HomeMy WebLinkAboutObservation of Excavation 09.06.2023
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
September 6, 2023
Daybreak Construction
Attn: Dana Yerian
P.O. Box 582
Glenwood Springs, CO 81602
daybreakconst@hotmail.com
Project No. 23-7-507
Subject: Observation of Excavation, Proposed Pole Barn, 700 Northridge Road, Garfield
County, Colorado
Dear Dana:
As requested, a representative of Kumar & Associates observed the excavation at the subject site
on August 28, 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 Daybreak Construction dated August 25, 2023.
The pole barn will be a single story wood-frame structure. The barn has been designed to be
supported on a monolithic slab-on-grade foundation with turned down edges sized assuming an
allowable soil bearing pressure of 2,000 psf by the structural engineer.
At the time of our site visit, the foundation excavation had been cut in one level about 2 feet
below the adjacent ground surface. The soils exposed in the bottom of the excavation consisted
of relatively dense, silty sandy gravel. The results of a gradation analysis performed on a sample
of the soils (minus 3-inch fraction) obtained from the site are presented on Figure 1. No free
water was encountered in the excavation and the soils were slightly moist.
Considering the conditions exposed in the excavation and the nature of the proposed
construction, a monolithic slab with thickened edges foundation placed on the undisturbed
natural granular soils designed for an allowable soil bearing pressure of 2,000 psf should be
adequate for support of the proposed pole barn. Thickened slab sections should be a minimum
width of 18 inches. Loose disturbed soils in footing areas should be removed and the bearing
level extended down to the undisturbed natural granular soils and the subgrade moistened and
compacted. Exterior footings should be provided with adequate soil cover above their bearing
elevations for frost protection. It should be feasible to provide reduced frost cover provided
some risk of frost heave. The monolithic slab should be well reinforced. Foundation walls
acting as retaining structures (if any) should also be designed to resist a lateral earth pressure
based on an equivalent fluid unit weight of at least 50 pcf for on-site soil as backfill. A perimeter
foundation drain should not be required for the proposed “slab-at-grade” construction. Structural
fill placed within floor slab areas can consist of the on-site granular soils compacted to at least
95% of standard Proctor density (SPD) at a moisture content near optimum. Backfill placed
Kumar & Associates