HomeMy WebLinkAboutObservation of Excavation 05.02.2024I(tA lfumr & Asoclates,lnc.
6-Jolecln,cal an-O ntateri6ls 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 Emdoyac owngd compony wwvv.kumarusa.com
Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado
N'{:ay 2,2024
Brackett Pollard
Attn: Jonathon Todd
6875 County Road 233
Silt, Colorado 81652
jontoddbja@gmail.com
Project No.24-7-246
Subject: Observation of Excavation, Proposed Addition, 6875 County Road 233, Garfield
CountY, Colorado
Dear Mr. Pollard:
As requested, a representative of Kumar & Associates observed the excavation at the subject site
on April 26,2024 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 April 17,2024.
The proposed construction will be a 12 feet by 14 feet addition on the southwest corner of the
existing residence. Foundations consist of spread footings designed for an allowable soil bearing
pressure of 2,000 psf.
At the time of our visit to the site, the foundation excavation had been cut in one level about
3 feet below the adjacent ground surface. The soils exposed in the bottom of the excavation
consisted of very stiff sandy silty clay. Results of swell-consolidation testing performed on
samples taken from the site, shown on Figures 1 and 2, indicate the soils are 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 2,000 psf can be used for support of the proposed addition. 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 16 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. Structural fill ptaced 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 gfaded to prevent
ponding within at least 10 feet of the building.
Brackett Pollard
May 2,2A24
Page2
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,
H{. ir c; E ;t r r,* A :.:l+t;t:i :,it s-'.'lu Ewc"
Staff Engineer
Reviewed by:
Robert L. Duran, P
SMMlkac
attachments Test ResultsFigures I
6t3U2
tloel e
Kumar & Associales, lnc. o Projeet No.24-7-246
I
SAMPLE OF: Sondy Sllty Cloy
FROM: Boltom of Excovotlon ot West Slde
Wc = 10.6 %, DD = 99 pcf
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I ADDITIONAL COMPRESSION
UNDER CONSTANT PRESSURE
DUE TO WETTING
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Fig. 1SWELL-CONSOLIDATION TEST RESULTS24-7-246 Kumar & Associates
I
SAMPLE OF: Sondy Sllty Cloy
FROM: Bollom of Excovollon qt South Slde
WC = 10.7 %, DD = 100 pcf
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ADDITIONAL COMPRESSION
UNDER CONSTANT PRESSURE
DUE TO WETTING
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=lr7
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Fig. 2SWTLL-CONSOLIDATION TEST RESULTS24-7-246 Kumar & Associates