PROJ02179

• Contract/PO #: 04000000014
• Contractor Name: Clear Creek Economic Development Corporation
• Contract Type: Grant
• Water District: 0
• Loan Projects - Doc Type: Feasibility Study

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soils repOli prepared for the feasibility study, we cun-ently anticipate using both native onsite material as
well as overlying emih fill and tailings material as pmi of the reservoir. The tailings material is less
desirable as fill material and will be used in pOliions of the reservoir where structural strength is not
critical. Based on the preliminalY grading shown, approximately 15,000 cubic yards offill would have to
be inipOlied in addition to the onsite material. A portion or all of this material import may be able to be
reduced or eliminated during final design but may also reduce the storable volume ofthe reservoir to
obtain a no impOli solution.

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Although removal of the tailings material could reduce potential risk, doing so would re~ult in greater
earthwork costs since more imported fill would be required and tailings would have to disposed of
offsite. Site soils are relatively sandy and a PVC or membrane liner will be utilized to control seepage
from the reservoir. Liners may eventually puncture or leak and a double liner with internal drainage
material could be provided to reduce the risk of seepage or impacts to potentially hazardous materials in
the tailings or underlying material, however, constructiori costs would increase substantially.

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A soil cover will be placed on the liner and soil cement will be utilized along the dam embankment to
minimize soil erosion due to waves when the reservoir is full. A pipe riser and outlet pipe will serve as
the spillway of the reservoir to release storm flows in excess of reservoir capacity safely to the West Fork
of Clear Creek. A low level gated outlet pipe will be utilized to release augmentation flows when
necessary or to drain the reservoir for maintenance.

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Flow will be diverted into the reservoir via a control structure and pipeline along Bard Creek Road from
its crossing with Bard Creek approximately Yz mile south of the reservoir to the reservoir site. A
plan/profile of the diversion pipeline is shown in Figure 4 of this report. The pipeline is designed for a
maximum capacity of 5.0 cfs. At a flow rate of 5.0 cfs, the reservoir will fill in 11.1 days_

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Alternatives Considered

During an initial site visit with Town ofEinpire officials, interest was expressed in providing a bench
above the normal pool elevation for use as an mnphitheater.- This was considered and would be possible,
but would significantly increase construction costs since a larger quantity of earth fill would have to be
impOlied to facilitate the request. Providing the bench would also reduce available storage volume below
the desired 110 acre-feet of storage capacity.

The eastern portion of the embankment extends onto property not currently owned by the Town of
Empire and it would have been desirable to avoid the necessity of acquiring additional land or easements
if feasible. Again, avo~ding the privately owned property would be physically possible, but would
greatly increase the volume of imported fill required and substantially decrease storage volume.

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