PROJ00077

• Contract/PO #: FS0008X
• Contractor Name: Longmont, City of
• Contract Type: Loan
• Water District: 0
• County: Boulder
• Loan Projects - Doc Type: Feasibility Study

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Plans and cross-sections of the dam are shown on Figures 3 through 6.
The radius of the arch is approximately 108 feet at the extrados and the
arch has a total angle of 75 degrees. The dam ranges in thickness from appro~l.-
,~.
mately 3.5 feet at the crest to 13 feet at the maximum section. :,
The spillway is 47 feet long and the invert of the spillway lies at
elevation 10,978, one foot below the dam crest. The spillway is incorporated
into the gravity section of the dam.
Two outlets exist within the dam. The lower outlet is a 24 inch diameter
No. 10 gage riveted steel pipe with a 24 inch downstream gate valve. The invert
is approximately 53 feet below the crest of the dam at station 0 + 45.
The upper outlet is ~ 36 inch diameter No. 10 gage riveted steel pipe
located at station 1 + 07, 25 feet below the dam crest. It is controlled by an
upstream 40x41 inch cast iron slide gate.
V. GEOLOGY
Regional Geology
Rocky Mountain National Park lies within the front range of the Southern
Rocky Mountain Physiographic Province. The mountains of the front range are
composed of faulted and uplifted Precambrian (over 570 million years old) meta-
morphic and igneous rocks.
The mountains underwent several episodes of glaciation during the last
million years (Pleistocene). Glacial processes have produced the single most
significant impact on the existing topography within the Park.
Site Geology
Bluebird lake is a natural feature known as a cirque-lake or tarn. A
cirque is a generally deep, steep-walled, flat-floored, half-bowl-like recess or
depression formed by ice-gouging and plucking at the head of the glacier. The
natural lake, dammed by a lip of bedrock, has a water surface a few feet

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