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Plans "CROSSING AT BULL MOUNTAIN" LOT 86 FOUNDATION CERTIFICATION E 2'. 2`2 — _ _ _ ',:7 =.RFr R: J C y-•, Ntic 7 .,, L: 5, i it 2 ~i -4t��.; Y J_.-ice _._- _ _ _ AND, ,':9 , T ::_Tc / U4Liti, N89'55'53"E 42.00' f [Y: 4 . 4 ,Y. n sr2G�3 --ors ti 5ti2 5,_ A ' N144+ woo sit oo 3a.C, 1 Trd /62 j 01-72z t: 7 CO i 3 2 3 a' CO j L 3 LOT w 6; O U 4d U O P _ Q Q z M 1 e ,Q 4f7 C O C i C v 7 r, M t: REGISTERED to PROFESSIONAL 1 1 1 LAND SURVEYOR I S89.42'03"W 42.00' _yv/y C < OREGON JULY 9. 2002 T TRAVIS C. JANSEN 57751 o RENEWS: 6/30/2025 C4--- 3 - - _ ^ Ors 07 THE SCALE o f FEf cER 20 0 10 20 r-' v F.'.1 1 INCH = 20 FEET `' _ PACIFIC COMMUNITY DESIGN z PLANNING - ENGINEERING - SURVEYING PROJECT %(").: 139 :, ; \ (503) 941-9484 GEOPPCIEIC Real-World Geotechnical Solutions Investigation• Design •Construction Support August 22, 2023 Project No. 19-5287 Ichijo USA Co., LTD Attn: Erik Gomez 1509 SW Sunset Blvd. Suite 2-D Portland, Oregon 97239 Via email to: erik.gomez©ichiiousa.com FOUNDATION SUBGRADE REVIEW LOT 86 RIVER TERRACE CROSSING AKA CROSSING AT BULL MOUNTAIN 15192 SW HUNTWOOD STREET TIGARD, OREGON This letter addresses the single-family home foundation subgrade on Lot 86 of the River Terrace Crossing development, also known as Crossing at Bull Mountain. We understand that the proposed building is a two-story daylight basement home. As part of this evaluation, GeoPacific visited the site on August 4, 2023 to observe the subgrade foundation preparation. At the time of our site visit, the foundation excavation was complete and generally extended approximately 6 to 36 inches below the surrounding grade on the north side and 30 inches below surrounding grade on the south side. There was a cut for the basement level, which was about 4 feet vertical and then at a 1 H:1 V slope for a total vertical relief of about 10 feet. Subgrade generally appeared to consist of gravelly silt engineered fill. The foundation layout of Lot 86 is stepped down to the south and is about 15 feet horizontal from the face of a Lock-n-Load retaining wall. Grades between the rear footing of the home and the Lock+Load retaining wall are relatively level. Footing-to-wall and footing-to-slope setbacks did appear to be adequate. The wall at the step for the basement should be backfilled with granular backfill. The backfill may either consist of 3/4"-0 crushed aggregate compacted in lifts or 1 1/2"-0 crushed angular drain rock. We returned to the site on August 9, to observe that a bench of%"-0 crushed aggregate about 12-18 inches thick had been placed and compacted at the base of the cut in an effort to reduce the height of the basement retaining wall. On that day, the bench did not extend far enough southward to provide adequate support for the wall, so we recommended extending it a few more feet. On August 11, we returned to the site and observed that the bench of%'-0 had been adequately extended and was suitable to support the basement retaining wall. The 3/"-0 had been compacted to a dense, unyielding state. On August 21, Ichijo provided photographs showing that a keyway had been excavated near the toe of the basement retaining wall. The keyway was excavated into the compacted '/"-0 crushed aggregate. Based on the photos, the sides of the keyway were standing well and it appeared that there were no loose soils in the keyway. It appears that the keyway was adequately prepared. Based on observed conditions, foundation subgrades as prepared are considered suitable to support the planned allowable bearing pressure of 1,500 psf. Estimated settlement under the 14835 SW 72nd Avenue Tel(503)598-8445 Portland,Oregon 97224 Fax(503)941-9281 GeoPacific Engineering, Inc.' Job No. 19-5287 Lot 86 River Terrace Crossing 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 '/2-inch of loose soils are present prior to pouring concrete. Construction should include typical measures for controlling subsurface water beneath the homes, including positive crawlspace drainage to an adequate low-point drain exiting the foundation, visqueen covering the exposed ground in the crawlspace, and crawlspace ventilation (foundation vents). The homebuyers should be informed and educated that some slow flowing water in the crawispaces is considered normal and not necessarily detrimental to the home given these other design elements incorporated into its construction. Adequate crawlspace drainage is not something that geotechnical consultants can verify; the purpose of our visit is for observations of foundation bearing conditions only. 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 Ichijo USA, 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. +. 'C � 9vt " �j ‘" v 12 Benjamin G. Anderson, P.E. Associate Engineer