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Report Mar. 8. 2012 3:38PM • No. 2746 P. 1/2 GeOP INC Engineering, Inc. 14835 SW 72 " Avenue Portland, Oregon 97224 Tel (503) 598 -8445 • Fax (503) 941 -9281 March 8, 2012 Project No. 03 -8449 Stonebridge Homes Job No. 1440 Attention: Andy Thomas Stonebridge Homes 4230 SW Galewood St., Ste. 100 Lake Oswego, OR 97035 Fax 503 -387 -7615 and 503 - 746 -6214 FOUNDATION EXCAVATION REVIEW LOT 69 — ARLINGTON HEIGHTS NO.3 - -t - 5340 SW SUMMERVIEW DRIVE CITY OF TIGARD, OREGON J G plc/ 2. —DSO o GeoPacific Engineering Inc. visited the site last week to review the single family home foundation layout on Lot 69. We understand that the proposed building is a two -story home. In our opinion, the observed subgrade is generally adequate for support to an allowable bearing pressure of 1,500 psf. % • 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. At the time of our first site visit, the upper portion of the excavation was benched 2 to 4 feet into the existing 25 percent side slope on the cut lot. We requested about 2 to 3 feet of deepening at the east side of the home to get down to a 2H:1V setback from the face of the rockery retaining wall below the home in order not to surcharge it. Once the excavator deepened the back footing line he encountered suitably stiff native soils. These soils are considered adequate to support the planned foundation loads. Due to silty clay 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. We observed some placement of crushed aggregate to protect the subgrade from wet • weather. If footing bearing soils become saturated or disturbed, any softened soil or slough should be removed and replaced with crushed aggregate or additional concrete. In general, footing excavations should be cleaned such that no more than about % inch of loose soils is present prior to pouring concrete. Mar, 8. 2012 3: 39PNi GeoPacit �iyb P. inc. Job No. 03 -8449 Lot 69 Arlington Heights No. 3 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. g PROP * . t GlNe 09 0O • 1inE, OREGON ' s D.1 EXPIRES:. 06 /30 /20th James D. lmbrie, G.E. Geotechnical Engineer �r � ' ' I •