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Report a-0 / L OCII S t S t- GooP 4Me Engineering.Inc Real-World Geotechnical Solutions Investigation• Design • Construction Support February 5, 2016 Project No. 15-3723 Mike Loomis Lennar Northwest, Inc. 11807 NE 99th Street, Ste. 1170 Vancouver, WA 98682 Phone: (360) 258-7900 Via email with hard copies mailed: (chuck.mcallister@lennar.com) SUBJECT: FOUNDATION SUBGRADE OBSERVATION FOR LOT 8 OAK STREET ESTATES SUBDIVISION TIGARD, OREGON Reference: GeoPacific Engineering, Inc., Summary Report of Geotechnical Observation and Testing, Oak Street Estates, Tigard, Oregon, October 21, 2015, Job No. 13-3175. GeoPacific Engineering Inc. visited the site on February 3rd to review the single family home foundation subgrade on Lot 8. We understand that the proposed building is a two-story daylight basement home, on a downward sloping lot to the west and north. In our opinion, the observed subgrade is generally adequate for support to an allowable bearing pressure of 1,500 psf. After concrete placement some structural backfilling is likely to be required. 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. At the time of our site visit, the excavation was nearly complete. The excavation consisted of predominantly stiff engineered fill soils at the front and stiff native soils on the lower portion that probed less than 1 to 12 inches with heavy pressure using a steel "T" bar probe. These soils are considered adequate to support the planned foundation loads. Footing-to-slope setbacks were adequate and foundation embedment depths appeared adequate. Due to 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. 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 Oak Street Estates Lot 8 GeoPacific Project No. 15-3723 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. '\`(-"°PRopess� Cr a7E/1 ►' OREGON -1'/ES0.10 EXPIRES:06/30120/7 James D. Imbrie, P.E., G.E. Geotechnical Engineer 2 GEOPACIFIC ENGINEERING, INC.