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HomeMy WebLinkAboutBuilding Correspondence 2013-9-26 of`I S 01/1- �Ie--- ranch • �E-NtINEERING= Since 1977 September 26, 2013 civil • transportation structural • geotechnical SURVEYING Mr.Derrick Westover Bruce Wiechert Custom Homes,Inc. 3073 Sky iew Lane Eugene, Oregon 97405 RE BUILDING PAD SUBGRADE EVALUATION GRAYSTONE LOOP LOT 74 MOUNTAIN GATE WEST SUBDIVISION(PHASE IV) SPRINGEIHD,OREGON BRANCH ENGI EERING INC PROJECT No.13-017 A geotechnical engineer visited the above referenced site on September 19 and 24, 2013 to observe 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 is cut into native basalt and covered with 4- to 5-inches of compacted crushed aggregate to smooth the surface. The rock subgrade has a low shrink/swell potential. The April 5, 2004 by Boire Associates Inc.indicates that Lot 74 is in a hard rock cut area as 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 psi. • 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, provided that surface drainage from the minor perimeter slope be conveyed to a suitable disposal area,and final perimeter landscape grades shall slope away from the foundation and surface water does not pond adjacent to the foundation. Sincerely, Branch Engineering Inc, cykieD•PROFF `�� 3/'o - Ale . di OREGON 12"� 15, 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