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The Leodville Mill Environmental Sampling Procedures <br />Water Sample Collection <br />Page 2 -4 <br />QUALITY CONTROL <br />• Between measurements, clean the electrode with deionized water; throw the <br />rinse -out. <br />• Duplicate measurements should be made after every ten samples, at a <br />minimum, or after each set of samples, whichever comes first. <br />• Verify the calibration of the electrode and meter after every ten samples or at <br />the end of each set, whichever comes first. The verification is conducted with <br />the pH 7.0 buffer solution to assure the calibration of the system is <br />maintained. <br />2.2.2 TEMPERATURE MEASUREMENT <br />The following procedure applies to mercury thermometers. Many pH and <br />conductivity meters available have electronic temperature probes that are not <br />subject to this procedure. <br />• Inspect thermometers for defects such as cracks or gaps in the mercury prior <br />to their use. <br />• Put a water sample of at least 200 milliliters into a beaker or sample bottle. <br />• Place the thermometer in the sample and allow the instrument to equilibrate <br />for about one minute. Do not allow the thermometer bulb to touch the sides <br />of the container. <br />• Read the temperature to the nearest one degree Centigrade ( °C) and then <br />record this value in the logbook. <br />• The thermometer should be checked against the NIST - calibrated field <br />laboratory thermometer on a quarterly basis. They should agree within 0.5 °C. <br />2.2.3 REFERENCES <br />Standard Methods for the Examination of Water and Wastewater, 17th Edition, <br />1989, APHA - AWWA -WPCF, pp. 4 -94 to 4 -101, pp. 2 -57 to 2 -61. <br />1989 Annual Book of ASTM Standards Volume 11.01 Water (I), Designation: D 1293- <br />84, Standard Test Methods for pH of Water, pp. 213 -221, and Standard Test Methods <br />for Electrical Conductivity and Resistivity of Water pp. 134 -139. <br />April 2013 <br />