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1"\ 11 II II II Ii 11 I! II II I) . II II I 11 J 1,1 II I 3. State of Colorado CoIistruction Materials Regular (112) Operation Reclamation , Permit Applications Form filled out by Four States Aggregates, LLC, File No. M- 2001-001. , 4. State of Colorado Division of Minerals and Geology response to objections received to the Four States Aggregates, LLC, Line Cml;lP Pit, File No. M-2001- 001. 5. USDA-F color stereo aerial photos 24-612130-198-56 and,198-57, 1998. 6. SCS b&w stereo aerial photos DKQ-4-147 and 4-148; 1950. 7. Website USGS Hydrograph and station description for 09166500 (http://water.uSgs.gov/peak.cgi?~tnum=09166500...), 2001. Findings 1. Four States Aggregates's final reclamation design (Exhibit Page 23, File No. M- 200-001) indicates a berm 350 ft long will occupy the ~outheastem edge parallel to the river and a 700 ft berm perpendicular to the valley slope at tb..e extreme southern edge of the gravel pit area 2. As can be seen frotp. aerial photo 198-57, the Dolores river is presently a single thread channel confined to the eastern valley wall north of the Akin property and then shifts to a single thread channel on the western valley wall south of the Akin property. The shift of the river from one side of the valley to' the O'thet: is indicated by a braided channel network. Braided channel patterns are indicative of ~~per gradients, unstable bedloads (gravel aild sand that Jri,akes up the stream bed) that result in shifting channels especially during flooding. Braided channels are associated with greater bedload than what the river discharge can handle and, thus,-the channel splits into multiple threads. 3. The Akin prop~rty is situated at the northeastern edge of the braided se~on. The, proposed Line Camp gravel pit is located on the west side of the valley just north of the braided section (see'photo 198-57). The Akin property is thus susceptible to the effects of braidirig and erosion of high banks during high discharge events. 4. High'discharge events are considered here as volumes greater than 6,000 cubic feet per second (cfs). There have been eight such events in the last 90 years (see Peak Streamflow for Colorado, Dolores River). Volumes between 6,000 cfs and ' 8,000 cfs would most likely involve the reoccupation of existing braided channels and if the flood had a duration of several days could form new channels: _I ! _I 5. Very high discharge events or catastrophic flood events would be volumes greater than 8,000 cfs. There have been three of these events in the past 90 years. During such events the channel configuration could be completely redesigned. It is likely that with the presences of gravel pits that pit capture would take place. lIDs is where the floodwaters will take the path of least resistance. Thus, human alteration of the natural floodplain would aid in the relocation' of the channel. To prevent this, berms are often constructed. Affidavit of Dr. Robert W. Blair, Ph.D. Page - 2