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downstream in an area that is essentially the upstream side of the next meander. But the major factor in the <br />intensification of the stream bank cutting at the breach was amid-stream sandbar that forced the river flow into <br />the bank. This created a very intense, localized erosion environment that normally would not be expected at this <br />location in a meander. <br />This technique, which was suggested by Anita Culp of the Corps of Engineers, involves constructing <br />small jetties out into the river with a separation of about 20 feet. The jetties were constructed of waste concrete <br />patties. They axe keyed into the bank and extend only about 10 or 15 feet into the river flow. It is important to <br />have the ends of the jetties stop at nearly the same distance from the bank so a smooth curve is created by a line <br />connecting the ends of the jetties. <br />The jetties then allow large amounts of sediment to accumulate in the covelets between the jetties. This <br />is then invaded by stream bank vegetation. At these locations it took about three years for the covelets to fill <br />and become densely inhabited by willows and herbaceous growth. The vegetation traps yet more sediment <br />which creates a more gentle slope into the xivex. Cottonwood eventually invades the inner portions of the filled <br />covelets and willows populate the wetter portions closer to the xivex. Interestingly, Tamarix, does not seem to <br />readily invade these areas as the willow and herbaceous growth is so dense this weedy species can't become <br />established. Eventually, a very smooth, almost fully vegetated bank is created that is made very strong with the <br />blend of woody plant roots and the mostly buried jetties. Flood waters thus do not have the opportunity to cut <br />into the bank because the bank is smooth and therefore generates a fairly non-turbulent flow along the shore. <br />This is different from what occurs with rip rap which tends to create a turbulent flow that, in some <br />circumstances, can actually make the erosion worse than no protection at all. The vegetation further limits <br />encroachment of the water and reduces the velocity of the water between the river and adjacent land where <br />overflow may accumulate. <br />At the time of this annual report, the operation is back into almost full production, but clean up of the <br />sediment and debris that flowed into the pit during the breach is continuing. During this winter, it is possible a <br />second sediment basin will be established along the south side of the pit which will help secure the weakened <br />south wall. The jetty approach to stxeambank stabilization is being proposed fox locations along the river <br />adjacent to Phase 2. At this point such jetties adjacent to the breach location would not be very effective. <br />Creating a very broad setback with a new sediment basin would be far more effective in protecting the pit next <br />summer. <br />Revegetation: None. <br />Expected Activity (2006-2007): Mining in the next year will continue to be done within the existing pextnit <br />area. The operation has xetumed to a more normal sequence of mining. The addition of the amended land, <br />Phase 2, will allow for a future expansion of the pit as the end of the reserves in Phase 1 are in sight, but still <br />probably 1 S to 24 months away. It is expected the amendment will be submitted by the end of 2006, if not <br />sooner. <br />Bonding: This operation is covered by a self bond. <br />Transit Mix of Pueblo 2006 Annual Report M-1986-015 Pueblo East Pit Page 3 of 3 <br />