HomeMy WebLinkAboutObservation of Excavation Report 02.21.2013HEPWORTH - PAWLAK GEOTECHNICAL
February 21, 2013
ECOS
Attn: Caleb Edelman
6690 Highway 82
Glenwood Springs, Colorado 81601
(cedelmaii@eco seavironme nta i . com)
Hepworth-P:Rvlak C;eracchnical, Inc.
5020 CI111nty Road 154
(_iknwOrai Springs, Cpl+lradt) 81601
Phone: 970-945-7%8
Fax: 970-945-8454
email h1t(4, Uhl- e.,rech.crn
Job No. 111 008A
Subject: Observation of Foundation Excavation, Retaining Wall and Storage
Garage Corrumercial Building, 6690 Highway 82, Glenwood Springs,
Colorado
Dear Caleb:
As requested, a representative of Hepworth-Pawlak Geotechnical, Inc. observed the
excavation at the subject site on February 21, 2013, to evaluate the soils exposed for
foundation support. The findings of our observations and recornrnendations for the
foundation design are presented in this report. We previously conducted a subsoil study
for design of foundations for retaining walls at the site and presented our findings in a
report dated January 27, 2011, Job No. 111008A. Evaluation of potential geologic hazard
impacts to the subject site was not included in our previous study and is beyond the scope
of this foundation excavation observation report.
Based on the project plans by Kurtz and Associates, the proposed retaining walls will
provide structural support for the two story storage garage and office building on the
south, east and north sides with isolated pad footings for interior support and an open
"walkout" west side. The foundations have been designed for a maximum allowable
bearing pressure of 2,500 psf as recommended for retaining walls in our previous report.
At the time of our visit to the site, the foundation excavation had been cut in one level
from 1 i to 2 feet below the adjacent interior ground surface and up to about 15 feet deep
at the uphill, east side. The soils exposed in the bottom of the excavation consisted of.
silty sandy gravel with cobbles. Boulders were visible in the cut face east of the retaining
wall foundation and several large boulders had been removed from the building area.
Soil in the bottom of the foundation excavation was firm when probed with a hand probe,
slightly moist to moist and no free water was encountered in the excavation.
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 2500 psf. Loose and disturbed soils should
be removed in the footing areas to expose the undisturbed natural soils. The soils are
compressible when wetted and foundation settlement of at least a few inches could occur
Parker 303-841-7119 0 Colorado Springs 719-613.3-5562 0 Silver borne 970-468-1989
ECOS
February 21, 2013
Page 2
depending on the depth of wetting. The bearing soils should be protected from frost and
concrete should not be placed on frozen soils. A perimeter foundation drain should be
properly installed and site a ading should be performed to achieve positive drainage away
from the foundation walls. Keeping the foundation hearing soils dry will be critical to
prevent excessive foundation settlement. 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 limited subsurface exploration
at the site. Variations in the subsurface conditions below the excavation could increase
the risk of foundation movement. We should be advises 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,
I IEPwOI TH - PAWLAK GEOTECHNICAL, INC.
. a lem/41°-
James ,4. Parker, P.E., P.G.
I
Reviewed by: Steven L. Pawlak, P.E.
cc: Kurtz and Associates - Attn: Brian Kurtz. (kurtzengineer cr yahoo.com)
Job No. 111 008A
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