WSP11936

• File Number: 8276.500
• Description: Glenwood-Dotsero Springs Unit - Salinity Control Projects
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 1/1/1983
• Author: Golder Associates
• Title: Geology Working Paper for the Contour Ponds Site Near Mack, Colorado
• Water Supply Pro - Doc Type: Report/Study

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Results from pinhole dispersion tests performed on samples C-4,
C-17, C-18, EP-l, and EP-2 indicate all samples are non-
dispersive when compacted in place. All soils were classified as
ND-1 (non-dispersive) (Sherard, et. al., 1976) when compacted
within 2% of optimum moisture content and to at least 90% of
Standard Proctor dry density.

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A summary of the permeability test results are provided in
Table 5-3. Surprisingly the highest (EP-2) and one of the lowest
(C-18) permeabilities both came from weathered Mancos shale. The
material in EP-2 consisted of residuum comprised of chips of
shale with very low plasticity while the material in C-18 was
more plastic and clayey in texture which resulted in a more
impermeable material. Overall both pediment and residual soils
are excellent materials for use as a liner. Of specific note is
the soil from EP-1 which contains only 41% fines yet had a very
low permeability. This was likely due to the well graded nature
of the material.

TABLE 5-3: Summary of Permeability Test Data
% of
% Passing Permeabili ty Standard
{ No. 200 (cm/sec) (in/hr~ Proctor % Wet of
Sieve (x 10-9) (x 10- ) Density mlC (
Pediment Soils
C-4 55 9.7 1.4 96.5 1.8
C-17 79 9.8 1.4 94.0 4.0
EP-1 41 19 2.7 95.4 2.8
Residual Soils
C-13 64 18 2.6 99.0 1.2
C-18 61 4.6 0.7 98.4 2.1
EP-2 67 42 6.0 95.1 2.0

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Pipeline construction on-site will require sand and gravel
sources for bedding. On-site sources are adequate for this use
but will require selective sorting on-site to remove cobbles and
large and cemented gravels. The on-site sands and gravels ~re
likely unsound due to the presence of shale, chert, and cemented
materials. Therefore, they would be unacceptable as a source of
concrete aggregate.

The results of soluble sulfate testing are presented in
Table 5-4. All of the soils with the exception of C-4 exhibited
high concentrations of soluble sulfates which indicate they would
severely attack any concrete used on-site. Since for the most
part, all the sulfate concentrations are above 0.2% it is
necessary that Type V cement be used in any concrete placed
on-site (USBR, 1975).

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