304 SE EVERETT MALL WAY PANERA BREAD Geotech Report 2025-07-25

KA No. 092-12004 August 24,2012 Page No. 15 operated equipment is recommended for fill compaction within 3 feet of walls so that excessive stress is not imposed on the walls. Pavement Design The near surface subgrade soils generally consist of medium dense silty sand with gravel. These soils are rated as good for pavement subgrade material. We estimate that the subgrade will have a California Bearing Ratio (CBR)value of 10 and a modulus of subgrade reaction value of k=200 pci,provided the subgrade is prepared in general accordance with our recommendations. If loose soils or undocumented fill are encountered in the pavement subgrade, we recommend that subgrade modification techniques be considered. Subgrade modification typically includes the over- excavation of unsuitable materials, the placement of a geotextile fabric at the bottom of the over- excavated area, and then the placement of structural fill. We recommend the use of a high-strength geotextile separation fabric,such as Mirafi 600X or equivalent for the geotextile. Subgrade modification such as this is intended to disperse surcharge loads and therefore aid in pavement performance. The western portion of the site consists of undocumented fill materials to depths of approximately 10 feet. Where soft/loose soils or undocumented fill are encountered in the pavement subgrade, we recommend overexcavation of the soft/loose soil and undocumented fill to at least 12 inches below the planned pavement subgrade elevation and backfilling these areas with geotextile-reinforced structural fill. In areas of overexcavation, we recommend the placement of high strength geotextile over the exposed soil,backfilled to the planned pavement subgrade elevation with structural fill. The structural fill should be compacted to at least 95 percent of the maximum dry density as determined by ASTM Test Method D1557. In-place density tests should be performed to verify proper moisture content and adequate compaction. In areas where the pavement subgrade soil consists of firm and unyielding native soils, a proof roll of the pavement subgrade soil may be performed in lieu of the compaction and in-place density tests. The recommended flexible and rigid pavement sections are based on design CBR and modulus of subgrade reaction(k)values that are achieved,only following proper subgrade preparation. The subgrade strength and performance characteristics of a silty subgrade material may be dramatically reduced if this material becomes wet. Traffic loads were not provided, however, based on our knowledge of the proposed project, we expect the traffic to range from light duty (passenger automobiles) to heavy duty (fire trucks). The following tables show the recommended pavement sections for light duty and heavy duty use. Krazan&Associates,Inc. Eleven Offices Serving The Western United States