Anderson Dragline, Inc. Anderson Dragline, Inc.
P: 530-695-1352  |  F: 530-695-3131  | Shop: 530-868-5121
P.O. Box 968, Gridley, CA 95948
Derby Dam Spillway

Owner: Bureau of Reclamation
Year Constructed: 2002
Approx. Subcontract Value: $2,000,000 


Project consisted of constructing a concrete spillway, grouted riprap spillway channel, a riprap-lined fish conveyance channel and mechanical and electrical upgrades to an existing diversion dam located on the Truckee River east of Sparks, Nevada. Anderson Dragline, Inc. worked as a grading and riprap subcontractor to S.D. Carmack Dirtmoving.

To accomplish installation of a new spillway and fish conveyance channel, cofferdams were installed in a segment of the Truckee River adjacent to the work sites. Pumping behind the cofferdams was continuous during construction to keep the work areas dry. Pumped water was discharged into stilling tanks prior to draining back into the river. Floating turbidity curtains were also installed to maintain water clarity downstream of the work area. Daily water quality sampling was conducted to confirm compliance for turbidity and settleable solids downstream of the work site.

A new concrete gate structure and spillway were constructed at the upstream ends of the fish conveyance channel and spillway channel, respectively. The fish conveyance channel and spillway channel were excavated with some spoils being disposed on site. Remaining spoils were screened and used in placement of new embankment and a stockpile for future use by the agency.

Approximately 5,000 tons of riprap was placed to line the slopes and invert in the 1,100 foot long fish conveyance channel. Two-ton and four-ton boulders were placed across the channel at regular intervals in the shape of a chevron to slow the flow velocity to enhance fish passage. "Tuning" of the boulders was accomplished by adjusting the position of the center boulders as directed by a fisheries biologist to optimize the pooling  of the water flow behind the boulders.

Approximately 20,000 tons of riprap were placed and grouted with concrete to face the spillway channel slopes.

Existing slide gate stems were removed and replaced at the dam. New electric actuators were furnished and installed on the slide gates, with a standby generator as emergency power source. Lead-based paint was removed from an existing radial gate and the gate was re-painted.

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Phone: 530-695-1352
Fax: 530-695-3131
Shop: 530-868-5121

Anderson Dragline, Inc.
P.O. Box 968
Gridley, CA 95948