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Real-World Geotechnical Solutions
Investigation •Design•Construction Support
March 5, 2015
Project No. 12-2704
Stone Bridge Project No. 1865
Stonebridge Homes
4230 SW Galewood St., Ste. 100
Lake Oswego, OR 97035
Fax 503-387-7615
Email Andv at stonebridgehomesnw.com; JimD(a stonebridgehomesrw.com
RE: FOUNDATION EXCAVATION REVIEW
SOUTH VIEW SUBDIVISION LOT 28
12071 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 on yesterday to review the single family home foundation
layout on Lot 28. 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 3f 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 soft to medium hard basalt bedrock that could be probed less than 1/4 inch with
heavy pressure using a steel •T" bar probe and very stiff soil that proved less than one inch. These
soil and rock conditions are considered adequate to support the planned foundation loads. Footing-
to-slope setbacks were adequate and foundation embedment depths appeared adequate. Some
backfilling of the rear wall below the lowest step will be necessary.
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.
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)5984445
Portland, Oregon 97224 Fax(503)941-9281
• Project No. 12-2704
South View Lot 28
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.
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EXPIRES:06130/2CV.
James D. Imbrie, G.E.
Geotechnical Engineer
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