HomeMy WebLinkAboutObservation of excavation 04.21.2022lac.
1(+A Kuniar & Amelates,sEn®
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
April 21, 2022
SCIB, LLC
Attn: Luke Gosda
0115 Boomerang Road, Suite 5201 B
Aspen, Colorado 81611
like. i!osdana.sunriseco.com
Project No. 21-7-685
Subject: Observation of Excavation, Proposed Residence, Lot 21, Ironbridge Phase III,
1796 River Bend Way, Garfield County, Colorado
Gentlemen:
As requested, the undersigned representative of Kumar & Associates, Inc. observed the
excavation at the subject site on April 21, 2022 to evaluate the soils exposed for foundation
support. The findings of our observations and recommendations for the foundation design are
presented in this report. We previously conducted a subsoil study for design of foundations at
the site and presented our findings in a report dated October 6, 2021, Project No. 21-7-685.
The residence is proposed in the lower part of the lot near Boring 2 of our previous subsoil study.
Spread footings placed on dense gravel or structural fill and sized for an allowable bearing
pressure of 2,500 psf were designed for the foundation support as recommended in our previous
report.
At the time of our visit to the site, the foundation excavation had been cut in one level up to
about one foot below the adjacent ground surface. The eastern garage area existing grade is
slightly below design footing bearing level. The soils exposed in the bottom of the excavation
consisted of sandy silty clay. Two pits were dug down to the dense gravel, 4 feet deep in the
middle residence area and 3 feet deep just east of the garage area. The clay soil was slightly
moist in the residence area and very moist in the garage area where surface water appears to
pond.
The soil conditions exposed in the excavation and two pits are consistent with those previously
encountered on the site but due to the proposed building location do not consist of the assumed
dense bearing soils. Based on the clay subsoils, we recommend the foundation be redesigned as
spread footings sized for an allowable bearing pressure of 1,500 psf. Due to the highly moist
soils in the eastern area, we recommend the east wall footing of the garage be placed on
structural fill supported by the dense gravel. Foundation settlements are estimated to be up to
around 1 inch. Alternately, the footings can be supported on the natural dense gravel or
structural fill supported by the dense gravel with the current design allowable bearing pressure
of 2,500 psf. Other recommendations presented in our previous report which are applicable
should also be observed.
SCIB, LLC
April 21, 2022
Page 2
The recommendations submitted in this letter are based on our observation of the soils exposed
within the foundation excavation and the previous limited subsurface exploration at the site.
Variations in the subsurface conditions below the excavation could increase the risk of
foundation movement. We should be advised of any variations encountered in the excavation
conditions for possible changes to 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.
•J
Steven L. Pawlak,
SLP/kac
cc: David Ockers
Kumar & Associates, Inc. '� Project No. 21-7-685