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

In addition, the USBR performed an earlier investigation which included

the logs of four drill holes designated as DH-101 through DH-104 along the

Hardin Dam axis. This work is reported in the Woodward-Clyde 1964 report, as

well as data obtained from water well test holes drilled in the general area

of the left abutment. The report indicated that the only information avail-

able was the depth to bedrock. No geote"hnical tests were performed by the

USBR during these field investigations.

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Office (John Shurer, 1982, Supervisory Engineer, Colorado Division of Water

Resources, personal communication, March 26) to an embankment failure at Horse

Creek Reservoir near Hudson, 23 miles southwest of the proposed Hardin site.

According to the USGS (Algermissen and Perkins, 1976) eastern Weld County

lies within Seismic Source Area 39. This designation indicates that an

average of 21.5 seismic events of MM Intensity V may be expected per 100

years. The maximum MM Intensity predicted in this report is Intensity VII and

the maximum predicted Richter magnitude is 5.5. The maximum horizontal.

acceleration in rock with a 90 percent probability of not being exceeded in 50

years may range from 0.04g to O.05g. We recommend a design acceleration of

0.05g.

C. GEOTECHNICAL INVESTIGATION

1. 1964 Geotechnical Data

In 1964, Woodward-Clyde-Sherard and Associates performed a geotechnical.

investigation of the Lower Weld County dam site. This site is essentially thE!

same as the Hardin Dam site. This investigation consisted of drilling Ii

rotary wash borings totalling 680 lineal ft and 12 a\lger borings totalling 425

lineal ft. In addition 53 auger borings were drillj!d within a 9 mile radius

of the site to investigate potential borrow materilll sources. A plot plan

showing the location of these borings and descriptive logs of the geological

materials encountered is presented in the Woodward-Clyde-Sherard 1964 report.

No quantitative geotechnical data such as standard penetration blow counts.

core recovery, rock quality, location of samples or laboratory test results

were available as a consequence of files being purged.

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