WSP02036

• File Number: 8220.128.J
• Description: Silt Project
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 1/1/1951
• Author: USDOI - BOR
• Title: Silt Project-Colorado - A Supplement to the Colorado River Storage Project Report - Part 1 of 2
• Water Supply Pro - Doc Type: Report/Study

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:HAPl'ER II

DESIGNS AND E3TlMh.:r:.J

Design and Construction .Problems

Accessibility

Rifle Gap D~n site is easily accessible. It is only 6 miles froD
Rifle which is served by the Denver and Rio Grande Western Railroad and
United States Highways Nos. 6 and 24. The road from Rifle to the dam
site includes 3 miles of State Higj:J.way No. l3, a bituminous-surfaced
road, and 3 miles of state Highway No. 325, a gravel-surfaced road.

Many points of Davie ditch and Grass Valley Canal can be reached
by road.

Rights-of-way and Relocation

Public land in the reservoir basin has been withdrawn for develop-
ment purposes. Rights-of-way would be required for privately owned land,
inCluding 220 acres irrigated and 660 acres used for grazing. Improve-
ments consist of a one-room school house, 8 dwellings, 24 farm bUildings,
and an abandoned coal tipple. Three of the dwellings and four farm
b'lildings are not in use.

State Highway No. 325 would be relocated around the eastern side of
the dam and reservoir. A road branching from this higj:J.way at the Rifle
Gap Dam site and paralleling Uest Rifle Creek would be relocated around
the western side of the reservoir basin. This road would be extended
across the dam to join the State highway. One electric power line and
two telephone lines also would be relocated around the reservoir basin.

No right-of-way prOblems are connected with the Grass Valley Canal
and Davie ditch.

Design Flood

The potential peak flood flow in Rifle Creek, which formed the basis
for the spillway design, was estimated at l5,~00 second-feet. This flow
was estimated before di scharge measurement s at the dam site were avail-
able and the design storm producing this flow was based on storm data
obtained trom nearby precipitation stations outside the drainage area.

Construction Period

After authorization of the project, about 1 year would be required
for preconstruction work. A minimum of 2 years would be required for
construc tion of the proje ct features. During the first year of construc-
tion the foundation would be prepared, the coffer dam constructed, the
nut-oft excavated, and the stilling hasin and outlet tunnel constructed.
D'J.I'ing the secorLd year dam embankment and ripre.p w0111d be plaooo and the

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