing with a stainless steel <br /> bailer to remove the major portion of fine-grained sediment from inside the well, surging to flush <br /> out or draw in sediment from the filter pack and additional ground water evacuation (purging) with <br /> a submersible pump to finish the removal of fine-grained sediment. Developmental purging activities <br /> will be continued until field parameter (pH, electrical conductivity, and temperature) readings have <br /> stabilized and purged water is visually sediment-free. <br /> 4.5. 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 /> 4.6. GROUND WATER MONITORING PROCEDURES <br /> - Groundwater sample collection will be performed in accordance with PHS-EHD guidelines (Sa=7 <br /> Joaquin County Public Health Services Environmental Health Division Well Standardv) and <br /> CVRWQCB guidelines (Tri-Regional Water Quality Control Board Recommendations for <br /> P1•elitninary 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 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 /> 4.6.2. 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 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 /> Advanced GcoEnvironmental,Inc. <br />