C154210 Contract - Laserfiche WebLink

Home Browse Search

The dam safety and operational issues described above combined with the value of the reservoir for optimizing water use for multiple stakeholders in the basin have driven the District to move forward with the rehabilitation of the Rio Grande Dam and Reservoir. The District is a proponent of the Rio Grande Cooperative Project where the District works with multiple stakeholders in the State,primarily the Colorado Water Conservation Board and the Colorado Division of Parks and Wildlife to restore the full use of the reservoir. The project is made up of three primary components(as shown on the attached figures), including: ■ Upstream Clay Blanket—In order to reduce seepage through the rock slide formation at the left dam abutment,a clay blanket slope liner will be installed on the upstream side of the dam at the left abutment. The clay blanket, shown on Figure 1 in plan and Figure 2 in cross-section,will be a zoned fill placed over the rock slide and extending across the west abutment of the dam approximately 100 feet. The zones include a filter layer, low permeability clay core,and cover zone. This improvement is expected to substantially reduce seepage and allow the full storage capability of the reservoir to be achieved. ■ Low Level Outlet—The existing low level outlet will be replaced with a hollow jet valve discharge structure at the downstream side of the dam. The existing low level outlet tunnel will continue to be used to provide conveyance between the upstream and downstream portals. The existing sluice gate control structure will either be demolished or abandoned in-place with a bypass tunnel providing conveyance around the structure;this is shown on Figure 1. Schedule constraints for the work and the uncertainty of the demolition costs(for removal of the existing sluice gate control structure)suggest that the construction bidding process may be the best way to determine the most economic solution. To that end,we recommend preparing the bidding documents with two options: Option 1 —Demolish Existing Sluice Gate Structure and Option 2 —Construct Bypass Tunnel and Abandon Sluice Gate Structure. The District can then select which option is most economic based on the results of the bidding. Another important element of the low level outlet work is the provision for the future addition of hydropower. To allow hydropower to be added in the future with minimal disturbance to the primary function of the project,a tap will be provided at the low level outlet(downstream of the tunnel portal)which can be used to route flows to future turbine generator units. • Spillway Improvements—In order to achieve the spillway capacity required by the State Engineer's Office(SEO),the entrance training walls will require a substantial raise and the main channel training walls will require a roughly 2 to 6-foot raise. This is expected to be accomplished by a combination of cast-in-place concrete and perhaps shotcrete. Additionally, some of the existing spillway floor slabs will require replacement or rehabilitation due to the condition of the existing concrete. The following section presents D&A's scope of services for the work. SCOPE OF SERVICES Task 1 - Project Management The San Luis Valley Irrigation District(the District)will use Deere&Ault Consultants,Inc.(D&A)as the prime subconsultant. Efforts under this task will include coordination between the District and subconsultant,other stakeholders,and the Office of the State Engineer, Division of Water Resources(SEO) through meetings,teleconferences,email,and correspondence; scheduling and coordinating the efforts of the design team;preparation of progress reports for the District;and monthly invoice preparation. Deliverables: Progress Reports, Meeting Minutes, and Monthly Invoices - 2 -