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-5- <br /> d. Record all calibrations, standardizations, and <br /> sample pH in the Field Log. <br /> 1 . 2 . 5 Groundwater Temperature Monitoring <br /> . Use a calibrated thermometer which is traceable to <br /> either the National Bureau of Standards (NBS) or an <br /> NBS traceable standard thermometer . <br /> . Collect samples in clean jars or plastic beakers . <br /> Swirl and discard the first portions . <br /> . Record the temperature in the Field Log. <br /> 1 . 2 .7 Groundwater Conductivity Monitoring <br /> . Calibrate the conductivity meter before the first <br /> well of the day with a known concentration of <br /> potassium chloride (KC1) solution as a standard. <br /> This information will provide an indication of the <br /> performance capabilities of the conductivity probe. <br /> • The following is a list of expected conductivities <br /> with varying concentrations ( normal = N) of KC1 <br /> solutions at 25°C: <br /> Concentration Conductivity . <br /> 0 .1 N KC1 12,856 umhos/cm <br /> 0 . 01 N KC1 1,408 . 8 umhos/cm <br /> 0. 001 N KC1 146 . 93 umhos/cm <br /> • Replacement or cleaning of the conductivity probe <br /> will be done if the degree of variance is greater <br /> than ±10% of the above known values. <br /> . Collect samples in clean jars or plastic beakers . <br /> Swirl and discard the first portions. <br /> . Follow the vendor ' s procedure for temperature <br /> correction. <br /> . Record all calibrations, temperatures, and con- <br /> ductivities (corrected to 25°C) in the Field Log. <br />