HomeMy WebLinkAboutObservation of ExcavationIC+AGeotectmical 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 Employee Owned Company www.kumarusa.com
Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado
November 16, 2022
Cole West Corp.
Attn: Chuck Cole
2321 County Road 100
Carbondale, Colorado 81623
244charliedeltaAgmail.com
Project No. 22-7-726
Subject: Observation of Excavation, Proposed Detached 3-Car Garage, 2341 County Road
100, East of Carbondale, Garfield County, Colorado
Dear Chuck:
As requested, the undersigned representative of Kumar & Associates observed the excavation at
the subject site on November 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 accordance with our agreement for professional
engineering services to Cole West Corp. dated November 11, 2022.
The proposed detached garage will be a one-story wood frame structure (26' by 39') with a
thickened slab foundation. The thickened portions of the foundation will be 16 inches wide and
were designed for an allowable soil bearing pressure of 1,500 psf.
At the time of our visit to the site, the foundation excavation had been cut in two levels from 1 to
1 %2 feet below the adjacent ground surface. The perimeter forms for the thickened slab were in
place. The soils exposed in the bottom of the excavation consisted of compacted 3-inch road
base. We understand that 1 foot of 3-inch minus road base was placed over the natural clay soils
and compacted to support the structure. Three inches of 3/-inch road base was then placed and
compacted for support of the thinner, interior slab section. No free water was observed in the
excavation and the soils were slightly moist to moist. We understand that rigid foam insulation
was placed around the outside of the building and under the interior slab fill to protect the
subgrade soils from freezing.
Considering the conditions exposed in the excavation and the nature of the proposed
construction, the thickened edge slab placed on the compacted granular fill over the undisturbed
natural clay soil designed for an allowable soil bearing pressure of 1,500 psf should be adequate
for support of the proposed garage. The bearing soils should be protected against frost and
concrete should not be placed on frozen soils. Exterior footings should be provided with
adequate insulation above their bearing elevations for frost protection. A perimeter foundation
drain should not be provided. Structural fill placed within floor slab areas, such as %-inch road
base, should be 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.
Cole West Corp.
November 16, 2022
Page 2
The recommendations submitted in this letter are based on our observation of the soils exposed
around the foundation excavation 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. 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,
Dan
Rev,
DEf
Kumar & Associates, Inc. ,� Project No. 22-7-726