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BRAUNSM
Braun Intertec Corporation
I 6032 N. Cutter Circle, Ste. 480
NTE RTEC P.O. Box 17126
Portland, Oregon 97217
503- 289 -1778 Fax: 289 -1918
I .. Engineers and Scientists Serving
the Built and Natural Environments
August 5, 1998
Project No. EAAX -98 -0303
Report No. 09 -088 -3961
I
Mr. Steve Turner, General Manager
In S.R. Turner Construction LLC
8835 S.W. Canyon Lane, Suite 408
Portland, Oregon 97225
II
1 Dear Mr. Turner:
I Re: Geotechnical Evaluation for the Proposed Fonner Woods Subdivision,
S.W. Fonner Street and S.W. 113th Place, Tigard, Oregon
I The geotechnical evaluation you authorized on July 27, 1998, has been completed.
of these services was to assist you, P The Purpose
I preparing plans and specifications for construction of the new buildings. The evaluation ation was
as
foundations w
completed in general accordance with our Proposal No.
• of Authorization for Services to Mrs. Mary Tongue dated Ju y 27, 1998 and our Confirmation
I Summa ry of Results
I Eight soil test pits (TP -1 to TP -8) were completed in the proposed construction area. The
general soil profile was 2 to 7 inches of topsoil underlain by bro n, medium stiff to stiff sandy
I silt to silt. The silt unit extended to the maximum explored dept of 10 feet. Groundwater was
not encountered during our explorations.
I Summary of Recommendations
Based on the results of our soil test pits, it is our opinion that the proposed buildings can be
I supported on conventional shallow spread footings designed for a net maximum allowable
bearing pressure up to 2,000 pounds per square foot when founded on the undisturbed native
silts or on properly prepared structural fill.
1
I
I
,
. S.R. Turner Construction
Project No. EAAX -98 -0303
Report No. 09 -088 -3961
August 5, 1998
III Page 2
I
I General 1
II Please refer to the attached report for a more detailed summary of our analyses and
recommendations. If we can provide additional assistance, or observation and testing services
during design and construction, please do hesitate to contact us at (503) 289 -1778 or
ar.1 1(800) 783 -6985.
Sincerely, �� P fp PROP
M e OREGON / qt.
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II Joel W. Jeffrey, R.P.G. Q EQLOCAS I
Registered, Geologist
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Travis T. Nguyen, P.E. OREGON I
II Project Engineer ''a / rts �Q�� /
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Attachment: Geotechnical Evaluation Report
II c: Braun Intertec Corporation, St. Cloud Office
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S.R. Turner Construction
Project No. EAAX -98 -0303
Report No. 09- 088 -3961
August 5, 1998
Page 6
I
5.2.1 Construction Dewatering
Groundwater seepage in excavations should be anticipated during the wet season of the year.
For most of the excavations for this project, pumping from sumps outside the limits of the
excavation should control groundwater seepage and surface water ponding.
5.2.2 Excavations /Slopes
Temporary earth slopes may be cut near- vertical to heights of 1feet. Excavations deeper than 5
P Y P Y g P
feet should be performed in accordance with Department of Labor Occupational Safety and
Health Administration (OSHA) guidelines for Type A soils. Job site safety is the sole
responsibility of the project contractor.
5.3 Foundation Support
Based on the results of our geotechnical investigation, it is our opinion, that the proposed new
building may be supported on the undisturbed native silt strata or on properly prepared
structural fill using continuous and individual shallow spread footings. We recommend that
continuous and individual spread footings be designed for a net maximum allowable bearing
pressure of 2,000 pounds per square foot (psf) with a minimum footing width of 18 inches and 2
feet square, respectively.
The allowable pressure of 2,000 psf is intended for dead loads #d sustained live loads and can
be increased by one -third for the total of all loads, including shim -term wind or seismic loads.
Continuous footings should extend to a minimum depth of 18 inches beneath the lowest adjacent
exterior grade to provide frost protection.
Allowable lateral frictional resistance between the base of footings and the subgrade can be
. expressed as the applied vertical load multiplied by a coefficient of friction of 0.30. In addition,
lateral loads may be resisted by passive earth pressures based on an equivalent fluid density of
250 pounds per cubic foot (pet) on footings poured "neat" against insitu soils or properly
• backf fled with structural fill. This recommended value includes a factor of safety of
approximately 1.5, which is appropriate due to the amount of movement required to develop full
passive resistance.
I
S.R. Turner Construction
Project No. EAAX -98 -0303
Report No. 09- 088 -3961
August 5, 1998
Page 7
I
If the footings are constructed during wet weather, it may be n essary to protect the foundation
excavation bottoms from disturbance during construction activities. In this regard, we
recommend that a 3- to 4-inch thickness of crushed rock be placed at the bottom of the footing
excavations immediately after the excavation is completed. If footings are constructed during
the drier summer months, this crushed rock layer should not be required.
We estimate that foundations designed and constructed in accordance with the above
• recommendations will experience total settlements generally less than 1 -inch and differential
settlement between columns generally less than '/ -inch.
5.4 Drainage Considerations
Any areas of the building which are to be developed below the exterior site grade must be
provided with a well- designed drainage system in order to control hydrostatic pressures against
walls, seepage of groundwater through base walls, etc.
Under no circumstances should surface runoff water be led into foundation drains. Foundation
drains should be placed at the base of the footings to prevent surface and shallow perched water
from migrating beneath the footings.
Surface run -off from roofs, parking areas, etc., should be tightlined to the storm sewer or other
approved disposal areas.
5.5 Pavement Recommendations
The following recommendations are presented as preliminary for your consideration. The civil
engineer for the project may have more traffic and project design data available than is presently
known and may wish to modify and refine these pavement sections. We will, upon request be
pleased to provide a more detailed pavement design when definite traffic and building plans are
available.
Prior to placing the base or leveling course the subgrade should be proof- rolled with a loaded
dump truck to detect areas or pockets of unusually soft material. These should then be
excavated and replaced with suitable compacted fill. A geotextile fabric (Manufacturer's and
Brands: Mirafi 500X, Amoco CEF Style 2002, or an approve& alternate) should be placed over
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