HomeMy WebLinkAboutObservation of Excavation 03.20.2025Kumar & Associates, Inc. 11
'( Geotechnical and Materials Engineers 5020 County Road 154
and Environmental Scientists Glenwood Springs, CO 81601
phone: (970) 945-7988
fax: (970) 945-8454
email: kaglenwood@kumarusa.com
An Employee Owned Company www.kumarusa.com
Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado
March 20, 2025
Judy Spasser
39 Sweetgrass
Carbondale, Colorado 81623
js ap sserg mail.com
Project No. 25-7-218
Subject: Observation of Excavation, Proposed Residence, 699 Wooden Deer Road, Lot 8
Wooden Deer Subdivision, Garfield County, Colorado
Dear Ms. Spasser:
As requested, a representative of Kumar & Associates observed the excavation at the subject site
on March 19, 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 March 19, 2025.
The proposed residence will be a two-story wood frame structure. Foundations were designed
for and allowable soil bearing pressure of 1500 psf.
At the time of our visit to the site, the foundation excavation had been cut in two levels with
cut depths up to 15 feet below the adjacent ground surface. The soils exposed in the bottom of
the excavation consisted of medium dense, slightly clayey, silty sand with gravel and scattered
cobbles. No free water was encountered in the excavation and the soils were slightly moist to
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 1,500 psf should be adequate for support of the proposed residence.
The exposed soils tend to compress when wetted and there could be some post -construction
settlement of the foundation if the bearing soils become wet. Footings should be a minimum
width of 18 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. The bearing soils should be protected against frost and concrete should not be placed on
frozen soils. Exterior footings should be provided with 36 inches of 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 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
Judy Spasser
March 20, 2025
Page 2
hydrostatic pressure behind retaining walls and prevent wetting of the lower level. Structural
fill placed within floor slab areas can consist of the on -site soils 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 12 feet
of the building.
The recommendations submitted in this letter are based on our observation of the soils exposed
within the foundation excavation and previous 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. 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,
Kumar & Associates, I
Daniel E
DEH/kac
Kumar & Associates, Inc. 0 Project No. 25.7-218