9930 19TH AVE SE 2018-01-02 MF Import

Addendum to Geotechnical Engineering Report for Everett Home Base Proposed Wendy's at Everett Home Base February 3, 1998 NCA File No. 2134D98 Page 3 In general, it typically appeared that the design for Wendy's was somewhat more conservative than what we recommended for Home Base. Accordingly, the Wendy's design is generally considered to conform to our design recommendations. Specific geotechnical aspects we identified on the plans provided to us are summarized below. • Continuous strip footings for Wendy's are shown to be 20 inches wide, 24 inches deep, and designed for an allowable bearing pressure of 2,000 pounds per square foot (pso. This is a greater width, greater depth, and lesser bearing pressure than we recommended for Home Base. Therefore, foundation design is considered to conform to our recommendations, as long as subgrade preparation is done properly. • The plans show perimeter footing drains, which agrees with our recommendations. • The slab -on -grade detail generally conforms to our recommendations, with the exception that the capillary break is only 4 inches thick, as compared to our recommended 6 inches thick. The greater thickness of gravel would provide a more effective capillary break, especially considering the silty nature of the till subgrade. In addition, it is probably more in line with typical construction tolerances. The Pavements sub -section in our report for Home Base addressed subgrade preparation, but not actual design of the pavement section. For proper subgrade preparation, it is our opinion that a pavement section consisting of 2 inches of asphalt concrete over 4 inches of 1-1/4-inch minus crushed rock base course (Section 9-03.9(3) of the 1994 WSDOT/APWA Standard Specifications For Road, Bridge, and Municipal Construction] should be adequate in areas of light traffic or parking for cars and small trucks. In main entryways and areas subjected to heavy truck traffic, the pavement section should be increased to 3 inches of asphalt concrete over 6 inches of crushed rock base. We were not supplied with design geometry or loads for the pole -supported sign. However, we understand that the structural engineer will likely design the pole foundation based on Uniform Building Code (UBC) methods. We expect the soil at the sign location will be medium dense to dense silty sand, which can be used as the soil type for the UBC design method. For these soil conditions, we would recommend that design passive soil resistance be based on an equivalent fluid density of 250 pounds per cubic foot (pcf). NELSON-COUVRETTE & ASSOCIATES, INC.