HomeMy WebLinkAboutObservation of ExcavationKumar & Associates, inc.®
'f 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 Employee Owned Company www.kumarusa.com
Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado
March 21, 2025
Levi Troyer
7295 County Road 233
Silt, Colorado 81652
lctroyerkmsn.com
Project No. 25-7-200
Subject: Observation of Excavation, Proposed Shed, 7295 County Road 233, Silt,
Colorado
Dear Levi:
As requested, a representative of Kumar & Associates observed the excavation at the subject site
on March 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
to you dated March 7, 2025.
The proposed shed will be a single -story wood -frame structure with a foot print of approximately
25 by 27 feet. The ground floor will be compacted earth. The shed has been designed to be
supported on spread footings sized for an allowable bearing pressure of 1,500 psf.
At the time of our visit to the site, the foundation excavation had been cut to one level from 1 to
3 feet below the adjacent ground surface. The soils exposed in the bottom of the excavation
consisted of sandy clay. Laboratory test results are presented in the table below. No free water
was encountered in the excavation and the soils were slightly moist to moist.
Sample
Location
Natural
Moisture
Natural
Dry
Percent
Passing
Atterberg Limits
Soil Type
Liquid
Plastic
Content
Density
No.200
Limit
Index
(Pcfl
Sieve
Southeast
9.4
86
Sandy Clay
Corner
Northwest
13.1
105
77
25
9
Sandy Clay
Corner
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 shed. 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 18 inches for continuous walls 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.
Levi Troyer
March 21, 2025
Page 2
The bearing soils should be protected against frost and concrete should not be placed on frozen
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 12 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 45 pcf for on -site soil as backfill.
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 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,
Kumar & Associates, I
VO�'J•�9 N' PAe
. PO
58663
James H. Parsons, P.E.; 3j2y/ZS
Reviewed by:
d
Robert L. Duran, P.E.
JHP/kac
Kumar & Associates, Inc. 0 Project No. 25-7-200