HomeMy WebLinkAboutObservation of Excavation 04.17.2024
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
April 17, 2024
Boulder Construction Services
Attn: Matt Jurmu
901 County Road 231
Silt, Colorado 81652
matt.jurmu@bouldercs.com
Project No. 20-7-684.A
Subject: Observation of Excavation, Proposed Addition, Lot 64, Spring Ridge Reserve,
549 Hidden Valley Drive, Garfield County, Colorado
Gentlemen:
As requested, a representative of Kumar & Associates, Inc. observed the excavation at the
subject site on April 15, 2024 to evaluate the soils exposed for foundation support. The findings
of our observations and recommendations for the foundation design are presented in this report.
We previously conducted a subsoil study for design of foundations at the site and presented our
findings in a report dated December 22, 2020, Project No. 20-7-684. The current observation
was performed in accordance with our agreement for professional engineering services with
Boulder Construction Services dated March 28, 2024.
The addition will be attached to the garage side of the residence and designed to be supported
by spread footings sized for the recommended allowable bearing pressure of 1,500 psf.
At the time of our visit to the site, the foundation excavation had been cut in one main level from
about 3 to 4½ feet below the adjacent ground surface with a one-foot step up to the foundation
of the residence. The soils exposed in the bottom of the excavation consisted of very silty sand
with scattered gravel. Results of swell-consolidation testing performed on a sample taken from
the cut depth, shown on Figure 1, indicate the soils are slightly compressible under light loading
and moderately compressible under additional loading after wetting. 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 can be used for support of spread footings designed for the recommended
allowable bearing pressure of 1,500 psf with a settlement risk mainly if the bearing soils are
wetted. Loose disturbed soils should be removed in the footing areas and the expose soils
moistened and compacted. Other recommendations presented in our previous report which
are applicable, especially those to keep the bearing soils dry, 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
Kumar & Associates