2021-10-29_PERMIT FILE - M2021064 (6)

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location and depth of other known wells in the area, the mining activities proposed will have no reasonable potential for any adverse impact. There will be no blasting at this site. 6. Prevention and mitigation actions: As discussed above,the area to be mined is well above all observed and recorded all bodies of water.There will be no planned surface discharge of storm water which has contacted exposed stripped areas, mining areas, or stockpiles of extracted materials,waste materials, or topsoil. As necessary, storm water pollution prevention and management actions, including erosion and sedimentation control,will be implemented as required by the Colorado Discharge Permit System storm water general permit for which coverage has been obtained for this site(prior to beginning mining), in case discharge is necessary.This meets the requirement for an NPDES permit and covers dewatering and process(wash)water as well as storm water, and application has been made for coverage. Since surface water flow will instead infiltrate into the bench's alluvial deposits at the west edge of pit and reclaimed areas (along the top of the cliff)and is presumed to flow into the creek alluvial aquifers as subsurface flows, no net impact on creek or river flow is anticipated. Overall design of the pit was done to plan for a minimum impact on surface and ground water. 7. Prohibited actions necessary to protect water systems: None known at this time,other than compliance with best management practices and specific items to protect the groundwater as listed above. Best management practices(BMP)forbid the discharge of heavily sediment-laden waters and implementation of spill control and countermeasures actions to prevent discharge of a spilled substance. No discharge of surface water is planned.The mining is planned to prevent negative impacts on ground and surface water and to make maximum use of existing water resources in accordance with state water law. G-3. PROJECT WATER REQUIREMENTS: WATER USE: Water use for extracting and processing aggregates from the pit will be low,amounting to less than 5 acre-feet per year under worst case conditions(including water contained in construction materials). This water will come from off-site registered municipal and industrial water sources and will be trucked in. No dry-up of irrigated land, and no augmentation or substitution is required. The primary use of water on the site is for dust control,with secondary use for washing (if washing is done on site) and compaction of backfill. Use of dust control chemicals will reduce water use on-site,particularly for traffic- generated dust control and control of dust from stockpiles. If materials are washed,water will be recycled, reducing use and discharge, as well as protect water quality. For evaluation purposes, based on the assumptions listed below Table G-2,the estimated operating losses of water for the operation are shown in this table.5 Table G-2. Maximum Project Water Requirements Activi Days gal/day gal/day Area Acre-feet Remarks Control dust on roads, stockpiles 120 800 1.5 ac 0.29 as needed Control dust on plant site 60 800 2.0 ac 0.15 As needed Control dust in processing 60 500 NA 0.09 As needed Control dust during extraction 60 500 1.0 ac 0.09 As needed Total trucked/site 2600 0.62 Max during processing Water removed with products - - NA 8.16 Worst case 2% by wt Washing of material - - NA 0 No planned Total consumed per year 9.41 acre-feet This is based on the following assumptions: • 72,000 tons per year produced. • Maximum areas requiring dust control per day is 4.5 acres(not all road,stockpile, storage and other affected land requires daily watering for dust control). 5 Based on assumptions as discussed in Exhibit M. C&J Gravel Products, Inc. Page 36 of 93 20 OCT 2021 Application for Permit: Oakbrush Hill Gravel M-2021- C&J-DPR-V5-001