HomeMy WebLinkAboutObservation of Excavation 09.21.20211(+A 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.kumarasa.com
Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado
September 21, 2021
Janice James & Sherman Muller
c/o Mata Design Co.
Attn: Martin Mata
P.O. Box 189
Carbondale, Colorado 81623
matadesign@.mac.co
Project No. 21-7-234
Subject: Observation of Excavation, Proposed Residence, Lot 24, Stirling Ranch, Clipper
Place, Garfield County, Colorado
Dear Martin:
As requested, a representative of Kumar & Associates, Inc. observed the excavation at the
subject site on September 20, 2021 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 April 30, 2021, Project No. 21-7-234.
Structural plans for the project were not provided prior to this letter. We understand the project
will consist of a one-story wood -frame structure over a lower walkout level with an attached
garage at the lower level. Footings placed on the natural soils and sized for the recommended
allowable bearing pressure of 2,000 psf were designed for the building support.
At the time of our visit to the site, the foundation excavation for the residence had been cut in
four levels from about 3 to 9 feet below the adjacent ground surface. The soils exposed in the
bottom of the excavation consisted of firm, moderately to highly calcareous, sandy silt. Results
of swell -consolidation testing performed on samples taken during our April 2021 study indicate
the soils have low compressibility under existing moisture conditions and light loading and
minor expansion or settlement potential when wetted under a constant light surcharge. 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 spread footings designed for the recommended allowable
bearing pressure of 2,000 psf with the risk of settlement mainly if the bearing soils are wetted.
Loose disturbed soils should be moistened and well compacted or removed in the footing areas
to expose the undisturbed natural soils. Other recommendations presented in our previous report
which are applicable, especially those to keep the bearing soils dry, 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 limited subsurface exploration at the site.
Janice James & Sherman Muller
c/o Mata Design Co.
September 21, 2021
Page 2
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.
Mark Gayeski, E.I.T.
Reviewed by:
Steven L. Pa`
SLP/kac
Kumar & Associates, Inc. Project No. 21.7-234