Laserfiche WebLink
<br />I <br /> <br />Purpose and Scope <br />This report was prepared to guide local officials in planning the use <br />and regulation of the floodplain areas such that flood hazards and future <br />flood damages are minimized. It includes information on historical <br />floods, existing factors which influence the flood hazard, dnd the nature <br /> <br />Related flood Studies <br /> <br />- <br /> <br />and extent of probable future floods. <br />The report data includes flooded area mdps delineating the lOQ-year <br />flood boundary and flood profiles showing the water surface elevations <br />for the 10-, 50-, 100-, and SOO-year fleeds. <br />Supplemental material to this report in the form of technical back-up <br />includes the supporting engineering and hydrologic data which may also be <br /> <br />Information on past floods and some bridge data were obtained fro ma <br />report entitled Floodplain Information Lefthand Creek, Volume I, Boulder <br />County, Colorado (Reference 1). Additional past flood infonnation was <br />obtained from a U.S. Geological Survey publication entitled "Floods in <br />Colorado, Water Supply Paper 997" (Reference 2). Federal Insurance <br />Administration floOd insurance studies were completed for Boulder County <br /> <br />and Longmont in 1979 and 1977, respectively (References 3, 4). <br />Differences between this study and the previous floodplain <br /> <br />information report can be attributed to updated survey data which <br /> <br />used in the location and design of roads, bridges and channel <br /> <br />included topographic mapping, additional years of historic flood data, <br />and updated hydrologic and ~draulic methodology. <br /> <br />modifications. <br /> <br />Acknowledgements <br />The assistance and cooperation of the individuals, agencies, firms, <br />and organiutions listed below was appreciated and is 9ratefu1ly <br /> <br />Maps and Surveys <br />Detailed topographic mapping and cross section data were provided by <br />the Colorado Water Conservation Board. Both the mapping and the cross <br />sections were compiled by Bell Mapping Company of Denver, Colorado, usin9 <br /> <br />acknowledged. <br /> <br />Bell Mapping Company - Denver, Colorado <br />I_~rry Buss. U.S. A!'1!\Y Corps of Engineers, O'nJhJ District <br />Larry Cieslik - U.S. Anny Corps of Engineers, Omaha District <br />James M. Landeck - City Engineer, Longment, Colorado <br />Larry F. Lan9 - Chief, Flood Control and Conservation Section <br />Colorado Water Conservation Board <br />Parker and Associates - Denver, Colorado <br />~eal Renfroe - Director of Public Works, Longment, Colorado <br />D. Randolph $eaholm - Water Resource Specialist, <br />Colorado Water Conservation Board <br />Mike G. Serlet - Public Works Department, Boulder County, Colo. <br /> <br />photograrrmetric mEthods from aerial photographs taken April 21,1978. <br />Parker g. Associates of Denver, Colorado prepared supplemental mappin9 <br />ne~r the confluence with 51. Vrain (reek from aerial photography hken <br />March24,1979. The topographic mapping scale is 1:2400 and the contour <br />interval is 2.0 feet. U.S. Geological Survey 7.S-minute quadrangle <br />mapping (Reference 5) with 10 foot contour intervals at a scale of <br />1:24,000 was also used in this study. Bridge data was supplied by the <br />Corps of Engineers and Boulder County. Additional surveys were furnished <br />by the City of Longmont, Boulder County. and the Colorado I;ater <br />Conservat ion Board. Survey contro 1 monument~ (Table 8) exist in the <br />field for use in relating infomationcontained in the report to actual <br />ground conditions. <br /> <br />, <br />