Report Apr, 19. 2012 10: 09AM No 2856 P, 3
CooP fi
Engineering, Inc.
Real-World Geotechnical Solutions
• Investigation
• Design
April 8, 2012 • Construction Support
Project No. 03 - 8449
Stonebridge Homes Job No. 1488
Attention: Andy Thomas
Stonebridge Homes
4230 SW Galewood St., Ste. 100
Lake Oswego, OR 97035
Fax 503 387 - 7615 and 503 - 746 -6214
FOUNDATION EXCAVATION REVIEW
LOT 117 - ARLINGTON HEIGHTS NO.3
12706 SW WILLOW POINT LANE ms-r,l .7 0 - Q0O ,) y
CITY OF TIGARD, OREGON
GeoPacific Engineering Inc. visited the site today to review the single family home foundation layout
on Lot 117. We understand that the proposed building is a two -story home. 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 3 /4 inch, respectively, over a span of 20 feet.
At the time of our first site visit, the front portion of the excavation was benched 1.5 to 2 feet into the
existing gentle fill slope. The rear of the lot was excavated to native soils and exposed some
organics beneath the fill in the rear and middle portion of the lot. It was excavated 2 to 4 feet to get
below poorly compacted fill on the rear and, middle portion of the lot. Once the excavator deepened
the excavation he encountered suitably stiff native soils. These soils are considered adequate to
support the planned foundation loads.
Due to silty clay soils encountered throughout the site, all foundations should incorporate
appropriate drainage measures. Crawispaces 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. 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 Avenue Tel (503) 5984445
Portland, Oregon 97224 Fax (503) 941 -9281
Apr, 19, 2012 10. l OAM GeoPacifi Inc.
Job No. 03 -8449
Lot 117 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 geotechnicai 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 Ens ineering, Inc.
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.. OREGON
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EXPIRES; O8/30i2O
James D. Imbrie, G.E.
Geotechnical Engineer