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INTRODUCTION <br /> This design report summarizes the basis for the design of the Southwest Reservoir Slurry Wall at <br /> the Stonewall Springs Quarry owned by operated by Stonewall Springs Quarry, LLC located east of <br /> Pueblo, Colorado. Presented in this report is a summary of the geotechnical information collected, <br /> the methods of analysis, and a description of the design of the slurry wall including a section of <br /> earthen embankment. The report includes a discussion of the bedrock key, an analysis of the <br /> supplemental fines available, an embankment design and seepage and slope stability analyses for <br /> the proposed slurry wall. This slurry wall design was prepared with the goal of meeting the leakage <br /> requirements outlined in the State of Colorado's document titled, "State Engineer Guidelines for <br /> Lining Criteria of Gravel Pits,"August 1999; and the design criteria set forth by the Division of <br /> Reclamation Mining and Safety(DRMS) in its "Guide to Specification Preparation for Slurry Walls <br /> and Clay Liners as a Component of Colorado Mined Land Reclamation Permits," September 2000. <br /> Upon completion of construction,the slurry wall will undergo a 90-day liner leak test to observe the <br /> performance of the slurry wall against the State's Design Standard for leakage. The construction <br /> drawings and technical specifications developed for use during construction of the Southwest <br /> Reservoir Slurry Wall are included as part of this design package. <br /> SITE DESCRIPTION <br /> The Stonewall Springs Quarry is located in Pueblo County, Colorado approximately ten miles east <br /> of the city of Pueblo. More specifically,the site is located in the South Half of Section 35, <br /> Township 20 South, Range 63 West of the 6th P.M. The Southwest Reservoir is a mined cell of the <br /> quarry located south of U.S. Highway 50 and north of the Arkansas River. The proposed slurry <br /> wall will be approximately 7,581 feet long and will encompass approximately 86.4 acres east of the <br /> current mining operation. The site is accessed via the mine access road that intersects U.S. <br /> Highway 50 approximately 1/2 mile east of Devine, Colorado. A gravel road winds south and east <br /> from Highway 50 to the scale house west of the cell. Figure 1 shows the site and surrounding area. <br /> GEOTECHNICAL INVESTIGATION <br /> Stonewall Springs Quarry is located in the Colorado Piedmont Physiographic Province between the <br /> Southern Rocky Mountain Province to the west and the Great Plains Province to the east. This is <br /> approximately 10 miles east of Pueblo and 41 miles east of the Wet Mountains,which consist of <br /> Cambrian age (1,700 - 1,800 m.y.)metamorphic rocks. The site is along the Arkansas River where <br /> regional geologic mapping(Scott et al., 1978) shows the near surface bedrock to be the Upper <br /> Cretaceous Pierre Shale. The shale is a thick sequence of clayey to silty marine shales containing <br /> fossils and local beds of limestone. The bedrock is overlain by Holocene(Quaternary age) sand and <br /> gravel deposits of the Piney Creek and Post Piney Creek alluvium deposited by the Arkansas River. <br /> These alluvial deposits are covered by calcareous overburden clay soils deposited by residual and <br /> slope wash processes. The overburden clay soils were eroded from sub-cropping Pierre Shale <br /> bedrock to the north. The site is relatively flat, sloping gently southeastward toward the Arkansas <br /> River. <br /> The site geology and geotechnical conditions were investigated between January 25, 2016 and <br /> January 27, 2016 by drilling 9 exploratory borings along the proposed slurry wall alignment around <br /> the cell. Additional site and bedrock geology information collected by D&A during previous <br /> SW RESERVOIR SLURRY WALL DESIGN REPORT PAGE 1 <br />