C153379 Feasibility Study

• Contract/PO #: C153379
• Contractor Name: Brook Forest Water District
• Contract Type: Loan
• Water District: 9
• County: Jefferson
• Bill Number: SB 80-67
• Loan Projects - Doc Type: Feasibility Study

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To the best of our knowledRe there are no geotechnical data or material

property data available from the 1964 investigations for borrow material or

foundation soils available for the Hardin Dam site. Such data are necessary

for design of the Hardin Dam embankment, consequently, an appropriate strategy

for collection of this data was developed with the CWCB and the procedures and

results of this work are described in the following sections.

2. 1982 Geotechnical Data Collection
a. General
A field exploration program was conducted to provide a quantitative
evaluation of the in situ soils along the lower Weld County dam axis and
also to explore possible on-site sources of potential impermeable borrow
material for construction of the dam core. The detailed description of the
field exploration program is presented in Appendix A. Five rotary wash
borings were drilled along the axis of the dam to obtain disturbed and
undisturbed samples of the foundation soils and to verify the subsurface soil
profile presented by Woodward-Clyde. Borings were drilled in the potential
Fox Hills and Pierre Shale borrow areas which are located immediately upstream
of the dam axis near both the right (south) and left (north) abutments. The
boring locations are shown in Figure 111-3 and the detailed Log of Borings are
presented in Appendix A on Plates A-1A through A-1M.

Fourteen test pits were excavated to further explore borrow sources after

the results of the boring program were evaluated. The test pit locations are

shown in Figures 111-3 and the Log of Test Pits are presented in Appendix A on

Plates A-2A through A-2C.

A laboratory testing program was designed to determine the in situ

properties of the foundation materials and also the remolded properties

of potential borrow materials. The laboratory testing program is described in

detail in Appendix A. The laboratory testing consisted of moisture-density,

lThe usual designation of looking downstream for the left and right abutments
is used throughout this report.

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