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Report (49) „, 1A5-1- a o 1 .ZgC w AiirkLi GeoP cific Engineering,Inc. Real-World Geotechnical Solutions Investigation•Design•Construction Support March 2, 2017 Project No. 15-3654 RECFVED Mr. Darrin Krause Westwood Homes, LLC MAR 0 6 2011 12700 NW Cornell Road Portland, Oregon 97221 CITY OF TIGARD PLANNING/ENGINEERING Via email to: darrinawestwoodhomesllc.com Subject: GEOTECHNICAL OBSERVATION OF FOUNDATION EXCAVATION HOGGANS PARK—LOT 7 TIGARD,OREGON Reference: GeoPacific Engineering, Inc., Summary Report of Geotechnical Observation and Testing, dated May 16, 2016. GeoPacific Engineering, Inc. (GeoPacific) performed a geotechnical engineering investigation of the site prior to development. We also conducted on-call testing and construction observation services during site development. This letter addresses the building pad subgrade for Lot 7 of the development. As part of this evaluation, GeoPacific personnel visited the site on March 1, 2017 to observe footing subgrade soils. At the time of our visit, the foundation excavation was complete and extended 12 to 18 inches below the surrounding grade. The foundation bearing soils consisted of native silt soils, which were evaluated with a 34-inch steel soil probe. Probing efforts indicated stiff consistency in the footing subgrade soils. The layout of Lot 7 and the adjacent properties is relatively flat. Wall and slope setbacks were not an issue. Based on observed conditions, the foundation soils are considered suitable for foundation support. Foundation subgrades as prepared are considered suitable to support the planned r allowable bearing pressure of 1,500 psf. Estimated settlement under the allowable bearing pressure is 1 inch total, and '/ inch differential, measured over a horizontal distance of 20 feet. 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. In general, footing excavations should be cleaned such that no more than approximately%inch of loose soils are present prior to pouring concrete. 14835 SW 72”Avenue .__. Tel(503)598-8445 Portland, Oregon 97224 Fax(503)941-9281 Hoggans Park—Lot 7 GeoPacific Project No. 15-3654 Construction should include typical measures for controlling subsurface water beneath the homes, including positive crawispace drainage to an adequate low-point drain exiting the foundation, visqueen covering the exposed ground in the crawlspace, and crawispace ventilation (foundation vents). The homebuyers should be informed and educated that some slow flowing water in the crawlspaces is considered normal and not necessarily detrimental to the home given these other design elements incorporated into its construction. Appropriate design professionals should be consulted regarding crawlspace ventilation, building material selection and mold prevention issues, which are outside GeoPacific's area of expertise. We have prepared this report for Westwood Homes, LLC and it should not be relied upon by third parties without consulting GeoPacific. 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. The conclusions and interpretations presented in this report should not be construed as a warranty of the subsurface conditions. No warranty, expressed or implied, is made. The scope of our work did not include flood hazard evaluations, environmental assessments, the presence or absence of wetlands; or potential hazardous substances in the soil, surface water, or groundwater at this site. We appreciate this opportunity to be of service. Sincerely, GEOPACIFIC ENGINEERING, INC. PROF � �-�,s AC'S ` GIN�F� ct" 14743PE' 117 OREGON (4,23 'I'1�S D.II* EXPIRES:06/30/2012 James D. Imbrie, G.E. Principal Geotechnical Engineer 2 GEOPACIFIC ENGINEERING, INC.