Ute Indian Tribe Sundance Reservoir Project

Client: Ute Indian Tribe
Project: Ute Indian Tribe Sundance Reservoir Project

Natural Resources Consulting Engineers, Inc. (NRCE) has provided design and construction management assistance to the Ute Indian Tribe for the Sundance Reservoir Project (Project). The proposed Project modifies an existing off stream pond formed from past sand and gravel operations along the West Branch of the Uinta River. The Reservoir will have expanded pool area and depth and controlled inlet and outlet facilities. The completed Reservoir will have an approximate surface area of 14.5 acres and storage capacity of 120 acre feet.

This Project is part of an overall Ute Indian Tribe program to establish small storages in strategic locations on the Reservation to impound water during high flow season and release water when supply flows are low. Specific purposes of Sundance Reservoir are to provide regulation of irrigation diversions and supplement late season irrigation supplies; to supplement culinary water supply; and to provide enhanced recreation, fish and wildlife, environmental opportunities for the Ute Tribe.

Substantial earthwork was necessary to form new embankments and enlarge existing embankments in order to increase the storage capacity of the Reservoir. NRCE evaluated the engineering properties of soil groups found on site for suitability for use as both foundation material and for embankment construction. In general terms, the soils were found to have good to excellent shear strength when compacted and saturated, negligible compressibility, and good to excellent workability as a construction material. Embankment slope stability was analyzed to investigate potential failure under various loading conditions. Slope stability analysis results generally showed the onsite soils will provide acceptable slope stability for a range of combinations of pore pressure ratio and soil cohesion investigated.

Standing water in the existing ponds was a reflection of the alluvial groundwater aquifer connected to the adjacent river. For the proposed Reservoir project, water must be retained in storage isolating it from the groundwater table, thus preventing water loss to the unconfined aquifer. After investigating pond lining alternatives, NRCE designed a clay blanket liner system to be installed across the entire Reservoir bottom and interior embankment slopes to form an impermeable barrier.

Controlled inlet works were designed consisting of a new diversion headgate structure on the River and pipe conveyance to the Reservoir to replace the existing diversion for the Ute Indian Irrigation Project D Ditch located just downstream. Controlled outlet works consisting of intake structure, pipeline, water control and measurement facility, and discharge structure into D Ditch were also designed. The water control and measurement facility contains control valves and plumbing to allow future deliveries to water treatment facilities for culinary water supplies, as well as control valves and water meter to regulate deliveries to D Ditch.

Autodesk Civil 3D 2015 software was used to model the design of the Sundance Reservoir. Initially, the site was surveyed before construction, and the resulting data was imported and processed by NRCE. Then, using design variables such as finished dam slopes, top of dam width, and initial pond bottom elevation, the reservoir was designed in Civil 3D. Civil 3D software was also used to perform various volume calculations such as storage volume, and various materials used in construction. Construction drawings were created for the dam and reservoir features such as inlet diversion structure, outlet works, control vault design, emergency spillway, infiltration pipe, and distribution pipeline to D Ditch. The mapping features of Civil 3D were used to properly map the site for finished design overview, as well as figures necessary for various permits associated with the dam location and construction.

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