HomeMy WebLinkAboutBuilding Correspondence 2013-9-26 of`I S 01/1- �Ie---
ranch
• �E-NtINEERING=
Since 1977
September 26, 2013 civil • transportation
structural • geotechnical
SURVEYING
Mr.Derrick Westover
Bruce Wiechert Custom Homes,Inc.
3073 Sky iew Lane
Eugene, Oregon 97405
RE BUILDING PAD SUBGRADE EVALUATION
GRAYSTONE LOOP
LOT 74 MOUNTAIN GATE WEST SUBDIVISION(PHASE IV)
SPRINGEIHD,OREGON
BRANCH ENGI EERING INC PROJECT No.13-017
A geotechnical engineer visited the above referenced site on September 19 and 24, 2013 to observe
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 is cut into native basalt and covered with 4- to 5-inches of
compacted crushed aggregate to smooth the surface. The rock subgrade has a low shrink/swell
potential.
The April 5, 2004 by Boire Associates Inc.indicates that Lot 74 is in a hard rock cut area as
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 psi.
• 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, provided that surface drainage
from the minor perimeter slope be conveyed to a suitable disposal area,and final perimeter
landscape grades shall slope away from the foundation and surface water does not pond adjacent to
the foundation.
Sincerely,
Branch Engineering Inc,
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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