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1.0 INTRODUCTION <br />The proposed Iverson Mine site is located in the Section 34, Township 6 North, Range 66 <br />West of the 6 Principal Meridian, Weld County, State of Colorado. The site is bounded to <br />the north, west and east by the Cache la Poudre River and to the south by the Poudre Trail <br />and rural residential /agricultural land. The site is located approximately 0.3 miles north of the <br />City of Greeley and contains 83.06 acres, more or less. The property contains a significant <br />commercial deposit of aggregate along the Cache la Poudre River. There are several existing <br />gravel mine operations in the project vicinity. The Iverson Mine is under review by the <br />Colorado Division of Reclamation, Mining and Safety (DRMS), (File Number M- 2011 -001). <br />A vicinity map is presented in Appendix A. <br />2.0 INTENT <br />The purpose of this report is to provide an evaluation of the exiting, mining and reclamation <br />conditions for the Iverson Mine property. The contents of this report are prepared in <br />accordance with Weld County Storm Design Criteria and the Urban Storm Drainage Criteria <br />Manual, Volumes 1, 2 and 3. This report examines the existing topography, existing, mining <br />and reclamation stormwater runoff through the site and describes the existing and proposed <br />site features. It is intended to show that the site development will not increase runoff to <br />adjacent property owners. <br />3.0 HISTORIC SITE TOPOGRAPHY AND DRAINAGE CHARACTERISTICS <br />Figure 1 is a vicinity map showing the site and surrounding area. The area of disturbance will <br />encompass approximately 64.3 acres of the site, with 45.1 acres of the site to be mined. The <br />remaining unmined acres will be used for overburden and topsoil stockpiles, an internal road <br />and conveyor access. The irregularly shaped parcel is relatively flat and low lying in the <br />greater floodplain of the Cache la Poudre River. There are no significant areas of <br />concentrated flow. <br />The site is owned by Tim and Jeanne Iverson and will be mined by Lafarge West under <br />license. For the names of all property owners and those within 200 feet of the Iverson Mine <br />Property boundary see the Adjacent Ownership Map presented in Appendix C. <br />According to the United States Department of Agriculture Soil Conservation Service Web <br />Soil Survey of Weld County, Colorado the site soils belong to Hydraulic Soil Groups B, C <br />and D. Gravelly substratum, Ascalon loam, Dacono clay loam, Nunn loam, and Otero sandy <br />loam are the soil types on the site. Please refer to the Soil Map provided in Appendix B for <br />the soil type reference. <br />Portions of the site are within a Zone A3 floodplain according to the Federal Emergency <br />Management Agency (FEMA) Flood Insurance Rate Map (FIRM) Community-Panel No. <br />080266- 0609 -C, dated September 28, 1992. The Corps of Engineers completed a Flood <br />Insurance Study in October 2003 for the Cache la Poudre River in the vicinity of the Iverson <br />site. This study is currently under review by FEMA but has not yet become the effective <br />study. For the purposes of this Flood Hazard Development Permit, the 100 -year floodplain <br />and floodway boundaries of this pending study will be adopted as the best available <br />- 1 - <br />Final Drainage Report Iverson Mine <br />P:\23511\ 133-23511-10002 \Deliverables \Drainage Report \Drainage Report.doc <br />February 2011 <br />