Report (14) I
GeoPacific
Engineering Inc
Real-World Geotechnical Solutions
Investigation• Design•Construction Support
March 18, 2016
Project No. 12-2704
Stonebridge Project No. 1869 2 D 5 �c. 1 vr^ti�4-' ' ®�
1 Stonebridge Homes {/`\ ST i 0 S
4230 SW Galewood St., Ste. 100
Lake Oswego, OR 97035
Fax 503-387-7615
Email Andy(Astonebrldgehomesnw.com; JimDc stonebridgehomesnw.corn;
kristen@dmhholding sco.corn
RE: FOUNDATION SUBGRADE REVIEW
SOUTH VIEW SUBDIVISION LOT 32
12052 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 March 17, 2016 to review the single family home
foundation subgrade on Lot 32. We understand that the proposed building is a two-story home, on
downward sloping lot. In our opinion, the observed subgrade is generally adequate for support to an
allowable bearing pressure of 1,500 psf. The expected maximum anticipated total and differential
footing movements (generally from soil expansion and/or settlement) are 1 inch and % inch,
respectively, over a span of 20 feet.
At the time of our site visit, the excavation was nearly complete. The front half of the excavation
consisted of predominantly stiff engineered fill soils that probed less than 1 to 3 inches with heavy
pressure using a steel "T" bar probe. The back half consisted of hard rock. One small area on the
east side near the middle has heavy seepage and caving soils; this area needs to be removed and
replaced with compacted crushed aggregate. Footing-to-slope setbacks were adequate and
foundation embedment depths appeared adequate. Some structural backfilling will likely be
required.
Due to 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 o
r additional concrete.
14835 SW 72'"'Avenue _� ___---______
Portland,Oregon 97224 Tel (503)598-8445
Fax(503) 941-9281
s
•
Project No. 12-2704
South View Lot 32
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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James D. Imbrie, P.E., G.E.
Geotechnical Engineer
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