HomeMy WebLinkAboutMiscellaneous Field Test & Inspection Report 2010-9-13
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K & A Engineering, Inc.
91051 S Willamette St., Coburg, OR 97408
PO Box 8486, Coburg, OR 9740B
(541) 684-9399 Voice
(541) 684-9358 FAX
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September 13, 2010
Project: FBH1001
Future B Homes, Inc.
PO Box 7425
Eugene, OR 97401
Subject: Springfield Building Permit COM201 0-00537
6018 Fernhill Loop, Springfield, Oregon
Foundation Soils "1
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PURPOSE AND SCOPE
At your request, K & A Engineering, Inc. has completed a geotechnical investigation of the existing soils on the
;'subject property. Our understanding is that conventionally framed single-family residential structure will be
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~~;. ti1~ purpdse of our investiga;i~n was to determine the suitability of the soils for construction of the proposed
structure; and provide recommendations for construction of the foundation. The scope of our services is limited
to general suitability with respect to bearing capacity and expansive soils.
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SITE OBSERVAT'IONS
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Existing Site Conditions ~
The subject property consists of a residential lot on the north side of Fernhill Loop in the Mountaingate
subdivision. The lot is on a north facing slope with a gradient of approximately 20 percent. We did not observe
any slope movement hazards or other indications of over1y soft or unstable soils on the subject project site.
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Prior to construction, vegetation on the site consisted of mOderately dense grass with a few coniferous and
deciduous trees.
We did not observe any slope movement hazards or other indications of overly soft or unstable soils on the
subject project site. '
Subsurface Soil Conditions . ...'....
Based on the foundation pad excavation. soils near the eastern property line generally consist of approximately
1.0 to 2.0-feet of brown, damp, loose to moderately dense, organic gravelly silt over yellow/orange/tan mottled,
. damp, moderately stiff, decomposed sandstone.
Soils near the western property line generally consist of approximately 1.0 to 2.0-feet of brown, damp, loose to
moderately dense, organic gravelly silt over 1.0 to 6.5-feet of mottled dark brown/tan, moist, organic, slightly
; plastic ,silt over re9l0range/tan mottled, wet, stiff, decomposed sandstone. . ,: ,. , .
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K & A Engineering, Inc.
Groundwater was not encountered anywhere in the excavation.
Foundation Pad Construction
. Foundation pad preparation involved constructing a foundation pad on undisturbed native red/orange/tan mottled
decomposed sandstone at a depth that would mitigate any geological hazards and was also below the desired
footing elevation. This required stripping and removing approximately 2 to 6-feet of loose organic silt and
plastic silt from the foundation pad area and grading the sUbgrade on native stiff decomposed sandstone.
After the excavation and removal of unsuitable soils, approximately 2 to 3-feet of 3/4-inch minus well-graded
crushed aggregate was placed on approved subgrade in 12-inch maximum lifts, graded, and compacted using a
vibratory steel drum roller. We observed placement and tested the in-place density and water content of the
crushed aggregate. We made random tests of the crushed aggregate during compaction and determined that
the average dry density meets or exceeds the 95% of maximum as determined by ASTM D698.
A copy of the test results are attached to this report.
RECOMMENDATIONS
General Suitability
The site is suitable for construction of the proposed foundation. There are no significant geologic or other
hazards. We recommend acceptance oflhe foundation pad, as constructed, by the local building official... .
Foundation Support
Undisturbed foundation soils at this site will provide an allowable bearing capacity of 2,000 pounds per square
foot. Conventional cast-in-place concrete spread and strip footings may be used for foundations.
Expansive Soils
The foundation pad subgrade presents a low shrink/swell hazard. The methods and materials used in
construction of the foundation pad mitigate this hazard.
Project: FBH1001
Client: Future B Homes, Inc.
6018 Fernhill Loop, Springfield, OR
Page 2 of 3
September 13, 2010
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K & A Engineering, Inc,
LIMITATIONS OF THIS REPORT
This report has been prepared for the exciusive use of Future B Homes and its design consultants for the subject
proposed structure.
This geotechnical evaluation, analysis, and recommendations meet the standards of care of competent
geotechnical engineers providing similar services at the time these services were provided. We do not warrant
or guarantee site surtace or subsurtace conditions.
Thank you for the opportunity to be of service. Please call us if you have questions or need further assistance.
Respectfully,
EXPIRES
Chuck Du Fau~, P.E.
K & A Engineering, Inc.
Project: FBH1 001
Client: Future B Homes, Inc.
6018 Fernhill Loop, Springfield, OR
Page 3 of 3
September 13, 2010
Density ot Soil and Soil-Aggregates In-Place
ASTM 02922 and 03017
Project: FBH1001
Site Address: 6018 Fernhill Loop
Permit No: COM2010-00537
Date: 9/10/2010
Density TestType': DT-8"
Operator: CCD
Material Type: 3/4-inch minus, dense graded crushed agg., Delta S&G
Maximum Dry Denstiy, pet 125.0
Standardization and Relerenee Check d Density 'I /~ Moisture, I
(Standard Deviations) (S.D.) 0.16 (S.D:) 1.16
Moist Dry '.
Density, Density, Waler Compaction,
Test No. pet pel Content, % % Remarks
1 143.9 127.4 10.6 101.9%
2 141.0 127.9 10.3 102,3%
3 136.9 125.2 9.3 100.2%
4 133.3 121.3 9.9 97.0%
5 140.5 127.8 9.9 102.2%
Average: 100.7%
Std. Dev.: 2.25%
1 Direct Transmission (DT) (specify depth, in.) or Air Gap Backscatter (AGB) (specifiy(T)ouchable or (U)ntouchable
rnode
Test performed using Seaman Nuclear Corp model C-300, SN 21113
Client Future B Homes
Project: FBH1001
K & A Engineering, Inc.
9/13/2010