HomeMy WebLinkAboutObservation of Excavation 08.05.2025
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
August 5, 2025
Longacre Property Management
Attn: Simon Longacre
810 Minter Avenue
Glenwood Springs, Colorado 81601
simon@longacreequine.com
Project No. 25-7-382
Subject: Observation of Excavation, Proposed ADU Residence, 178 Mountain Shadow
Drive, Glenwood Springs, Colorado
Gentlemen:
As requested, a representative of Kumar & Associates, Inc. observed the excavation at the
subject site on July 25, 2025 to evaluate the soils exposed for foundation support. The findings
of our observations and recommendations for the foundation design are presented in this report.
The observation was performed in accordance with our agreement for professional services with
Longacre Property Management dated June 2, 2025.
The proposed ADU residence will be above crawlspace and supported by spread footings sized
for an assumed allowable bearing pressure of 1,500 psf.
At the time of our visit to the site, the building foundation excavation had been cut in 2 levels
from about 2 to 4 feet below the adjacent ground surface with a 2-foot step down to the south
between levels. The soils exposed in the bottom of the excavation consisted of silty clayey
sand to sandy silt and clay with gravel. Results of laboratory testing performed on samples
taken from the site are summarized in Table 1. 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 expected to be
encountered on the site and can be used for support of spread footings designed for the
assumed allowable bearing pressure of 1,500 psf. The soils tend to compress under loading
and, based on experience, there could be post-construction differential settlement of around 1
to 2 inches mainly if the bearing soils are wetted. The exposed soils in the footing areas should
be moistened and compacted. Foundation wall backfill should be well compacted and have a
positive slope away from the building. A perimeter foundation subdrain is not recommended for
the shallow foundation to help keep the bearing soils dry. Landscape irrigation should be kept
at least 5 feet away from the foundation.
The recommendations submitted in this letter are based on our observation of the soils exposed
within the foundation excavation and do not include 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. Our services do
not include determining the presence, prevention or possibility of mold or other biological
TABLE 1
SUMMARY OF LABORATORY TEST RESULTS
Project No. 25-7-382
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)
Northeast
Corner 6.2 100 Silty Clayey Sand
Southwest
Corner 4.2 56 Sandy Silt and Clay with
Gravel