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SOP-009 Standard Operating Procedure Low-Flow Groundwater Quality and Sample Collection Page 5 of 9 Revision No. 1 April 2019 Sharpe Army Depot • Dissolved oxygen: ± 10 percent (milligrams per liter [mg/L]) • Temperature: ± 1.0 °C • Turbidity: ± 10% or less than 10.0 NTU Well purging will be continued until the field parameters meet the criteria above and requested groundwater samples have been collected, or until a maximum of three well volumes have been purged. 1. Measure the depth to water in the well. 2. Calculate well volume: V = ((π * D2)/4)*h V= Well Volume π = 3.1416 D=diameter of well (ft) h =depth of well (ft) An additional water level measurement should also be taken after monitoring is completed to assure the drop-in water level is not excessive. Complete paperwork as needed. 4.6 Water Level and Pre-Purge Procedures Prior to purging and sampling monitoring wells, all participants should discuss health and safety issues with their task leader and/or field manager. Field activities may change due to variations in equipment and well setup; therefore, always be prepared and document all changes in procedure. The following are typical procedures: • Confirm the well location with the proper data sheet by using a site map and checking the associated well’s identification tag. • Position the vehicle and/or the equipment downwind to reduce the possibility of contamination due to exhaust or other surrounding circumstances (such as wind, rain, or sampling close to a busy road or construction site); sample upwind, when possible. Any ambient condition, such as contaminants or weather, shall be noted in the sampling database. • Don appropriate protective equipment (i.e., gloves, protective clothing, and glasses). • For new wells, using a calibrated (hand-held) photoionization detector (PID), measure any off gas at the wellhead opening, immediately upon unlocking and opening the well. This practice is used for newly installed monitoring wells until a baseline has been established (generally four quarterly events). Refer to the Health and Safety Plan for hydrocarbon response criteria and response actions to be taken if specific levels are exceeded. • Decontaminate the water level meter on the first 3 feet of the tape and probe: rinse with deionized (DI) water followed by a Liquinox/water solution, and then DI water. • Remove the 3/4-inch hole plug from the well cap.