HomeMy WebLinkAboutObservation of Excavation 04.24.2018[1_171
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Geotechnical Engineering 1 Engineering Geology
Materials Testing 1 Environmental
5020 County Road 154
Glenwood Springs, CO 81601
Phone: (970) 945-7988
Fax: (970) 945-8454
Email: hpkglenwood@kumarusa.com
Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, Summit County, Colorado
April 24, 2018
Andrew Tarrazas
c/o Russel Cartwright
284 Meadow Creek Dive
Parachute Colorado 81635
(russccart @grnail.com )
Project No, 17-7-869.01
Subject: Observation of Excavation, Proposed Residence, Lot 24, Block 4, Battlement
Mesa, 88 Boulder Ridge Drive, Garfield County, Colorado
Gentlemen:
As requested, a representative of H-P/Kumar observed the excavation at the subject site on April
13, 2018 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 services to you dated December 13, 2017.
We previously conducted a subsoil study for design of foundations at the site and presented our
findings in a report dated January 30, 2018, Project No. 17-7-869.01. The proposed construction
is similar to that discussed in the previous report. Spread footings bearing on the natural soils
designed for an allowable bearing pressure of 1,500 psf, with some risk of movement and
building distress, were recommended for support of the residence.
At the time of our site visit, the foundation excavation which was essentially complete had been
cut in two levels from about 3 to 9 feet below the adjacent ground surface. The soils exposed in
the bottom of the excavation consisted of stiff to very stiff, sandy and occasionally clayey silt.
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 moderate hydro -compression potential. The sample was probably partly
disturbed due to the sampling process. No free water 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 bearing soils do not appear to be
expansive but will tend to settle when wetted, and precautions should be taken to prevent
wetting. Prior to the footing construction, all loose disturbed soils should be removed to expose
the undisturbed natural soils, and the subgrade compacted. Other recommendations presented in
our previous report which are applicable should also be observed.
Andrew Tarrazas
April 24, 2018
Page 2
The recommendations submitted in this letter are based on our observation of the soils exposed
within the foundation excavation and the previous limited 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,
H -Pt KUMAI
David A. Young, P.E.
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attachment Figure 1, Swell -Consolidation Test Results
cc: Garfield County Building Dept. — Jim Wilson (jwilson@garrcld-county.com)
H-P%KUMAR
Project No. 17-7-869.01