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

According to the report, the Laramie River Faul t, the Spring Creek Fault, and
the unnamed fault showed evidence of movement between the late Tertiary period
(15 million years) and the Pleistocene, and therefore in MKE's opinion, should
not be considered as potentially active.

An earthquake was felt in the region on October 18, 1984. This event has come
to be known as the Larami e Mountai ns I earthquake. The epi center of the
earthquake was located about 60 miles to the north of the Barnes Meadow
Reservoir and had a Richter magnitude of 5.5. Other events have occurred
historically in the same epicentra1 vicinity. The next nearest recorded
seismic activity has been in the Denver Basin approximately 8D miles to the
southwest and was probably associ ated wi th deep well i njecti on at the Rocky
Mountain Arsenal.

O-"l....,\o\O*'
.,
.{'c,o......\-t; .

::;:;. wyo-:~o-

In order to be conservati ve, a maximum credi b1 e earthquake of 6.5 on the
Richter scale, producing a horizontal acceleration of O.lg, was used in the
stability analyses of the dam.

2.4 Slope Stability of Existing Dam

2.4.1 Procedure

Stati c and
embankment
procedure.
were:

pseudo-static (dynamic) stability analyses of the existing
dam were performed usi ng the Modifi ed Bi shop 1 imi t equil i bri urn
Two different embankment loading conditions were analyzed. These

A. Steady-State Seepage Conditions - The stabil ity of the
downstream slope was analyzed with the reservoir at
normal pool elevation 9087 (G.H. 40). This is the
reservoir level that will control the development of the
steady-state phreatic surface in the embankment.

B. Operational Conditions - The stabil ity of the upstream
slope was analyzed for rapid reservoir drawdown from the

1231 H

-56-