|
<br />1.0. Reconnaissance
<br />
<br />Crqss-sectiqns for use in the hydraulic ~na1ysis were either
<br />field surveyed or interpreted from the topo']raphic ltlo.pping.
<br />Approximately 94 cross. sections were used for the hydraulic
<br /><lnalysis. Of these, 44 were field surveyed,
<br />
<br />During the course of this study many on-site investigations were
<br />made to gain familiarity wlth the drainage basin and to gather
<br />field data for the analysis, !:luring these investig~tions,
<br />photographs were taken during minor storms documenting flood-
<br />prone areas. These photos are available in the Technical Addendum,
<br />Photographs were also taken along the various reaches to aid Ln
<br />determining Manning's Roughness coefficient ("n") for use in the
<br />hydraulic analysis. These photographs are contained within a
<br />separate "Manning's "n" Value Verification" report which is
<br />on file with the City of Fort Collins. Field surveys were
<br />conducted to verify topographic mapping, measure existing
<br />drainage structures, aid in determining complex drainage patterns,
<br />and determine first floor elevations of flood prone residences.
<br />
<br />Location Mi'lpping consultant Flight Date
<br />SW~, Sec, 2 ARIX April, 1980
<br />'" Sec. 3 ARIX April, 1980
<br />S~ , Se<;, , i\RIX April, 1980
<br />EJ.;, See, 7 ARIX June, 1979
<br />""0, 8 ARIX June, 1979
<br />See, 9 M , , Consulting Engineers May-July, 1978
<br />NE,,.,[W , '" " M , , consulting t:nglneers May-July, 197a
<br />See, 10
<br />NE,NW , 8W " M , ! Comm1ting Engineers May-July, 1978
<br />See, 17
<br />
<br />I,F. Previous Studies
<br />Various drainage studies and reports Which have been prepared
<br />for areas within the drainage basin were reviewed and utilized
<br />where possible. These studies inclUde'
<br />1, "Report on Storm \~ilter Drainage Facilities for
<br />Fort Collins, Colorildo"; BlilCk and Veatch Consulting
<br />Engineers; June, 1971
<br />2, "college Lake Improvements Study"; Colorado State
<br />University; October, 1976
<br />3. Ili:lnna Subdivision Drainage Calculations; James H.
<br />Stewart and Associates; June, 1977
<br />4, Granada Heights Subdivision Drainage CalCUlations;
<br />James H, Stewart and Associates; June, 1979
<br />~ith the exception of the Black and Veatch study, all studies
<br />indicated were ~repared for relatively small, individual sub-
<br />catchments. In addition, methods of determining rates of runoff
<br />differed sig"lificantly from the iit_omwater Manaqement Model used
<br />to prepare this study. 1'herefore, comparison of results was
<br />virtually meaningless, The Black and Veatch study used a unit
<br />hydrograph approach to determine rates and volumes of runoff.
<br />Again, a meaningful comparison does not present itself because
<br />different deslgn rainfallS and different loss parameters were
<br />used for the Black and Veatch study, None of the studies listed
<br />delineat~ floodplains, caples at the aforelOOntlun"d studies arc
<br />on file with the City of Fort collins,
<br />
<br />I,E, Mappinq and Surveys
<br />Tu~ographic mapping used to delineate and ~odc1 subbasins for
<br />the hydrologic analysis and prepare cross-sections for use in
<br />the hydraulic analysis was furnished by the City of Fort Collins.
<br />The quarter-section maps used throughout the study, all of which
<br />are in Township 7 North, Range 69 West, are listed as follows:
<br />
<br />Vertical control information relative to the mappinq and floodplain
<br />information provided in this study is available through the City
<br />of Fort collins.
<br />
<br />'3-
<br />
<br />-4-
<br />
|