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&A Hydrogeological and Environmental Consultants <br />October 4, 2013 <br />Ross Bachofer <br />P.O. Box 652 <br />LaSalle, Colorado 80645 <br />RE: Evaluation of the Cause(s) of Water Level Increases in the South Platte Alluvium at the <br />Ross Bachofer Property; 7525 Highway 85, Fort Lupton, Colorado <br />Ganser Lujan and Associates (GL &A) have conducted a desktop study and literature search to <br />determine the impacts of aggregate mining adjacent to and in the vicinity of the Bachofer <br />property at 7525 Highway 85 in Fort Lupton on the hydrogeologic regime in the South Platte <br />Alluvium. This study was performed in general accordance with our proposal dated June 25, <br />2013 as accepted and approved on June 27, 2013. <br />Summary <br />The results of this study indicate that aggregate mining adjacent to and upstream of the subject <br />property has resulted in higher river flood stage levels, higher ground water levels and water <br />seepage into the lower level of the residence at this location. The impact of aggregate mining <br />to this property is based on the fact that slurry wall construction around open pit aggregate <br />mines has caused alluvial groundwater to back up or mound behind these walls on the up- <br />gradient side of the walls and decline on the down- gradient side. Mounding has caused higher <br />water levels than previous and historic levels in the river alluvium and as result has induced <br />greater groundwater flow into the river. The impermeable slurry walls from the Suburban Pit <br />and the Everist Pits are located in close proximity to the west bank of the South Platte River <br />and as such have also significantly reduced the bank storage capabilities of the river alluvium. <br />In addition, the slurry walls and berms have adversely altered the floodplain characteristics of <br />the river by obstructing the land adjacent to the river that was naturally reserved for base <br />flooding without increasing the water surface elevation. Historically, high flows in the past <br />have not caused flooding on the Bachofer property. Since 2004, flows that are considerably <br />lower than previous discharge are now flooding the subject's property. <br />Extensive mining operations with lined pits upstream of the Bachofer property have also <br />altered the river dynamics and regime causing what was normal river swells in the past to <br />exceed the 100 year floodplain elevation. These mining activities coupled with the L.G. <br />Everist pits located primarily along the west side of the South Platte River have altered the <br />river morphology contributing to an increase in the number and size of sand bars. These bars <br />have reduced the cross - sectional area of the river channel thus causing higher stage levels and <br />the potential for more frequent flooding. <br />As discussed above, all of these factors together have increased the likelihood of flooding <br />with lower river flows than what previously caused flooding on the Bachofer property. <br />12610 W Bayaud Ave, Unit 11, Lakewood, CO 80228 <br />303- 888 -9078 <br />