17 E MARINE VIEW DR 2019 Geotech Report 2025-10-01

promote drainage of surface water. Fill volume estimates to achieve proposed site grades should include an allowance for the anticipated settlement. Estimated Preload Settlement Magnitudes Preloading and surcharging the proposed building footprints will induce significant settlement immediately below the preloaded areas with decreasing settlement from the edge of the preload out laterally a distance of about 15 feet. We anticipate negligible settlement beyond 15 feet from the preloaded stockpiles. Estimates of the quantity of settlement were developed using the settlement analysis software Settle3D (version 4.010), available subsurface information and assumed soil properties based on correlations for water content and limit properties.Settlement estimates for each preload area are summarized below: Soil Storage Shed Estimated settlement under the planned west soil remediation storage shed is difficult to determine based on past material stockpiles in these areas. However, we estimate additional settlement under a 30-foot preload/surcharge may be on the order of approximately 3 to 5 inches in this area. Based on a review of historic site imagery, it appears that this area has been previously loaded in some areas by asphalt stockpiles up to 20 feet high. However, the location of past stockpiles likely did not cover the planned building footprints to the extent needed. Solt Remedlation Plant and Storage Bul►ding We estimate settlement to be on the order of approximately 4 to 10 inches under a 30-foot-high preload/surcharge. The load at the southern end of the building will be much less where the soil remediation plant is planned and a smaller surcharge could be used in this area if desired. We suggest a minim surcharge height of 10 feet for the south half of this storage shed. However,we recommend that the northern half of the building footprint be preloaded/surcharged up to 30 feet high due to the planned soil stockpile in this area. Based on a review of historic site imagery, it appears that the southwest portion of this soil remediation plant shed footprint has been previously loaded by asphalt stockpiles although the historic heights of the stockpiles are not known. Recycled Asphalt Product Storage Bullding We estimate settlement to be on the order of approximately 6 to 9 inches under the recommended 30 feet of preload/surcharge fill on the footprint for the proposed recycled asphalt product storage building. This estimated settlement range depends on the thickness of compressible soil underlying the building footprint and assumes that this location has not been previously loaded with material stockpiles.We anticipate that approximately half of the estimated settlement to occur immediately after the preload/surcharge is constructed and the other half will occur in primary consolidation during the preload program. Some secondary settlement may occur due to the decaying wood-waste observed in a nearby boring.Our analysis suggests that the existing Everett Engineering building will not be impacted by the proposed recycled asphalt building loading conditions.We anticipate about 1 inch of settlement at a distance of about 5 feet from the edge of the building footprint and about 1/2-inch of settlement at a distance 15 feet from the edge of the building footprint. Estimated Preload Settlement Rates The estimated time for the settlement to occur is 12 to 16 weeks, but the actual duration of preloading should be based on settlement plate readings. The thicker compressible silt layers will require more time to consolidate and will likely be on the 16-week end of this range. GWENGINEERS� August3,2018 Page9 File No.0643-015-00