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<br />FLOODPLAIN REPORT - Tyra Tract D and Sawmill Gulch, Breckenridge, Colorado <br />(D..AFT) <br /> <br />Table 1 <br />Sawmill Gulch Flow and Profile Data <br /> <br /> FLOW WATER SURFACE <br />SECTION IN CFS ELEVATION. <br />Culvert 130 9716.00 <br />52.1 130 97]5.98 <br />52.2 ]80 97]6.65 <br />53.1 180 97] 7.62 <br />54.0 180 9719.55 <br />55.0 180 9723.98 <br />56.0 212 9726.57 <br />57.0 212 9731.44 <br />58.0 248 9735.17 <br />59.0 248 9739.63 <br />59.1 248 9742.44 <br /> <br />. Datum is NGVD 1929, <br /> <br />Existing Conditions Model-Upper Sawmill Gulch <br /> <br />In accordance with the direction of John Liou, a minimum of 14 cross-sections were deemed <br />sufficient to evaluate the floodplain upstream of the Tyra Tract D parcel according to FEMA <br />standards. Cross-sections were taken from the Town topographic mapping; they were not <br />surveyed (this was agreed-upon by FEMA and by the Town). Mannings "n" values of 0.080 and <br />0.120 were used for the channel and overbank areas, respectively. A flow rate of 248 cfs was <br />used throughout this upper reach. <br /> <br />The HEC model ran successfully and identified the limit of flooding without any significantly <br />unusual aspects. Table 2 presents the water surface profile data, while Plate I shows the <br />floodplain map in plan view. Plate I is the Town topography map, and uses the NAVD 1988. <br />The floodplain limits are accurate, but the elevations require an adjustment (subtract 5.91 feet) to <br />match the Tyra Tract D mapping. <br /> <br />971-055.010 <br /> <br />Wright Water Engineers, Inc_ <br /> <br />Page 11 <br />