3301 SEAWAY BLVD Geotech Report 2022-10-25

January 13,2016 Project No. T-7342 5.11 Utilities. Utility pipes should be bedded and backfilled in accordance with American Public Works Association (APWA) or local jurisdictional requirements. At minimum, trench backfill should be placed and compacted as structural fill, as described in Section 5.2 of this report. As noted, the on-site soils should be suitable for use as backfill material. However, at the time of our study, the upper soil's moisture content appeared to be above optimum. Therefore, drying back or other means to condition the material will likely be necessary to facilitate proper compaction. If utility construction takes place during the winter, it may be necessary to import suitable wet weather fill for utility trench backfilling. 5.12 Pavements Pavement subgrade should be prepared as described in the Section 5.2 of this report. Regardless of the degree of relative compaction achieved, the subgrade must be firm and relatively unyielding before paving. The subgrade should be proofrolled with heavy rubber-tire construction equipment such as a loaded 10-yard dump truck to verify this condition. The pavement design section is dependent upon the supporting capability of the subgrade soils and the traffic conditions to which it will be subjected. We expect traffic at the facility will consist of cars and light trucks, along with heavy traffic in the form of tractor-trailer rigs. For design considerations, we have assumed traffic in parking and in car/light truck access pavement areas can be represented by an 18-kip Equivalent Single Axle Loading (ESAL) of 50,000 over a 20-year design life. For heavy traffic pavement areas, we have assumed an ESAL of 300,000 would be representative of the expected loading. These ESALs represent loading approximately equivalent to 3 and 18, loaded (80,000 pound GVW) tractor-trailer rigs traversing the pavement daily in each area, respectively. With a stable subgrade prepared as recommended,we recommend the following pavement sections: Light Traffic and Parking: • Two inches of hot mix asphalt(HMA)over four inches of crushed rock base(CRB) • 3 1/2 inches of full depth HMA Heavy Traffic: •; Three inches of HMA over six inches of CRB • Five inches of full depth HMA The paving materials used should conform to the current Washington State Department of Transportation (WSDOT)specifications for 1/2-inch hot mix asphalt HMA and CRB surfacing. Page No. 14