Report (19) GEHPf#CIFIC
Real-World Geotechnical Solutions
Investigation • Design • Construction Support
October 24, 2023
Project No. 22-6162
Ichijo USA Co., LTD
Attn: Erik Gomez r✓l 5 "r
1509 SW Sunset Blvd. Suite 2-D
Portland, Oregon 97239 9171 S f M jsSQi/k(
Via email to: erik.gomez@ichijousa.com l
FOUNDATION SUBGRADE REVIEW
LOT 149 RIVER TERRACE CROSSING AKA CROSSING AT BULL MOUNTAIN
TIGARD, OREGON
This letter addresses the single-family home foundation subgrade on Lot 149 of the River Terrace
Crossing development, also known as Crossing at Bull Mountain. We understand that the proposed
building is a two-story home with a crawlspace. As part of this evaluation, GeoPacific visited the site
on October 17, 2023 to observe the subgrade foundation preparation. At the time of our site visit,
the foundation excavation was complete and generally extended approximately 12 to 18 inches
below the surrounding grades.
Subgrade generally appeared to consist of medium stiff to stiff, gravelly silt engineered fill. The
foundation layout of Lot 149 is gently sloping down to the front of the house, with a deeper footing
excavation at the front right corner. Footing-to-wall and footing-to-slope setbacks appeared to be
adequate. Based on observed conditions, foundation subgrades as prepared are considered
suitable to support the planned allowable bearing pressure of 1,500 psf. Estimated settlement under
the allowable bearing pressure is 1-inch total, and 3/4 inch differential, measured over a horizontal
distance of 20 feet.
Care should be taken to avoid saturation or disturbance of footing subgrade soils during and after
excavation. If footing bearing soils become saturated or disturbed, any softened soil or slough
should be removed and replaced with crushed aggregate or additional concrete. In general, footing
excavations should be cleaned such that no more than approximately 1/2-inch of loose soils are
present prior to pouring concrete.
Construction should include typical measures for controlling subsurface water beneath the homes,
including positive crawlspace drainage to an adequate low-point drain exiting the foundation,
visqueen covering the exposed ground in the crawlspace, and crawlspace ventilation (foundation
vents). The homebuyers should be informed and educated that some slow flowing water in the
crawlspaces is considered normal and not necessarily detrimental to the home given these other
design elements incorporated into its construction. Adequate crawlspace drainage is not something
that geotechnical consultants can verify; the purpose of our visit is for observations of foundation
bearing conditions only. Appropriate design professionals should be consulted regarding
crawlspace ventilation, building material selection and mold prevention issues, which are outside
GeoPacific's area of expertise.
14835 SW 72nd Avenue Tel (503)598-8445
Portland,Oregon 97224 Fax(503)941-9281
GeoPacific Engineering, Inc.
Job No.22-6162
Lot 149 River Terrace Crossing
We have prepared this report for Ichijo USA, and it should not be relied upon by third parties without
consulting GeoPacific. Within the limitations of scope, schedule and budget, GeoPacific attempted
to execute these services in accordance with generally accepted professional principles and
practices in the fields of geotechnical engineering and engineering geology at the time the report
was prepared. The conclusions and interpretations presented in this report should not be construed
as a warranty of the subsurface conditions.
No warranty, expressed or implied, is made. The scope of our work did not include flood hazard
evaluations, environmental assessments, the presence or absence of wetlands; or potential
hazardous substances in the soil, surface water, or groundwater at this site.
We appreciate this opportunity to be of service.
Sincerely,
GEOPACIFIC ENGINEERING, INC.
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Benjamin G. Anderson, P.E.
Associate Engineer