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Engineering,Inc.
Real-World Geotechnical Solutions
Investigation • Design •Construction Support
June 6, 2019
Project No. 15-3853
Matt McBride
Windwood Construction, Inc.
12655 SW North Dakota
Tigard, Oregon 97223
SUBJECT: FOUNDATION SUBGRADE REVIEW
LOT 16 ANNAND HILL SUBDIVISION
TIGARD, OREGON
Reference: 1. GeoPacific Engineering, Inc., Geotechnical Engineering Report, Annand Hill Subdivision,
SW 109th Avenue, Tax Lots 2S110AC00200 and 2S110AD0880, Washington County, Tigard,
Oregon, dated July 30, 2015,
2. GeoPacific Engineering, Inc., Summary Report Of Geotechnical Observation and Testing,
Annand Hill Subdivision, Tigard, Oregon, dated June 26, 2017.
GeoPacific Engineering Inc. visited the site yesterday to review the single-family home foundation
subgrade on Lot 16. We understand that the proposed building is a two-story home, In our opinion,
the observed subgrade is adequate for support to an allowable bearing pressure of 1,500 psf.
At the time of our site visit, the excavation was complete and soils exposed in foundation excavation
consisted of predominantly stiff compacted fill soils in the front half and stiff, native soils in the rear
half that could be probed about 1 to 2 inches with moderate pressure using a steel "T" bar probe.
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. It should
be noted that the on-site soils are very moisture sensitive and will soften significantly in wet weather
conditions if not adequately protected. Footing-to-slope setbacks are adequate, but some structural
backfilling may be necessary to support vertical cuts.
Due to relatively impervious silty and clayey 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.
Outwork scope pertains- oa_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.
14835 SW 72nd Avenue Tel(503)598-8445
Portland, Oregon 97224 Fax(503)941-9281
4 GeoPacific Engineering, Inc.
Job No. 15-3853
Lot 16 Annand Hill
Sincerely,
GeoPacific Engineering, inc.
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EXPIRES:06/30/201
James D. lmbrie, G.E.
Geotechnical Engineer
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