2022-07-18_PERMIT FILE - M2022018

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South Hinsdale Response to Objections �e 12 July 2022 Although Exhibit C (Items 11-12 on Page 17) specifically does include washing of construction materials, we do not expect any washing will be done. Washing was included in case future customers need washed material, so that washing can be done without requiring a technical revision (although DWR, DRMS and County would of course be notified). However, we have not yet been told by any potential customer of that need. a. The excavated material, due to the terrain, soils and geology and anticipated seasons, is expected to be very moist and using water sprays to control dust is unlikely, even under current drought conditions. Screening and other methods of dust control for processing would be used. Because this may arguably be "ground water" we have, at DWR request, submitted the above-referenced Forms to DWR. Again, we do not expect to expose or impound actual ground water. b. Magnesium Chloride "Magwater" or lignin sulfate will be applied as needed for dust control on the access road and in/around the plant/work area. We will use water only if necessary to meet federal and state standards for dust. Note that both magnesium chloride and lignin sulfate ARE approved by EPA for use even in areas with potential discharge into waters of the US. c. Approximately 1.5 acres of irrigated land is located within the affected area and will be dried up during the mining operations until reclamation is done. Based on a normal irrigation rate of 48-60 inches per year, drying up 1.5 acres will provide 6 to 7.5 acre- feet per year. As identified in item 11 of Exhibit 5, annual water consumption is calculated to be less than 1 acre-foot. This is not legally required as the water in this basin is not under administration, but provides extra assurance of protecting both water quality and quantities in this operation. d. We are not aware of any reference to using impounded water for anything, including irrigation, in Items 11 and 12 or elsewhere in Exhibit C. The only time impoundment MIGHT be done would be tanks or basins for recirculating wash water — if washing were to be done. Stormwater basins are intended and designed to detain, not retain water, and meet state requirements for having no visible surface water contained within them for more than 72 hours. Water would exit those basins by infiltration, evaporation, or pumping onto other portions of the affected area. Outlets for discharge are good engineering practice to provide for emergency and exceptional storm events and designed to control water in case of spills or excessive erosion and generation of sediment, and to prevent damage. 1.7 Backfill. A volumetric estimate of 1210 CY of backfill is provided as part of the table of reclamation costs in item 5b of Exhibit D. If mining is done as planned, without unforeseen conditions, there will be no backfill required. The excavation of materials would taper off at the final planned slope of 3H:1V or (if necessary) 2H:1V). Any flattening of slopes would be done via pushing material from the top of the working face, and not from the bottom, but the plan, as followed, requires neither. The 1210 CY was calculated to provide some contingency funds in case of unexpected problems. 1.8 Seeding on 2:1 Slopes. We cannot firmly commit to the total area that might be necessary to slope at 2H:1 V rather than 3HAV. However, we expect this to be 1.0 acre or less of the 9.1 acres significantly affected. This is in conjunction with the construction of the new alignment of Kleckner Lane, assuming USFS approval. This estimate is based on engineering approximations 5182.22-003 WASTELINE, INC. Page 7 of 107