Report (6) A43%2020- 002/8
/6z19 COPPe/L Lt9ilf CA / GEUPRCI IC
Real-World Geotechnical Solutions
• Investigation•Design•Construction Support
September 15, 2020
GeoPacific Project No. 18-5063
David Weekley Homes
1905 NW 169th Place, Ste. 210
Beaverton, OR 97006
Email: Morse, Elizabeth; emorse(a.dwhomes.com
SUBJECT: LOW POINT AND FOOTING DRAIN OUTFALL RECOMMENDATIONS
RIDGECREST FKA ERIKA COURT SUBDIVISION LOTS 6-10
TIGARD, OREGON
This letter addresses the outlet for low point drains and perimeter footing drains for the single-
family homes on Lot 6 through 10. There are no known springs on these lots and we do not
expect any outflow. The maximum outflow we have seen in our vast experience is 1 gpm; such
a small amount that no adverse impacts to adjoining properties are possible. The low point and
footing drains should not be connected to the rain drains and may outfall in the rear yard on
these lots. No rip rap is considered necessary.
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. 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 David Weekley Homes, 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.
14835 SW 72nd Avenue Tel(503)598-8445
Portland,Oregon 97224 Fax(503)941-9281
GEOPACIFIC ENGINEERING, INC.
Project No. 18-5063
Ericka Court Lots 6-10
We appreciate this opportunity to be of service.
Sincerely,
GEOPACIFIC ENGINEERING, INC.
.«` 3 ti#k
1,471
OREGO
EXPIRES:06/30/20A.
James D. Imbrie, G.E.
Geotechnical Engineer
14835 SW 72nd Avenue Tel(503)598-8445
Portland,Oregon 97224 Fax(503)941-9281
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