HomeMy WebLinkAboutEngineer's Observation Letter 03.21.23K+AGeotechnipl 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.kumarasa.com
Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Sumrnit County, Colorado
March 21, 2023
Joe O'Malley
45705 Highway 6
Glenwood Springs, Colorado 81601
joe iisoundstructural.com
Project No. 22-7-56LA
Subject: Review of Foundation Underpinning, Existing Residence, 45705 Highway 6,
near Canyon Creek, Garfield County, Colorado
Dear Joe:
As requested by Great Divide Construction, we have reviewed the micro -pile installation for
underpinning of the residence at the subject site. Our comments and recommendations are
presented in this report. The services are supplemental to our agreement for professional
services to you dated September 16, 2022.
Kumar & Associates previously performed a subsoil study for design of the foundation
underpinning at the site and presented our findings in a report dated August 10, 2022, Project
No. 22-7-561. Nine micro -piles with allowable (working) capacities of 3.3 to 11.5 kips each
have been designed to underpin the foundation on the west side of the building. The
underpinning loading design was done by Sound Structural in plans dated October 24, 2022.
The piles were installed in early December, 2022 by Great Divide Construction. We did not
observe the pile installation but have been provided installation records of the install and the lift
measurements on the west foundation wall achieved from the underpinning by Great Divide.
The piles were 3%2-inch diameter with 1 r/-inch bars installed to depths of typically 5 to 5rh feet
below existing footing grade and apparently refusing in boulders and/or large cobbles. Pile
No. 5, 10-kip design capacity, was installed to 41/2 feet length and a second adjacent pile (Pile
No. 10) was later added and installed to 5r/2 feet length. The piles were subsequently grouted
with a neat cement mix batched on site.
We understand the foundation on the west side of the residence was lifted from %2 to 13/ inches
with considerable loading on the piles to achieve the lift. We also understand that recent level
measurements made on the structure indicate minor settlement after the foundation was lifted.
We believe the piles were installed to achieve the design working capacities with adequate factor
of safety. The structure should continue be monitored on a regular basis for excessive
foundation settlement. If excessive settlement were to occur, we should be contacted to review
the conditions, and additional foundation underpinning may be needed.
This study has been conducted in accordance with generally accepted geotechnical engineering
principles and practices in this area at this time. We make no warranty either express or implied.
Joe O'Malley
March 21, 2023
Page 2
The recommendations submitted in this letter are based on information provided to us, the
previous subsoil information from our borings, and our experience in the area. Variations in the
subsurface conditions below the site from those encountered in our borings could increase the
risk of foundation movement.
If you have any questions or need further assistance, please call our office.
Sincerely,
Kumar & Associoes,.
0
David A. Young, P.E. z of
•,, Z��,•
DAY/kac 0,�/ •••••NG���
�IUAL E
cc: Great Divide Const omas Weber ( rdivideconst(a�gmail.com)
Kumar & Associates, Inc. Project No. 22-7-561.A