C150094 Contract - Laserfiche WebLink

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:: . ~ .:'J . . Exhibit A Grant for Proposed Feasibility Study of Long Hollow Reservoir and Red Mesa Reservoir Enlargement This task will consist of evaluating alternative embankment sections, reservoir geometry and borrow area locations consistent with the existing topography and engineering and geotechnical findings. Phase I initial findings will be presented assuming a homogeneous embankment with a 3:1 upstream slope and a2.5:l downstream slope. The embankment height will be based on an area vs. capacity curve generated using the new aerial topography information. Phase II efforts will be used to confirm Phase I findings and further refine embankment section including delineation of zones and which are compatible with available borrow materials. 2. Borrow Area Alternatives. ~ ;--.i We anticipate borrow material will be obtained primarily from within the reservoir area. Two alternatives may be evaluated for the embankment alignment. However, we anticipate the principal focus will be alternative embankment heights. Phase I will determine available borrow areas based on the reconnaissance engineering geology results. Phase II will confirm that these areas are feasible and define the volume of material available based on geotechnical drilling and laboratory testing. 3. Seepage Reduction Alternatives. The available information will be reviewed in order to develop feasible methods for reducing water seepage through abutment and foundation soils and rock. Potential seepage control measures could include partial or complete blanketing of the reservoir area; grouting the soils and rocks in the foundation and abutments in order to increase seepage paths; constructing a cutoff trench in the foundation and abutment materials; and combining one or more of these measures in a seepage control program. Two appropriate seepage control options will be selected based on technical feasibility, constructability and cost. 4. Spillway and Outlet Alternatives. Spillway and outlet alternative locations will be evaluated based on the Phase I geologic studies as part of Phase 1. During Phase II, the geotechnical engineering characteristics of the site and the ability to release water from the reservoir as required by the regulations of the State Engineer's Office (SEO) will be evaluated. We anticipate that two spillway options and two outlet options will be evaluated. The alternatives analysis will focus on the most cost-effective and technically feasible alignments.