HomeMy WebLinkAboutB12-0254 OBSERVATION OF EXCAVATION 090612G 000** H
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HEPWORTH - PAWLAK GEOTECHNICAL
August 29, 2012
Slopeside Construction, Inc.
Attn: Mike Dantas
2121 North Frontage Road West
PMB 206
Vail, Colorado 81657
(mikedantas@comcast.net)
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Hepworth - Pawlak Geotechnical, Inc.
5020 County Road 154
Glenwood Springs, Colorado 81601
Phone: 970- 945 -7988
Fax: 970-945-8454
email: hpgeo@hpgeotech.com
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5 SEP e s 2u12
TOWN OF VAIL
Job No. 112 293A
Subject: Observation of Excavation, Proposed New Entryway Canopy, Holiday
Inn, 2211 North Frontage Road West, Vail, Colorado
Dear Mike:
As requested, a representative of Hepworth - Pawlak Geotechnical, Inc. observed the
excavation at the subject site on August 28, 2012 to evaluate the soils exposed for
foundation support. The findings of our observations and recommendations for the
foundation design are presented in this report. The services were performed in
accordance with our agreement for professional engineering services to Slopeside
Construction, Inc., dated August 28, 2012.
The new entryway canopy will be on the east side of the building. The structure has been
designed to be supported on four isolated footing pads. The footings were sized assuming
an allowable soil bearing pressure of 1,500 psf.
At the time of our site visit, the foundation excavation for the four footing pads was
essentially complete and had each been cut in one level from about 3%Z to 5 feet below the
adjacent ground surface. The soils exposed in the bottom of the excavations consisted of
medium stiff, sandy silty clay. Results of swell - consolidation testing performed on
samples taken from the site, shown on Figure 1, indicate the soils are moderately
compressible under conditions of loading and wetting. No free water was encountered in
the excavations and the soils were generally moist.
Considering the conditions exposed in the excavations and the nature of the proposed
construction, spread footing pads placed on the undisturbed natural soil designed for an
allowable bearing pressure of 1,500 psf can be used for support of the proposed canopy
addition. There could be some differential settlement with respect to the existing
structure which should be considered in the design. The footing pads should be a
minimum width of 2 feet. Loose and disturbed soils in footing areas should be removed
and the bearing level extended down to the undisturbed natural soils and the subgrade
compacted. The footings should be provided with adequate soil cover above their bearing
elevations for frost protection. The foundation backfill should be compacted to at least
Parker 303 - 841 -7119 • Colorado Springs 719- 633 -5562 • Silverthorne 970- 468 -1989
Slopeside Construction, Inc.
August 29, 2012
Page 2
95% of standard Proctor density at a moisture content near optimum and the surface
graded to prevent ponding within at least 10 feet of the building and the footing pads.
The recommendations submitted in this letter are based on our observation of the soils
exposed within the footing pad excavations and do not include subsurface exploration to
evaluate the subsurface conditions within the loaded depth of foundation influence. This
study is based on the assumption that soils beneath the footings have equal or better
support than those exposed. The risk of foundation movement may be greater than
indicated in this report because of possible variations in the subsurface conditions. In
order to reveal the nature and extent of variations in the subsurface conditions below the
excavation, drilling would be required. It is possible the data obtained by subsurface
exploration could change the recommendations contained in this letter.
If you have any questions or need further assistance, please call our office.
Sincerely,
HEPWORTH — AK GAF EICAL, INC.
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David A. Young, P.E. -o!
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attachment: Figure 1, Swells i Mation Test Results
Job No. 112 293A
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Moisture Content = 18.7 percent
Dry Density = 97 pcf
Sample of: Sandy Silty Clay
From: Bottom of NE Pad Excavation
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2
Compression
upon
wetting
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cc
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4
5
6
7
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9
10
11
0.1 1.0 10 100
APPLIED PRESSURE (ksf )
112 293A
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HEPWORTH- PAWLAK GEOTECHNICAL
SWELL- CONSOLIDATION TEST RESULTS
FIGURE 1