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GeoP iff
Engineering.Inc
Real-World Geotechnical Solutions
Investigation• Design•Construction Support
February 23, 2016
Project No. 12-2704 t‘572015- 6 61 4
Stonebridge Project No. 1860
Stonebridge Homes
4230 SW Galewood St., Ste. 100
Lake Oswego, OR 97035
Fax 503-387-7615
Email AndvccOi,stonebridgehomesnw.com; JimD(pstonebridgehomesnw.com
RE: FOUNDATION SUBGRADE REVIEW
SOUTH VIEW SUBDIVISION LOT 23
12050 AUTUMNVIEW STREET
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 Wednesday to review the single family home foundation
subgrade on Lot 23. We understand that the proposed building is a two-story daylight basement style
home. In our opinion, the observed subgrade is generally adequate for support to an allowable
bearing pressure of 2,000 psf. The expected maximum anticipated total and differential footing
movements (generally from soil expansion and/or settlement) are less than 1 inch and 3/4 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 very stiff engineered fill soil that could be probed less than 1 inch with heavy pressure
using a steel "T" bar probe. This material is considered adequate to support the planned foundation
loads. Footing-to-slope setbacks were adequate at 5 feet horizontal and foundation embedment
depths appeared adequate.
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. A small seep is evident coming from fractures in the rock.
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)598-8445
Portland,Oregon 97224 Fax(503) 941-9281
+ Project No. 12-2704
South View Lot 23
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:06/30120/j
James D. Imbrie, G.E.
Geotechnical Engineer
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