HomeMy WebLinkAboutObservation of Excavation 05.28.2025
5020 County Road 154
Glenwood Springs, CO 81601
phone: (970) 945-7988
email: kaglenwood@kumarusa.com
www.kumarusa.com
Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado
May 28, 2025
Aaron Maisch
525 County Road 109
Glenwood Springs, Colorado 81601
admaisch@gmail.com
Project No. 25-7-343
Subject: Observation of Excavation, Proposed Shop Building, 525 County Road 109,
Garfield County, Colorado
Dear Aaron:
As requested, a representative of Kumar & Associates observed the excavation at the subject
site on May 20, 2025 to evaluate the soils exposed for foundation support. The findings of our
observations and recommendations are presented in this report. The services were performed
in accordance with our agreement for professional engineering services to Aaron Maisch dated
May 19, 2025.
The proposed shop building will be built to the northeast of and detached from the existing
residence. The building has been designed to be supported on spread footings sized for an
assumed allowable bearing pressure of 1,500 psf.
At the time of our visit to the site, the foundation excavation had been cut in one level from 2½
to 4 feet below the adjacent ground surface. The soils exposed in the bottom of the excavation
consisted of fill soils placed as part of the original driveway construction for the residence. The
fill consisted of silty clayey gravel with scattered cobbles that by probing with a bar appeared at
least medium dense. The results of a gradation analysis performed on a sample of the fill soil
(minus 3-inch fraction) obtained from the site are presented on Figure 1. No free water was
encountered in the excavation and the soils were slightly moist. Depth of the fill appeared to
be approximately 4 to possibly 6 feet deep below the excavation subgrade.
Considering the conditions exposed in the excavation and the nature of the proposed
construction, spread footings placed on the exposed fill soil designed for an allowable soil
bearing pressure of 1,500 psf should can be used for support of the proposed shop with a risk
of foundation settlement possible resulting in distress. Settlements could be on the order of 1 to
2 inches. A lower risk option would be to sub-excavate and replace 2 to 3 feet of the onsite
soils as compacted structural fill below the footing (and floor slab) areas. If recommendations
for structural fill are desired, we should be contacted to provide them. Subsurface exploration
to determine the depth and quality of the of fill such as with an augur boring would be needed to
better evaluate the magnitude of possible settlement.
Footings should be a minimum width of 18 inches for continuous walls and 2 feet for columns.
Loose disturbed soils in footing areas should be removed and the bearing level extended down
to the undisturbed natural soils. Exterior footings should be provided with adequate soil cover
above their bearing elevations for frost protection. Continuous foundation walls should be
Kumar & Associates