PROJ00259

• Contract/PO #: C153424
• Contractor Name: Colorado River Water Conservation District
• Water District: 0
• Bill Number: XB 99-999
• Loan Projects - Doc Type: Feasibility Study

I

I
I
I
I
I
I
I

Hydrologic and Hydraulic Criteria. The peak inflow of the design
flood is 15,666 cfs for the upper site and 13,473 cfs for the lower
site. Routing this flood through each of the three reservoir sizes in
the upper reservoir results in a maximum spillway width of 120 feet
for the smallest reservoir and a spillway widths of 80 and 50 feet for
the intermediate and large reservoirs respectively. Spillway sizes
for the lower site range from 120 feet for the small and intermediate
sized dams to 110 feet for the large dam. Spillway sizes are the same
for both RCC and earth embankment dams.

5. Outlet Works Design

I

The criteria used for the outlet works design are presented
in Section IV, A, 4. The two largest dams at the Upper Middle Mamm
Creek site utilize a 36 inch concrete outlet pipe. The smallest
requires a 24 inch outlet pipe, as do all size ranges at the lower
site. Flow control for all three layouts is provided by hydraulically
operated sluice gates at the upstream inlet of the outlet pipe.
Controls for the gates will be located on the dam crest in all cases.
A standard USBR impact type stilling basin is included in the quantity
and cost estimates for each dam.

I
I
I
I
I
I
I
I
I
I

6. Quantities and Cost Estimates

Estimates of the quantities and costs of materials needed for
the major features of each of the six Mamm Creek dams at both sites
are presented in Appendix D and summarized below:

UPPER MAMM CREEK DAM AND RESERVOIR

TYPE STORAGE TOTAL COST UNIT STORAGE COST
(ac-ft) ($1,000) ($/ac-ft)
Earth 3,000 7,764 2,590
Earth 6,000 12,428 2,070
Earth 9,000 13,843 1,540
RCC 3,000 10,317 3,440
RCC 6,000 15,671 2,620
RCC 9,000 23,863 2,650

IV-24