PROJ00137

• Contract/PO #: C153467
• Contractor Name: Greeley, City of
• Contract Type: Loan
• Water District: 0
• County: Weld
• Bill Number: XB 99-999
• Loan Projects - Doc Type: Feasibility Study

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boul der layer ei ghteen to forty-feet thi ck, wi th a vel oci ty of 3500 fps.
Bedrock was detected at a depth ranging from twenty-five to fifty feet;
characterized by velocities of 9000 to 14,000 fps,

2.1.3.3 Borrow Area

Seven test pits were excavated within the reservoir area to locate potential
construction material s for rehabil itating the dam and spillway. With the
exception of TLP-2, TLP-8, and TLP-9, the pits were all in bedrock weathered
to varying degrees of silty, sandy gravel. A high percentage of mica was
noted, making the material poor for anything other than a shell zone. Test
pit TLP-B revealed at least 16 feet of silt and clay that would be suitable
for impervious core or facing material; however, the quantities appeared to be
limited. Test pit TLP-2, like TLP-l in the spillway, encountered sand,
gravel, and boulders of glacial origin. This material would make satisfactory
shell material or aggregate for RCC or soil cement. Riprap could be obtained
from the outcrops of bedrock along the north shore of the reservoi r or by
gathering the glacial erratics from the upper part of the reservoir.

2.2 laboratory Testing

Samples for laboratory testing were obtained from the bore holes and test
pits. Dam materi al s were tested for physi cal and engi neeri ng characteri sti cs
to aid in stability and seepage analyses. Potential borrow materials were
tested to determine their suitability as construction materials for the
various rehabilitation alternatives listed in Section 4 of this chapter: All
1 aboratory testi ng was performed at Chen and Associ ates in Denver; A copy of
their report is included in Appendix C.

Sampl es from the dam bore holes and test pi ts were generally cl assi fi ed as
silty sand with gravel (SM), using the Unified Soil Classification System.
The percentage of gravel sizes ranged from 5 to 40 percent.

Shear strength values of the dam materials were obtained using consolidated-
undrained triaxial compression tests. The tests indicated effective angles of

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