HomeMy WebLinkAboutSubsoils Report for Foundation Designrcn l(umar & Assoclales, lns.'
Geolechnical and Materials Engineers
and Envirsnmental Scienfists
5020 CountY Road 154
Glenwood $prlngs, CO 81601
phone: (970) 945-7S88
email: kaglenwood@kumarusa.com
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An EnruSoyas $rned SonnPonY
Gffice Locations: Denver (HQ), Parker, Coicrado Springs, Fort Collins. Glenwood Springs, and Surnmit County, Coiorado
June 1 3,2025
David Dorr
P.O. Box 4782
Aspen, Colorado 81612
ddorr@hdegpen.coln
Project No.25-7-217
Subject:Observation of Pit Excavations, Proposed Residence, 555 Wooden Deer Road,
Lot 11, Wooden Deer, Garfield County, Colorado
Dear Mr. Dorr:
As requested, a representative of Kumar & Associates observed the pit excavations at the subject
site on March 19,2A25 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
to you dated March 19,2025.
The proposed residence will be one to two stories over a walkout basement level.
The site slopes down to the southeast at grades of 20 to 30 percent. The site is vegetated with
pinon pine. A driveway has been cut to access the site from Wooden Deer Road. Two pits were
dug near the driveway to evaluate the subgrade soils. Pit 1 was the western pit and Pit 2 was the
eastern pit. The pit profiles were similar and consisted of about 6 inches of topsoil and 4 feet of
silty sand with rock fragments over siltstone bedrock of the Maroon Formation at the bottom of
each pit. No free water was encountered in the pit excavations and the soils were slightly moist-
Considering the conditions exposed in the excavation and the nature of the proposed
construction, spread footings placed on the undisturbed siltstone bedrock designed for an
allowable soil bearing pressure of 4,000 psf can be used for support of the proposed residence.
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 bedrock. We should observe the 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 unsuppofied 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 within floor slab areas can consist of the on-site soils or a suitable imported
material, compacted to at least 95o/o af 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.
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David Dorr
June 13,2025
Project No.25-7-217
Page 2
The recommendations submitted in this letter are based on our observation of the soils exposed
within the pit excavations. This study is based on the assumption that soils throughout the building
site and at greater 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. ln order to reveal the nature and extent of variations in the subsurface
conditions below the excavation, drilling would be required. lt is possible the data obtained by
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. lf the client is concerned about MOBC, then a
professional in this special field of practice should be consulted.
lf you have any questions or need further assistance, please call our office.
Sincerely,
Kumar & Asso*i
Daniel E. Hardin,
Rev. by:SLP
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