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Mr. Jeffrey W. Schwi~Esq. • <br />July 12, 2001 <br />Page 3 <br />unconsolidated fill had been removed from the Macintosh property by the Brantner Ditch <br />Company and used to re-build the levee. <br />There was no indication from Mr. McIntosh's statements on June 13 that [he repair made <br />by the Brantner Ditch Company was engineered nor did representatives of the Brantner <br />Ditch Company that were present at the meeting make any such representations. <br />Photographs of the failed levee displayed by the UDFCD, in cross section, were <br />presented a[ the June 13th meeting. These photographs substantiate the materials that <br />were used in the construction of the levee. It was stated that lazge flat slabs of concrete <br />rubble were added for erosion protection to the west, or river side of [he levee. The upper <br />reach of the Bull Seep Slough that was created during the 1965 flood event, and that was <br />located immediately adjacent to the South Platte River, was not filled during the 1973 <br />Brantner repair effort and can be clearly seen in yearly photographs up to present day. <br />In 1995, the Bull Seep was relocated to its present location to accommodate an expansion <br />of the Howe Pit mining operation. Photographs taken after the Bull Seep relocation, from <br />1996 to present, show little to no change in the appearance or location of the Bull Seep <br />Slough, as compazed to its historic condition. In the six years since the alignment, there <br />has been virtually no evidence of problems that can be attributed to the historic feature to <br />which the Bull Seep was routed. <br />During the June 13`" meeting, Mr. Macintosh described the failure of the levee in <br />question. He stated that he observed large slabs of concrete, placed on the west river side <br />of the levee, sliding into the river. Once the concrete slid, he described a rapid failure of <br />the remaining embankment. It was stated that the levee had failed in approximately the <br />same location as the previous levee failure in 1973. This type of failure is consistent with <br />improperly shaped and sized riprap and the subsequent failure of an embankment that is <br />not constructed from materials that aze adequate for this type of channel protection. It is <br />also consistent with a scenario whereby the erosive forces are generated from the river <br />side of the embankment, and not the historic inboazd side of the structure. <br />We believe that a breach would have occurred in the levee at this location on May 5, <br />2001 regardless of the current location of the Bull Seep. The levee breached into the <br />portion of the Bull Seep Slough that was created originally during the 1965 flood event. <br />Once .the breach occurred in 1973, the remaining portions of the levee likely failed <br />causing the South Platte River to "head-cut" back along the existing channel and enlazge <br />the width of the breach opening. There was some mention of a "piping" failure of the <br />levee during the June 13 meeting, which would be difficult to now substantiate given that <br />the original structure is no longer in place. However, if materials that were prone to <br />piping were used in the 1973 levee reconstruction, this would constitute poor engineering <br />and construction practice that was outside the control of Mobile Premix. <br />Finally, it should be noted that the upstream channel entrance of the Bull Seep Slough <br />starts on the outside bend of the South Platte River. The river is constantly moving as <br />was pointed out by the IJDFCD at the June 13 meeting. The erosion caused from the <br />