Report 12, 22, TUE 15:54 FAX 503 670 9147 CARLSON TESTING 2002
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Main Office D'anch Mice
P.O. Box 23814 40E0 Hudson Ave., NE
Tigard, Oregon 97281 Salem, OR 9730i
Carl s Q n Testing, Inc. Phone (503) 684 -3460 Phone (503) 589-1252
FAX (503} 6840954 FAX (503) 589.1309
December 22, 1998 /457 ! - 0 .--f
CTI 1198-G1880
011ie.ara Townhomes
2 Oswego Summit
Lake Oswego, OR 97035
GEOTECHNICAL REVIEW FOR RETAINING WALL CieNSTRUCTION
12630 PATHFINDER
TIGARD, OREGON •
Pursuant to your request, an engineer from Carlson 'resting, Inc. (CTI) has visited the above -
referenced single family home with regards to revue:vine the up to approximately 4 ± foot tall
cantilever reinforced concrete retaining walls along the driveway and the subgrade and backfill
conditions around the walls. Based on information you 0 )vided, the walls are a maximum 49
inches in total height. The wall and footing are about 8 and 6 inches thick respectively. The
toe width is about 3 inches and the heel is about 6 inches.
' Steel reinforcement, concrete strength, and reinforced concrete design is beyond the scope
of our review, however, the steel spacing and concrete quality appeared more than adequate.
The wall is backfilled with crushed drain rock that we estimate would have an equivalent fluid
pressure of 30 pct. The soil beneath the wall probed adequately for support. Based on our
analyses, the factors of safety against wall overturning is in excess of 1.6 even without taking
the resisting influence of the soil backfill weight into account, The factor of safety against
sliding is estimated to be in excess of 2.
From our review it is our opinion that the nonengineered walls were constructed in a mariner
consistent with good construction practice and should adequately and safely retain the yard
along the driveway.
Information contained herein is not to be reproduced, except in full, without prior authorization
from this office. If there are any further questions regarding this matter, please do not hesitate
to contact this office.
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James D. Imbrie, P.E., C.E.G.
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Principal Engineer
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