C150094 Application ‎(2)‎

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

WC, .
Evaluation of Alternatives
A. Interpretation of Data
The existing data(and supplemental field and laboratory test results, if any,)
will be analyzed to establish strength, compressibility and permeability
characteristics of the soils and rock,which are in situ or proposed as
compacted,borrow materials at the dam and reservoir site. It may be that
additional geological and geotechnical studies may be included with pre-
design studies in the Grant/Loan request workplan submitted to the
Colorado Water Resources and Power Authority.
Geologic maps, logs of test borings, laboratory test results and periodic
groundwater readings in the piezometers will be used to develop design
parameters for use in the Conceptual level embankment design.
B. Conceptual Level Embankment Design
1. Embankment Section, Reservoir Geometry.
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.
2. Borrow Area Alternatives.
We anticipate borrow material will be obtained primarily from the
reservoir and the left abutment near the spillway.
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 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 to develop 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 alternatives will be evaluated based on the geology
and geotechnical engineering characteristics of the site, the condition and
configuration of the existing outlet works, and the ability to release water
from the reservoir as required by the regulations of the State Engineer's
Office (SEO).
We anticipate that two spillway options and outlet options will be
evaluated. The alternatives analysis will focus on the most cost-effective
and technically feasible alignments.
8