HomeMy WebLinkAboutObservation of Excavation 03.16.20215020 County Road 154
Glenwood Springs, CO 81601
phone: (970) 945-7988
fax: (970) 945-8454
email: kaglenwood@kumarusa.com
An Employcc Owncd Compony trvww'kumarusa'com
Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado
March 16,2021
Cruz Holguin
6492Highway 13
Rifle, Colorado 81650
cruzhol guin@hotmail.com
Project No.2l-7-252
Subject: Observation of Excavation, Proposed Residence. 6492 Highway 13,2Yzmiles
North of Rifle, Garfield County, Colorado
Dear Mr. Holguin:
As requested, a representative of Kumar & Associates observed the excavation at the subject site
on March 8,2021to 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 March8,202l.
The proposed residence will be about 1,400 square feet, one-story wood frame modular house
over a crawlspace. Spread footing foundations were designed for an allowable soil bearing
pressure of 1,500 psf and 20 inches wide.
At the time of our visit to the site, the foundation excavation had been cut in two levels from 2 to
5 feet below the adjacent ground surface. The soils exposed in the bottom ofthe excavation
consisted of loose to medium dense silty sand. Results of swell-consolidation testing performed
on samples taken from the site, shown on Figures I and2, indicate the soils tend to settle under
conditions of loading and wetting. No free water was encountered in the excavation and the soils
were slightly 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 1,100 psf can be used for support of the proposed residence with a high
risk of settlement and building distress. The exposed soils tend to compress when wetted and
there could be post-construction settlement of the foundation if the bearing soils become wet. If
the risk of settlement and distress is not acceptable to you then a deep foundation such as piles
should be used. Footings should be a minimum width of 28 inches for continuous walls and
3 feet for columns. Loose and disturbed soils in footing areas should be moistened and
compacted or be removed and the bearing level extended down to the undisturbed natural soils.
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 heavily reinforced top
and bottom to span local anomalies such as by assuming an unsupported length of at least
Cruz Holguin
March 16,2021
PageZ
14 feet. Foundation walls acting as retaining structures should also be designed to resist a latcral
earth pressure based on an equivalent fluid unit weight of at least 50 pcf f'or on-site soil as
backfill. Backfill placed around the structure should be compacted and the surface graded to
prevent ponding within at least l0 feet of the building. Landscape that requires regular heavy
irrigation, such as sod, and sprinkler heads should not be located within 10 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) cleveloping in the future. If the client is concerned about
MOBC, then a professional in this special field of practice shoulcl be consultert.
If you have any questions or need further assistance, please call our office.
Sincerely,
K.r¡nlar & ¡{ssocia{es, Inc.
Daniel E. Hardin,
Rev. by: SLP
DEH/kac
attachments Figures 1 &2--Consolidation Test Results
cc: Studio M - Mic Baca (studiom.ensineer6Ðnnail.corn)
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Kumar & Associates, lnc. ö Project No. 21-7-252
SAMPLE OF: Silly Sond
FROM: NW Corner @ Fooling grode
WC = 3.9 %, DD = 99 pcf
-2OO = 35 %
ADDITIONAL COMPRESSION
UNDER CONSTANT PRESSURE
DUE TO WETTING
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Fig. 1SWELL-CONSOLIDATION TEST RESULTS21 -7 -252 Kumar & Associates
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SAMPLE 0F: Silly Sond
FROM: SE Corner @ Footing Grode
WC = 4.4 %, DD = 95 pcf
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ADDITIONAL COMPRESSION
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DUE TO WETTING
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21 -7 -252 Kumar & Associates SWELL_CONSOLIDATION TEST RTSULTS Flg. 2