2008-01-04_HYDROLOGY - M1984108 - Laserfiche WebLink

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1.0 Infir®ducfiion Western Gravel, Inc. proposes to establish the Western Gravel Wetlands Bank, a wetland mitigation bank in Delta County, Colorado. The bank will be completed in one phase. Map l provides a vicinity map that depicts the location of th.e bank and its service area. The site is owned by Westerns Gravel, Inc. The large parcel will be subdivided. prior to final release to a non-profit entity or a governmental agency. The lots sui-~-ounding the bank will be 4 acres or larger rural residential lots. The subdivision of the lots will handled separately from this bank application. Western Gravel, Inc. will construct and maintain the Bank for a ten (l0) year monitoring and maintenance period, after which a conservation easement will be placed on this site prior to donation of this property. Western Gravel will be responsible for all monitoring and maintenance required for a ten (10) year period, as specified by the proposed Mitigation Banking Instrument (M:BI). The Western Gravel Wetlands and. Stream Bank is expected to create, restore, enhance, and protect valuable wetlands, as well as upland buffers, along the Uncompahgre River. This project will also serve to reclaim an existing gravel. pit to a highly beneficial use. Please see the EPA document describing conversion of mining areas to wetland mitigation banks in Appendix A. Z.Q Sifie ~e~cripfiion 2.1 Current Use The site currently is pei7nitted for gravel extraction by the Colorado Division of Minerals and Geology (DMG). The Olathe Pit has been mined and permitted since 1984, under the D1VIG identification number VI-1984-1.08. Currently the mine is permitted as a l1Oc on 9.9 acres. The operation has mined approximately 9 acres of the permitted area as of November 2003. A hydraulic, excavator working on top of the gravel and reaching below grade, is used to mine the deposit. A survey perforned in the Fall of 2004 shows the current site conditions. Map 2 shows the site topography as well as tree locations anal the surrounding terrain. It is included in Appendix C. Photos taken during the survey are included in Appendix B. 2.2 Ff%Stor%cal Use The h.istorica.l use of the site was irrigated field. The site has existing water r7ghts that will be used to establish vegetation. during the creation of the wetland bank. The water may also be used for maintenance of the wetland bank. However, the design of the bank will allow growth without additional. water. 2,3 Situ Geology The site has very little overburden (1.5') and topsoil (0.5'), which overlays the gravel deposit. The deposit is approximately 15' deep. This infornation. comes from. existing