Report (11) 3187i
GeoPific
Engineering.Inc
Real-World Geotechnical Solutions
Investigation • Design•Construction Support
March 2, 2016
Project No. 12-2704
Stonebridge Project No. 1871 S���E S Qz
Stonebridge Homes 57 ' (
4230 SW Galewood St., Ste. 100
Lake Oswego, OR 97035
Fax 503-387-7615
Email Andvastonebridoehomesnw.com; Jim Dastonebridgehomesnw.corn;
kristenc >dmhholdinasco.com
RE: FOUNDATION SUBGRADE REVIEW
SOUTH VIEW SUBDIVISION LOT 34
15181 HARVEY'S VIEW AVENUE
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 today to review the single family home foundation
subgrade on Lot 34. We understand that the proposed building is a two-story garage under style
home. In our opinion, the observed subgrade is generally adequate for support to an allowable
bearing pressure of 2,500 psf. The expected maximum anticipated total and differential footing
movements (generally from soil expansion and/or settlement) are less than 1 inch and % inch,
respectively, over a span of 20 feet.
At the time of our site visit, the excavation was complete. The excavation consisted of
predominantly medium hard, basalt rock. This rock is considered adequate to support the planned
foundation loads. Footing-to-slope setbacks were adequate and foundation embedment depths
appeared adequate. Due to the nature of the hard rock, the stepped walls are not considered to be t
surcharging lower walls, however granular structural fill will be required to support vertical cuts
behind interior retaining walls.
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. Seep may become active 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
i
Project No. 12-2704
South View Lot 34
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:06/3W2012
James D. Imbrie, P.E., G.E.
Geotechnical Engineer
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