2014-01-29_HYDROLOGY - P2009025 (8)

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SOP for Operation and Calibration of Field Water Quality Instruments 1 1. INTRODUCTION This standard operating procedure (SOP) manual describes the general materials, equipment, and procedures for the operation and calibration of field water quality sampling instruments. Specific requirements for individual pH, temperature, dissolved oxygen, and specific conductance measuring instruments can be found in the manufacturers' manuals for these instruments. The objective of this document is to define the standard procedure for the operation and calibration of various field water quality instruments to ensure the collection of accurate data. 2. MATERIALS REQUIRED • Field pH meter, specific conductance meter, dissolved oxygen meter, ORP meter, and thermometer • Calibration standards (i.e., pH 4.01, 7, and 10 solutions, conductivity standard solutions) • Beaker or clean plastic container • Distilled or deionized water in a spray bottle or squirt bottle dispenser • Ice (office use) • GPS or altimeter 3. PROCEDURE 3.1 Temperature Field thermometers will normally be calibrated semi - annually in the office prior to field work using a high - precision NIST - traceable thermometer. However, some thermometers are factory calibrated, and the following procedures do not apply. Whetstone typically uses an Oakton® PC 10 pH/conductivity /temperature meter or a YSIO 550A D.O. meter to measure temperature. These meters have factory calibrated temperature probes which do not require calibration. In no cases shall a liquid mercury thermometer be used in the field for water quality sampling. 3. 1.1 Calibration 1. Set up an ice -bath in a suitable container. 2. Place identifying number on thermometer(s) to be used. 3. Immerse in ice -bath and read temperature while still immersed to the nearest tenth of a degree centigrade. Compare to high- precision laboratory thermometer. Record thermometer number and corresponding reading. Record calibration factor - difference between laboratory and field thermometer readings. 4. Immerse thermometers in water at room temperature. Read temperature while still immersed to the nearest tenth of a degree centigrade. Compare to high- precision laboratory thermometer. Record thermometer number and corresponding reading. Record calibration factor - difference between laboratory and field thermometer readings. 3.1.2 Field Operation 1. Immerse the thermometer probe in a container filled with a sample (for groundwater) or directly into the stream (for surface water). If a container is used, the sample should not be allowed to sit more than five minutes before the temperature is measured. 2. Immediately measure the temperature. Read the meter, while still immersed, to the nearest tenth of a degree centigrade. Record in the field log book or on an appropriate water quality form. 3. Rinse the thermometer probe thoroughly with deionized water before storing. 4153A.140129 Whetstone Associates