117 79TH PL SE 2016-01-01 MF Import

CG -1 I ( -Do`1 FIELD REPORT U Project: 117- 79'h Place Addition File No.: 440010_ Cornerstone ')UBLI(('' �(//� ® Geotechnical, Inc. Owner: Cascade Testing Date: 20T0.W9RKS A Division of Robinson&Noble,Ina 17625130^Avenue NE C102 Location: Everett Report No: 2 Woodinville,WA 98072 Weather: Sunny--70 deg. Page: I of 2 Purpose of Addition Footing Subgradc Phone: 425-844-1977 Visit: Evaluaftri Fax: 425.844-1987 3y: KWB We were onsite at the request of Pat, with American Home Builders, for the purpose of evaluating foundation subgrade for the residential addition located at 117—791h Place SE in Everett. We have previously evaluated the foundation subgrade in the back yard. Some loose fill soil was encountered and documented in Field Report I. We were onsite today to observe the removal of the loose fill and provide recommendations for backfill. We observed the contractor remove the undocumented fill to expose a thin layer of native organic topsoil than was roughly 3 to 9 inches thick. The fill consisted of gray to dark brown silty sand with gravel and trace garbage, angular rock spalls and organics. We estimate that the fiil was ''/n to 3 feet duck. We observed the contractor remove the loose native soils exposing medium dense netive rust mottled brown silty sand with gravel and silt with sand and gravel. Using repeated effort,we probed through the 8 to 12 inches of medium dense soil and consistently encountered very dense gray glacial till that we could not penetrate with our probe rod. We observed the contractor use a jumping jack to compact the thin zone of native soil overlying the till. The compacted subgrade was probed 1 to 4 inches prior to the backfill being placed. The trencli was about 3 feet wide at the base,4 feet wide at the top and varied in depth of roughly 1 %to 4'/2 feet deep. The approximate depths of overexcavation are shown on page two. We informed the contractor that the onsite 1 '/. inch crushed rock would make suitable backfill if adequately compacted in lifts less than n foot in thickness. We departed the site because the spoils needed to be loaded in a truck and hauled away and it would be a couple hours before work on the footing subgrade overexcavation would resume. We were requested to return in about three hours. We returned approximately three hours later and observed the contractor placing and compacting 8 inch Hill of crushed rock within the trench area shown. Some of the trench had been backfilled up to the final elevation. The crushed rock appeared dense and we probed less than 3 inches into it. It is our opinion that the overcxcavation and backfill process we observed should provide the specified 2,000 psf bearing pressure as shown on the onsite plans. The contractor informed us that the backfill proc.•s was taking longer than expected and that no more footing subgradc would be excavated. We were requested to be onsite Monday at 10:30 em. Attachment Signed: Distribution: