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<br />@_ Engineers
<br />_ Planners
<br />~ Economists
<br />_ Scientists
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<br />Mr, Ben Urbonas, p, E,
<br />Page 2
<br />December 1, 1995
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<br />maximum rise in energy grade line, Floodway limits have been adjusted to provide for relatively
<br />consistent flow widths and stable water surface results, In some steep, narrow channels, floodway
<br />limits were adjusted to match floodplain boundaries to preclude increasing velocity and erosion
<br />problems that would result from channel filling,
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<br />December I, 1995
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<br />The channels in the study area are erodible and may undergo changes in shape, width, and direction
<br />during flood events. Therefore, flood hazards may exist outside the floodplain limits indicated in
<br />this report,
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<br />Mr. Ben Urbonas, p, E,
<br />Chief, Master Planning and South Platte River Programs
<br />Urban Drainage and Flood Control District
<br />2480 West 26th Avenue, Suite-B
<br />Denver, CO 80211
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<br />It has been a pleasure to work with the projecl sponsors and Advisory Committee throughout the
<br />development of the FHAD report,
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<br />Sincerely,
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<br />Subject:
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<br />Flood Hazard Area Delineation (FHAD), Coyote Run and Upper Box Elder Creek
<br />UDFCD Agreement No, 92-11.06
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<br />CH2M HILL
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<br />Dear Ben:
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<br />Project Manager
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<br />CH2M HILL is proud to submit the attached Flood Hazard Area Delineation, Coyote Run and Upper
<br />Box Elder Creek, dated December 1995,
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<br />Jon H, Sorensen, p, E,
<br />Senior Consultant
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<br />We would like to acknowledge the staff of UDFCD, the City of Aurora, Arapahoe County, Adams
<br />County and others on the Project Advisory Committee for their contributions to the FHAD report,
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<br />DEN413S.lXlC
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<br />The FHAD report provides floodplain information for approximately 33 miles of Coyote Run and its
<br />tributaries and approximately 15 miles of Upper Box Elder Creek and one of its tributaries, The
<br />delineated portion of Box Elder Creek comprises the northern half, more or less, of the length of the
<br />creek addressed in the companion Preliminary Design Report, Coyote Run and Upper Box Elder
<br />Creek Outfall Systems Planning Study, dated December, 1995,
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<br />The picture on the cover of this report shows Box Elder Creek at a point about one mile north of 1-
<br />70, The picture shows the typically dry, sandy bottom of the wide channel bordered by cottonwood
<br />trees in many areas, The channel and overbank section is very shallow and flood flows are predicted
<br />to spread out over a wide area, Spills are expected to occur outside of main channel banks in
<br />numerous locations,
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<br />This FHAD report provides a tool to the sponsoring agencies which will enable them, through their
<br />planning and development approval processes, to manage development activities adjacent to
<br />floodplains in the area ofthe study,
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<br />The report provides drawings showing the 100-year floodplain, 10- and 100-year water surface
<br />profiles, representative channel cross sections, and major roadcrossings, Tabular information is
<br />included showing floodplain data and floodway information based on both a O,5-foot and I,D-foot
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<br />Rocky Mountain Region 100 Inverness Terrace fast, Englewood, CO 80112-5304
<br />Mailing address: p.o. Box 241325, Denver, CO B0224-9325
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<br />303 771-0900
<br />Fax No, 303 754-0/99
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