HomeMy WebLinkAboutObservation of Excavation 02.15.2023Kumar & Associates, Inc.0
'( 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
February 15, 2023
Cleary Building
Attn: Tyler Mize
715 Highway 50
Delta, Colorado 81416
tmize(&,cleMbuilding com
Project No. 23-7-146
Subject: Observation of Excavation, Proposed Detached Garage, 159 River Boat Drive,
New Castle, Colorado
Gentlemen:
As requested, a representative of Kumar & Associates observed the excavation at the subject site
on February 14, 2023 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 Cleary Building dated February 9, 2023.
We understand the proposed detached garage is designed to be founded on 14 footing pads sized
for an assumed allowable soil bearing pressure of 1,500 psf.
At the time of our visit to the site, the foundation footing pad excavations had been cut from 4 to
4'/2 feet below the adjacent ground surface. The soils exposed in the bottom of the excavation
consisted of silty sandy clay. About 3 inches of free water was encountered in one of the pad
excavations and the soils were moist to wet.
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 1,500 psf can be used for support of the proposed detached garage. The
exposed soils tend to compress settlement of the foundation if the bearing soils become wet.
Footings should be a minimum width of 14 inches for columns. Loose and disturbed soils in
footing areas should be removed and the bearing level extended down to the undisturbed natural
soils. The bearing soils should be protected against frost and concrete should not be placed on
frozen soils. Exterior footings should be provided with adequate soil cover above their bearing
elevations for frost protection. 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. Landscape that requires regular heavy
irrigation, such as sod, and sprinkler heads should not be located within 5 feet of the foundation.
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
Cleary Building
February 15, 2023
Page 2
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,
Robert L. Duran,
Reviewed by:
Daniel E. Hardin, P.E.
RLD/kac
Kumar & Associates, Inc. ` Project No. 23-7-146