Applicant's Proposal dated 03/15/99cost to city taxpayers.
— All services are place: water,
znd police protection.
revenue- $! "i!! annual, -
'4 !!!r
Blends• surrounding neighborhood well.
Complies with plan.
No adverse _health or • factorl
No adverse - effect on i envirom-nent,, or
agriculture.
— City would - - an addition t ! • Lawrence Park.
Medical facility within one mile.
Complies Flathead •Subdivision
Regulation.
engineer approved drainage plan is
installed to meet statecode.
— Best possible use forland.
,ML2fffj=
Contiguous to City Boundary.
51 commons Loop Glacier Bank Kalispell, MT 59901
Phone 406-755-7888 0 Fax 406-257-7220 ® Email a2zbg@cyberport.net
March 12, 1999
Mr. Earl McPeek
UNICORE DEVELOPMENT INC.
Kalispell, MT 59901
Re: Chokecherry Ridge Condo's
Slope Stability Analysis
Dear Mr. McPeek:
Per your request, I reviewed the site and soil borings from Billmyer Engineering for the
proposed development which is north of East California Street just east of 6th Ave. E.N. for the
purpose of reporting margins of safety of the slopes thereon down to the Stillwater River Flood
Plain.
The review of the borings, indicated the presence of a fill reported at boring # 3 on the
east side about 12' from the slope crest. In order to more fully explore this condition, two more
boring were ordered, 94 18' to the west of 93 and 95 at 40' to the north of #4. The fill was
encountered at these borings also, but at shallower depths. With this additional information a
better site evaluation was possible.
The site is a triangular level bank overlooking the Stillwater River to the west, north and
east by an elevation of some 30 feet. The overlook banks slope away to the flood plain at about
38 degrees.
The soil borings reveal the presence of a crushed gravel fill covering the east half of the
site. From the depths encountered, it is evident that the level portion of the site at the existing
structure and to the North for about 150' is MADE land. The fill was probably related to the
original construction of the building and possibly the nearby roads as it appears to be road base
quality material. Below the fill is a tan Clay and below the clay are sands. At the north part of the
site at silt loam overlays the clay and to the west the material is more silty.
The banks all appear to be stable and are well vegetated. The surrounding property banks
show no significant slope failures.
Structures, Foundation wid Sort Engineering
From the borings and the site topographic plan, a slope crossection was developed
as shown in figure 1. The methods of analysis were traditional and ordinary as developed
in the following references:
References: Das (1985), pp 429-485
Winterkorn and Fang (1975), p 354
Liu and Evett (1981), pp 293-311
Anderson and Richards (1987)
The approach was to develop factors of safety for slope stability at the crest and
10 and 20 feet away from the crest using existing soil conditions and any future changes
such as water table increases. These are summarized in Figures 2, 3 and 4.
At the crest of the slope, the computed factor of safety is 1.05. This is indicative
of the slope being at it's natural angle of repose. Any additional loads here would need to
be placed on a deep foundation. At 10 feet from the crest, the factor of safety against
slope failure is 1.32. For normal footings at 3' frost depth, this is sufficient (See Fig 3).
With a 20' setback from the slope the factor of safety is 1.55 (See Fig 4). At this level,
placement of normal frost footings and a maximum of 2 feet of fill would be possible.
111W6111MMM 6-COMM
1. For normal construction of 2 story frame buildings, the frost footings maintain
a setback from the slope crest (Elev. 2968) of 10 feet. This is basically the
UBC setback requirement of 1/3 of the slope height.
In the silt loam materials on the west side of the site foundation bearing
pressures not exceed 1000 psf.
3. In the granular fill on the east side of the site, the foundation pressures not
exceed 1500 psf.
Sin ely,
Robert J. Guditis
............................................................................................................................... bT%
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