2023-05-25_PERMIT FILE - M2022048 (18)

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i All data collection will be completed at L.G. Everist' s expense . Data will be provided to DRMS and the well owner upon their request . If a well owner chooses not to allow the permittee access to collect the above data, they will be provided with a form that they can sign and date to document that they have been provided with an opportunity to have their well characterized at the permittee' s expense, but have chosen to decline to participate . L.G. Everist, Inc. has installed 6 piezometers (a.k. a. Monitoring Wells) around the mine and plan to install an additional 6-7 wells to collect more groundwater elevation data and to be used for water quality monitoring and research. Their locations are shown on the maps and on trap ExxiBiT G-1 WELL Map. L.G. Everist started data collection in July 2019 and will do monthly depth readings throughout the life of the mine . We will provide a summary of the data yearly with the Annual Report . Mitigation Trigger-- Starting in July 2019, L.G. Everist, Inc. began to collect groundwater elevations from newly installed monitoring wells on and around the mine area to establish historic ground water elevations around and on the site . The period July 2019 until installation of the Phase 1 liner will be used as the baseline for triggering mitigation actions . Thisbe way the baseline data needed for the areas are in place well before installation of the slurry walls will begin . The permit area has two areas where the depth below ground level area vastly different . The dividing line between these land features is a natural bank where the river valley transitions from the floodplane-plain on the east side to the upland area along the west side . In the eastern area, Phases 1 and 24, the natural groundwater depths vary from 2 . 9 to 4 . 4 feet, average 3 . 5 ft . below the surface. On the western areas, Phases 3� and 4, the natural groundwater depths vary from 16 . 7 to 23 . 9 feet, average 19 . 5 ft . , below the surface between June 2019 and October 2022 . These ground water depths and averages may change prior to mining commencing. The important area for mitigation lies along the eastern section of the south line or area along the Abbett Farms land. Along this line the average depth to ground water varies from 7 . 2_ on the west to 4 . 4 feet below the surface at MW #7, near the river . This covers a section approximately 1860 feet west of the river . The mitigation plan is designed for this area as it could likely be the most impacted if there was a significant increase to the groundwater elevations due to mounding. The model predicts that the potential mounding affect would vary from as much as 2 . 5 feet on the west end of this strip to approximately 1 foot at the eastern corner of the slurry wall on the east . It also indicates that if needed, a simple perforated pipe, 12 30