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GeoPacilic
Real-World Geotechnical Solutions
Investigation • Design • Construction Support
August 14, 2015 -f3(°['3 2
Project No. 12-2704
Stonebridge Project No. 1864
Stonebridge Homes
4230 SW Galewood St., Ste. 100
Lake Oswego, OR 97035
Fax 503-387-7615
Email Andy(c�stonebridgehomesnw.corn; JimD(a stonebridgehomesnw,corn
RE: FOUNDATION SUBGRADE REVIEW
SOUTH VIEW SUBDIVISION LOT 27
12055 TURNAGAIN DRIVE
TIGARD, OREGON
References: GeoPacific Engineering, Inc., Geotechnical Explorations, Knauss Property
Subdivision, 12035 Southwest Beef Bend Road, Washington County, Oregon, report
dated August 10, 2012
GeoPacific Engineering Inc. visited the site Wednesday to review the single family home foundation
subgrade on Lot 35. We understand that the proposed building is a two-story garage under style
home. In our opinion, the observed subgrade is generally adequate for support to an allowable
bearing pressure of 2,500 psf. The expected maximum anticipated total and differential footing
movements (generally from soil expansion and/or settlement) are less than 1 inch and 3/4 inch,
respectively, over a span of 20 feet.
At the time of our site visit, the excavation was nearly complete. The excavation consisted of
predominantly medium hard, basalt rock and stiff soils at the rear of the home. This stiff soil and
rock is considered adequate to support the planned foundation loads after a compacted leveling
course of crushed aggregate is placed. Footing-to-slope setbacks were adequate and foundation
embedment depths appeared adequate.
Due to rocky and silty soils encountered throughout the site, all foundations should incorporate
appropriate drainage measures. Crawlspaces should be provided with a low-point drain and pass
through pipes should be installed through footings which would otherwise restrict water flow to the
low-point drain. A small seep is evident coming from fractures in the rock.
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.
14835 SW 72nd Avenue Tel (503) 598-8445
Portland, Oregon 97224 Fax (503) 941-9281
Project No. 12-2704
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South View Lot 27
Our work scope pertains to a geotechnical engineer's foundation excavation review only and the
conditions existing and exposed at the time of our site visit. 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. No warranty, express or implied, is made. If you have
any questions, please call.
Sincerely,
GEOPACIFIC ENGINEERING, INC.
PRaFFs
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OREGON
EXPIRES:06/30/20/7
James D. Imbrie, P.E., G.E.
Geotechnical Engineer
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