HomeMy WebLinkAboutBuilding Miscellaneous 2014-4-14 .. _ ; .. i(
117,
T�
�4
-S'J`
• (Branch ', s
ENGINEERING_ `:;
Since 077 '
. April 14, 2014 ; C .4.-
. civil • transportation
. , ' structural • geotechnical -
SURVEYING •
_ Walter Custom Homes - t
2863 Riverwalk Loop .
Eugene, Oregon 97401 SoR-20/4,0/46(o
Attn: Mr. Tom Walter '
RE: SUBGRADE EVALUATION FOR RESIDENTIAL BUILDING PAD • •
6428 D0Gwoo0-LOT 41 • .\_
-• " _'� MTN GATE SUBDIVISION 'F-;. •
SPRINGFIELD,OREGON • - ,
Branch Engineering Inc Project No. 13-116 ' .
On April 9, 2014, a geotechnical engineer from Branch Engineering Inc. (BEI) visited the site to -
assess the building pad subgrade shrink/swell potential and soil bearing capacity for
construction of a single-family residence. The multi-tier building pad has been excavated on a
north facing slope with 6- to 24-inch cuts around the perimeter and 8- to 24-inch steps between
tiers. The level tiers are 'covered with up to 12-inches of compacted 1"-0 crushed aggregate.
Hand-probing indicated that the residual basalt subgrade with rock fragments is consistently
-` stiff/hard and the overlying aggregate is compacted to at least 90% of the materials maximum
dry density. Testing of a representative sample of the subgrade soil indicates a Free Swell
potential (IS 2720) of 10%, which is low.
. The soil subgrade and aggregate fill are suitable for a conventional perimeter-style, shallow
spread foundation stepped to match the excavated terraces. The allowable soil bearing capacity
is 1,500 psf, and differential settlement will be less than 3/4-inch over a span of 20 feet. Any
footings placed parallel to the slope shall be setback a horizontal distance equal or greater than
the vertical height between steps. The building lot and surrounding area are sloped; therefore, a
footing drain is recommended on the upslope side of the foundation. Perimeter landscape
grades shall slope away from the foundation and surface water shall not be allowed to pond
adjacent to the foundation. ,
Sincerely
Branch-Engineering Inc,
ra PROFESS 1-NEB, X .
71 ,t//ry
�"I O GON
/3 0 ,2 .1,15. 1°°ti ��-,
EXPIRES:DECEMBER 31, 2015
Ronald J. Derrick, P.E., G.E. ,
Principal Geotechnical Engineer •
. I .
• EUGENE-SPRINGFIELD SALEM-KEIZER .
310 5th Street,Springfield,OR 97477 I p: 541.746.0637 I www.branchengineering.com
1
/ ,-C