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3.0 RESPONSE PLAN SAMPLING <br />The first objective of the Response Plan sampling was to use a low -flow sampling technique to <br />determine if the TDS concentrations could be stabilized. The second goal was to analyze the <br />Response Plan data and other historical records to identify if the historical variability of results <br />and concentrations of TDS in well M -14 could be attributed to any identifiable site conditions. <br />Low -flow sampling was utilized during the Response Plan because it reduces the variability in <br />sampling technique that is inherent in other sampling methods, minimizes physical and chemical <br />stress on the aquifer, increases the ability to determine well stabilization, and reduces the chance <br />that changes in chemical concentrations are induced by the sampling technique. <br />3.1 Field Measurements and Observations <br />Samples collected under this Response Plan were collected utilizing a portable Grundfos Redi -Flo <br />2 pump with variable frequency drive (VFD) to control flow rates. Samples were collected from <br />well M -14 with the pump - intake located at a depth of 165 feet for each sampling event during the <br />Response Plan. Pump - intake placement at 165 feet was at the middle of the screened interval and <br />ensured that there would be limited or no entrainment of solids which may have accumulated in <br />the well bottom over time. Additional samples, beyond those required under the Response Plan, <br />were collected on September 25, 2013 and October 8, 2013 at sample depths of 155 and 175 feet <br />in order to determine if there might be localized analyte concentration variations in the vertical <br />profile of water in well M -14. <br />Water - quality indicator parameters and water levels were measured during purging, prior to <br />sample collection. Water - quality stabilization parameters were collected utilizing a YSI Pro Plus <br />with flow - through cell and included electrical conductivity (EC), dissolved oxygen (DO), <br />oxidation - reduction potential (ORP), pH, and temperature. Turbidity was also monitored in the <br />field utilizing a Hach 2100Q test kit. Water levels were monitored and pump flow rates (0.1 to 0.5 <br />L/min) maintained to ensure that minimal drawdown (approximately 0.33 feet) was maintained <br />during purging. Samples were collected after parameter stabilization and sufficient water was <br />purged from all tubing and equipment. Table 1 shows the field parameters at the times of sample <br />collection. <br />TR -32 M -14 TDS Response Plan Report . AES, Inc. <br />Battle Mountain Resources — San Luis, CO 3 January 2015 (Update) <br />