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WA S_ T EL I N1 E-, I N C., <br /> P.O. Box 3471 Rapid City, SD 57709-3471 PO Box 88 Cortez, CO 81321-0088 <br /> (605)348-0244 (605)939-0650(970)564-1380 <br /> WASTELINE.84532@gmail.com WASTELINE.57709@gmail.co <br /> 21 April 2021 <br /> Colorado Division of Reclamation Mining and Safety <br /> ATTN: Lucas West, Environmental Protection Specialist <br /> 1313 Sherman Street Room 215 <br /> Denver, CO 80203 <br /> VIA Email to lucaswest(a-)-state.co.us <br /> Subject: Response to Comments on 110c Application, Schoen Farm M2020-062 <br /> Dear Mr. West: <br /> As discussed today, this letter responds to your comment letter of 20 April 2021. <br /> 1. Site Description <br /> a. Groundwater information: <br /> i. Summary: Depth to saturated water 24 feet below original ground level of 8128 ft ASL, or <br /> at 8104 ft ASL (8 feet below proposed depth of mining),with flow to the northeast-east, <br /> and maximum flow of 6 feet/minute. <br /> ii. Discussion: The Site is located west of the larger Rio Grande Groundwater Basin which <br /> occupies most of the San Luis Valley, and therefore the groundwater is the alluvial <br /> aquifer associated with the Rio Grande itself, which is a losing stream at this point <br /> (although there is some potential for"mountain-front recharge"through volcanic rock <br /> formations above the valley to the north). Based on this and the depths of surrounding <br /> wells (varying from 34 to 80 feet in depth from the surface, and assuming a minimum of <br /> 10 feet of water in the most shallow recorded well), estimated depth to saturated water is <br /> at least 24 feet. Ground water flow is generally from the river(flowing to the <br /> north/northeast) and to the east (along the river valley). Based on typical coarse to cobbly <br /> sand in the profile below 60 inches, hydraulic conductivity can be assumed to be up to <br /> 0.1 feet/second, or 6 feet/minute. Excavations for utilities and other construction have <br /> encountered no ground water within 24-25 feet of the surface. The Yard is on a low ridge <br /> in the valley floor, and approximately 10-12 feet above the ordinary highwater mark of the <br /> Rio Grande. <br /> b. Wildlife statement: the CPW local office was contacted but provided no information. The <br /> statement was prepared by Nathan A. Barton and Deborah A. Barton. Deborah is a <br /> certified biological assessor of the Navajo Nation. (Attachment A) <br /> C. GPS Coordinates: See Attachment B. <br /> 2. Mining Plan: <br /> a. Temporary processing plants: All hazardous and/or water priority materials stored on- <br /> site, including those for use by processing plants, will have secondary containment in <br /> accordance with good engineering practice and State and County requirements to <br /> prevent discharge of such materials. Please note that this is already addressed in the last <br /> sentence of Item 14, which should refer to the ORE spill response plan and not the CAS <br /> plan. <br /> b. Soil salvage:As stated in 5.a of the exhibit., the 600 CY gross and 400 CY net soil to be <br /> salvaged is per acre. The 400 CY is intended to be a conservative minimum, based on <br /> surface observations of cobble content of the surficial material. Therefore, the total for the <br /> entire Yard of 7.74 acres for the project would be at least 3,096 CY. Replaced at a <br /> thickness of 4 inches (Exhibit D 4.c.i.) each acre may require approximately 540 CY, or <br /> 4,180 CY total. This deficit of 1,084 CY(140 CY/acre) is less than 3% of the amount of <br /> crushing/screening fines, not including any imported materials, anticipated to be <br /> available. <br /> Based on mining at other nearby locations on the Rio Grande, fines are expected to be <br />