PROJ00400

• Contract/PO #: C153588
• Contractor Name: Greeley, City of
• Contract Type: Loan
• Water District: 3
• County: Larimer
• Bill Number: SB 89-85
• Loan Projects - Doc Type: Feasibility Study

I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I

2.4.5

Results

For the purpose of slope stabi1 ity analysis, the factor of safety is defined
as the ratio of total available shear strength of the soil to shear stress
required to maintain equilibrium along a potential surface of sliding. The
factor of safety indicates a relative measure of stability for various
conditions, but does not precisely indicate the actual margin of safety.

While it is prudent not to think of safety factors in terms of absolute
va 1 ues, the foll owi ng criteri a was used to assess the exi sti ng stabil i ty of
Barnes Meadow Dam:

Loading Condition

Steady-State Seepage (static)
(dynami c)

Minimum Allowable Safety Factor
1.5
1.0
1.2

Rapid Drawdown

The safety factors resulting from the stabil ity analyses are summarized on
Figure V.3. Based on the above criteria, the embankment is stable under the
present conditions.

2.5 Existing Seepage Conditions

Seepage concerns downstream of the dam are minor. The toe drain system
designed by the City and installed in 1985 appears to be functioning
properly. Since the installation, the area downstream of the embankment toe
and adjacent to the outlet works stilling basin has remained dry with no signs
of seepage observed. Weirs installed at the ends of both the left and
right-side toe drain pipes are read and maintained on a regular basis by" City
personnel.

The only seepage area of minor concern is a general damp area downstream of
the toe, roughly located between dam stations 8+00 and 9+00. Between the end
of the right-side toe drain at about dam station 5+00 and this general damp

1231 H

-60-