PROJ00414

• Contract/PO #: C153326
• Contractor Name: Fruitland Mesa Water Conservancy District
• Contract Type: Grant
• Water District: 0
• County: Montrose
• Bill Number: XB 99-999
• Loan Projects - Doc Type: Feasibility Study

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Pin-hole Dispersion

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Three samples were tested for potential dispersiveness or colloid
erodibility. Results of the tests, presented in Figure 13, indicated
that the soils are not of a dispersive nature.

Grain-size Analysis

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Hydrometer analyses of the three samples indicate that about 55
percent is silt sized and 45 percent is clay size. Gradation curves
are presented in Figures 9 through 11. F1gure 12 is a super-position
of the three curves with an interpreted best-fit curve drawn in for
later use in evaluating filter criteria.

Triaxial Testing

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Triaxial tests were performed on laboratory prepared samples to

develop shear strength parameters for use in design. Both consoli-

dated undrained tests with pore pressure measurements and unconsoli-

dated undrained tests were performed. The samples were compacted to

98 percent of maximum dry density at a moisture content approximately

2 percent wet of optimum, based on the results of the respective

compaction tests presented in Figures 14 through 16. The results for

triaxial testing performed are as follows:

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Sample
No.

Represen-
tative
Depth
(ft to ft)

Effective
Cohesion
(C', PSF)

Internal
Effective
Friction
Angle
(00)

Atterberg Limits
Liquid Plastic Plasticity
Limit Limit Limit
(%) (%) (%)

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A-2-l 4.0-7.5 500 28.5 34.4 18.8 15.6
A-5-2 2.0-8.0 800 26 48.5 20.5 28.0
B-5-l* 2.0-8.5 1500 0 42.5 16.8 25.7
Used in 300 260
design
* Unconsolidated Undrained Shear Strength

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