HomeMy WebLinkAboutObservation of ExcavationKumar & Associates, Inc.® 5020 County Road 154
'( Geotechnical and Materials Engineers Glenwood Springs, CO 81601
and Environmental Scientists phone: (970) 945-7988
email: kaglenwood@kumarusa.com
www.kumarusa.com
An Employee Owned Company
Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado
May 21, 2025
Dave Cardiff Construction
Attn: Dave Cardiff
506 Mesa Verde Avenue
Carbondale, Colorado 81623
davecardiffconstruction mail.corr
Project No. 17-7-147.01
Subject: Observation of Excavation, Proposed Garage, 798 Callicotte Ranch Road, Lot 22,
Callicotte Ranch Subdivision, Garfield County, Colorado
Dear Dave:
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 for the foundation support are presented in this report. The
services were performed in accordance with our agreement for professional engineering services
to you dated May 19, 2025.
The proposed detached garage will be a one-story wood frame structure with a slab -on -grade
floor, located just to the northeast of the existing residence.
At the time of our visit to the site, the foundation excavation had been cut in two levels from 3 to
8 feet below the adjacent ground surface. The soils exposed in the bottom of the excavation
consisted of basalt rocks in a gravelly sandy silt matrix. No free water was encountered in the
excavation and the soils were slightly moist.
Considering the conditions exposed in the excavation and the nature of the proposed
construction, spread footings placed on the undisturbed natural soil designed for an allowable soil
bearing pressure of 2,000 psf can be used for support of the proposed garage. Footings should
be a minimum width of 16 inches for continuous walls and 2 feet for columns. Loose and 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 reinforced top and bottom
to span local anomalies such as by assuming an unsupported length of at least 10 feet.
Foundation walls acting as retaining structures should also be designed to resist a lateral earth
pressure based on an equivalent fluid unit weight of at least 50 pcf for on -site soil as backfill. A
perimeter foundation drain should be provided to prevent temporary buildup of hydrostatic
pressure behind the garage walls and prevent wetting of the lower level. Structural fill placed
within floor slab areas can consist of the on -site soils or imported gravel compacted to at least
95% of standard Proctor density at a moisture content near optimum. Backfill placed around the
structure should be compacted and the surface graded to prevent ponding within at least 10 feet
of the building.
Dave Cardiff Construction Project No. 17-7-417.01
May 21, 2025 Page 2
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 to evaluate the
subsurface conditions within the loaded depth of foundation influence. This study is based on the
assumption that soils beneath the footings have equal or better support than those exposed. The
risk of foundation movement may be greater than indicated in this report because of possible
variations in the subsurface conditions. In order to reveal the nature and extent of variations in
the subsurface conditions below the excavation, drilling would be required. It is possible the data
obtained by subsurface exploration could change the recommendations contained in this letter.
Our services do not include determining the presence, prevention or possibility of mold or other
biological contaminants (MOBC) developing in the future. If the 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,
Kumai
Daniel
Rev. b
DEH/k
Kumar & Associates, Inc