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HomeMy WebLinkAboutBuilding Field Test & Inspection Report 2013-12-10 (äianch ` December lo,2013 ENGINEERING- . +in::1977 Mr.Derrick Westover tl tranpOitdta:n Bruce%%techert Custom Homes,Inc. t nuc:a rat+ =geavchilcai' 3073 Skyview Lane W_�.-s,u,R.v Eugene,Oregon 97 405 RE: SUBGRADE EVALUATION 621;GR.1YS[ONE LOOP LOT 62 31011'C-LIN GATE WEST SUBDIVISION(PHASE I"1 SPRINGFIELD,OREGON BRANCH ENGINEERING INC.PROJECTNO.13-317 November 21, 2013: A Branch Engineering, Ina (BEI) geotechnical representative visited the above referenced site to observe the building pad excavation, assess the shrink/swell potential of the subgrade soil and the suitability for placement of fill for the construction of a level building pad. The site is situated below adjacent lots to the west and north on a hillside that generally slopes down to the east Graystone Loop traverses the hillside borders the lot on the east. Two test pits were excavated to depths of approximately 42- inches below the ground surface (BGS). Beneath topsoil and vegetation approximately 24-inches of brown silty clay fill with occasional organics was observed at 24- inches BGS the soil transitioned to medium stiff brown silty clay. The material exposed beneath the 24-inches was identified as suitable subgrade for the placement of compacted crushed rock aggregate fill within the building pad. November 26, 2013: The BEI geotechnical engineer of record visited the site to document the placement of compacted crushed rock aggregate and observe proof rolls with a fully loaded to CV haul truck on compacted crushed rock aggregate structural fill. At the time of visit the building pad was excavated level into the hillside with cuts along the majority of site, specifically the northwest portion of the building pad advancing into the hillside and the southeast corner of the pad subgrade excavated at a daylight erade. 34C- (a)compacted crushed rock aggregate fill was placed on the approved subgrade. Fill thickness ranged from 6- inches in the southeast portion of the site up to 24- inches across central portions of the building pad_ Proof rolls with a fully loaded to CT haul truck were obsessed across the compacted aggregate;no significant deflection under load was observed. December 5, 2013; A BEI geotechnical representative visited the site to document the finished condition of the building pad prior to placement of concrete forms. The finished building pad consisted on one upper elevation tier covering the majority of the building pad and one lower elevation tier sunken 24-inches in the southeast portion of the pad. The compacted crushed rock aggregate was dense to probing and the entire surface of the building pad was compacted. The southeast portion of the pad was excavated subgrade at daylight grades while along the northwest portion of the pad cuts ranging from 12- to 24- inches were present with the larger cuts concentrated in the northwest corner. A light brown to tan clay with claystone was exposed along the deeper cuts in the northeast corner of the excavation which was probed and found to be stiff in consistency. The depth of excavation to suitable subgrade had been'reduced across the northeast portion of the pad as the stiffer subgrade material was encountered during excavation.. The building pad is suitable for a conventional perimeter-style foundation, and an allowable soil bearing capacity of 1,50o psf. We recommend that the foundation perimeter be bacldilled and graded to slope away from the structure as soon as concrete curing allows. Differential settlements are expected to be less than 1/2-inch over a span of 20 feet Footing drains are recommended as the subject lot lies below adjacent lots and may receive runoff. Surface drainage shall be conveyed to a suitable disposal area, and final perimeter landscape grades shall slope away from the foundation and surface water not be allowed to pond adjacent to the foundation EUGENE-SPRINGFIELD SALEM-KDZER 310 5th Street, Springfield, OR 97477 p: 541.746.0637 www.branchengineering.com 6215 Craystone Loop December 10. 2013 • Sincerely, Branch Engineering Inc, 9 . ,ii# �/*'9 OREGON ° Sef 15. ry 1u9 �V 4‘0J. D01/4� EXPIRES: 12131/2013 Ronald J.Derrick,P.E.,G.E. Principal Geotechnical Engineer • Branch Engineering. Inc.