Duncan Creek Crossing Replacement and Sediment Removal

Duncan Creek Crossing Replacement and Sediment Removal

The project consists of replacement of the structural plate culvert crossing Duncan Creek upstream of Duncan Diversion Dam, which was destroyed by storm flows and debris during the storm of December 31, 2005 to January 1, 2006. Embankment material surrounding the culvert was washed away, a portion of which was deposited at the upstream end of the Duncan Diversion pool. Engineering and design of a replacement crossing is planned for 2006, and construction is planned for summer/fall 2006 or 2007, after necessary permits are obtained. The replacement crossing will be designed to better handle large debris, which may be more likely since the Star Fire of 2001. Embankment material for the crossing abutments will be obtained at least partially from the sediment at the upstream end of the diversion pool, which can be excavated without unwatering the pool. No uncured concrete will be allowed to contact surface waters. A stream flow bypass system may be required during construction of the crossing. The work will be performed under a California Department of Fish and Game 1601 Agreement, a US Army Corps Nationwide permit, a #401 Water Quality Certification, a Tahoe National Forest Special Use Permit, which include requirements for environmental protection, and authorization to proceed from FERC prior to construction.

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