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Groundwater Well Development Field Standard Operating Procedure SWE-FSOP-602;Revision 1 Ahtna Southwest Environmental Operations 3. Begin surging the entire well screen using a surge block.A general rule for well development is to start slowly and gently,and gradually increase agitation as the well is developed.After a minimum of fifteen minutes, remove the surge block and immediately begin to bail the sediment-laden water. The length of time required at this stage will depend on various conditions such as water clarity, sediment levels, etc. Contain all development water for proper disposal, according to the site-specific work plan and SWE-FSOP-802 (Investigation Derived Waste Management). 4. Repeat surging and bailing for several cycles developing the well from the bottom of the screened interval upward by alternately using the surge block and the bailer. Record the surge interval and duration of surging and bailing. 5. During development, monitor the clarity of the water removed from the well. Measurements can be collected using a calibrated turbidity meter, with results recorded on the development log or FLB/notepad. [PFAS Project]: Fill a clear PFAS-free container with development water to observe turbidity if necessary. 6. Once it is determined that the well has been adequately developed using the bailer and surge block, use an appropriately sized pump to continue development, typically placed near the bottom of the screen interval. Wells with screen lengths greater than ten feet may be pumped from multiple depths during this process. 7. Pumping should begin at a rate to minimize drawdown. Monitor groundwater levels with a sounder and adjust accordingly. Ideally,the pump should be operated at the maximum discharge rate as long as groundwater levels remain above the pump intake. Collect water quality parameters to check for water quality stability, emphasizing turbidity until the well is determined to be fully developed. Generally, at least ten well volumes are removed or until turbidity reaches the desired level (DTSC, 2014). Typically, 5 NTUs is considered satisfactory. If turbidity stabilization cannot be achieved, contact the FTL for their recommendation. 8. If the well recovers naturally (i.e., drawdown can be controlled/eliminated during pumping), continue development with formation water only. However, if the well is purged dry at any point during development,the process to complete the well development should be determined by the FTL. 9. Variability in geologic, ambient water, and well construction characteristics create conditions where exact criteria for determining adequate completion of well development are not feasible. The purpose of the well, type of contaminant, and geologic conditions must be considered when deciding on the appropriate level of development. Therefore, determining what constitutes acceptable development is considered a professional judgment determined by the Project Geologist or PL. 10. Measure and record a final depth to water and total well depth after well development. 11. Manage development water generated during well development as IDW, in accordance with the designated work plan or site waste management plan, and SWE-FSOP-802 (Investigation Derived Waste Management). Page 10 of 11