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RECEIVED <br /> JUL 2 3 2024 <br /> DIVISION OF RECLAiVIAT10id <br /> March 17, 2017 <br /> MINING AND SAFTEY <br /> Mr. Mark Johnson, Compliance Manager <br /> Bestway Concrete&Aggregates <br /> 301 Centennial Drive <br /> Milliken, Colorado 80543 <br /> Re: Stability Analysis for the Lee Amendment—N. La Poudre Gravel Mine(M-2000.144) <br /> Dear Mr. Johnson <br /> This letter has been prepared to address the Mined Land Reclamation Board (MLRB)Construction Materials Rule <br /> 6, Section 4, Subsection 19, Exhibit S - Permanent Man-Made Structures (6.4.19, Exhibit S) for the proposed Lee <br /> Property Amendment for the N. La Poudre Gravel Mine. This letter describes the project and slope stability <br /> calculations carried out to evaluate the minimum distance between the edge of mining and adjacent structures to <br /> avoid damage to the structure. <br /> The site is located north of the Cache La Poudre River, east of WCR 13 and south of Highway 392. The site is <br /> within the northwest'/4 of Section 19, Township 6 North, Range 67 West of the 61h Principal Meridian. The project is <br /> located in Weld County, Colorado, as shown on Figure 1. <br /> Bestway Concrete&Aggregates plans to wet mine the entire mining area on the Lee Amendment Property with a <br /> mining slope of 1:1 (horizontal to vertical), as indicated in the DRMS permit application. <br /> This report lists proposed safe setbacks for mining from structures within 200 feet of the permitted mining boundary <br /> based on stability calculations. Actual setbacks may be greater due to permit limitations, zoning requirements, <br /> construction issues, agreements with owners, and extent of economically mineable aggregate or other issues <br /> GEOLOGY <br /> The site is located approximately twenty(15)miles east of the foothills of the Colorado Front Range on the western <br /> flank of the Denver Structural Basin The basin is a down warp of sedimentary strata that trends north-northwest, <br /> parallel to the mountain front. Based on regional geologic mapping (Colton, 1978),the near surface material in the <br /> project area is the Piney Creek Alluvium(0p). The Piney Creek Alluvium consists of dark-yellowish brown or <br /> grayish-orange, clayey to fine sand, and well-stratified silt, The bedrock unit consists mainly of claystone and may <br /> contain lenses of siltstone and sandstone, <br /> GEOTECHNICAL CONDITIONS <br /> The mine site is located on a terrace of the Cache La Poudre River. The Piney Creek Alluvium most likely overlies <br /> sandstone and claystone bedrock of the Denver Formation. Well construction data obtained for the area <br /> encountered approximately four feet of overburden topsoil overlying sand and gravel ranging in depth from 16 feet <br /> to 19 feet. As a conservative approach based on experience and information gathered from existing mines in the <br /> area, it was assumed that the top four feet of bedrock is weathered claystone overlying non-weathered claystone. <br />