HomeMy WebLinkAboutSubsoils Report for Foundation DesignKumar & associates, Inc.® 5020 County Road 154
'f Geolechnical and Matenals Engineers Glenwood Springs, CO 81601
and Environmental Scientists phone: (970) 945-7988
J email: kaglenwood@kumarusa.com
www.kumarusa.com
An Employee Owned Company
Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado
June 12, 2025
TE Builders
Attn: Thad Eshelman
178 County Road 100
Carbondale, Colorado 81623
thadCcDtebuilders. net
Project No. 25-7-413
Subject: Observation of Pit Excavation, Proposed Residence, 7332 County Road 100,
Garfield County, Colorado
Dear Mr. Eshelman:
As requested, a representative of Kumar & Associates observed the pit excavation at the subject
site on June 11, 2025 to evaluate the soils exposed for foundation support. The findings of our
observations and recommendations for the foundation support are presented in this report. The
services were performed in accordance with our agreement for professional engineering services r r
to you dated June 11, 2025. tOMA
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The proposed residence will be a one to two story wood -frame structure over a walkout baseme :Yl �
The building area slopes down to the west at 15 to 20% grade. Vegetation consists of oak brush
with an understory of grass and weeds. An existing rough driveway crosses the site above the
building area.
At the time of our visit to the site, we observed the exploratory pit dug in the proposed building
area. The pit was about 5 feet deep. Below about 1'/2 feet of topsoil/root zone, the subsoils
consisted of whitish, sandy silt with basalt gravel and cobbles. No free water was encountered in +
the pit excavation and the soils were slightly moist. +�
Considering the conditions exposed in the pit excavation and the nature of the proposed
construction, spread footings placed on the undisturbed natural soil designed for an allowable soil
bearing pressure qL2,000 psf should be adequate for support of the proposed residence. The
exposed soils tend to compress when wetted and there could be some post -construction
settlement of the foundation if the bearing soils become wet. Footings should be a minimum width
of 16 inches for continuous walls and 2 feet for columns. Loose and disturbed soils in footing
areas should be removed and the bearing level extended down to the undisturbed natural soils.
2111111
We should observe the completed foundation excavation for bearing conditions prior to forming
footings. Exterior footings should be provided with adequate soil cover above their bearing
elevations for frost protection. Continuous foundation walls should be reinforced top and bottom
to span local anomalies such as by assuming an unsupported length of at least 10 feet.
Foundation walls acting as retaining structures should also be designed to resist a lateral earth
pressure based on an equivalent fluid unit weight of at least 50 pcf for on -site soil as backfill. A
perimeter foundation drain should be provided to prevent temporary buildup of hydrostatic
pressure behind the basement walls and prevent wetting of the lower level. Structural fill placed
TE Builders Project No. 25-7-413
June 12, 2025 Page 2
within floor slab areas can consist of the on -site soils compacted to at least 95% of standard
Proctor density at a moisture content near optimum. Backfill placed around the structure should
be compacted and the surface graded to prevent ponding within at least 10 feet of the building.
The recommendations submitted in this letter are based on our observation of the soils exposed
within the pit excavation. This study is based on the assumption that soils throughout the building
area and beneath the pit depth 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 further subsurface exploration could change the recommendations contained in this
letter. Our services do not include determining the presence, prevention or possibility of mold or
other biological contaminants (MOBC) developing in the future. If the client is concerned about
MOBC, then a professional in this special field of practice should be consulted.
If you have any questions or need further assistance, please call our office.
Sincerely,
Kumar & Associates. Inc. �7�p.REGIs y.
2 443
Daniel E. Hardin, P.E. •
Rev. by: SLP �`'•-..,...•-'
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Kumar & Associates, Inc