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Response to DRMS Michael Cunningham <br /> CEMEX Sandstone Quarry Division of Reclamation Mining;and Safety <br /> June 30, 2014 Project No. 110307a <br /> Michael Cunningham <br /> Division of Reclamation Mining and Safety <br /> 1313 Sherman St,Room 215 <br /> Denver, CO 80203 <br /> RE: Response to CEMEX Sandstone Quarry;DRMS File No M-1977-361; Preliminary <br /> Adequacy Review(AM-0 1) <br /> Dear Mr. Cunningham, <br /> 1.0 INTRODUCTION <br /> Engineering Analytics, Inc. (EA) has received and reviewed the comments provided by the <br /> Colorado Division of Reclamation Mining and Safety (DRMS) as part of their preliminary <br /> adequacy review for the reclamation of the CEMEX Sandstone Quarry in Lyons, Colorado. This <br /> report has been written in response to DRMS comment number 10 and the associated <br /> memorandum dated May 15, 2014 provided by DRMS. Please note that Figures 1 and 2 were <br /> produced previously and are not included in this discussion. Only Figures 3, 4 and 5 were <br /> reproduced for the DRMS response. Additionally, Figure 6 has been added. <br /> 2.0 RESPOSNE TO DRMS COMMENTS <br /> 1. DRMS Comment: "Please give rationale for the use of the strength parameters used, and <br /> address bedding and jointing that may be present in the rock mass." <br /> EA Response: As noted in the DRMS memorandum and shown on the USGS geological map <br /> (Braddock, et al., 1988) for the area, the quarry is located in the Plainview Sandstone member of <br /> the South Platte Formation and Lytle Formation east of Lyons (Braddock et al., 1988). The <br /> USGS map indicates that this member varies from a thinly bedded carbonaceous fine grained <br /> sandstone to coarse-grained to conglomerate sandstone and blocky weathering to a non- <br /> carbonaceous mudstone. Based on conversations with CEMEX, the mudstone is not exposed in <br /> the highwall and is only present at sporadic points in the bottom of the pit. <br /> Engineering Analytics, Inc. visited the site on March 19, 2013 and took photographs of the pit <br /> wall. Based on the review of these photographs, jointing in the pit wall appears to be on the <br /> order of 2 to 8 feet wide. Bedding planes appear to be on the order of inches to feet thick. <br /> June 30, 2014 1 Engineering Analytics,Inc. <br />