HomeMy WebLinkAboutObservation of Excavation 01.29.24
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
January 29, 2024
Darren Gallegos
56 Surrey Street
Carbondale, Colorado 81623
darrengallegos@hotmail.com
Project No. 21-7-565.A
Subject: Observation of Excavation, Proposed Residence, Lot 16, Pinyon Mesa, 157 Sage
Meadow Road, Garfield County, Colorado
Dear Darren:
As requested, a representative of Kumar & Associates, Inc. observed the excavation at the
subject site on September 28, 2023, 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 September 13. 2021, Project No. 21-7-565.
The proposed residence will be a two-story wood frame structure over a crawlspace.
Foundations were designed for an allowable soil bearing pressure of 1,200 psf as recommended
in our previous report. The footings were designed to be placed on at least 6 feet of recompacted
structural fill consisting of the on-site silty clay soils.
At the time of our visit to the site, the foundation excavation had been cut in one level, about
9½ feet below the adjacent ground surface. The soils exposed in the bottom of the excavation
consisted of stiff, gravelly sand and clayey silt. The results of a gradation analysis performed
on a sample of the natural soils (minus 3-inch fraction) obtained from the site are presented on
Figure 1. Atterberg Limits testing indicates that the soils have low plasticity. No free water was
encountered in the excavation and the soils were slightly moist.
Density testing of the structural fill placement was conducted as the fill was placed between
September 25 and October 2, 2023. The test results are attached and indicate that satisfactory
compaction was achieved.
The soil conditions exposed in the excavation are consistent with those previously encountered
on the site and suitable for support of spread footings placed on 6 feet of structural fill designed
for the recommended allowable bearing pressure of 1,200 psf. In general, the structural fill was
compacted to at least 98% of the maximum standard Proctor density. The bearing soils should
be protected from frost and concrete should not be placed on frozen soils. Other
recommendations presented in our previous report which are applicable should also be observed.
The recommendations submitted in this letter are based on our observation and testing of the
soils exposed within the foundation excavation and the previous subsurface exploration at the