Laserfiche WebLink
Water Quality Measurements Field Standard Operating Procedure <br /> SWE-FSOP-101;Revision 1 Ahtna Southwest Environmental Operations <br /> If the pH of the water being measured is unknown, use a 3-point calibration method. The pH sensor is <br /> calibrated using a pH 7 buffer and two additional buffers, commonly pH 4 and pH 10. The 3-point <br /> calibration method accounts for the entire pH range and assures maximum accuracy when the pH of the <br /> media to be monitored cannot be anticipated. <br /> 4.1.2 Conductivity Calibration <br /> Perform calibration for conductivity according to the recommended manufacturer's calibration <br /> instructions. Conductivity is typically entered as mS/cm or uS/cm at 25°C. The typical conductivity <br /> standard solution has a specific conductance value of 1.413 mS/cm. Check the standard solution to <br /> confirm the value. <br /> 4.1.3 Oxidation Reduction Potential Probe Calibration Check <br /> A calibration check of the ORP probe can be performed by placing it into an ORP solution within <br /> approximately 10°C of the expected groundwater temperature or as close to groundwater temperature <br /> as possible. This solution is not intended for calibration purposes. It is a check to ensure the probe is <br /> working correctly. The reading is dependent upon temperature and should fall within a temperature- <br /> specific range described on the solution bottle before taking measurements. <br /> 4.1.4 Dissolved Oxygen Calibration <br /> Perform calibration for DO according to the recommended manufacturer's calibration instructions. <br /> Record the DO readings on the Field Calibration Sheet. <br /> 4.1.5 Turbidity Calibration <br /> Perform turbidity calibration with known standards according to the recommended manufacturer's <br /> instructions. Record the turbidity readings and the known standard units on the Field Calibration Sheet. <br /> 4.2 Flow-Through Cell Procedure <br /> 1. Secure the multimeter sonde into the flow-through cell. Connect a short discharge tube to the <br /> effluent connector at the top of the flow-through cell and place the other end into a 5-gallon <br /> bucket or discharge container. <br /> 2. Attach the second length of tubing from the pump's effluent to the bottom connector of the flow- <br /> through cell. <br /> 3. Turn on the pump and adjust the flow rate, so the flow-through cell slowly fills at an approximate <br /> rate of 100 mL/min. Monitor the water level in the well to stabilize the drawdown and adjust the <br /> flow rate accordingly. <br /> 4. Routinely measure and record the DO, ORP,conductivity, pH,turbidity,temperature, and current <br /> groundwater level throughout the purge at approximately 3-to 5-minute intervals. <br /> 5. Continue to measure and record the groundwater parameters and current groundwater level until <br /> the parameters stabilize according to criteria in specific sampling SOP's and project documents. <br /> 4.3 Open-Probe Procedures <br /> Water quality measurements may be necessary in lakes, streams, drainages, buckets receiving effluent, <br /> etc.where use of a flow cell isn't possible or required. In these cases, an "open-probe" measurement can <br /> Page 7 of 8 <br />