Laserfiche WebLink
i • <br />6. Of most concern is the construction of the 300 ft berm by Four States Aggregates <br />that is designed to have heights of several feet to possibly six feet or more. When <br />there are volumes of water in excess of 6,000 cfs, the river channel will be <br />artificially confined just north of the Akin property. This impedes the natural <br />tendency for the river floodwaters to spread out and dissipate. <br />The Four States Aggregates recognizes this problem. To quote from pages 27D <br />and 27E: <br />"The construction of vegetated stockpile berms along the pit side <br />closest to the river will also further reduce the ability of the river to <br />change its current channel, which at this point is relatively straight <br />and along the east side of the valley. Because of the current <br />channel configuration, there is a greater chance of stream course <br />changes further downstream (such as on the Robinson and Akin <br />properties and beyond) regazdless of the Line Camp Pit presence." <br />8. By confuung the channel and preventing floodwaters from spread out in the <br />normal floodplain, greater erosion of the streambed occurs which in this case is <br />just north of the Akin property. These eroded stream gravels will be dumped in an <br />azea where the channel naturally spreads out. That would be in the braided section <br />on the Akin and Robinson property. Thus, there is Beater flooding and lateral <br />migration of the braided stream channels. Where these new channels would occur <br />is unpredictable, but almost assuredly they would negatively impact the Akin and <br />Robinson property. <br />Conclusion <br />The proposed berm design of the Line Camp gravel pit increases the risk of flooding <br />from a high dischazge event on the land of Jack Akin and Cazol Stepe. This type flood <br />event could threaten human lives and buildings on this property. <br />Additional Comments <br />Obstructing the natural course or channel of waters in the U.S. is contrary to the <br />provisions of federal law (33 U.S.C. Sec. 403). The south berm that Four States <br />Aggregates plans to build spans 50 to 60 percent of the width of the Dolores River <br />Valley. During a major dischazge event that breaches the gravel pits through pit capture, <br />this south berm would impede water flow. The two gaps in the south berm that aze <br />designed to drain backup waters in such an event could easily be overwhelmed. Because <br />the berms aze composed of soil and gravel fines, the berm could easily be eroded and <br />increase suspended sediment load. This load would ultimately be dischazged and <br />deposited in the McPhee Reservoir. In addition, the water flow through the gaps would <br />Affidavit of Dr. Robert W. Blair, Ph.D. Page - 3 <br />