HomeMy WebLinkAboutObservation of Excavation 02.26.20241(+AKumar & Associates, Inc.
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 Ci NMW Company www.kumarusa.com
Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado
February 26, 2024
Spartan Construction Management
Attn: Ross Sherrod
17301 W. Colfax Ave., Unit 20
Golden, Colorado 80227
rsherrod(&spartanbuilt. com
Project No. 24-7-146
Subject: Observation of Excavation, Proposed Free Up Storage Facility, 357 S. 16a` Street,
Silt, Colorado
Dear Mr. Sherrod:
As requested, a representative of Kumar & Associates observed the excavation at the subject site
on February 22, 2024 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 Spartan Construction Management dated February 6, 2024.
The proposed storage facility will be a one-story frame building with a slab -on -grade floor. We
understand the assumed soil bearing pressure is about 300 to 400 psf.
At the time of our visit to the site, the foundation excavation had been cut in one level from 2 to
3 feet below the adjacent ground surface. The soils exposed in the bottom of the excavation
consisted of silty sand to sandy silt. Results of testing performed on samples taken from the site
indicate the soils are silty sand to sandy silt. The results of percent finer than sand size gradation
analysis performed on two samples of the subgrade soils obtained from the site range from 44 to
57 percent finer than sand size. Moisture/density testing indicates densities of 94 to 101 pcf at
moisture contents of 14 to 18 percent. No free water was encountered in the excavation and the
soils were slightly moist to 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 can be used for support of the proposed storage building.
The exposed soils tend to compress when loaded and 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 20 inches for continuous walls and 2 feet for columns. 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. Structural fill placed 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.
Spartan Construction
Feb. 26, 2024
Page 2
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, In
Daniel E. Hardin, P. .Q, a la(WIY
Rev. by: SLP
DEH/kac
Kumar & Associates, Inc. 8 Project No. 24-7-146