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NELSON GEOTECHNICAL
N 19 A AsSOCIATES, INC.
GA GEOTECHNICAL ENGINEERS & GEOLOGISTS
Main Office
17311 — 135" Ave NE, A-500
Woodinville, WA 98072
(425) 486-1669 - FAX (425) 481-25 10
August 16, 2018
Mr. Jeff Sterling and Mrs. Lisa Sterling
9504 Edmonds Way
Edmonds, Washington 98020
Geotechnical Final Summary Letter
Cascadian Apartments Foundation Stabilization
9504 Edmonds Way
Edmonds, Washington
NGA File No. 98791317
Engineering -Geology Branch
5526 Industry Lane, 42
East Wenatchee, WA 98802
(509) 665-7696 - FAX (509) 665-7692
Dear Mr. and Mrs. Sterling:
This letter summarizes our geotechnical construction monitoring services for the foundation stabilization
activities at the Cascadian Apartments project located at 9504 Edmonds Way in Edmonds, Washington.
Introduction
The project consisted of the installation of underpinning supports for the central building foundations
consisting of pin piles, slab -on -grade replacement, and exterior foundation footing drain installation.
We previously prepared a geotechnical engineering evaluation for this site dated May 25, 2017, along
with supplemental memos dated December 12, 2017, January 16, 2018, and April 27, 2018.
Site Observations
We monitored pin pile installation activities on a part-time basis from December 20, 2017 through July
20, 2018. Our observations during the foundation stabilization at this project were documented in Field
Reports I through 20, which have been submitted to you and the City of Edmonds.
We observed the installation of approximately 117, 2-inch diameter schedule 80 piles that were driven
with a 140-pound air hammer to a total embedment depth in the approximate range of 7.2 feet to 15.8 feet
below the existing ground surface. All of the piles were driven to the recommended refusal rate of less
than I -inch of movement during 60 seconds of driving using a 140-lb jackhammer. Some of the piles did
encounter obstructions at relatively shallow depths. These pile were then shifted slightly and re -driven to
Geotecbnical Final Summary Letter
Cascadian Apartments Foundation Stabilization
Edmonds, Washington
NGA File No. 9879B 17
August 16, 2018
Page 3
We appreciate the opportunity to be of service to you on this project. Please contact us if you have any
questions regarding this letter or require further information.
Sincerely,
NELSON GEOTECHNICAL ASSOCIATES, INC.
Lee S. Bellah, LG
Project Geologist
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Khaled M. Shawish, PE
Principal
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NELSON GEOTECHNICAL ASSOCIATES, INC.