C150094 Application ‎(2)‎

• Contract/PO #: C150094
• Contractor Name: La Plata Water Conservancy District
• Contract Type: Grant
• County: La Plata
• Loan Projects - Doc Type: Application

Phase II — Final Feasibility
If the Phase I, Initial Feasibility indicates that there are no unresolvable threshold issues
(fatal flaws), then Phase II,Final Feasibility work will be done. This scope of work
would include:
• Perform a subsurface investigation at the dam axis, spillway location and
proposed borrow areas.
• Conduct a laboratory testing program to determine the strength, compressibility
and permeability of the soil and rocks encountered in the subsurface investigation.
• Formulate and evaluate alternatives based upon the geological/geotechnical data
obtained. Results will be presented for:
(a) suitability of borrow material available in situ for use as compacted fill
material in zones of the embankment.
(b) The suitability of material in proposed borrow areas for compacted
embankment,riprap and concrete aggregate.
(c) Preliminary embankment section, including zones compatible with the
available fill material(s).
(d) Methods to reduce seepage at the abutments and beneath the foundation of the
dam.
(e) Slope protection.
(f) Alternate emergency spillway and outlet alignments and configurations based
upon cost, safety and subsurface conditions.
(g) Other geotechnical and geologic considerations for design and construction.
• Evaluate hydraulic issues associated with the proposed dam.
Study Plan—Phase II Final Feasibility
Each work task is described below. Cost estimates for each task are presented in Table
3b.
Subsurface Exploration Program&Exploration Observation
Feasibility level plans, designs, geotechnical analysis, yield analysis, cost estimates, and
general construction schedule will be prepared in this phase. The CWCB criteria for
feasibility level plans will be used to conduct the engineering analysis.
A subsurface exploration program will be conducted to define the subsurface profile,
obtain samples for laboratory testing and estimate the groundwater level at the axis of the
dam, the proposed spillway alignment, and borrow areas within the reservoir.
The subsurface exploration program will be conducted using test borings and test pits.
Drilling will be conducted to obtain relatively undisturbed soil samples using standard
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