Laserfiche WebLink
11rdrogeological and Environmental C'onsiiltants <br />The earliest photo from 12/11/2002 (Figure 7) was taken several years before the pits were <br />lined and shows there were fewer and less developed sand bars present than in later years. <br />When compared to 10/7/2012 (Figure 10), there are fewer less developed bars near the <br />Bachofer property. A long bar is visible directly across the river from the property on the <br />2002, but is wider and longer on the 2012 photo. North of the Bachofer property, there are <br />several other bars that are present on the 2012 photo but do not appear on the 2002 photo. <br />As noted on the series of Figures 7 to 10 from 2002 until 2012, there appears to be a steady <br />increase in the quantity of sand being deposited near the Bachofer property. As mentioned <br />in the DRMS's letter the presence of these bars reduces the cross - sectional area of the <br />stream channel and raises the stage level in the river upstream of the bars. <br />What has caused this change in the river over the past 10 years? GL &A believes that bars <br />may have formed due to alterations in the channel geometry upstream of the Bachofer <br />property. These alterations may be attributable to the presence of lined pits that are located <br />upstream of the Bachofer property as shown on Figure 34 of the USGS Report. In order for <br />the bars to form downstream, higher water velocities upstream have occurred because of the <br />change in energy grade due to the lined pits. Higher velocities upstream have increase the <br />bed load of the river and have carried more sediment downstream. Deposition of this bed <br />load has occurred in the formation of point bars where stream velocities have decreased. As <br />in the case of the river near the Bachofer property, the bars have formed near the inside <br />banks of the river, where stream velocities tend to be lower. The formation of these sand <br />bars coupled with groundwater mounding adjacent to sand bars has created a silmificant <br />change in the surface water levels and stage in this area of the South Platte River. As a <br />result of these two factors, more frequent flooding has been occurring on the Bachofer <br />property. <br />Close -up pictures of these bars are shown below in a sequence of site -visit photos that show <br />the South Platte River adjacent to the Bachofer property. <br />13 <br />