Laserfiche WebLink
<br />e <br /> <br />e <br /> <br />e <br /> <br />FLOODPLAIN REPORT - Tyra Tract 0 and Sawmill Gulch, Breckenridge, Colorado <br /> <br />which is part of the upper collection system. Flood flows are released essentially at the same <br /> <br /> <br />place and at the same rate as in pre-project conditions. These collection systems are discussed in <br /> <br /> <br />more detail in the next major section, entitled "Hydraulic Structure Analyses." It is not the intent <br /> <br /> <br />nor the design for these facilities to significantly alter the existing floodplain of Sawmill Gulch <br /> <br /> <br />or the out-of-bank flooding except to route it around the proposed building. The approach was <br /> <br /> <br />requested/confirmed by FEMA and Town representatives. <br /> <br />Proposed Conditions Model-Upper Sawmill Gulch Reach <br /> <br />The proposed floodplain conditions for upper Sawmill Gulch, that portion from Tyra Tract D to <br />the Town boundary, do not differ from the existing condition. There are no proposed <br />construction activities upstream of Tyra Tract D. Thus, the floodplain on Plate I presents both <br />existing and proposed conditions for upper Sawmill Gulch. <br /> <br />The profile data for the existing conditions model, Tables I and 2, applies to the proposed <br />conditions as well. <br /> <br />HYDRAULIC STRUCTURE ANALYSES <br /> <br />This section provides a description of the proposed facilities that are intended to capture out-of- <br />bank flooding from Sawmill Gulch. One set of facilities captures flooding in the vicinity of <br />Sawmill Gulch Cross-Sections No. 55 through No. 58; this is referred to the "upper collection <br />system," and provides for the estimated out-of-bank flooding peak flow rate of 68 cfs with a <br />safety factor of an extra 50 cfs. <br /> <br />An additional 50 cfs is predicted as out-of-bank flooding at Four O'Clock Road. The facilities <br />proposed to capture this flow are referred to herein as the "lower collection system." This <br />captures flows that are forced out of Sawmill Gulch due to the existing culvert at Four O'Clock <br />Road. Each system is discussed below. <br /> <br />971-055.010 <br /> <br />Wright Water Enginee~, Inc. <br /> <br />Page 14 <br />