Report (41) N\S \C —c �� �3 �� Ac\ ems
Geor cihc
Engineering,Inc.
Real-World Geotechnical Solutions
Investigation•Design•Construction Support
August 13, 2019
GeoPacific Project No. 15-4010
Riverside Homes, LLC
17933 NW Evergreen Parkway, Suite 370
Beaverton, OR 97006
Via email to Amo Avgi (aavgi akriversidehome.com)
Subject: GEOTECHNICAL OBSERVATION OF FOUNDATION SUBGRADE
ELDERBERRY RIDGE SUBDIVISION—LOT 12
TIGARD,OREGON
GeoPacific Engineering, Inc. (GeoPacific) conducted on-call density testing and construction
observation services for the Elderberry Ridge Subdivision site. This letter addresses the footing
subgrade conditions for Lot 12. It is our understanding that the planned structure will consist of
a single-family residence utilizing conventional spread footings.
GeoPacific personnel visited the site August 13th, 2019 to observe subgrade soils during the
foundation excavation for Lot 12. The excavation depth was approximately 12 to 48 inches
below the surrounding grade. The foundation bearing soils consisted of engineered fill soils,
which were evaluated with a hand probe. Probing efforts stiff soils. The footing layout of Lot 38
and the adjacent lots is stepped on a 3H:1V slope. Footing-to-slope setbacks were adequate,
however, some structural backfilling in the interior of the foundation is necessary to support the
vertical cuts.
Based on observed conditions, the footing subgrade soils are considered suitable for foundation
support. The foundation subgrade as prepared is considered suitable to support the planned
allowable bearing pressure of 1,500 psf. Estimated settlement under the allowable bearing
pressure is 1 inch total, andY-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 are incorporated into its construction. 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
. Elderberry Ridge- Lot 12
GeoPacific Project No. 15-4010
We have prepared this report for Riverside Homes, 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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EXPIRES:06(30/204
James D. Imbrie, P.E., G.E., C.E.G.
Principal Geotechnical Engineer
2 GEOPACIFIC ENGINEERING, INC.
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FOUNDATION CERTIFICATION
LOT 12 OF "ELDERBERRY RIDGE"
WASHINGTON COUNTY, OREGON
DATE: AUGUST 14, 2019
NS�N LANE L=50.69'
SOil HP R-225.00'
SETBACK REQUIREMENTS:
FRONT: 15 FEET
FRONT GARAGE: 20 FEET
_ _ -------------I SIDE: 5 FEET
REAR: 15 FEET
- '' a' - w
-- - - I_ ad Q
Foy
SCALE 1" = 20 FEET
5.0' GARAGE '� ---5.0'
R , iii-e1W!
LOT 11 4 2 LOT 13
LOT 12
J`' o REGISTERED
PROFESSIONAL
Q LAND SURVEYOR
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SETBACK UNE / Y i
YPICAL OREGON
I T ) JANUARY 15, 200
r CUNTON H. STUBBS JR.
I -20' STORM SEWER 55469LS
o 1 & SANITRAY SEWER RENEWS: 06/30/20
- - _`;'j EASEMENT
--^____ I, CUNTON H. STUBBS ,fit., A REGISTERED
____ _ PROFESSIONAL LAND SURVEYOR IN THE STATE
._________ "--_
OF OREGON, HEREBY CERTIFY THAT I HAVE
ACCURATELY SURVEYED AND MAPPED THE
c,83'3913 W 50.43 FOUNDATION FOR LOT 12 OF "ELDERBERRY
RIDGE", AS STAKED ON AUGUST 14, 2019. THE
_....--__L_______ BOUNDARY LINES DEPICTED k� Yom-
r
____ _---- ESTABLISHED BY HOLDING RECORD INFORMATION
0 '-- - AND MONUMENTATION FROM THE PLAT OF SAID
'TRACT C' SUBDIVISION, THIS CERTIFICATION SHOULD NOT
SERVE AS A BOUNDARY SURVEY.
PREPARED FOR: JOB NAME: ELDERBERRY RIDGE
RIVERSIDEHOMES, JOB NUMBER: 1884 �OR 1 1-IWEST 1815 NW 169th PLACE,
LLC. SUITE 2090
17933 NW EVERGREEN PLACE DRAWING NUMBER: 1884 STAKEDBEAVERTON, OR 97006
SUITE 370 PHONE:503-848-2127
BEAVERTON, OR 97006 DRAWN BY: BJA URVEYING Inc. Ax:503-848-2179
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CHECKED BY: CHS