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HomeMy WebLinkAboutBuilding Correspondence 2013-7-8 ( }anch E-NtINEERING- Sing 1977 July 8,2013 civil transpoitaliOA structural geotechnical • SURVEYING' Mr.Derrick Westover Bruce Wiechert Custom Homes,Inc. 3073 Skyview Lane Eugene,Oregon 97405 RE BUILDING PAD SUBCRADE EVALUATION 6125 GRAYSTONE LOOP LOT 20 MOUNTAIN GATE WEST SUBDIVISION(PHASE IV) SPRINGFIELD,OREGON BR.W CH ENGINEERING INC Pao>fcr No.13017 A geotechnical engineer visited the above referenced site on July 3, 2013 to obsen-e•the building pad excavation and assess the shrink/swell potential of the subgrade soil, and determine the bearing capacity of the final building pad grade for construction of a single-family residence. The flat building pad has perimeter cuts of 10- to 18-inch to expose a hard bedrock subgrade. The pad was leveled by covering the subgrade with 1- to 4-inches of 3/4"-0 crushed aggregate. Testing of the subgrade soil indicated a low shrink/swell potential(IS 2720 result of<5%). The April 5, 2004 by Boire Associates Inc.indicates that Lot 20 was ungraded and in a hard rock area that is confirmed by our observations. The slope stability of the lot is good and no other geologic/geotechnical factors will impede site development as planned. The subgrade is suitable for a conventional perimeter-style foundation,and an allowable soil bearing capacity of 2,000 psf. We recommend that the foundation perimeter be backfilled and graded to slope away from the structure as soon as concrete curing allows. Differential settlements are expected to be less than 1/4-inch over a span of 20 feet. Footing drains are not required as the subject and adjacent lots area relatively flat, and surface water not be allowed to pond adjacent to the foundation. Sincerely, Branch Engineering Inc, dipPROpe /t, ` • • OREGON -. 15,t4° Ronald J.Derrick,P.E.,G.E. Expires 12/31/2013 Principal Geotechnical Engineer EUGENE-SPRINGFIELD SALEM-KEIZER 310 5th Street,Springfield,OR 97477 I p: 541.746.0637 I www.branchengineering.com