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Home My WebLink About1.09 Floodplain Analysis North Hangs Mine February 2023 37 Floodplain Analysis See the attached floodplain analysis. North Hangs June 2021 1 MEMO: North Hangs Mine – Garfield County Conditional Use Permit Application Floodplain Impact Evaluation DATE: June 15, 2021 TO: Garfield County Flood Control Officer The North Hangs Mine, as proposed by Western Slope Materials, near Silt, CO, will disturb 72.8 acres of ground through sand and gravel mining. Mining of sand and gravel material at the site will entail the excavation of substantial depth of alluvium within the floodplain of the Colorado River in this area. In accordance with Garfield County Land Use Code (Section 3-301), WSM has prepared this floodplain analysis for the North Hangs Mine. It will analyze the baseline (existing) conditions of the floodplain in this area and demonstrate how the proposed mining operation will not lead to any increase in the water surface elevation of the 100-YR flood event in the area of proposed operation. 1. Modelling Basis and Methodology A flood routing model was built in the US Army Corps of Engineers HEC-RAS software. A steady state flow model using the Colorado Water Conservancy Board’s (CWCB) determined flow of 34,900 CFS for the 100-YR event was built. An upstream and downstream Normal Depth of 0.2- 0.3% was used as boundary conditions. These slopes are measured from the LIDAR survey data available from Garfield County. Garfield County LIDAR survey data was used as the basis for cross sections in the HEC-RAS model in both the baseline and developed conditions. The I-70 bridge was modelled as a single entity in each model based on the LIDAR captured elevations at of its abutments. Using Civil 3D models of the proposed maximum mining scenario (end of Phase 2), the LIDAR topography was modified for use in a developed scenario model. The results of the two models are compared to see if the change in topography adjacent to the Colorado River leads to offsite flood impacts. Baseline Conditions The baseline conditions of the area represent the current, pre-mining state of the Colorado River corridor in the area of the proposed operation. This includes portions of the Town of Silt, the I-70 bridge over the Colorado River, the Silt Pit south of the river, and the existing agriculture properties along the river downstream of I-70. Developed Conditions The developed conditions of the area represents the maximum mining state of the Colorado River corridor in the area of the proposed operations. Cross sections used in the baseline condition model are re-used in the developed conditions model, with the only change being the presence of the North Hangs June 2021 2 mining excavation and onsite berms. No permanent facilities are proposed as part of the mining and processing operations, and therefore no building pads are included. To be conservative in the HEC-RAS model, the mining excavation is modelled as an obstruction at its top. When pit dewatering is not taking place, the active mining cell will fill with groundwater to an elevation roughly four feet below the existing grade. If this condition was modelled completely in HEC-RAS, the four feet of depth to groundwater would provide some storage for floodwaters and potentially lowering the downstream flooding extents. Therefore, the mining excavation is modelled as an obstruction to ensure this storage component is not part of the model. 2. HEC-RAS Results Results of the HEC-RAS models are summarized in the table below. As shown, the water surface elevation (WSE, ft.) does not increase from the baseline to developed condition. This is expected as the mining activity does not create a fill in the floodplain that would cause floodwaters to route into new areas. North Hangs June 2021 3 Table 1. HEC-RAS Data Results River Sta Plan Q Total Min Ch El Crit W.S. E.G. Elev E.G. Slope Vel Chnl Flow Area Top Width Froude # Chl W.S. Elev W.S. Elev Change 190208 Baseline 34,900 5402.4 5407.8 5409.9 0.0 12.1 3368.1 2143.3 0.9 5407.8 -0.1 190208 P2 Mining 34,900 5402.4 5407.7 5409.9 0.0 12.5 3237.4 2116.3 1.0 5407.7 189185 Baseline 34,900 5399.5 5406.0 5409.1 1.0 14.1 2484.2 474.7 1.0 5406.0 0.0 189185 P2 Mining 34,900 5399.5 5406.0 5409.1 0.0 14.1 2484.2 474.7 1.0 5406.0 189067 I-70 Bridge Bridge 189060 Baseline 34,900 5399.3 5405.7 5408.7 1.0 13.9 2505.7 419.8 1.0 5405.7 -0.4 189060 P2 Mining 34,900 5399.4 5405.7 5408.7 0.0 14.9 2342.8 421.8 1.1 5405.3 188860 Baseline 34,900 5398.6 5405.2 5408.0 0.0 13.6 2619.9 1990.2 1.0 5405.2 0 188860 P2 Mining 34,900 5398.6 5405.1 5408.0 0.0 13.6 2620.5 1990.2 1.0 5405.1 188427 Baseline 34,900 5398.3 5401.9 5403.6 0.0 14.4 3799.0 7823.9 1.4 5401.9 -0.4 188427 P2 Mining 34,900 5398.3 5401.4 5403.2 0.0 14.4 3550.8 7818.8 1.6 5401.4 187293 Baseline 34,900 5393.6 5394.9 5396.5 0.1 14.5 3731.9 5660.3 2.2 5394.9 0 187293 P2 Mining 34,900 5393.6 5394.9 5396.5 0.1 14.7 3678.6 5608.8 2.3 5394.9 185842 Baseline 34,900 5390.3 5393.0 5394.4 0.0 12.2 4137.2 5353.5 1.4 5393.0 -0.1 185842 P2 Mining 34,900 5390.2 5392.9 5394.3 0.0 12.2 4167.2 5359.2 1.4 5392.9 184556 Baseline 34,900 5387.3 5390.4 5391.4 0.0 11.3 5721.6 5893.0 1.2 5390.4 0 184556 P2 Mining 34,900 5387.3 5390.4 5391.4 0.0 11.4 5714.9 5881.5 1.2 5390.4 183265 Baseline 34,900 5382.0 5386.9 5388.1 0.0 10.6 5773.0 5666.3 1.1 5386.9 -0.1 183265 P2 Mining 34,900 5382.0 5386.8 5388.1 0.0 10.8 5603.6 5706.3 1.2 5386.8 North Hangs June 2021 4 Cross Sections Cross sections are the basis of steady state flood modelling in HEC-RAS. The baseline and developed condition at each cross section is show in the figures below attached as Appendix 1. The cross sections at the mine location are shown in Figure 1. Each cross section shows the channel geometry at the cross section along with the water surface level (WS) for each scenario. The mining excavations are modelled as obstructions (solid black). Figure 1. Baseline vs. Developed Conditions North Hangs Phase 2 Mining Excavation Colorado River channel North Hangs June 2021 5 3. Floodplain Revisions The Federal Emergency Management Association and the Colorado Department of Public Health and Environment are currently working with Garfield County to revise the floodplain in this area. Prior to developing the HEC-RAS model for the North Hangs Mine, Lewicki & Associates consulted with CDPHE staff and reviewed the draft floodplain. The cross sections used in the North Hangs Mine HEC-RAS model are based on the draft floodplain model. Furthermore, the draft floodplain model was compared to both baseline and developed conditions as a general control of the model. Floodway No floodway is mapped in the area of North Hangs Mine. CDPHE staff informed Lewicki & Associates that no modelling of the floodway through this area is planned. Given that the developed condition shows no increase in the WSE from the baseline conditions, the North Hangs Mine will not alter flood patterns in this area, and thus will not affect whatever floodway may exist. North Hangs Phase 2 Mining Excavation Colorado River channel North Hangs June 2021 6 4. Conclusion Modelling of the North Hangs Mine’s potential impact on the flood waters of the Colorado River in this area shows no increase in WSE. Therefore, the North Hangs Mine will have no impact on flooding in the valley. Ben Langenfeld, P.E. benl@lewicki.biz (720) 842-5321 North Hangs June 2021 Appendix 1 – HEC-RAS Cross Sections 0 500 1000 1500 2000 2500 3000 3500 5395 5400 5405 5410 5415 5420 North Hangs Plan: 1) Baseline 6/16/2021 2) P2 Mining 6/16/2021 Merged US Survey 47000XS (ft) ( f t ) Legend EG PF 1 - P2 Mining EG PF 1 - Baseline Crit PF 1 - Baseline WS PF 1 - Baseline WS PF 1 - P2 Mining Crit PF 1 - P2 Mining Ground Ineff Bank Sta .04 .07 .035 .07 .1 0 500 1000 1500 2000 5398 5400 5402 5404 5406 5408 5410 5412 5414 North Hangs Plan: 1) Baseline 6/16/2021 2) P2 Mining 6/16/2021 (ft) ( f t ) Legend EG PF 1 - Baseline EG PF 1 - P2 Mining Crit PF 1 - Baseline WS PF 1 - P2 Mining WS PF 1 - Baseline Crit PF 1 - P2 Mining Ground Ineff Bank Sta .07 .035 .07 0 500 1000 1500 2000 5395 5400 5405 5410 5415 5420 North Hangs Plan: 1) Baseline 6/16/2021 2) P2 Mining 6/16/2021 (ft) ( f t ) Legend EG PF 1 - Baseline EG PF 1 - P2 Mining Crit PF 1 - Baseline WS PF 1 - P2 Mining WS PF 1 - Baseline Crit PF 1 - P2 Mining Ground Ineff Bank Sta .07 .035 .07 0 500 1000 1500 2000 5398 5400 5402 5404 5406 5408 5410 5412 5414 North Hangs Plan: 1) Baseline 6/16/2021 2) P2 Mining 6/16/2021 (ft) ( f t ) Legend EG PF 1 - P2 Mining EG PF 1 - Baseline Crit PF 1 - Baseline WS PF 1 - Baseline Crit PF 1 - P2 Mining WS PF 1 - P2 Mining Ground Ineff Bank Sta .1 .07 .035 .07 .1 0 500 1000 1500 2000 5396 5398 5400 5402 5404 5406 5408 5410 5412 5414 North Hangs Plan: 1) Baseline 6/16/2021 2) P2 Mining 6/16/2021 (ft) ( f t ) Legend EG PF 1 - Baseline EG PF 1 - P2 Mining Crit PF 1 - Baseline WS PF 1 - Baseline WS PF 1 - P2 Mining Crit PF 1 - P2 Mining Ground Ineff Bank Sta .07 .035 .1 0 2000 4000 6000 8000 10000 5380 5400 5420 5440 5460 North Hangs Plan: 1) Baseline 6/16/2021 2) P2 Mining 6/16/2021 (ft) ( f t ) Legend EG PF 1 - Baseline EG PF 1 - P2 Mining Crit PF 1 - Baseline WS PF 1 - Baseline WS PF 1 - P2 Mining Crit PF 1 - P2 Mining Ground Ineff Bank Sta .07 . 0 3 5 .07 0 2000 4000 6000 8000 5360 5380 5400 5420 5440 5460 North Hangs Plan: 1) Baseline 6/16/2021 2) P2 Mining 6/16/2021 Surveyed XS 4546000XS (ft) ( f t ) Legend EG PF 1 - Baseline EG PF 1 - P2 Mining Crit PF 1 - Baseline WS PF 1 - Baseline WS PF 1 - P2 Mining Crit PF 1 - P2 Mining Ground Ineff Bank Sta .1 .035 .07 0 1000 2000 3000 4000 5000 6000 7000 8000 5380 5390 5400 5410 5420 5430 5440 5450 North Hangs Plan: 1) Baseline 6/16/2021 2) P2 Mining 6/16/2021 (ft) ( f t ) Legend EG PF 1 - Baseline EG PF 1 - P2 Mining Crit PF 1 - Baseline WS PF 1 - Baseline WS PF 1 - P2 Mining Crit PF 1 - P2 Mining Ground Ineff Bank Sta .07 .035 .07 0 1000 2000 3000 4000 5000 6000 7000 8000 5360 5380 5400 5420 5440 5460 5480 5500 North Hangs Plan: 1) Baseline 6/16/2021 2) P2 Mining 6/16/2021 (ft) ( f t ) Legend EG PF 1 - Baseline EG PF 1 - P2 Mining Crit PF 1 - Baseline WS PF 1 - Baseline WS PF 1 - P2 Mining Crit PF 1 - P2 Mining Ground Ineff Bank Sta .07 .035 .07 0 1000 2000 3000 4000 5000 6000 7000 5360 5380 5400 5420 5440 5460 5480 North Hangs Plan: 1) Baseline 6/16/2021 2) P2 Mining 6/16/2021 (ft) ( f t ) Legend EG PF 1 - Baseline EG PF 1 - P2 Mining Crit PF 1 - Baseline WS PF 1 - Baseline WS PF 1 - P2 Mining Crit PF 1 - P2 Mining Ground Ineff Bank Sta .1 .035 .07 North Hangs June 2021 1 MEMO: North Hangs Mine – Garfield County Conditional Use Permit Application Floodplain Impact Evaluation DATE: June 15, 2021 TO: Garfield County Flood Control Officer The North Hangs Mine, as proposed by Western Slope Materials, near Silt, CO, will disturb 72.8 acres of ground through sand and gravel mining. Mining of sand and gravel material at the site will entail the excavation of substantial depth of alluvium within the floodplain of the Colorado River in this area. In accordance with Garfield County Land Use Code (Section 3-301), Western Slope Materials (WSM) has prepared this floodplain analysis for the North Hangs Mine. It will analyze the baseline (existing) conditions of the floodplain in this area and demonstrate how the proposed mining operation will not lead to any increase in the water surface elevation of the 100-YR flood event in the area of proposed operation. 1. Modelling Basis and Methodology A flood routing model was built using the US Army Corps of Engineers HEC-RAS software. A steady state flow model using the Colorado Water Conservancy Board’s (CWCB) determined flow of 34,900 CFS for the 100-YR event was built. An upstream and downstream Normal Depth of 0.2- 0.3% was used as boundary conditions. These slopes are measured from the LIDAR survey data available from Garfield County. Garfield County LIDAR survey data was used as the basis for cross sections in the HEC-RAS model in both the baseline and developed conditions. The I-70 bridge was modelled as a single entity in each model based on the LIDAR captured elevations at its abutments. Using Civil 3D models of the proposed maximum mining scenario (end of Phase 2), the LIDAR topography was modified for use in a developed scenario model. The results of the two models are compared to see if the change in topography adjacent to the Colorado River leads to offsite flood impacts. The only difference between Baseline and Development Conditions is the presence of the Phase 2 mining topography. Baseline Conditions The baseline conditions of the area represent the current, pre-mining state of the Colorado River corridor in the area of the proposed operation. This includes portions of the Town of Silt, the I-70 bridge over the Colorado River, the Silt Pit south of the river, and the existing agriculture properties along the river downstream. The baseline topography can be seen as a color gradient with the cross-section locations in Figure 1. The project area is marked in red. North Hangs June 2021 2 Figure 1. Baseline Conditions HEC-RAS Map Developed Conditions The developed conditions of the area represent the maximum mining state of the operation along the Colorado River corridor. Cross sections used in the baseline condition model are re-used in the developed conditions model, with the only change being the presence of the mining excavation and onsite berms. No permanent facilities or sturctures are proposed as part of the mining and processing operations, and therefore no building pads are included. Figure 2 shows the Developed Conditions topography and cross sections. To be conservative in the HEC-RAS model, the mining excavation is modelled as an obstruction at its top. When pit dewatering is not taking place, the active mining cell will fill with groundwater to an elevation roughly four feet below the existing grade. If this condition was modelled completely in HEC-RAS, the four feet of depth to groundwater would provide some storage for floodwaters and potentially lowering the downstream flooding extents. Therefore, the mining excavation is modelled as an obstruction to ensure this storage component is not part of the model. North Hangs June 2021 3 Figure 2. Developed Conditions HEC-RAS Map 2. HEC-RAS Results Results of the HEC-RAS models are summarized in the table below. As shown, the water surface elevation (WSE, ft.) does not increase from the baseline to developed condition. This is expected as the mining activity does not create a fill in the floodplain that would cause floodwaters to rise. North Hangs June 2021 4 Table 1. HEC-RAS Data Results River Station Plan Q Total (CFS) Min Ch El (ft) Crit W.S. (ft) E.G. Elev (ft) E.G. Slope (ft/ft) Vel Chnl (ft/s) Flow Area (sq. ft.) Top Width (ft) Froude # Chl W.S.E. (ft) W.S.E. Ch (ft) 190208 Baseline 34,900 5402.4 5407.8 5409.9 0.0 12.1 3368.1 2143.3 0.9 5407.8 -0.1 190208 P2 Mining 34,900 5402.4 5407.7 5409.9 0.0 12.5 3237.4 2116.3 1.0 5407.7 189185 Baseline 34,900 5399.5 5406.0 5409.1 1.0 14.1 2484.2 474.7 1.0 5406.0 0.0 189185 P2 Mining 34,900 5399.5 5406.0 5409.1 0.0 14.1 2484.2 474.7 1.0 5406.0 189067 I-70 Bridge Bridge 189060 Baseline 34,900 5399.3 5405.7 5408.7 1.0 13.9 2505.7 419.8 1.0 5405.7 -0.4 189060 P2 Mining 34,900 5399.4 5405.7 5408.7 0.0 14.9 2342.8 421.8 1.1 5405.3 188860 Baseline 34,900 5398.6 5405.2 5408.0 0.0 13.6 2619.9 1990.2 1.0 5405.2 0 188860 P2 Mining 34,900 5398.6 5405.1 5408.0 0.0 13.6 2620.5 1990.2 1.0 5405.1 188427 Baseline 34,900 5398.3 5401.9 5403.6 0.0 14.4 3799.0 7823.9 1.4 5401.9 -0.4 188427 P2 Mining 34,900 5398.3 5401.4 5403.2 0.0 14.4 3550.8 7818.8 1.6 5401.4 187293 Baseline 34,900 5393.6 5394.9 5396.5 0.1 14.5 3731.9 5660.3 2.2 5394.9 0 187293 P2 Mining 34,900 5393.6 5394.9 5396.5 0.1 14.7 3678.6 5608.8 2.3 5394.9 185842 Baseline 34,900 5390.3 5393.0 5394.4 0.0 12.2 4137.2 5353.5 1.4 5393.0 -0.1 185842 P2 Mining 34,900 5390.2 5392.9 5394.3 0.0 12.2 4167.2 5359.2 1.4 5392.9 184556 Baseline 34,900 5387.3 5390.4 5391.4 0.0 11.3 5721.6 5893.0 1.2 5390.4 0 184556 P2 Mining 34,900 5387.3 5390.4 5391.4 0.0 11.4 5714.9 5881.5 1.2 5390.4 183265 Baseline 34,900 5382.0 5386.9 5388.1 0.0 10.6 5773.0 5666.3 1.1 5386.9 -0.1 183265 P2 Mining 34,900 5382.0 5386.8 5388.1 0.0 10.8 5603.6 5706.3 1.2 5386.8 North Hangs June 2021 5 Cross Sections Cross sections are the basis of steady state flood modelling in HEC-RAS. The baseline and developed condition at each cross section are shown Appendix 1. The cross sections at the mine location are shown in Figure 3 and Figure 4. Each cross section shows the channel geometry at the cross section along with the water surface level (WS) for each scenario. The mining excavations are modelled as obstructions (solid black). Figure 3. Baseline vs. Developed Conditions at Cross Section 188427 North Hangs Phase 2 Mining Excavation Colorado River channel North Hangs June 2021 6 Figure 4. Baseline vs. Developed Conditions at Cross Section 187293 3. Floodplain Revisions The Federal Emergency Management Association and the Colorado Department of Natural Resources (CNDR) are currently working with Garfield County to revise the floodplain in this area. Prior to developing the HEC-RAS model for the North Hangs Mine, Lewicki & Associates consulted with CDNR staff and reviewed the draft floodplain. The cross sections used in the North Hangs Mine HEC-RAS model are based on the draft floodplain model. Furthermore, the draft floodplain model was compared to both baseline and developed conditions as a general control of the model. No inconsistencies were found. Floodway No floodway is mapped in the area of North Hangs Mine. CDNR 1 staff informed Lewicki & Associates that no modelling of the floodway through this area is planned. Given that the developed 1Discussions with Marta Blanco Castano, CDNR 05/12/21 North Hangs Phase 2 Mining Excavation Colorado River channel North Hangs June 2021 7 condition shows no increase in the WSE from the baseline conditions, the North Hangs Mine will not alter flood patterns in this area, and thus will not affect whatever floodway may exist. 4. Conclusion The analysis in this report has been conducted to satisfy the requirements of Garfield County Land Use and Development Code Sections 4-109 7-1002.A. Modelling of the North Hangs Mine’s potential impact on the flood waters of the Colorado River in this area shows no increase in WSE. Therefore, the North Hangs Mine will have no impact on flooding in the valley. Ben Langenfeld, P.E. benl@lewicki.biz (720) 842-5321 North Hangs June 2021 Appendix 1 – HEC-RAS Cross Sections 0 500 1000 1500 2000 2500 3000 3500 5395 5400 5405 5410 5415 5420 North Hangs Plan: 1) Baseline 6/16/2021 2) P2 Mining 6/16/2021 Merged US Survey 47000XS (ft) ( f t ) Legend EG PF 1 - P2 Mining EG PF 1 - Baseline Crit PF 1 - Baseline WS PF 1 - Baseline WS PF 1 - P2 Mining Crit PF 1 - P2 Mining Ground Ineff Bank Sta .04 .07 .035 .07 .1 0 500 1000 1500 2000 5398 5400 5402 5404 5406 5408 5410 5412 5414 North Hangs Plan: 1) Baseline 6/16/2021 2) P2 Mining 6/16/2021 (ft) ( f t ) Legend EG PF 1 - Baseline EG PF 1 - P2 Mining Crit PF 1 - Baseline WS PF 1 - P2 Mining WS PF 1 - Baseline Crit PF 1 - P2 Mining Ground Ineff Bank Sta .07 .035 .07 0 500 1000 1500 2000 5395 5400 5405 5410 5415 5420 North Hangs Plan: 1) Baseline 6/16/2021 2) P2 Mining 6/16/2021 (ft) ( f t ) Legend EG PF 1 - Baseline EG PF 1 - P2 Mining Crit PF 1 - Baseline WS PF 1 - P2 Mining WS PF 1 - Baseline Crit PF 1 - P2 Mining Ground Ineff Bank Sta .07 .035 .07 0 500 1000 1500 2000 5398 5400 5402 5404 5406 5408 5410 5412 5414 North Hangs Plan: 1) Baseline 6/16/2021 2) P2 Mining 6/16/2021 (ft) ( f t ) Legend EG PF 1 - P2 Mining EG PF 1 - Baseline Crit PF 1 - Baseline WS PF 1 - Baseline Crit PF 1 - P2 Mining WS PF 1 - P2 Mining Ground Ineff Bank Sta .1 .07 .035 .07 .1 0 500 1000 1500 2000 5396 5398 5400 5402 5404 5406 5408 5410 5412 5414 North Hangs Plan: 1) Baseline 6/16/2021 2) P2 Mining 6/16/2021 (ft) ( f t ) Legend EG PF 1 - Baseline EG PF 1 - P2 Mining Crit PF 1 - Baseline WS PF 1 - Baseline WS PF 1 - P2 Mining Crit PF 1 - P2 Mining Ground Ineff Bank Sta .07 .035 .1 0 2000 4000 6000 8000 10000 5380 5400 5420 5440 5460 North Hangs Plan: 1) Baseline 6/16/2021 2) P2 Mining 6/16/2021 (ft) ( f t ) Legend EG PF 1 - Baseline EG PF 1 - P2 Mining Crit PF 1 - Baseline WS PF 1 - Baseline WS PF 1 - P2 Mining Crit PF 1 - P2 Mining Ground Ineff Bank Sta .07 . 0 3 5 .07 0 2000 4000 6000 8000 5360 5380 5400 5420 5440 5460 North Hangs Plan: 1) Baseline 6/16/2021 2) P2 Mining 6/16/2021 Surveyed XS 4546000XS (ft) ( f t ) Legend EG PF 1 - Baseline EG PF 1 - P2 Mining Crit PF 1 - Baseline WS PF 1 - Baseline WS PF 1 - P2 Mining Crit PF 1 - P2 Mining Ground Ineff Bank Sta .1 .035 .07 0 1000 2000 3000 4000 5000 6000 7000 8000 5380 5390 5400 5410 5420 5430 5440 5450 North Hangs Plan: 1) Baseline 6/16/2021 2) P2 Mining 6/16/2021 (ft) ( f t ) Legend EG PF 1 - Baseline EG PF 1 - P2 Mining Crit PF 1 - Baseline WS PF 1 - Baseline WS PF 1 - P2 Mining Crit PF 1 - P2 Mining Ground Ineff Bank Sta .07 .035 .07 0 1000 2000 3000 4000 5000 6000 7000 8000 5360 5380 5400 5420 5440 5460 5480 5500 North Hangs Plan: 1) Baseline 6/16/2021 2) P2 Mining 6/16/2021 (ft) ( f t ) Legend EG PF 1 - Baseline EG PF 1 - P2 Mining Crit PF 1 - Baseline WS PF 1 - Baseline WS PF 1 - P2 Mining Crit PF 1 - P2 Mining Ground Ineff Bank Sta .07 .035 .07 0 1000 2000 3000 4000 5000 6000 7000 5360 5380 5400 5420 5440 5460 5480 North Hangs Plan: 1) Baseline 6/16/2021 2) P2 Mining 6/16/2021 (ft) ( f t ) Legend EG PF 1 - Baseline EG PF 1 - P2 Mining Crit PF 1 - Baseline WS PF 1 - Baseline WS PF 1 - P2 Mining Crit PF 1 - P2 Mining Ground Ineff Bank Sta .1 .035 .07