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efforts, which are planned for late 2002. When the dike berm is removed, the water will flow <br />onto the existing 100 year floodplain which extends a distance of 1750 feet to the east. There- <br />fore, in this direction, a huge storage volume is available to absorb the change in direction of <br />the water, and no erosion of the east bank of the river would take place. <br />Item 2 -Concrete Blocks at Toe of Bank <br />Map C-2 shows that the toe of the embankment slope below the jetty will be armored for a <br />length of 680 feet. As shown on Map C-5, the top of the embankment elevation varies from <br />6662' to 6668'. It is planned to use concrete block of base dimensions of 4.0' x 4.0' with a <br />height of 3.0'. The block will have a "U" shaped rebar placed in the block on three sides so <br />that it can be welded or clamped to the rebar from the adjacent blocks. As show on Map C-5, <br />the block will be placed in two layers and the bottom layer will be buried approximately 1.0 <br />to 1.5 feet into the bottom of the slope. Earth and grave] will be filled in the 2.0 feet gaps be- <br />tween the blocks and these areas will be seeded with the mix described in Item 3 below. Wil- <br />lows will also be planted at the base for added stability. It is believed [hat this design will <br />provide maximum long term stability while at the same time, the spacing and planting will <br />reduce visual impacts. The planting described should make the blocks less visible. The slope <br />of the embankment will be no steeper than 2.OH:1.OV. The blocks will be placed so that a <br />minimum height of 5.5 feet exists from the existing toe of slope to the top of blocks. Most <br />large flood events will not rise above the level of the upper row of block. This block is <br />shown to be very stable for bed and bank conditions as shown on the following page. <br />The actual safety factors for these cases should also be somewhat higher since the upstream <br />jetty will reduce the velocities and shear forces on this material. <br />Received <br />Thomas Pit 2/02 17 MAR n 7 ~pD2 <br />Durango Field OfliCe <br />Division of Minerals 8 Geology <br />