HomeMy WebLinkAbout03616 111011.1:00. DF CAoP'Y
HI p /...��(�� V Hepworth- Pam lak Geotechnical. Inc.
5020 tV � d County Road 154
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Glenwood Springs, Colorado 81601
Phone: Phn o o945.7 9 970-945-7988
Fax: 970-945-8454
hpgeo@hpgeotech.com
March 30, 2001 `--t'' -
James Surls and Charmaine Locke �; '
C/O Lipkin Warner Design & Planning /
Attn: J. Ray Barlow
P.O. Box 2239 -
Basalt, Colorado 81621 Job No. 101 186
Subject: Subsoil Study for Foundation Design and Percolation Test, Proposed
Residence and Shop /Barn, Northeast Corner of County Roads 103 and
100, Garfield County, Colorado
Dear Mr. Surls and Ms. Locke:
As requested, Hepworth - Pawlak Geotechnical, Inc. performed a subsoil study and
percolation test for foundation and septic disposal designs at the subject site. The study
was conducted in accordance with our agreement for geotechnical engineering services
to you dated February 27, 2001. The data obtained and our recommendations based on
the proposed construction and subsurface conditions encountered are presented in this
report. Evaluation of potential geologic hazard impacts on the site are beyond the scope
of this study.
Proposed Construction: The proposed residence will be a one story wood frame
structure over a combination of slab -on- grade, crawlspace and partial walkout basement
located on the site as shown on Fig. 1. Ground floors are proposed to be slab -on -grade
and structural over crawlspace. The proposed shop /barn building will be a large single
story wood frame structure with a slab -on -grade floor. Cut depths are expected to
range up to about 8 feet. Foundation loadings for this type of construction are assumed
to be relatively light and typical of the proposed type of construction. The septic
disposal system is proposed to be located about 300 feet south of the residence and
about 150 feet west of the existing well.
If building conditions or foundation loadings are significantly different from those
described above, we should be notified to re- evaluate the recommendations presented in
this report.
Site Conditions: The site was vacant and had patchy snow cover at the time of our
field work in mid March, 2001. The ground surface in the building areas slopes
moderately to strongly down to the south at grades of 5% to 15%. The lot is vegetated
with scattered juniper and pinon pine trees, sage brush, weeds and grass. Basalt
cobbles and boulders were observed on the ground surface.
James Suris and Charmaine Locke
March 30, 2001
Page 3
should be placed beneath basement level slabs to facilitate drainage. This material
should consist of minus 2 inch aggregate with Less than 50% passing the No. 4 sieve
and Less than 2% passing the No. 200 sieve.
All fill materials for support of floor slabs shouT'd be compacted tout least 95% of
maximum standard Proctor density at a moisture content near optimum. Required fill
can consist of the on -site soils or imported road base gravel devoid of vegetation,
topsoil and oversized rock.
Underdrain System: Although free water was not encountered during our exploration,
it has been our experience in the area that local perched groundwater can develop
during times of heavy precipitation or seasonal runoff. Frozen ground during spring
runoff can create a perched condition. We recommend below -grade construction, such
as retaining walls, crawlspace and basement areas, be protected from wetting and
hydrostatic pressure buildup by an underdrain system. Shallow crawlspace and slab -on-
grade areas may not need an underdrain provided backfill is properly placed and
compacted.
The drains should consist of drainpipe placed in the bottom of the wall backfill
surrounded above the invert level with free - draining granular material. The drain
should be placed at each level of excavation and at least 1 foot below lowest adjacent
finish grade and sloped at a minimum 1% to a suitable gravity outlet. Free - draining
granular material used in the underdrain system should contain less than 2% passing the
No. 200 sieve, less than 50% passing the No. 4 sieve and have a maximum size of
2 inches. The drain gravel backfill should be at least 1' feet deep.
Surface Drainage: The following drainage precautions should be observed during
construction and maintained at all times after the buildings have been completed:
1) Inundation of the foundation excavations and underslab areas should be
avoided during construction. Drying could increase the expansion
potential of the clay soils.
2) Exterior backfill should be adjusted to near optimum moisture and
compacted to at least 95% of the maximum standard Proctor density in
pavement and slab areas and to at least 90% of the maximum standard
Proctor density in landscape areas. Free - draining wall backfill should be
capped with about 2 feet of the on -site, finer graded soils to reduce
surface water infiltration.
3) The ground surface surrounding the exterior of the building should be
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GEOTECHNICAL, INC.
Moisture Content = 11.2 percent
Dry Density = 89 pcf
0 Sample of: Slightly Sandy Clay
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- Moisture Content = 10.3 percent
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101 1B6 HEPWORTH- PAWLAK
GEOTECHNIC INC. SWELL CONSOLIDATION TEST RESULTS I Fig. 4