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Report (3) Nf s?2020- 00/ ?2 /0/419 GO/P/ 2 c Lit/ GEOPRCIFIC 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 cCadwhomes.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 .s{Y12d1.S8Lt4..l. AYA'.�..•f' .X.V.1', *44{*."JWb"�^"1*V v '" y��.Wi•"'i lii b'm3�� .�y,.... 't +,,...�.a.u.�., a••„ A_wa3w4i� �irarva*loi5k%i}4i Mk+ib f. GEOPACIFIC ENGINEERING, INC. Project No. 18-5063 Ericka Court Lots 6-10 We appreciate this opportunity to be of service. Sincerely, GEOPACIFIC ENGINEERING, INC. 'it) OREGO rj EXPIRES:06/30/20' , James D. Imbrie, G.E. Geotechnical Engineer 14835 SW 72n4 Avenue Tel(503)598-8445 Portland,Oregon 97224 Fax(503)941-9281 Page 2