Report /14 7r -qT- 0-6 /zo 9, S Ste' :
Construction In & Related Tests
Carlson Testing, Inc. Geotechnical Consulting
P.O. Box 23814
Tigard, Oregon 97281
Phone (503) 684 -3460
July 10, 1998 FAX (503) 684 -0954
CTI JOB NO. 98 -G1569
Constructco Inc
P.O. Box 54
West Linn, OR 97068
FINAL REPORT OF EARTHWORK OBSERVATION AND TESTING
LUNDMARK PARTITION
TIGARD, OREGON
Carlson Testing Inc. (CTI), has conducted on -call inspection services for the utility and street
construction at the above residential development. This final letter briefly summarizes our test
results and our observations regarding soil conditions.
ANTICIPATED HOUSE EXCAVATION GUIDELINES
An estimated 12 to 18 inches of uncompacted soil was spread over the surface of the lots.
The native soil is also organic and /or soft for an additional estimated depth of 18 to 24 inches.
Therefore, we expect that foundation excavations will need to be at least 3 feet deep to reach
suitable bearing soils. The crawl spaces may then need to be backfilled with soil to achieve
adequate surface drainage.
If existing or future excavated material is spread around the lot and is expected to support
appurtenant structures such as deck footings and sidewalks, it should be placed, compacted,
and tested as engineered fill.
FOUNDATIONS
The proposed residential buildings, of the type anticipated, will likely be founded on shallow
spread footings bearing on competent native soils or engineered fill. Spread footing design
and construction should generally conform to Chapter 4 of the CABO One and Two Family
Dwelling Code (CABO), except where we specifically recommend otherwise.
For protection against frost heave, spread footings on nonexpansive soils should have a
minimum embedment depth of 12 inches for exterior grades on level ground. The
recommended minimum widths for continuous wall footings are tabulated below:
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CTI# 98-G1569
Lundmark Partition
Page 2 of 2
Minimum Width for
No. of Stories Continuous Footing
(floors supported) (in)
1 -story 12
2 -story 15
3 story 18
We anticipate that the allowable bearing pressure can be taken as 1,500 lb/ft for footings
bearing on competent native subsoils or engineered fill to a maximum of 15 kips for column
footings. For heavier column loads and masonry chimneys, a soil engineer should be
consulted. The coefficient of friction between on -site soil and poured -in -place concrete may
be taken as 0.35. The maximum anticipated total and differential footing movements
(generally from soil expansion and /or settlement) are 1 inch and 3 /4 inch over a span of 20 feet,
respectively.
CLOSING AND LIMITATIONS
Our reports pertain to the materials tested /inspected only. This letter should be made available
to each builder in the development; however, information contained herein is not to be
reproduced, except in full, without prior authorization from this office. This letter should not
be construed to relieve or lessen the responsibility of the contractor or owner's site
representative for this site work, but is provided for the minimum required governmental
assurance. Our support was given on an as- needed basis as requested. If conditions are
encountered during foundation excavation which differ from this report, then the developer,
the contractor, and CTI should be allowed to review the condition before corrective actions
are taken. Corrective work performed by the builder without notifying the above parties will
be interpreted as an acceptance of the conditions encountered.
Respectfully submitted, � :ED PROp
CARLSON TESTING, INC. �� ' �5 t1GINE£ 6"/
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v4N OREGON
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James D. Imbrie, P.E. /tie p I'18sk\ F, E 3L' j
Geotechnical Engineer
Attachments: Summary report of in -place soil density tests
cc: Sisul Engineering
City of Tigard