HomeMy WebLinkAboutObservation of Excavation 11.01.2019I(+A
Kumar & gssnciatas, km."
Geotechnical and Materials Engineers
and Environmental Scientists
5020 County Road 154
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
November 1, 2019
Joel Ruiz
P. O. Box 37
Silt, Colorado 81652
ioel-ruiz(a Iive.com
Subject:
Dear Joel:
q, Asso4�f 1
Project No. 19-7-235.01
Observation of Excavation, Proposed Residence, TBD County Road 346, South
of Silt, Garfield County, Colorado
As requested, a representative of Kumar & Associates observed the excavation at the subject site
on October 28, 2019 to evaluate the soils exposed for foundation support. The findings of our
observations and recommendations are presented in this report. The services are supplemental to
our agreement for professional engineering services to you dated April 16, 2019.
We previously conducted a subsoil study for design of foundations at the site and presented our
findings in a report dated May 20, 2019, Project No. 19-7-235. The proposed construction is
similar to that discussed in our previous report. The building has been designed to be supported
on spread footings bearing on the natural soils sized using an allowable bearing pressure of 1,500
psf with a risk of settlement.
At the time of our site visit, the foundation excavation which was essentially complete had been
cut in two levels from about 2 to 4 feet below the adjacent ground surface. The soils exposed in
the bottom of the excavation consisted of medium dense, slightly clayey to clayey silty sand.
Results of swell -consolidation testing performed on samples taken from the site, shown on
Figure 1, indicate the soils are moderately to highly compressible under conditions of loading
and wetting with a low hydro -compression potential. The sample may have been partly
disturbed due to the sampling process. No free water was encountered in the excavation and the
soils were slightly moist.
The soil conditions exposed in the excavation are consistent with those previously encountered
on the site and suitable for support of spread footings designed for the recommended allowable
bearing pressure of 1,500 psf. The risk of settlement is primarily if the bearing soils were to
become wetted and precautions should be taken to prevent wetting. Providing a depth of
structural fill below the footings as discussed in our subsoil study report would act to reduce the
risk of settlement. Prior to the footing construction, all loose disturbed soils should be removed
to expose the undisturbed natural soils, and the subgrade moistened and compacted. The bearing
Joel Ruiz
November 1, 2019
Page 2
soils should be protected from frost and concrete should not be placed on frozen soils. Other
recommendations presented in our previous report which are applicable should also be observed.
The recommendations submitted in this letter are based on our observation of the soils exposed
within the foundation excavation and the previous subsurface exploration at the site. Variations
in the subsurface conditions below the excavation could increase the risk of foundation
movement. We should be advised of any variations encountered in the excavation conditions for
possible changes to recommendations contained in this letter.
If you have any questions or need further assistance, please call our office.
Sincerely,
Kumar & Asso tep, Inc.
David A. Young,
DAY/kac
attachment Figureolidation Test Results
Kumar & Associates, Inc. `� Project No. 19-7-235.01
W
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1
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SAMPLE OF: Clayey Silty Sand
FROM: Bottom of Excavation
WC = 6.4 %, DD = 98 pcf
U
ee Int ,..o . appy eek to uw
pamplM �a11 l 0.lt. 1M I.1I:,g Lyon
.11d na! prc giten ..*Npl 1n
lu., ., W.1l IN. x110111 eppn,wl of
1.0,,10, 1111 Jsw ude01*,1 .,I10 Sr AI
.10x111,1..0 00011 t1eAe.
1.D
ADDITIONAL COMPRESSION
UNDER CONSTANT PRESSURE
DUE TO WETTING
APPLIED PRESSURE — KSF 10 100
19-7-235.01
Kumar & Associates
SWELL—CONSOLIDATION TEST RESULT
Fig. 1