HomeMy WebLinkAboutObservation of Excavation 12.13.23Kumar & Ass hits, Ilnc.0
'f 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
December 13, 2023
SCIB, LLC
Attn: Luke Gosda
0115 Boomerang Road, Suite 5201 B
Aspen, Colorado 81611
luke. og sda(&sunriseco.com
Project No. 20-7-786.A
Subject: Observation of Excavation, Proposed Residence, Lot 52, Ironbridge Phase I1I,
399 Blue Heron Drive, Garfield County, Colorado
Gentlemen:
As requested, a representative of Kumar & Associates, Inc. observed the excavation at the
subject site on December 13, 2023 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 February 19, 2021, Project No. 20-7-786.
The proposed residence is similar to that described in our previous report and has been designed
to be supported by spread footings sized for an allowable bearing pressure of 1,500 psf with up
to about 6 feet of native silt/clay soil below about 4 feet of compacted structural fill.
At the time of our visit to the site, the foundation excavation had been cut in 2 levels from about
5'/2 to 7 feet below the adjacent ground surface including 4 feet of sub -excavation depth in most
areas. The soils exposed in the bottom of the excavation consisted of stiff sandy silt and clay.
The downhill, north excavation area was about 5'/ feet deep and it was recommended to deepen
the excavation 11/z feet to achieve the maximum silt/clay soil depth of 6 feet below the structural
fill. No free water was encountered in the excavation and the soils were slightly moist.
The soil conditions exposed in the excavation are consistent with those previously encountered
on the site and suitable for support of compacted structural and spread footings designed for the
recommended allowable bearing pressure of 1,500 psf. Loose disturbed soils should be
compacted in footing areas prior to placing structural fill. The soils exposed in bearing areas
should be protected from frost and concrete should not be placed on frozen soils. Other
recommendations presented in our previous report which are applicable should also be observed.
The recommendations submitted in this letter are based on our observation of the soils exposed
within the foundation excavation and the previous 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
SCIB, LLC
December 13, 2023
Page 2
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.
We are tentatively scheduled to perform compaction testing of the structural fill as it is placed in
lifts. In the meantime, if you have any questions or need further assistance, please call our
office.
Sincerely,
Kumar & Associates, Inceg5�_'�p0 RE
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Steven L. Pawlak, P. 6 *..J L��� ,
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Kumar & Associates, Inc. 0 Project No. 20-7.786.A