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v plc'y( <br /> Ameopme N� <br /> January 2,2014 <br /> Mr. Mark Johnson, Compliance Manager <br /> Bestway Concrete&Aggregates <br /> 301 Centennial Drive <br /> Milliken,Colorado 80543 <br /> Re: Stability Analysis for the Burch Amendment to the Shores Gravel Mine(M 4998.013) <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 Burch <br /> Property Amendment for the Shores Aggregate 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 approximately one-half mile south of St. Wain Creek. The site is within the east half of the <br /> northwest A Section 1,Township 2 North, Range 68 West of the 61h Principal Meridian. The site is generally <br /> bounded on the west by Weld County Road(WCR) 11.25,the north by WCR 26,on the east by an agricultural field, <br /> and on the south by a single family residence and an existing gravel mine. The project is located in Weld County, <br /> Colorado,as shown on Figure 1. <br /> Approximately five feet of overburden is underlain by a relatively deep alluvial aggregate deposit. The aggregate <br /> will likely be transported via conveyor to a processing plant located at the southwestern portion of the active mine <br /> area. <br /> Bestway Concrete&Aggregates plans to construct a slung wall around the entire mining area on the Burch <br /> Property at a 3:1 (horizontal to vertical)slope,as indicated in the DMG 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,extent of economically mineable aggregate or other issues. <br /> GEOLOGY <br /> The site is located approximately 15 miles east of the foothills of the Colorado Front Range on the western flank of <br /> the Denver Structural Basin. The basin is a down warp of sedimentary strata that trends north-northwest, parallel to <br /> the mountain front. Based on regional geologic mapping(Colton, 1978),the near surface material in the project <br /> area is the Piney Creek Alluvium(Qp). The Piney Creek Alluvium consists of dark-yellowish brown or grayish- <br /> orange,clayey to fine sand, and well-stratified silt. The bedrock unit consists mainly of claystone and may contain <br /> lenses of siltstone and sandstone. <br />