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~:: ~a~~ <br />Lidstone and Associates, Inc. <br />Errgineerin~ Gea~ogJ & Water Resource Gansu~tartts <br />October 10, 2001 <br />Jeffrey W. Schwarz <br />Massey, Semenoff, Schwarz & Bailey <br />Hudson's Bay Centre <br />1600 Stout Street <br />Suite 1700 <br />Denver. CO 80202 <br />Re: Forensic Analysis of Bank Failure and SVeam Capture adjacent to Mobile Premix <br />Concrete, Inc., Howe Pit <br />Dear Mr. Schwarz: <br />At your request, I have investigated the mechanism of "bank failure" and the resultant flood <br />damage along the Bull Seep Slough at a location adjacent to the Mobile Premix Concrete, Inc. <br />(MPC) Howe Pit Permit, No. M-1978-052. The site is located along the east bank of the South <br />Platte River, approximately 1.5 miles upstream of [he Henderson Bridge and approximately 1600 <br />feet upstream of the Brantner Diversion near Brighton, Colorado. The bank failure coincided <br />with the hydrologic flood event of May 4'" and 5"` , 2001 and based on photographic evidence <br />may have occurred at least five (5) months prior to the date of that event. A portion of the South <br />Platte River was captured by the Bull Seep Slough and the resultant capture impacted lands <br />within and outside of the MPC permit azea. The nature of these damages include bank erosion, <br />channel widening and channel downcutting. It is also my understanding that the State of <br />Colorado has issued two notices of Reasons to Believe a Violation Exists. As stated by these <br />notices, the Division has reasons to believe that: <br />/. MPC failed to construct the Bull Seep Relocation in the manner and at the location described <br />in their permit documents: CRS 34-32.5-11b(1) 'f'ailure to perform the reclamation <br />prescribed by the reclamation plan ". <br />2. The damages that occurred both within and outside of the MPC permit area area "direct <br />result ojMPC's failure to relocate the Bull Seep channel in the approved location and not <br />properly installing the other associated drainage control structures as required by the <br />approved application. " (CRS 35-32.5-116.4(1) and Rule 3.1.5(3); CRS 34-32.5-I /6.(4)(h) <br />and Rule 3. /.6(!). <br />My investigation and forensic analysis of the bank failure and stream capture of May 5, 2001 <br />includes both qualitative geomorphic analysis and quantitative hydraulic analysis of the mode of <br />failure. These studies have included site visits to the MPC and adjacent permit areas; traverse <br />and geomorphic observations of existing bank conditions both within and outside the MPC <br />permit area; traverses along both the east and west banks of the South Platte River to review <br />historical channel avulsion, abandonment and areas of active erosion; interviews with MPC <br />employees, consultants and a local landowner; a review of historical aerial photographs spanning <br />the period from June 21, 1950 [o October L0, 2001; data review and hydrologic analysis of <br />FEMA records and HEC 2 studies; review of the MPC Mine Permit and Land Use application; a <br />760 Whalers Way, Swte B-200. Fort Collins, Colorado 80525337? 715 Roosevelt, Riverton, Wyoming 82501-3662 <br />(970) 223-A705 fax (970) 233-1706 a-mail water:mlidstone com (307) 856-5271 fax (307) 856-5281 <br />