Report (2) GEOPACIFIC
Real-World Geotechnical Solutions
Investigation • Design • Construction Support
September 29, 2023
Project No. 20-5615
Lennar NW Inc.
11807 NE 99th Street, Ste. 1170
Vancouver, WA 98682
Email: iose.calixtolara.(a�lennar.com
FOUNDATION SUBGRADE REVIEW
LOTS 4 AND 5 SKYLINER CROSSING
12167 AND 12135 SW WINTERVIEW DRIVE
TIGARD, OREGON
This letter addresses the single-family home foundation subgrades on Lots 4 and 5. We understand
that the proposed buildings are a two-story homes. As part of this evaluation, GeoPacific visited the
today to observe the subgrade foundation preparation. At the time of our site visit, the foundation
excavation was complete and extended and estimated 6 to 12 inches below existing ground surface.
The foundation bearing soils generally consisted of medium stiff, moist lean clay shallow native soils
and some compacted fill. Probing efforts with a '/2-inch soil probe resulted in less than 4 to 6 inches
of penetration into the subgrade soils, indicating medium stiff consistency. The layout of the lots is
generally nearly flat.
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
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 1/2-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
crawlspaces 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.
14835 SW 72nd Avenue Tel(503)598-8445
Portland,Oregon 97224 Fax(503)941-9281
GE®PACIFIC
Job No.20-5615
Lots 4 and 5, Heights at Bull Mountain
We have prepared this report for Lennar, 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.
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EXPIRES:06/30/2 i,
James D. Imbrie, G.E.
Geotechnical Engineer