HomeMy WebLinkAboutObservation of Excavation1(+AKumar & 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 Co mpony
Office Locations: Denver (HO), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado
July 23, 2025
Pegasus Custom Homes
Attn: Koby Kempel
292 Newberry Street
Boston, Massachusetts 02115
kobykempel(a.vahoo.com
Project No. 25-7-468
Subject: Observation of Excavation, Proposed Residence, 2950 Elk Springs Drive, Lot 40,
Filing 9, Elk Springs, Garfield County, Colorado
Dear Koby:
As requested, a representative of Kumar & Associates observed the excavation at the subject
site on July 23, 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 Pegasus Custom Homes, dated July 11, 2025.
The proposed residence will be a multi -level, wood frame structure over a partial crawlspace/
partial basement level.
At the time of our visit to the site, the foundation excavation had been cut in several levels from 4
to 10 feet below the adjacent ground surface. The soils exposed in the bottom of the excavation
consisted of a slightly clayey, silty sand matrix with gravel to boulder -size basalt rocks. No free
water was encountered in the excavation and the soils were slightly moist. Due to the large rocks,
compacted road base was being placed to create flat footing grade.
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 residence. 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 compacted or removed and the bearing level extended down to
the undisturbed natural soils/rocks. 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 45 pcf for on -
site soil as backfill. A perimeter foundation drain should be provided to prevent temporary buildup
of hydrostatic pressure behind the basement 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 10 feet
of the building.
Pegasus Custom Homes Project No. 25-7-468
July 23, 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,
Kumar & Associates, Inc p0 REG/s
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Daniel E. Hardin, P.E.•• .7 31-7�:o
Rev. by: SLP "*0460(000098••4
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Kumar Kumar & Associates, Inc