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2"a Adequacy Review Comments <br />Page 4 of 5 <br />2. Figure 28G, included in the response for #28 below, gives vertical <br />information regarding the berm between the pits and the Cache la Poudre <br />River based on 1972 and 1973 topographic information pulled from the <br />1974 hydraulic modes. <br />The FEMA produced Floodway maps (see Response #27.A.1.a above) <br />utilize a topographic which is believed to be circa 1972. The 1972 <br />topography is of limited value due to the poor quality of the reproduction. <br />28. Existing Flood Control Dike: <br />A. Anderson Consulting Engineers, Inc, has developed a thalweg profile of the <br />Cache la Poudre River between Fern Avenue and Ash Avenue (See Figure 28A). <br />Unfortunately, limited channel bed information was available for this reach of the <br />Cache la Poudre River. The available 1973 and 1995 topographic information <br />utilized water surface elevations rather than actual channel bed elevations. It <br />should be noted that the 1995 data obtained from the USACE's 2003 floodplain <br />study did not include the Ogilvy Ditch Diversion Dam. <br />B. Additionally, Anderson Consulting Engineers, Inc. has provided representative, <br />river cross sections that compare the 1995 topography to the 2004 topography <br />obtained by American West Surveyors, Inc. {See Figures 28B - 28F). <br />C. Historic profiles of the berm between the Cache ]a Poudre River and the Durham <br />Pit are shown on Figure 28G. Also included on Figure 28G is the 2004 bed <br />elevation and an estimate of the historic right bank profile. The estimated historic <br />right channel bank was developed utilizing: (a) existing tree base elevations and <br />(b) undisturbed ground information from the 1974 hydraulic model, 1995 <br />topography, and 2004 topography. Aline approximately 9 feet above the thalweg <br />(channel bed elevation) can be drawn on this figure. <br />D. The volume of material to be removed (excess) or the volume of berm material <br />left to be constructed will be provided in the Flood Control/Mitigation Plan (See <br />Response to 6.4.5 Exhibit E, # 16). <br />E. Design plans and details for backfilling, grading, and slope protection measures <br />for the flood control berm will be provided in the Flood Contro]/Mitigation Plan <br />(See Response to 6,4.5 Exhibit E, #16). <br />Information contained in the figures developed by Anderson Consulting Engineers, Inc. <br />was obtained from the sources provided in Response #27. <br />COVC03 ACE 2nd Adequacy Rvw Comments mml.doc ~ 7/6/2004 <br />