HomeMy WebLinkAboutBuilding Correspondence 2013-7-8 ( }anch
E-NtINEERING-
Sing 1977
July 8,2013 civil transpoitaliOA
structural geotechnical
• SURVEYING'
Mr.Derrick Westover
Bruce Wiechert Custom Homes,Inc.
3073 Skyview Lane
Eugene,Oregon 97405
RE BUILDING PAD SUBCRADE EVALUATION
6125 GRAYSTONE LOOP
LOT 20 MOUNTAIN GATE WEST SUBDIVISION(PHASE IV)
SPRINGFIELD,OREGON
BR.W CH ENGINEERING INC Pao>fcr No.13017
A geotechnical engineer visited the above referenced site on July 3, 2013 to obsen-e•the building pad
excavation and assess the shrink/swell potential of the subgrade soil, and determine the bearing
capacity of the final building pad grade for construction of a single-family residence. The flat
building pad has perimeter cuts of 10- to 18-inch to expose a hard bedrock subgrade. The pad was
leveled by covering the subgrade with 1- to 4-inches of 3/4"-0 crushed aggregate. Testing of the
subgrade soil indicated a low shrink/swell potential(IS 2720 result of<5%).
The April 5, 2004 by Boire Associates Inc.indicates that Lot 20 was ungraded and in a hard rock area
that is confirmed by our observations. The slope stability of the lot is good and no other
geologic/geotechnical factors will impede site development as planned. The subgrade is suitable for
a conventional perimeter-style foundation,and an allowable soil bearing capacity of 2,000 psf. We
recommend that the foundation perimeter be backfilled and graded to slope away from the structure
as soon as concrete curing allows. Differential settlements are expected to be less than 1/4-inch
over a span of 20 feet. Footing drains are not required as the subject and adjacent lots area
relatively flat, and surface water not be allowed to pond adjacent to the foundation.
Sincerely,
Branch Engineering Inc,
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OREGON -.
15,t4°
Ronald J.Derrick,P.E.,G.E. Expires 12/31/2013
Principal Geotechnical Engineer
EUGENE-SPRINGFIELD SALEM-KEIZER
310 5th Street,Springfield,OR 97477 I p: 541.746.0637 I www.branchengineering.com