HomeMy WebLinkAboutObservation of Excavation 05.24.2024lGrtf,#;*[',ffi*Nrnt$'""5020 County Road 154
Glenwood Springs, CO 81601
phone: (970) 945-7988
fax: (970) 945-8454
email : kaglenwood@kumarusa.com
An Employcc Owncd Compony www.kumarusa.com
Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado
May 24,2024
James Madden
2510 Highway 133
Carbondale, Colorado 81 623
imaddenemailtOemail.com
Project No. 24-7-318
Subject: Observation of Excavation, Proposed Barn and ADU, 2510 Highway 133,
Garfield County, Colorado
Dear James,
As requested, a representative of Kumar & Associates observed the excavation at the subject
site on May L7,2024 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 you dated May 17,2024.
We understand the proposed construction to be a metal framed bam with an attached ADU.
Ground floors will be slab-on-grade.
At the time of our visit to the site, the foundation excavation had been cut in one level from
about 2 to 7 feet below the adjacent ground surface. The soils exposed in the bottom of the
excavation consisted of medium stiff sandy silty clay in almost all of the excavation, with a
small area of silty sandy gravel exposed in the northeast comer. Results of swell-consolidation
testing performed on samples taken from the site indicate the soils have a low bearing capacity
and are moderately compressible under conditions of loading and wetting. 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 1,000 psf can be used for support of the proposed structure. The exposed
soils tend to compress'ffihiedand there could be some post-construction movement of the
foundation if the bearing soils become wet. Footings should be a minimum width of 24 inches
for continuous walls and2 feet for columns. Loose and 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.
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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 55 pcf for on-site soil as backfill. Structural filI placed within floor slab
areas can consist of the on-site soils compacted to at least 95% of standard Proctor density at a
James Madden
May 24,2024
Page2
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. Any landscaping
that requires regular heavy irrigation, such as sod, and sprinkler heads should not be located
within l0 feet of the foundation.
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 fuither assistance, please call our office.
Sincerely,
trr, a I l ;i :l l' & /i'i;! t?i.: i :': i c:ti. $ il'-:.
David A. Noteboom, Staff
Reviewed by:
James H. Parsons, P
DAN/kac
Attachments: Figure I -Test Results
Table 1 - Summary of Laboratory Test Results
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SAMPLE OF: Sondy Silly Cloy
FROM: Fooler Grode, Center
WC = 1 4.5 74, DD = 100 pcf
ADDITIONAL COMPRESSION
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Fig. 1SWELL-CONSOLIDATION TEST RESULTS24-7 -318 Kumar & Associates
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TABLE 1
SUMMARY OF I.ABORATORY TEST RESULTS
Project 24-7-318
Footer Grade
Center
Footer Grade
West Side
SAMPLE LOCATON
14.5
10.3
100
94
NATUML
MOISTURE
CONTEI.IT
NATURAL
DRY
DENSITY
Sandy Silty Clay
Sandy Silty Clay
LIQUID LIMIT
GRADATION LIMITS
PERCENT
PASShIG NO.
200 SIEVE
UNCONFINED
cofttPREsstvE
STRENGTH
sotLoR
BEDROCKTYPE
GRAVEL
t%)
SAIID
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PLASTIC
INDEX
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