HomeMy WebLinkAboutObservation of Excavation
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
December 2, 2025
Morton Buildings, Inc
Attn: Kyle Hendrix
7853 Red Granite Loop
Colorado Springs, Colorado 80939
kyle.hendrix@mortonbuildings.com
Project No. 25-7-697
Subject: Observation of Excavation, Proposed Detached Garage, 232 Cedar Way, Garfield
County, Colorado
Gentlemen:
As requested, a representative of Kumar & Associates observed the excavation at the subject
site on November 22, 2025 to evaluate the soils exposed for foundation support. The findings
of our observations and recommendations for the foundation support are presented in this
report. The services were performed in accordance with our agreement for professional
engineering services to Morton Buildings, Inc dated November 20, 2025.
The proposed garage has been designed to be supported on spread footings sized for an
assumed allowable bearing pressure of 2,000 psf with a slab-on-grade floor. The uphill, back
wall will retain up to around 5 feet of earth backfill.
At the time of our visit to the site, the building excavation had been cut in 2 levels from about
4 to 8 feet below the adjacent ground surface. The interior slab area was about 4 feet higher
than the perimeter footing trench. The soils exposed in the bottom of the excavation consisted
of lightly calcareous, silty clayey sand with gavel and scattered cobbles. Results of swell-
consolidation testing performed on a sample taken from the site, shown on Figure 1, indicate
the soils have low to moderate compressibility under conditions of loading and wetting. The
laboratory test results are summarized in Table 1. No free water was encountered in the
excavation and the soils were slightly moist. The excavation bottom soils had been loosened
from the excavation equipment.
Considering the conditions exposed in the excavation and the nature of the proposed
construction, spread footings placed on the undisturbed natural soil designed for the assumed
allowable bearing pressure of 2,000 psf can be used for support of the proposed garage with a
risk of settlement. The exposed soils tend to compress when wetted under load and there could
be post-construction settlement of the foundation if the bearing soils become wet. Footings
should be a minimum width of 16 inches for continuous walls and 2 feet for columns. Loose
disturbed soils in footing areas should be removed and the exposed soils moistened and
compacted prior to forming footings. The bearing soils should be protected against frost and
concrete should not be placed on frozen soils. Exterior footings should be provided with
adequate soil cover above their bearing elevations for frost protection. Continuous foundation
walls should be reinforced top and bottom to span local anomalies such as by assuming an
unsupported length of at least 12 feet. Foundation walls acting as retaining structures should
Kumar & Associates
TABLE 1
SUMMARY OF LABORATORY TEST RESULTS
Project No. 25-7-697
SAMPLE
LOCATION NATURAL
MOISTURE
CONTENT
NATURAL
DRY
DENSITY
GRADATION PERCENT
PASSING
NO. 200
SIEVE
ATTERBERG LIMITS UNCONFINED
COMPRESSIVE
STRENGTH SOIL OR
BEDROCK TYPE BOTTOM OF
EXCAVATION
GRAVEL SAND LIQUID
LIMIT
PLASTIC
INDEX (%) (%)
(%) (pcf) (%) (%) (PSF)
Northwest
Corner 14.3 91 36 Silty Clayey Sand
Southeast
Corner 15.8 95 Silty Clayey Sand