HomeMy WebLinkAboutObservation of Excavation 07.11.2022Assoclaft,
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If+A Kumw
Geotechnical and Materials Engineers 5020 County Road 154
and Environmental Scientists Glenwood Springs, CO 81601
phone: (970) 945-7988
fax: (970) 945-8454
email: kaglenwood@kumarusa.com
An Empioyee Owned Company www.kumarusa.com
Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado
July 11, 2022
Liz Tucker
6 Silver Spruce Drive
Carbondale, Colorado 81623
lzrd25(a)icloud.com
Project No. 22-7-489
Subject: Observation of Excavation, Proposed Barn, Lot 5, Roaring Fork Preserve, 6 Silver
Spruce Drive, Garfield County, Colorado
Dear Liz:
As requested, a representative of Kumar & Associates observed the excavation at the subject site
on July 11, 2022 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 general accordance with our agreement for professional engineering
services to you dated July 8, 2022.
The proposed barn will be a single -story wood -frame structure with a partial slab -on -grade floor.
The barn will be supported on isolated columns/pads that have been designed for an allowable
bearing pressure of 1,500 psf.
At the time of our visit to the site, the foundation excavation consisted of multiple isolated pads
cut to approximately 3 feet below the adjacent ground surface. The soils exposed in the bottom
of the excavation consisted of dense, silty sandy gravel and cobbles. No free water was
encountered in the pad excavations and the soils were slightly moist to very moist.
Considering the conditions exposed in the excavation and the nature of the proposed
construction, spread footings placed on the undisturbed natural soil designed for an allowable
soil bearing pressure of 1,500 psf should be adequate for support of the proposed barn. Footings
should be a minimum width of 16 inches for continuous walls (is used) and 2 feet for columns.
Loose disturbed soils in footing areas should be removed and the bearing level extended down to
the undisturbed natural soils. 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. Structural fill placed within floor slab areas can consist of the on-site soils,
excluding topsoil and rocks larger than about 6 inches, 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 5 feet of the building.
The recommendations,submitted in this letter are based on our observation of the soils exposed
within the foundation excavation and do not include subsurface exploration to evaluate the
Liz Tucker
July 11, 2022
Page 2
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. 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,
Off. •.- p ..1
James H. Parsons, P.E .
••x,`7/13 z7 -
Rev. by: SLP,4_�,r';
JHP/kac
Kumar & Associates, Inc. Project No. 22-7-489