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T� <br />� App�egate <br />Grvu�, �n�. <br />Water Resource Advisors for the West <br />July 31, 2013 <br />Attn: Tom Smitli <br />1701 East 147`h Street <br />Kansas City, MO 64146 <br />RE: Droz Creek Dam Inundation Study — Scope of Services <br />Dear Mr. Smith: <br />� <br />��`��` �'' <br />���� <br />� � <br />Applegate Group, Inc. (AG) has prepared a scope of services for dam breach modeling, flood <br />routing, breach inundation mapping and preparing an Emergency Action Plan for the Droz Creek <br />dam, in Chaffee County, Colorado. It is our understanding that this dam was recentiy reclassified as a <br />significant hazard dam and the purpose of this project is to provide an estimate of the inundation area <br />resulting from a breach of the dam. The process of developing the maps consists of four main tasks: <br />1) Data Gathering, 2) Breach Modeling, 3) Flood Routing, and 4) F(ood Inundation Mapping. <br />Droz Creek Dam is IQcated approximately 6 miles southwest of Poncha Springs, Colorado. The flood <br />wave from a simulated breach at Droz Creek dam will be routed East and North of Droz Creek Dam <br />and wiil converge with Poncha Creek and eventually the Arkansas River East of Poncha Springs. <br />With the above information in mind, please see the below scope of services. <br />SCOPE OF SERVICES <br />To complete the investigations described above, we propose the following tasks: <br />� <br />3. <br />Data Gathering <br />a. Any existing breach modeling on file with the DWR will be reviewed for pertinent data. <br />b. Stage-storage information will be obtained from the construction plans and survey. <br />c. Existing LiDAR will be attained from the Colorado Geologicai Survey if available. <br />Breach Modeling <br />a. Develop estimates of breach parameters using guidance provided by the Division of <br />Water Resources (DWR) for a"simple" level analysis. Overtopping and piping failure <br />modes will be considered, and the failure mode resuiting in the greatest estimated peak <br />discharge at each dam wili be utilized in the analysis. <br />b. Develop an estimated breach hydrograph at the dam by performing a dam breach analysis <br />in HEC-RAS. <br />Flood Routing <br />a. Develop a FLO-2D model from best available elevation data. This model will be 2- <br />dimensional, allowing the model to more accurately model dispersion of the dam breach <br />flood-wave immediately downstream of the dam. <br />129'/� W Third St, Suite 2 1490 W. 121� Avenue, Suite 100 118 W. 6�' Stree� Suite 100 <br />Salida, CO 81201 Denver, CO 80234 Glenwood Springs, CO 81601 <br />303-052-661 l <br />w�vw.applegategroup.com <br />