REVIEWED BLD2023-1271+SI QUALIFICATIONS+10.30.2023_2.41.13_PM+3869680sFa
SFA Design Group., LLC
STRUCTURAL ENCINEERINC
PORTLAND, OR I LIVERMORE, CA . SEATTLE. WA
503.641 -$31 1 1 www.sfadg-com
I:11DYN04911MAI
October 301h, 2023 RECEIVED
City of Mill Edmonds— Building Division Oct 30 2023
ATTN: Building Inspections CITY OFEDMONDS
DEVELOPMENT SERVICES
DEPARTMENT
RE: Special Inspection — Deep Foundation Elements..............RE.VIEW.E�..............
BY
CITY OF EDMONDS
Dear Building Official: `• BUILDING DEPARTMENT;
This letter is meant to summarize the installation and testing of the Safebasements driven push
pier system and describe our qualifications to perform the inspections described below.
Continuous special inspection is required during installation of deep foundation elements per
2018 CBC Section 1704.2.1.
The following is a description of the system and its installation process observed by a special
inspector with SFA Design Group, LLC:
• The pier installation locations are excavated.
• Contractor provides clean straight surfaces and ensures full contact with the back,
vertical plate of the bracket and full contact with bottom of footing to ensure proper
seating of the bracket. Once retrofit bracket is securely seated to the foundation at
proposed pier location the sleeve and lead are inserted through bracket.
• The round steel tubes and retrofit brackets are used to stabilize and/or lift settling
foundations. Installer adds pier extensions as required such that pier penetrates ground
using the weight of the existing structure to apply downward hydraulic pressure on push
pier until minimum depth and pressure on plan notes are met, thus indicating sufficient
load bearing stratum has been encountered.
• Piers are cut to enable attachment of pier cap with threaded rod.
• Special Inspector places an independent and calibrated dial indicator with probe aligned
vertically to retrofit bracket and begins load testing in accordance with ASTM method
D1143 (Quick Method). 20 percent of piers shall be tested to 150 percent of design
load. Load testing creep acceptance criteria shall be no greater than 0.04 inches within.
If movement is observed greater than 0.04 inches within the 10 minute period the load
test shall be held for an additional 50 minutes, the pier is to be deepened and re -tested,
or the pier is to be abandoned and replaced with a new pier. If the load test is to be held
the pier movements shall be measured at 15, 20, 30, 40, 50, and 60 minutes. The creep
versus the logarithm of time shall be plotted. If the creep rate is less than 0.080 inches
between 6 and 60 minutes, the load test shall be considered successful.
• Once testing has been successfully completed, contractor connects all push piers to
individual hydraulic cylinders. Continuous and even downward pressure is applied on
piers simultaneously ensuring even force distribution until desired lift or stabilization is
achieved.
• Finally, nuts at threaded rods are tightened to engage pier cap and lock pier in place.
As described herein, the process of performing a special inspection on driven push piers is very
simple and well within
our experience and capabilities as an inspector to perform. SFA Design
Group has performed
the analysis, design, and special inspections on thousands of foundation
piers in Oregon, Washington,
and California over the past four years. Of the hundreds of
underpinning projects, below are a few of the projects inspected by the listed special inspectors:
Special Inspector:
Frank Keenan
Project Name:
Hernandez Residence Underpinning
Permit No.:
BLDRA23-0832
Address:
5002 S M St., Tacoma WA 98408
Special Inspector:
Frank Keenan
Project Name:
Bennette Residence Underpinning
Permit No.:
23109055 RPB
Address:
13121 5811 Dr. SE, Snohomish, WA 98296
Special Inspector:
Frank Keenan
Project Name:
Korbuszewski Residence Underpinning
Permit No.:
1018949
Address:
13025 Valley Ave. E, Sumner, WA 98390
Special Inspector:
Frank Keenan
Project Name:
Hendix Residence Underpinning
Permit No.:
ADDL23-0259
Address:
46805 284th Ave. SE, Enumclaw, WA 98022
If you have any questions or need further correspondence regarding the above statements
please don't hesitate to call.
Sincerely,
SFA Design Group, Inc.
Jeff Fitch, P. Eng., PE
EXPIRES: 12/24/24