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Active Groundwater Sampling Standard Operating Procedure SWE-FSOP-401;Revision 1 Ahtna Southwest Environmental Operations 7. If the well dewaters, collect samples after the well recharges to approximately 80 percent of its pre-purge volume. 8. 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. 9. The bladder pump is then removed and cleaned with all other downhole equipment. Similarly, the tubing is removed and discarded unless it is dedicated to the well. 4.5 Submersible Pump Sampling 1. Measure groundwater level, then depth to bottom if needed. Decontaminate the sounder. 2. When using a submersible motorized pump,the pump is lowered into the water column. 3. Secure the electrical line to the appropriate power supply and the discharge line from the pump to a marked container such as a tank, drum, or bucket. The container has markings to track the volume of water purged from the well. 4. Start pump 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. Purge rates are not defined for submersible sampling, but the rate cannot drop the water level if higher rates are used. 5. 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. 6. Continue pumping until at least three well volumes have been removed. 7. Collect one set of water quality measurements from a fresh aliquot of sample after finished the well purging. Measurements are taken from a cup supplied with the multimeter. Note. Some project work plans specify water quality measurements after each well volume. Consult the PL or FTL for the project specifications. 8. Fill the laboratory-supplied sample containers (See Section 4.7 "Filling Sample Containers"). Typically,the a bailer is used to collect samples. However, if an appropriate tubing material is used and the pump can operate at less than 150 mL/minute,the samples can be collected directly from tubing connected to the pump. 9. If the well dewaters, collect samples after the well recharges to approximately 80 percent of its pre-purge volume. 10. In cases where recharge volume is insufficient to fill all containers,the PL will prioritize 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. 11. The pump is then removed and cleaned with all other downhole equipment such as tubing and electrical cables. 4.6 Temporary Well Sampling Procedures used to purge groundwater from temporary wells differ from permanent wells because the well is installed for immediate sample acquisition, and the well is usually not developed as is done with Page 11 of 14