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Ill. Sample Collection <br />Well Purging and Sampling: <br />The deep monitoring wells will be purged and then sampled. The monitoring wells will be <br />purged until the water quality characteristics (pH, temperature, and conductivity) have <br />stabilized. Stabilization is achieved when the pH reading stabilize to within 0.1 and the <br />temperature and conductivity readings stabilize to within 10 percent over a casing volume. <br />Purge water is considered to be non - hazardous at all sampling locations. <br />Before purging each well, the depth from the top of the well casing to the top of the water level <br />in the well will be determined and recorded. <br />The following equations can be used to calculate the casing volume. The first equation gives <br />the results in cubic feet (V1) and the second equation gives the results in gallons (V2): <br />Equation 1: <br />Equation 2: <br />Where:d = <br />V1 = 0.0057 * (d*d) * W <br />V2 = 0.043 * (d *d) * W <br />the well casing diameter in inches; and <br />W = the depth of water in the well casing measured in feet, calculated <br />by subtracting the measured depth to water in the well from the <br />total well casing length reported on the well installation details. <br />If a well is evacuated during purging, it will be allowed to recharge until the water level has <br />recovered to 80% of the static level or for a period not exceeding 24 hours before sampling. If <br />the well has not recovered sufficiently to allow sampling after 24 hours, this well will be noted as <br />"dry" during this sampling event. <br />After all samples have been collected, sampling equipment to be used at other sampling <br />locations will be decontaminated using DS /DI water. <br />