2024-02-01_REVISION - M1973021 (2)

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Ninth Technical Revision (TR09) to Permit M-1973-021, Holcim- WCR, Inc. Morrison Quarry January 2024 | 19 5 Exhibit G - Water Information This section summarizes changes to groundwater and stormwater/surface water management in the South Quarry. 5.1 Groundwater As discussed in Section 3.2, Groundwater Management subsection, groundwater water level measurements in and around the proposed Satellite Pit location identify groundwater present between El. 6,588 and El, 6600. These water levels indicate the need for groundwater management as the proposed Satellite South Pit is advanced. To manage this anticipated groundwater, as mining proceeds in the South Quarry, mining operations will proceed from east to west, creating a low point on the east side of the pit, south of the spur road. A sump will be maintained in this location of the pit where accumulated groundwater will be pumped and either discharged to Outfall 006 (directly east of the proposed sump location) or will be stored on site and either used to support operations or evaporated. Holcim is preparing a SWSP and plan for augmentation to replace depletions from evaporation or potential on-site use and a well permit to expose groundwater, which will be filed in 2024. Per AM07, the three monitoring wells surrounding the South Quarry, summarized in the table below, were installed and monitored monthly to evaluate water levels and determine if groundwater would be encountered. Since a plan for augmentation, SWSP, and well permit applications are under development, the monitoring wells around the South Quarry are no longer needed to determine if groundwater has been encountered. To streamline monitoring requirements, the monitoring wells located side- and up-gradient of the South Quarry, MW-2019-02 and MW-2019-03, will be abandoned. MW-2019-01 will continue to be monitored quarterly until Holcim receives an approved augmentation plan. MW-2019-02 and MW-2019-03 will be abandoned in 2024 and well abandonment reports (State of Colorado Form GWS-09) will be completed and submitted to the Division of Water Resources within 60 days of plugging and sealing the well/hole. Well ID #/ Permit # Location TR09 modification Well Information Top Elevation Depth (ft) Bottom Elevation MW-2019- 01/ 316737 East (hydraulically downgradient) of the South Quarry Continue groundwater level monitoring. Reduce to quarterly monitoring frequency. 6,646.0 246.4 6,339.6 MW-2019- 02/ 316738 South (hydraulically side gradient) of the South Quarry Discontinue monitoring. Abandon well. 6,670.0 274.3 6,395.7