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.. .......4../' 002391 Animas-La Plata Annual Operating Plan Major structural features of the Animas La-Plata Project include: the Ridges Basin Dam and Reservoir, an intake structure and pumping plant of 280 cubic feet per second (cfs) capacity on the Animas River below Santa Rita Park (formerly Gateway Park) in Durango, and an inlet conduit to the reservoir from the pumping plant along a route south of Bodo Creek and County Road 211. The design for Ridges Basin Dam consists of a zoned earthfill dam containing a thick impervious core bordered by filters and drains and supported by sloping pervious shells upstream and downstream, The height of the dam, streambed to crest would be 217 feet and the length of the crest 1,670 feet. The crest elevation would be 6,892 feet; the full level would be 6,882 feet; and bottom of active storage would be 6,801 feet. Upstream and downstream slopes would be 2:1 (horizontal to vertical) in the active storage range with a bench at the bottom level of active storage and below that level; 3:1 upstream and 2-1/2:1 downstream. The core would bear directly on the foundation rock and the compressible alluvium would be removed both upstream and downstream for placement of the shell of the dam. Foundation excavation would amount to 2,600,000 cubic yards (cy) and dam fill would require 5,700,000 cy. Reservoir capacity would be 120,000 acre-feet. The Durango Pumping includes an intake structure with trash grate, fish screens and fish bypass conduit to the river; a pumping plant building housing four 56 cfs horizontal centrifugal pumps, two 28 cfs horizontal centrifugal pumps and two 14 cfs pumps for a total capacity of 280 cfs. The design would also include an electrical switchyard next to the building to receive power from the Western Area Power Administration (y.I AP A) transmission line and supply electricity for the motors and plant. The Ridges Basin Inlet Conduit feasibility design proposes a 66-inch diameter pipeline buried along a route from the pumping plant south across CR 211 and up Bodo Draw south of the creek line, on the alignment described in the 1996 FSFES, terminating at a discharge structure over the crest of the ridge. Water from the discharge structure would flow in a rock-lined channel leading to the reservoir. Hydraulic surge in the conduit would be controlled with a spherical surge chamber located next to the pumping plant, away from the river. Reservoir Operations Annual Operating Plan (AOP) Develop an AOP for the reservoir, based on historic data and snowpack surveys. This will include projected pumping rates and bypass flows as established by the FSEIS and downstream Project needs. Pumping will be regulated as defined in the FSFEIS. Prepare annual OM&R budget as well as work plan. Establish 1 and 3 year work plans as required. Based on reservoir needs, develop an operation scheme to minimize power usage costs. Track water usage and bill accordingly. :--: . ~. _. 1 -. ::l ---, i ---, , -, , I -, I -I -I -!