Plans (26) "CROSSING AT BUL i 1 MOUNTAIN" 1557 Still
FOUNDATION CERTIFICATION
SE 1/4 SEC. 8. T 2 S, R 7 W, W.M. wood Ave
CITY OF TIGARD. WASHINGTON COUNTY, OREGON
SURVEYED JUNE 26, 2023 MST Z022- 06507
PREPARED FOR:
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TRAVIS C. JANSEN
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o RENEWS:6/30/2025
1 I CERTIFY THAT I HAVE VERIFIED THE LOCATION OF THE SCALE
2 FOUNDATION UPON THE HEREIN DESCRIBED REAL PROPERTY 20 0 10 20
o AND THAT I FOUND THE IMPROVEMENTS AS SHOWN TO BE %MTMIITIMM
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a UPON THE PREMISES AS HEREIN DESCRIBED, AND THEY DO 1 INCH = 20 FEET
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o DRAWN BY: MJL DATE:06/27/23 PACIFIC COMMUNITY DESIGN
REVIEWED BY: T2 DATE:06/27/23 PLANNING ENGINEERING SURVEYING
Z PROJECT NO.: 139-001 (503) 941-9484 __
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GEOPPCIFIC
Real-World Geotechnical Solutions
Investigation • Design •Construction Support
June 30, 2023
Project No. 19-5287
Ichijo USA Co., LTD
Attn: Erik Gomez
1509 SW Sunset Blvd. Suite 2-D
Portland, Oregon 97239
Via email to: erik.gomez(u�ichijousa.com
FOUNDATION SUBGRADE REVIEW
LOT 111 RIVER TERRACE CROSSING AKA CROSSING AT BULL MOUNTAIN
15757 SW VANDERWOOD AVENUE
TIGARD, OREGON
This letter addresses the single-family home foundation subgrade on Lot 111 of the River Terrace
Crossing development, also known as Crossing at Bull Mountain. We understand that the proposed
building is a two-story daylight basement home. As part of this evaluation, GeoPacific visited the site
on June 21, 2023 to observe the subgrade foundation preparation. At the time of our site visit, the
foundation excavation was complete and generally extended approximately 6 to 36 inches below the
surrounding grade on the north side and 30 inches below surrounding grade on the south side.
There was a vertical cut for the basement level, measuring about 8 feet tall at the east side of the
house and 6 feet tall for most of the rest of the width of the house.
Subgrade generally appeared to consist of complicated silt fill. The foundation layout of Lot 111 is
stepped down to the south and is within about 15 feet horizontal to the face of a 7-foot tall Lock-n-
Load retaining wall supporting a short 3H:1V slope above the wall and below the proposed home.
Since the rear footing is embedded down about 30 inches below surrounding grades, footing-to-wall
and footing-to-slope setbacks did appear to be adequate. The wall at the step for the basement
should be backfilled with at least 4 vertical feet of granular backfill. The backfill may either consist of
%"-0 crushed aggregate compacted in lifts or 1 'W-0 crushed angular drain rock.
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 % 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'/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
14835 SW 72nd Avenue Tel (503)598-8445
Portland, Oregon 97224 Fax(503)941-9281
GeoPacific Engineering, Inc.
Job No. 19-5287
Lot 111 River Terrace Crossing
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.
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