Report Oct. 28. 2012 12:40PM No. 33.46 P. 1
Geo , cdic
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Real World Geotechnical Solutions
• Investigation
• Design
• Construction Support
October 28, 2012
Project No. 03 -8449
Stonebridge Homes Job No. 1455
Attention: Andy Thomas
Stonebridge Homes
4230 SW Galewood St., Ste. 100
Lake Oswego, OR 97035
Fax 503 -387 -7615
FOUNDATION SUBGRADE REVIEW
LOT 84 — ARLINGTON HEIGHTS NO.3
15306 SW OAKMONT PLACE S T gc7I —
CITY OF TIGARD, OREGON
GeoPacific Engineering Inc. visited the site several times this last week to review the single family
home foundation subgrade on Lot 84. 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 and exposed compact rocky clayey
silt fill at the front half of the home and native soil and rock at the rear of the home. Approximately
30 inches of STB structural fill was placed at the rear of the home. These soils are considered
adequate to support the planned foundation loads. Footing to wall setbacks appeared adequate at
approximately 2H:1V from the base of the bedrock at the back of the wall.
Due to relatively impervious clayey silt soils encountered throughout the site, all foundations should
incorporate appropriate drainage measures in accordance with the International Residential Code.
Adequate crawlspace drainage is not something that geotechnical consultants can verify; the
purpose of our visit is for observations of foundation bearing conditions only.
Care should be taken to avoid saturation or disturbance of footing subgrade soils during and after
excavation. We observed some placement of crushed aggregate to protect the subgrade from wet
weather. 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 about 1 /2 inch of loose soils is present prior to
pouring concrete.
14835 SW 72"4 Avenue Tel (503) 598 -8445
Portland, Oregon 97224 FaX (503) 941 -9281
O c t • 2 8 . 2012 12 : 4 Q r' M GeoPacif engi Inc.
0 V Job No. 03 -8449
Lot 84 Arlington Heights No. 3
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.
147 �
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EXPIRES:06/30/201i
James D. Imbrie, G.E.
Geotechnical Engineer
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