C150063 Feasibility Study

• Contract/PO #: C150063
• Contractor Name: Jackson Lake Reservoir & Irrigation Company
• Contract Type: Loan
• Water District: 1
• County: Morgan
• Bill Number: SB 94-29
• Loan Projects - Doc Type: Feasibility Study

I

I
I
I
I

Company's repairs have generally been successful in maintaining the integrity of the
embankment and facing materials.

Additional Desion Issues

I

Additional design issues include the potential wave runup height on the dam
slope. Differing repair options provide varying degrees of wave resistance to runup.
For instance, a 10 (horizontal) to 1 (vertical) beaching slope dissipates the wave energy
over a long flat reach, and the maximum wave runup is approximately 1/3 that of the
same wave against a concrete slab placed at, a 1. 6 (horizontal) to 1 (vertical) slope. A
key factor in evaluating the wave runup is the wind fetch length and maximum wind
velocity. Wind fetch was evaluated using the SCS T.R. 69 method, and wave runup
calculations were determined using both ACER T.M. No 2 and the SCS methods. Table
7 provides a summary of the results obtained at Jackson Lake Reservoir, assuming an
83 miles per hour design wind velocity, and varying slope protection surfaces and slope
angles. These calculations are presented in Appendix E.

I
I

I
I
I
I

The size and thickness of a rock riprap blanket for slope protection was also
determined using the SCS method. These calculations indicate that a median rock size
of about 24-inches and a minimum rock layer thickness of 36-inches would be required.
These calculations are also presented in Appendix E.

I

I

I
I
I
I
I

23