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September 23, 2015 <br />Project: Inundation Mapping for the Crooked Arroyo Flood Control District Dams <br />Vendor: Board of County Commissioners Otero County <br /> Mr. Lex Nichols <br /> 13 West 3rd Street, Rm 208 <br /> La Junta, CO 81050 <br /> <br />Consultant: Kleinfelder <br /> Mr. Brad Rastall, P.E. <br /> 1801 California Street, Suite 1100 <br /> Denver, CO 80202 <br /> Phone: (303) 237-6601 <br /> <br />CWCB funding source: Severance Tax Trust Fund Operational Account <br /> <br />SCOPE OF WORK <br />Kleinfelder (Consultant), at the direction of the BOCC Otero County (Vendor), will perform a dam breach <br />modeling study and flood inundation mapping for four dams within the Vendor’s system. The dams to <br />be modeled are the Crooked Arroyo CA-1, CA-2, CA-3, and CA-4 which are all Significant Hazard dams <br />located in Otero County in the Arkansas River Basin. The dams are normally dry flood control structures <br />located on Crooked Arroyo south of La Junta, CO. <br /> <br />Consultant or Vendor will submit the final report and mapping to the Colorado Division of Water <br />Resources, Dam Safety Branch, for approval. Grant funds will not be disbursed until the project has been <br />approved by the Dam Safety Branch. <br /> <br />PROPOSED METHODOLOGY <br />The Consultant shall perform a clear dam breach analyses in accordance with the State of Colorado <br />Rules and Regulations for Dam Safety and Dam Construction (1/1/2007), and the Dam Safety Guidelines <br />for Dam Breach Analysis (2/10/2010). Correspondence shall be with Mark Perry, P.E., of the Colorado <br />Division of Water Resources, Dam Safety Branch, to present preliminary dam breach parameters, water <br />surface profile modeling, and inundation mapping and to determine if field measurements are necessary <br />for critical bridges. <br /> <br />Inundation mapping for High Hazard dams shall show the calculated extents of the dam breach flood <br />wave. The mapping will also include cross sections at critical locations showing lateral and vertical flood <br />extents, flood wave velocity, and flood wave arrival time. Inundation mapping shall be extended <br />downstream to a location where no potential for loss of life and/or no significant property damage exist. <br /> <br />Inundation mapping for Significant Hazard dams shall show the route of the dam breach flood wave, the <br />estimated time of arrival of the flood wave at critical sections, and the estimated lateral extent of <br />inundation. The inundation mapping shall be extended downstream to a location where no significant <br />property damage exists. The inundation mapping requirements for Significant Hazard dams may be <br />modified for good cause, with the approval of the State Engineer. <br />