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

Inflow Spillway Flood Surcharge
Design Design Required
Flood Flood (ft. )
Reservoir Capacity (cfs) (cfs)
6,200 ac"ft 6,923 3,086 4.5
13 , 500 ac"ft 6,923 618 3.8
19,000 ac"ft 6,923 366 2.3

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5. Outlet Works

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The outlet works at Dry Hollow Dam was designed based on eva-
cuation criteria. Because the draitlage basin is small and irrigated
area is small, the requirement that 90% of the reservoir be evacuated
in 30 days controls the design. In this case the outlet conduit is
36" diameter for the 6200 and 13,500 ac"ft reservoirs and 48" diameter
for the 19,000 ac-ft reservoir.

6. Quantities and Cost Estimates

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The six quantity and cost estimates were done in conformance
with the criteria described in section IV,A,5. The results are sum"
marized below:

TYPE STORAGE TOTAL COST UNIT STORAGE COST
(ac"ft) ($1,000) ($/ac"ft)
Earth 6,200 8,538 1,380
Earth 13,500 11,012 820
Earth 19,000 17,512 920
RCC 6,200 8,576 1,380
RCC 13,500 13,334 990
RCC 19,000 15,903 840

IV"14

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It is apparent from this summary that the Dry Hollow site
offers some cost advantages to the use of an RCC dam, particularly at
the larger levels. Unfortunately, as will be described later in the
report, there is little need for a large dam at the Dry Hollow site.
Because, at the small sizes (2000 and 5000 ac-ft), there is little
advantage to the RCC dam, the cost estimates assume an embankment dam
when used in conjunction with the operation studies and optimum
configuration.