C153644 Final Report

• Contract/PO #: C153644
• Contractor Name: Harris Water Engineeering Company
• Contract Type: Grant
• Water District: 0
• County: Statewide
• Bill Number: HB 93-1273
• Loan Projects - Doc Type: Report

DAM EMBANKMENT
Both dams would be jurisdictional requiring preparation of plans
and specifications for approval by the State Engineer prior to
construction. Beaver Dam is expected to be an intermediate Class
II structure; there would probably be no loss of life if the dam
failed. Bear Creek Dam is expected to be an intermediate Class I
dam, there would be loss of life if the dam failed. The
reconnaissance designs described herein are based upon data taken
from Quad maps and general knowledge of the area; more detailed
engineering work may result in a different designs.
The "Rules and Regulations for Dam Safety and Dam Construction"
prepared by the Colorado State Engineer, Division of Water
Resources state the following criteria should be met:
* a minimum of 5 feet of freeboard,
* an outlet pipe capable of draining the top 5 feet of storage
in 5 days,
* a crest width equal
10 feet, 25 feet
* a spillway capable
Class I and 50~
* upstream rip rap to
* and complete soils
to the vertical height divided by 5 plus
maximum,
of passing 100 of the PMP flood for
of the PMP for Class II,
protect the embankment,
investigation and analysis.
EMBANKMENT: Both dams are expected to be homogeneous earth
embankments constructed from impervious material in the reservoir
basin. Two alternative sites were looked at for the Beaver Creek
dam with the site resulting in the greatest capacity for the
shortest embankment chosen and is described herein.
The Bear Creek drainage was inspected for suitable sites and the
site chosen at the mouth of the creek is by far the best location.
Sites upstream not only had poor reservoir basins but access would
be a major problem because there are no roads.
Tables 3 and 4 show the estimated embankment volumes for the Beaver
and Bear Creek dams respectively. The Bear Creek dam has a
significantly greater volume and associated cost, the cost of the
two dams are shown in Tables 5 and 6. The following description is
for the Beaver Creek Dam and Reservoir only because the cost of
Bear Creek dam does not appear to be feasible.
Beaver Creek Dam would have the following the dimensions:
* 49 feet high, 10 feet of freeboard
* crest length of about 600 feet,
* crest width of 20 feet,
* 3.25H:1.OV upstream and 2.SH:I.OV downstream slopes
* 36 inch diameter outlet pipe,
* 90 foot wide spillway to pass 50$ of the PMP.
Beaver Creek Dam 10