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Active Groundwater Sampling Standard Operating Procedure SWE-FSOP-401;Revision 1 Ahtna Southwest Environmental Operations VOC/GRO analysis without waiting. Volatile compounds will escape if the water column is small, use your best judgment, and log the actions taken. 9. In cases where recharge volume is insufficient to fill all containers, the PL will priortize the order based on project objectives. If necessary, allow the well to recharge overnight, but not more than one day, and continue with the remaining bottles. 10. The bailer and any equipment coming into contact of contaminated surfaces are cleaned. 4.4 Low-Flow Sampling 1. Measure groundwater level, then depth to bottom if needed. Decontaminate the sounder. 2. Set the pump inlet: Bladder Pump. When using a bladder pump,the pump itself is lowered into the water column. Attach the appropriate length and diameter of the tubing, so the blader pump intake is within the screened-interval at the depth determined during the pre-sample planning. Adjust for site conditions and record depth. Secure the airline to the pump controller. Connect the discharge line from the pump to the bottom intake of the flow-through cell of the water quality meter. Note. Bladder pump pressures, refill, and discharge rates are adjusted to achieve the desired flow rates. Equipment operators should be thoroughly familiar with the operation of bladder pumps. Peristaltic Pump.The pump remains at the ground surface, and tubing is lowered into the water column when using a peristaltic pump. Attach the appropriate length and diameter of the tubing, so the peristaltic pump intake is within the screened-interval at the depth determined during the pre-sample planning.Adjust for site conditions and record depth. Note. Peristaltic pumps are limited in that water can be pumped to the surface from a maximum depth of approximately 25-30 feet. 3. Start pumping and record time.The initial rate should be low enough to avoid drawing down the water table, increasing the rate while maintaining the water level. Low-flow sampling is achieved in the range of 100 mL/minute to 500 mL/minute. 4. If a drawdown of more than 4 inches or 1%of the water column,whichever is lesser, is observed, adjust the pumping rate to reduce the drawdown as much as possible. If the pump rate exceeds the well's recovery rate,the pump intake will have to be lowered as needed to accommodate the drawdown. 5. Once drawdown is stable, and water has begun to discharge from the flow-through cell, start recording water stabilization/quality parameters and depth to water measurements. Continue measurements until the water stabilization parameters meet criteria (Section 4.2.2"Groundwater Parameters"). 6. Disconnect the tubing from the inlet of the multimeter flow cell to begin filling the laboratory- supplied sample containers directly from tubing connected to the pump (See Section 4.7 "Filling Sample Containers"). Page 10 of 14