Report (34) rn57ao/7 - vv YS-6
CeoPaciffc
Engineering,Inc.
Real-World Geotechnical Solutions
Investigation•Design•Construction Support
April 23,2018
Project No. 15-3853
Matt McBride
Windwood Construction, Inc.
12655 SW North Dakota
Tigard, Oregon 97223
SUBJECT: FOUNDATION SUBGRADE REVIEW
LOT 10 ANNAND HILL SUBDIVISION
TIGARD, OREGON
Reference: 1. GeoPacific Engineering, inc.,Geotechnical Engineering Report,Annand Hill Subdivision,
SW 109"Avenue,Tax Lots 28110AC00200 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 last week to review the single family home foundation
subgrade on Lot 10. We understand that the proposed building is a single-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 that could be probed about 1/2 inch 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 $/.
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.
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.
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.
14835 SW 72"d Avenue
Portland,Oregon 97224 Tel(503)598-8445
Fax(503)941-9281
GeoPacific Engineering, Inc.
Job No. 15-3853
Lot 10 Annand Hill
Sincerely,
GeoPacific Engineering,Inc.
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James D. Imbrie,G.E.
Geotechnical Engineer