HomeMy WebLinkAboutBuilding Correspondence 2013-5-20 ranch
• �E-N�GINEERING-
Since 197
May 20, 2013 civil • transportation
structural • geotechnical
SURVIVING
Mr.Derrick Westover
Bruce Wiechert Custom Homes,Inc.
3073 Skyvietr Lane
Eugene,Oregon 97405
RE: SUBGRADE EVALUATION
6109 GRAYSTONE LOOP
MOUNTAIN GATE WEST SUBDIVISION(PHASE IV)
SPRINGFIELD,OREGON
BR.wat ENGINEERING INC.PROJECT Na 13-017
A Branch Engineering,Inc.geotechnical representative has visited the above referenced site on May
16, 2013 to observe the building pad excavation,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 pad was excavated 6-to 18-inches to create a relatively flat pad with the
excavated material stockpiled along the west and rear edge of the pad. The spoils observed next to
the pad contained a significant amount of basalt removed from the building pad.The pad was
leveled by covering the subgrade with 3-inches of 3,G"-0 crushed aggregate. The aggregate was track
walked in-place. Hand-probing of the native soil indicated a firm subgrade with substantial amounts
of native bedrock present. Previous testing of the subgrade soil has indicated a low shrink/swell
potential(IS 2720 result of 10%).
The April 5, 2004 by Boire Associates Inc.indicates that the subject lot is in cut and will expose hard
rock,and the July 21, 2006 PSI Summary of Earthwork letter indicates the lot was not assessed.
Slope stability of the lot is suitable and no other geologic/geotechnical factors will impede site
• development as planned. The soil 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 are relatively flat. Surface drainage shall be
conveyed to a suitable disposal area,and final perimeter landscape grades shall slope away from the
foundation and surface water not be allowed to pond adjacent to the foundation.
Sincerely,
Branch Engineering Inc,
OP PROD
.�` 0k `%
6, 70 ? � (p7 n y7
a.PREGON (n� , I I J
.15,N. MAY 8 2 2013 111
Ronald J.Derrick,P.E., G.E. Expires 12/31/2013 By
Principal Geotechnical Engineer
EUGENE-SPRINGFIELD SALEM-KEIZER
310 5th Street,Springfield,OR 97477 I p: 541.746.0637 I www.branchengineering.com
•
•