PROJ00173

• Contract/PO #: C153369
• Contractor Name: St. Vrain and Left Hand Water Conservancy District
• Water District: 0
• County: Boulder
• Bill Number: XB 99-999
• Loan Projects - Doc Type: Feasibility Study

I
I
II

I

I
:1
,I
I
,I
II
I!I
,~ I

I

II
II
I
II

I

,II

I

:1
I
I
'I
,
I

'I
I

SECTION 3. PROJECT DESCRIPTION

The St. Vrain Left Hand Water Conservancy District proposes to build a
dam from ridge to ridge in the eastern part of the Study Area. As shown on
Geologic Cross Sections A and B (Plate 10 and Plate 11) the finished crest
elevation of the dam would be roughly 5,740 feet and the spillway elevation
would be approximately 5,720 feet. The dam would rise some 320 feet above the
lowest existing elevation of the valley floor. Excluding excavation in the
abutment areas, the crestal length of the dam axis would be approximately
2,900 feet if located as Geologic Section A and some 2,450 feet if located as
Section B.

As illustrated in Figure I,
elevation, the dam would create a
700 acres.

if water were impounded to spillway
reservo ir with a surface area of some

If an earthfill-rockfil1 dam is built, the emergency spillway would be
located in an existing broad, natural drainage course which is located just
south and east of the proposed north abutment area. If the dam is built
solely of concrete the spillway would be entirely incorporated into the
structure.

Although Coffintop Dam is planned as a part of a larger 150 MW
hydroelectric enterprise, this report does not address the geotechnical
feasibility of any facilities other than the Coffintop Dam and Reservoir.

.~-

UEBLACKER ASSOCIATES. INCo