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Report /r 57-?D 161--6 o a 3 L-1 / O '72/ S LA) <t HA/.444,0 HILL '— r Gee !fie Engineering,Inc. Real-World Geotechnical Solutions Investigation•Design•Construction Support August 5, 2019 Project No. 15-3853 Matt McBride Windwood Construction, Inc. 12655 SW North Dakota Tigard, Oregon 97223 SUBJECT: FOUNDATION SUBGRADE REVIEW LOT 4 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 today to review the single-family home foundation subgrade on Lot 4. 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 stepped excavation was complete on the northwesterly sloping lot, and, after removal of about 2 to 3 feet of soft fill soils in areas, soils exposed in foundation excavation consisted of predominantly stiff, native silt, and compacted fill soils that could be probed about YZ to 3 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 9/e inch, respectively, over a span of 20 feet. Some structural backfilling will be necessary to laterally support vertical cuts. It should also 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 crawispace 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 72nd Avenue Tel(503)598-8445 Portland,Oregon 97224 Fax(503)941-9281 GeoPacific Engineering, Inc. Job No. 15-3853 Lot 4 Annand Hill Sincerely, GeoPacific Engineering,Inc. •0 I'RO v,,, �" ()HE =t ))Ni M' 1 � 1/k: