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Mr. Jeffrey W. Schwarz, Esq. 10/14/01 Page 3 located immediately adjacent [o the South Platte River, was not filled during the 1973 Brantner repair effort and can be clearly seen in the yearly photographs up to present day. (See Figures 1-4 and l-5). In 1995, the Bull Seep was relocated to its present location to accommodate an expansion of the Howe Pit mining operation. Photographs taken after the Bull Seep relocation, 1996 to present, show little to no change in the appearance or location of the Bull Seep Slough, as compared to its historic condition. In the six years since the alignment there has been virtually no evidence of problems that can be attributed to the historic feature to which the Bull Seep was routed. (See Figures 1-5 and 1-6). The flood events in 1965 and 1973 are much lazger than the one in question on May 5, 2001 and as such would not be comparable directly when discussing channel breaches. The reason we bring these events up are to point to the history of flows in the South Platte and the origin of the Bull Seep Slough, which exists from natural forces in the river created by major floods. The smaller flood event on May 5`h was contained within the river channel and as such is exerting maximum energy on the riverbanks. These types of flows are river-forming flows that tend to move channel alignments and cause maximum erosion. Once a flow overtops the riverbanks and spreads into the floodplain, it loses some energy, because the overbank area absorbs the flows. We have no evidence to suggest that the May 5`" event was an overtopping flow and believe that the bank full flows caused sufficient erosion to allow the eventual collapse of the riverbank. The eyewitness accounts support this contention. During the June 13`h 2001 meeting, Mr. Ken Macintosh described the failure of the levee in question. He stated that he observed large slabs of concrete, placed on the west/river side of the levee, sliding into the river. Once the concrete had slid, he described a rapid failure of the remaining embankment. It was stated that the levee had failed in approximately the same location as the previous levee failure in 1973. This type of failure is consistent with improperly shaped and sized riprap and the subsequent failure of an embankment that is not constructed from materials that are adequate for this type of channel protection. It is also consistent with a scenario whereby the erosive forces are generated from the river side of the embankment, and not the historic inboard side of the structure. (See Figure 1-8). Further conversations with representatives of the Brantner Ditch Company indicate that they have spent approximately $100,000 in construction materials from 1980 to present in attempts to stabilize their diversion structure from continued degradation in the South Platte River. This degradation has happened from downstream mining in the river, rechannelization of the river, and sediment affinity caused by mining upstream of the diversion structure. This continued degradation of the river would also impact the Bull Seep Slough where it discharges to the South Platte River downstream of the Brantner Diversion structure by increasing the slope of the channel and thereby increasing velocities throughout the channel. (See Figure 1-9). All of these factors are outside of the control of Mobil Premix and have no connection to the present location of the Bull Seep ditch.