HomeMy WebLinkAboutBuilding Miscellaneous 2011-4-26
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Branch Engineering,
Inc.
Corporate Headquarters
(541) 746-0637
310 5~ Street
Springfield, OR 97477
Salem Engineering Office
(503) 779-2577
4310 Cheny Avenue NE
Salem, OR 97303
Principals
M. Lane Branch, PE
Damien Gilbert, PE
Renee D. Clough, PE, PLS
Rene" Fabricant, PE, SE
Ronald J. Denick, PE, GE
www.Branch~gineerin9.com
April 26, 2011
..
Bruce Wiechert Custom Homes, Inc.
3073 Skyview Lane
Eugene, Oregon 97405
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RE: SUBGRADE EVALUATION & AGGREGATE COMPACTION TEsTING
.6095 GRAYSTONE Loop
SPRINGFIELD, OREGON
Branch Engineering Inc Project No. 10-207
A geotechnical engineering representative visited the above referenced site on April 25, 2011, to observe the
building pad dig-out and assess the shrink/swell potential and soil bearing capacity of the subgrade for
construction of a single family residence. On Ap'ril26, 2011 a geotechnical engineer visited the site to access
the building pad and compaction of the approxiniately 12-inched of%"-O crushed aggregated from Springfield
Quarry that was placed on the pad. The relatively flat building pad was excavated 6- to 8-inches to remove
loose surface material and expose the weathered basalt bedrock. Hand-probing ofthe exposed subgrade
indicatea stiff, light reddish brown silty clay with basalt fragment. Free Swell (lS2720) testing of the soil
indicatl7S ~ low to moderate shrink/swell potential (25%).
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Subsequently, 8-'to 12-inches of compacted %"-0 crushed aggregate was placed and compacted using a
smooth-drum vibratory compactor. Field testing indicated 970/0 relative compaction of the aggregate. The soil
~ubgrade and aggregate fill are suitable for a conventional perimeter-style foundation, and an allowable soil
bearing capacity of2,000 psf. We recommend that the foundation perimeter be backfilled and graded to slope
away from the structure as soon as concrete curirig allows. Differential settlements are expected to be less
than 1/4-inch over a span of20 feet. Footing drains are not required as the subject lot and surrounding .
properties are relatively flat and near the same elevation. Final perimeter landscape grades shall slope away
from the foundation and surface water shall not be allowed to pond adjacent to the founda~ion.
Sincerely,
BrancH'Engineering Inc,
Ronald J. Derrick, P.E., G.E.
Principal Geotechnical Engineer
Expires 12131120 II
CML
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