HomeMy WebLinkAboutObservation of Excavation 10.17.2022
5020 County Road 154
Glenwood Springs, CO 81601
phone: (970) 945-7988
fax: (970) 945-8454
email: kaglenwood@kumarusa.com
www.kumarusa.com Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado
October 17, 2022
Eric and Denee Berhalter
4062 County Road 331
Silt, Colorado 81652
bird@awd.com
Project No. 22-7-278.01
Subject: Observation of Excavation, Proposed Steel Building, Lot 27, Grass Mesa,
209 Cedar Breaks Road, Garfield County, Colorado
Dear Eric and Denee:
As requested, a representative of Kumar & Associates observed the excavation at the subject site
on August 23 and September 30, 2022 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 April 6, 2022.
We previously conducted a subsoil study for design of foundations at the site and presented our
findings in a report dated August 11, 2022, Project No. 22-7-278. The proposed construction is
similar to that discussed in our previous report. The building was originally designed to be
supported on a thickened slab foundation then redesigned for a spread footing foundation using
an allowable soil bearing pressure of 2,500 psf, as recommended, with a slab-on-grade floor.
On August 23 the excavation had been dug for a shallow thickened slab foundation with cut
depths from about 1 to 2½ feet below adjacent ground surface, and stiff sandy clay exposed at
subgrade. At this time, we recommended the clay soil be removed to bear on the underlying
calcareous soils. The building was then designed for a conventional spread footing foundation.
At the time of our September 30 site visit, the foundation excavation had been cut in two levels
from 3½ to 4 feet below the adjacent ground surface. The soils exposed in the bottom of the
excavation consisted of generally medium dense, basalt gravel and cobbles in a sandy silty clay
matrix. The soils were highly calcareous. Results of swell-consolidation testing performed on
samples taken from the site, shown on Figure 1, indicate the soils are slightly to moderately
compressible under conditions of loading and wetting. The sample was likely partly disturbed
due to the sampling process. No groundwater was encountered in the excavation and the soils
were generally 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 2,500 psf. Loose and disturbed soils should be
removed in the footing areas to expose the undisturbed natural soils, and the subgrade
compacted. Other recommendations presented in our previous report which are applicable
should also be observed.
Kumar & Associates