HomeMy WebLinkAboutObservation of Excavation - 8.30.22icon G&,.
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
August 30, 2022
Abdi Pirzadeh
1101 Village Road, #LL -1 B
Carbondale, Colorado 81623
abdi(&aspenbuilt.net
Project No. 22-7-602
Subject: Observation of Excavation, Proposed Addition, 110 Spur Drive, Tellar Springs,
Garfield County, Colorado
Abdi:
As requested, a representative of Kumar & Associates observed the excavation at the subject site
on August 29, 2022 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 August 29, 2022.
The addition will be attached to the west side of the residence which has a basement level. The
addition will be above crawlspace and supported on spread footings sized for an assumed
allowable bearing pressure of 2,000 psf.
At the time of our visit to the site, the excavation had been cut in one level about 4 feet below the
adjacent ground surface. The soils exposed in the bottom of the excavation consisted of mainly
silty sandy gravel with cobbles except for existing backfill of the basement wall. 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 gravel soil designed for an
allowable soil bearing pressure of 2,000 psf should be adequate for support of the proposed
addition. Footings should be a minimum width of 16 inches for continuous walls and 2 feet for
columns. Loose disturbed soils should be removed in footing areas 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 and to span
the existing basement wall backfill. 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 onsite soil as backfill excluding rock larger than 6 inches. Structural fill placed within
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 10 feet of the building. Landscape that
requires regular heavy irrigation, such as sod, and sprinkler heads should not be located within
5 feet of the foundation.
Abdi Pirzadeh
August 30, 2022
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,
Kumar & As
Steven L. Pavy
SLP/kac
Kumar & Associates, Inc.' Project No. 22-7-602