HomeMy WebLinkAboutObservation of Excavation 03.06.2023
5020 County Road 154
Glenwood Springs, CO 81601
phone: (970) 945-7988
fax: (970) 945-8454
email: kaglenwood@kumarusa.com
www.kumarusa.com Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado
March 6, 2023
Ulf Builders
Attn: Eric Bontrager
P. O. Box 509
Edwards, Colorado 81632
eric@ulfbuilt.com
Project No. 23-7-103
Subject: Observation of Excavation and Helical Pier Installation, Proposed Addition to
Stann Ranch Residence, 5097 Sweetwater Road, Garfield County, Colorado
Dear Eric:
As requested, a representative of Kumar & Associates observed the excavation at the subject site
on January 9, 2023 to evaluate the soils exposed for foundation support. We also observed
helical pier installation on January 26 and February 10, 2023 to evaluate the piers also for
foundation support. The findings of our observations and recommendations are presented in this
report. The services were performed in general accordance with our agreement for professional
engineering services to Ulf Built dated January 3, 2023.
The addition will be an enclosure and “bump out” of the porch area of the residence for a single
story of wood frame construction over crawlspace. The addition was originally designed to be
supported on spread footings sized assuming an allowable soil bearing pressure of 3,000 psf by
the structural engineer. Subsequently, due to fill being encountered at the footing excavation
subgrade, two helical piers with downward allowable working capacities of 5 kips each were
designed by the structural engineer to support the addition.
At the time of our January 9 site visit, the foundation excavation for the addition had been cut to
design footing bearing elevation at one level about 4 feet below the adjacent ground surface.
The soils exposed in the bottom of the excavation consisted of silty clayey sandy gravel with
cobble and topsoil fill. The results of a gradation analysis performed on a sample of the fill
(minus 5-inch fraction) obtained from the site are presented on Figure 1. No free water was
encountered in the excavation and the soils were moist and frozen.
We observed the installation of the two helical piers on January 26 and February 10 for support
of the addition. The piers were 1½ inch square bars with a single helix and were installed at the
approximate locations requested by KRM Consultants on their plans for the project. The piers
were installed to torque refusal with 2 shear pins each (= 5 kips per pin) at depths of 12½ and
14½ feet. The piers have ultimate capacities of 10 kips to support the design 5 kip loading with
adequate factor of safety. There could be some differential settlement of the addition with
respect to the existing building which should be considered in the design.
Kumar & Associates