2004-09-27_REVISION - M1987064 - Laserfiche WebLink

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i ~~ DEPARTMENT OFTHE ARMY U.S. ARMY ENGINEER DISTRICT, SACRAMENTO CORPS OF ENGINEERS 1325 J STREET REPLY TO SACRAMENTO, CALIFORNIA 95814-2922 ATTENTION OF February 24, 2004 Regulatory Branch (199475346) Mr. David Dillon Sandco, Inc. P. O. Box 4440 Durango, Colorado 81302 Dear Mr. Dillon: We are responding to your streambank stabilization design for the Dalton Pit. This office does not generally encourage the use of structural designs (i.e. concrete blocks, gabion structures, seawalls, etc...), when other natural alternatives for stabilization may exist. However, due to the implementation of natural landscaping over the proposed concrete blocks, and due to the high velocity of the Animas River, this office approves your proposed stabilization design as shown in the enclosed plan. You shall incorporate the following conditions into your design plan: 1. You shall use 2 foot diameter or larger boulders mixed with the river run material for backfill around the exposed portions of the concrete blocks. 2. The concrete blocks shall be 75 to 100 buried into the side of the bank. 3. The slope of the bank shall be no greater than 3:1 and shall be planted with willows or other native vegetation as shown in your design plan. 4. You shall inspect the vegetative plantings within the following growing season to ensure their livelihood. After the first year, if less than 800 of the vegetation survived, you shall replant and monitor the following year. This procedure shall continue until the site achieves an SOo or greater success rate. 5. The work shall be performed during the 2004 low-flow period. 6. The work shall be performed in all critical areas as discussed in our January 26, 2004 meeting and as referenced in our February 2, 2004 letter. In addition, Special Condition number 12 of your permit states that you shall conduct an annual meeting among Federal, 0