Report Jun, 24. 2011 $,27AM No. 1897 P. 1
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�x Engineering, Inc.
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\_ 13910 SW Galbreath Drive
Sherwood, Oregon 97140
Tel (603) 62544455 • Fax (503) 6254406
June 24, 2011 •
Project No. 03 -8449
Attention: Blake Agate
Stonebridge Homes
4230 SW Galewood St., Ste. 100
Lake Oswego, OR 97035
Fax 503-387-7615
FOUNDATION EXCAVATION REVIEW " 94 1
LOT 76 — ARLINGTON HEIGHTS NO.3
CITY OF TIGARD, OREGON
GeoPacific Engineering Inc. visited the site today- to review the single family home foundation layout .
} on Lot 76. We understand that the proposed' building is a two -story home. (n' 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 inch, respectively, over a span of 20 feet.
At the time of our first site visit, the excavation was 2 to 4 feet bench intO:;,the 3H:1 V fill slope. We
requested about 6 to 7 feet of deepening at the back of the home to ge =down to a 2H:.1V setback
from the face of the soil filled Lock -n-Load retaining wall below the home in order not to surcharge it.
Once the excavator deepened the back footing line he encountered straw and soft topsoil and had to
remove an additional 3 feet. This was replaced with compacted reject rock that was hand probed
upon a return visite. After our second site visit, soils exposed in the bottom of the foundation
excavation consisted of predominantly very stiff silt fill with some rock and compacted reject rock.
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. Crawlapaces 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'/ inch of loose soils is present prior to
pouring concrete.
Jun, 24. ,2011 8:27AM GeoPacift Inc.
Job No. 03 -8449
Lot 76 Arlington Heights No. 3 -F 2
o"Z °
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 En neering, Inc.
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• EXPIRES: 06/30/200
James D. Imbrie, G.E.
Geotechnical Engineer