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<br />-~ <br />, <br /> <br />~~ <br /> <br />Colorado Water Conservation Board <br /> <br />Department of Natural Resources <br /> <br />721 Centennial Building <br />1313 Sherman Street <br />Denver, Colorado 80203 <br />Phone: (303) 866-3441 <br />FAX: (303) 866-4474 <br /> <br />STATE OF COLORI\DO <br /> <br />- <br /> <br />Mr. Stan Szabelak, City Engineer <br />City of Federal Heights <br />2380 West 90'h Avenue <br />Federal Heights, CO 80221 <br /> <br />Roy Romer <br />Governor <br />James S. Lochhead <br />Executive Director, DNR <br />Danes C. Ule, P.E. <br />Director, ewCB <br />Peter H. Evans <br />Acting Director, eWeB <br /> <br />April 27, 1998 <br /> <br />Dear Mr. Szabelak: <br /> <br />I have reviewed the CLOMR materials sent to us by Carroll & Lange, Inc. regarding <br />Tributary L of Niver Creek within the City of Federal Heights. The materials show <br />detailed floodplain information for Tributary L of Niver Creek from its crossing of Huron <br />Street upstream to a point approximately 2200 feet upstream of that crossing. The current <br />Flood Insurance Rate Map (FIRM) for Adams County and Incorporated Areas shows <br />approximate floodplain information for Tributary L. The CLOMR application proposes <br />replacement of that approximate information with the new detailed information. The <br />application also proposes modifications to the "existing conditions" floodplain, based on <br />filling on the south side of the floodplain. Both the "existing conditions" floodplain and <br />the "proposed conditions" floodplain are included in the CLOMR materials. <br /> <br />I would like to offer some comments on the CLOMR request. <br /> <br />"Existin!!: Conditions" Maooin!!: of the Floodolain <br />The applicant researched the current FEMA mapping for Tributary L and found no <br />detailed backup information for that mapping. The applicant then chose to use <br />hydrologic information prepared by Kiowa Engineering for the Urban Drainage and _ <br />Flood Control District, Adams County, and the Cities of Federal Heights and Thornton.. <br />That information included both "existing conditions" and "future conditions" hydrology <br />information. Field-surveyed cross-sections were used for the hydraulic analysis. The <br />methodology used and the results computed for the "existing conditions" floodplain are <br />reasonable. <br /> <br />"Prooosed Conditions" Maooin!!: of the Floodolain <br /> <br />The applicant used the "'pture conditions" flood flows from the Kiowa Engineering <br />analysis to calculate and map the "future flows" floodplain. Then the proposed physical <br />changes (filling along the south side of the floodplain to accommodate proposed lots in <br />