HomeMy WebLinkAboutObservation of Excavation 12.16.20241(+AKumar & Associates, Inc.®
Geotechnical and Materials Engineers 5020 County Road 154
and Environmental Scientists Glenwood Springs, CO 81601
phone:fax: (970) 945-8454
email: kaglenwoodCcokumamsa.com
An brOw" Owned Company www.kamarusa.com
Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado
December 16, 2024
Lyndsay Jammaron
4909 Highway 82
Glenwood Springs, Colorado 81601
1 i ammaron316 (c� gmail . com
Project No. 22-7-266
Subject: Observation of Excavation, Proposed Deck Addition, 169 Deer Park Court,
Garfield County, Colorado
Dear Lyndsay,
As requested, a representative of Kumar & Associates, Inc. observed the deck pier excavations
at the subject site on December 16, 2024 to evaluate the subsurface materials 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 June 9th, 2022, Project No.
22-7-266. The current observations were performed supplemental to our agreement for
geotechnical engineering services with you dated March 31 ", 2022.
We understand the proposed deck has been designed to be supported on 2' by 2' spread footing
pads bearing on the natural sandstone/siltstone bedrock and sized for an assumed allowable
bearing pressure of 1,500 psf.
At the time of our visit to the site, thirteen 14-inch diameter pier holes had each been drilled to
about 6 to 36 inches below the adjacent ground surface. The four deck supports along the
western side of the proposed deck are planned to be directly doweled into the existing foundation
wall of the residence. The subsurface materials exposed in the pier holes consisted of hard red
sandstone/siltstone bedrock with a steep bedding dip down to the southwest. No free water was
encountered in the pier holes and the subsurface materials were slightly moist.
The three pier holes that were only 6-inches deep should be deepened to at least 12-inches deep,
or a square spread footing pad should be used in place of the pier. The spread footing pad should
be a minimum width of 18 inches with a flat, level bottom.
The bedrock condition exposed in the excavation is consistent with that previously encountered
on the site and suitable for support of spread footings or 14-inch diameter piers designed for an
allowable bearing pressure of 4,500 psf. Any soil or loose and disturbed bedrock materials
should be removed in the footing areas to expose the undisturbed natural bedrock prior to the
placement of concrete. Due to the hard indurated bedrock condition at the site, footings/piers
placed directly on bedrock do not need to bear below frost depth.
Lyndsay Jammaron
December 16, 2024
Page 2
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.
If you have any questions or need further assistance, please call our office.
Sincerely,
Kumar &
Robert L. Duran, P.E. V�17X;L
11t��Reviewed by: 0�
Steven L. Pawlak, P.E.
cc: Garret Jammaron (garretjammaron(&alpinebank.com)
Kumar & Associates, Inc. 0 Project No. 22-7-266