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<br />D. Mappini( and Su~veying <br /> <br />E. Related Flood Studie~ <br /> <br />Specific topog~aphic data provided to the consultant includes' <br /> <br />tn 1973 a "Major Sto~m D~ainage" manual was publish"d fo~ the City <br />of Longmont. Flood haza~d a~eaS ~e~e delineated on U.S. Ceo logical <br />Su~vey quadrangle maps for all majo~ drainage~ays in the city. The O~y <br />C~eek No.1 basin waS also studied and the results indicated the poten- <br />tial for substantial flooding in improved areas. A detailed floodplain <br />delineation waS not made for the manual, howeve~, the description of <br />flooding is in gene~al ag~eement with the findings of this study. <br /> <br />Contou~ mapping for the study was provided by the ColoradO Water <br />Conse~vation Boa~d. This mapping ~as prepared by Parker and Associates <br />under a separate contract. <br /> <br />1. Sixteen reproducible mylar planimetric - topographic map sheet. <br />wieh a contour interval of 2 feet and a scale of 1"-20Q'. <br /> <br />2. One set of Xl and GR cards (aEC-2 Computer Program) for 105 <br />digitized c~oss sections of the Dry Creek No.1 valley. <br /> <br />A Flood Insurance Study for the City of Longmont was published in <br />January 1977. The flooded a~eaS were delineated only from Sunset Street <br />to the confluence with the St. Vrain Creek. The flooded area boundaries <br />.how sOme disagreement, but the Flood Insurance Study waS not based on <br />the detailed mapping which was prepared fo~ this study. <br /> <br />3. One set of 9" x 9" black and white photog~aphic contact p~ints; <br />date of photog~aphy March 24, 1979. <br /> <br />The hyd~ologic analyses fo~ both p~evious studies indicated highe~ <br />discharges could be expected for D~y Creek No. I. Extensive analysis <br />of the effects of the i~rigation rese~voirs and the canals was ~adc <br />for this study. The peak flows will be reduced substantially due to <br />the te~po~a~y flood storage in the ~eservoirs. Results of the hydrologic <br />analysis fo~ this study a~e presented in Chapre~ IV. <br /> <br />Th~ itc~s listed abov~ are available fc~ reVlew at the Colo~ado <br />Water Cons~rvation Boa~d. <br /> <br />The City of Longmant conducted field su~veys and p~ovided info~mation <br />related to the first floo~ elevations of all imp~ovements located in the <br />flOOdplain. Futthe~, the info~mation on the type of buildings and thei~ <br />location was p~ovided by the City of Longmont. This information waS used <br />in determining damage assessments f~om different frequency floods. <br /> <br />Additional field su~veys were perfo~med by Water Resources Consultants, <br />Inc. roubtain bridge "nd culvert opening sizes and to verify the computed <br />limits of flooding. <br /> <br />6 <br /> <br />5 <br />