HomeMy WebLinkAboutObservation of Excavation 04.28.2021I (trt i;,ffil.*,ffifffiinilÍå' * "
An Employcc Onrncd Compony
5020 Counry Road 154
Glenwood Springs, CO 81601
phone: (970) 945-7988
fax: (970) 945-8454
email : kaglenwood@kumarusa.com
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Office Locatious: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit Corurty, Colorado
ApnI28,202l
Russell Cartvwight
35 Willowview Way
Parachute, Colorado 8 I 63 5
russecart@gmail.com
Project No. 21 -7-1 21.01
Subject Observation of Excavation, Proposed Klase Residence, Lot12, Block 4,
Battlement Mesa" 121 Boulder Ridge, Garfield County, Colorado
Dear Russell:
As requested, a representative of Kumar & Associates observed the excavation at the subject site
on April l5,2\2l 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 geotechnical services to you dated January 12,2021.
We previously conducted a subsoil study for design of foundations at the site and presented our
findings in areport dated February l2,2027,ProjectNo. 21-7-121. Theproposed construction is
similar to that discussed in our previous report. Spread footing sized for an allowable soil
bearing pressure of 1,500 psf were recommended for foundation support with a risk of
settlement.
At the time of our site visit, the foundation excavation had been cut in three levels from about
I to 7 feet below the adjacent ground surface. The steps in grade between the excavation levels
were about 3 to 3% feet. The soils exposed in the bottom of the excavation consisted of stif{
sandy clayey silt. Results of swell-consolidation testing performed on samples taken from the
site, shown on Figure l, indicate the soils are moderately compressible under conditions of
loading and wetting with a low hydro-compression potential. The soils are not expansive. No
groundwater was encountered in the excavation and the soils were slightly moist to moist.
The soil conditions exposed in the excavation are generally 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 of the
bearing soils. Prior to the footing construction, all loose disturbed soils should be removed in the
to expose the undisturbed natural soils, and the subgrade moistened and compacted. 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
Russell Cartwright
April28,202l
Page2
in the subsurface conditions below the excavation could increase the risk of foundation
movernent. 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 &
David A. Young, P
DAY/kac
attactrment Test ResultsFigure I -
Kumar & Associates, lnc. @ Project No. 21-7-121.01
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SAMPLE OF: Sondy Cloyey Sllt
FROM: Bottom of NE Porllon of Excovollon
WC = ,l1.1 N, DD = 94 pcf
ADDITIONAL COMPRESSION
UNDER CONSTANT PRESSURE
DUE TO WETTING
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21-7-121.01 Kumar & Associates SWELL_CONSOLIDATION TEST RESULT Fig. 1ió