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Page 4 of 14 <br />SOP NUMBER 0.0 Monitor Well Groundwater Sampling <br />4.1.3 Instrument Calibration <br />Electronic equipment used during sampling includes a water level measurement probe, a pH <br />meter with temperature scale, a specific conductivity meter, dissolved oxygen meter and a <br />oxidation reduction potential meter. Before daily field operations and at end of day, the sampler <br />shall verify that all of these are operating properly. The pH and specific conductivity meters <br />require calibration prior to use each day at a minimum. Periodic calibration checks should be <br />performed to ensure that meters are reading consistently. If not, the meters should be recalibrated <br />and the calibration schedule adjusted accordingly. Calibration times and readings will be <br />recorded in a notebook or log sheets to be kept by the field sampler. Specific instructions for <br />calibrating the instruments are given in SOP No. "*. <br />4.1.4 Well Volume Calculations <br />The following equation shall be used to calculate the volume of water to be removed during well <br />evacuation: <br />For 0 -inch (inside diameter) well: <br />Evacuation Volume _ Total Depth - Water Level Depth 0.16 gal <br />[gal] [ft] x ft <br />For 4 -inch (inside diameter) well: <br />Evacuation Volume _ Total Depth - Water Level Depth x 0.65 gal <br />[gal] [ft] ft <br />For 6 -inch (inside diameter) well: <br />Evacuation Volume _ Total Depth - Water Level Depth x 1.47 gal <br />[gal] [ft] ft <br />— gallons/ 1 well casing volume <br />-- gallons/ 1 well casing volume <br />- gallons/ 1 Well casing volume <br />Multiply the volume of one well casing volume by three (3) to obtain the minimum volume of <br />water to be evacuated. <br />4.1.5 Well Evacuation <br />The purpose of well evacuation is to remove stagnant water from the well and obtain <br />representative water from the geologic formation being sampled while minimizing disturbance to <br />the collected samples. Before a sample is taken, the well will be evacuated until a minimum of <br />three well casing volumes have been removed and field parameters have stabilized or until the <br />well is bailed /pumped dry. Wells shall be evacuated on the same clay that samples are taken. <br />Evacuated well water will be disposed of according to SOP'"'`. Spent decontamination water <br />will be disposed of away from the well head. <br />Before well evacuation begins, the following procedures are to be performed at each well: <br />•• Note the condition of the outer well casing, concrete well pad, protective posts (if present), <br />and any other unusual conditions of the area around the well. <br />o Open the well. <br />a Note the condition of the inner well cap and casing. <br />0 -4 <br />