HomeMy WebLinkAboutObservation of Excavation 07.16.24rcrf $.{ffi ,xffii$tr11',ir;'*"'
An Employsc Chrncd Compony
5020 County Road 154
Glenwood Springs, CO 81601
phone: (970) 945-7988
fax: (970) 945-8454
email : kaglenwood@kumarusa.com
www.kumarusa.com
Offrce Locations: Denver (HQ) Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado
July 16,2024
AM2,Inc
Attn: Andy Mishmash
P.O. Box 2140
Basalt, Colorado 81621
andy.am2@gmall.com
Project No. 24-7-390
Subject:Observation of Excavation, Proposed Mud Room Addition, 1854 County Road
109, Garfield County, Colorado
Gentlemen:
As requested, a representative of Kumar & Associates, Inc. observed the excavation at the
subject site on July 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.
The observation was performed in accordance with our agreement for professional engineering
services with AM2, Inc dated July 8, 2024.
The addition will be attached to the northwest comer of the residence and be single-story above
mostly slab-on-grade with crawlspace in the south part. Spread footings placed on the natural
soils and sized for an allowable bearing pressure of 2,000 psf were assumed for the foundation
support. The existing foundation consists of cinder block walls supported by spread footings.
At the time of our visit to the site, the foundation excavation had been cut in 2 levels from about
4%to 5% feet below the adjacent ground surface. The grade step down between levels at the
east end, north side was about one foot and exposed the existing footing of the residence. The
soils exposed in the bottom of the excavation mainly consisted of silty sandy gravel with
cobbles. The south end of the west side was above foundation wall backfill. A buried waterline
and exposed sewer line crossed the west part of the excavation. No free water was encountered
in the excavation and the soils were slightly moist to moist.
AM2,lnc
July 16,2024
Page2
The natural gravel soils exposed in the excavation are consistent with those expected to be
encountered in this area and suitable for support of spread footings designed for the assumed
allowable bearing pressure of 2,000 psf. Loose disturbed soils should be removed in the footing
areas to expose the undisturbed natural soils. The new foundation wall should be designed to
span the existing backfill (around 5 feet wide) and dowel into the existing foundation. Footings
should be a minimum width of 16 inches for walls and2 feet for columns. A foundation drain is
not needed for the shallow crawlspace and slab-on-grade floor with proper grading and drainage
away from the foundation. The onsite soils excluding rock larger than 6 inches are suitable for
use as skuctural backfill compacted to at least 95% of standard Proctor density at near optimum
moisture content.
T'he 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 inctease the risk of
foundation movement. Our services do not include determining the presence, prevention or
possibility of mold or otherbiologiial contaminants (MOBC) developing in the futwe. If ttre
client is concerned about MOBC, then a professional in this special field of practice should be
consulted.
If you have any questions or need further assistance, please call our office.
Sincerely,
Kumar & Associates, lnc.
Steven L. Pawlak, P.E.
slP/ljf
Kumar & Associates, lnc.6 Project No.24-7-390