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HomeMy WebLinkAboutMiscellaneous Field Test & Inspection Report 2010-9-13 ......0:4 .). -a (If) -{3r 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 ',' ~ngin~~ring ,. 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 '.',' 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 /,. constructed on the sUbject proje.9tsite:-' . . "t . .K'. ~~;. 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. ~";-, ., " . SITE OBSERVAT'IONS , ..... 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. " ,,~ 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. . ,: ,. , . > ..._.:it'< ""''''It, ,';"1 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 " .. 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