905 80TH ST SW MTORRES AMERICA 2018-09-18

February 22,2016 Project No. T-7364 4.11 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 4.2 of this report. As noted, the native soils are moisture sensitive and will require careful control of moisture to facilitate proper compaction. If utility construction takes place during the winter or if it is not feasible to properly moisture condition the excavated soil at the time of construction, it may be necessary to import suitable wet weather fill for utility trench backfilling. 4.12 Pavements Pavement subgrades should be prepared as described in the Section 4.2 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-tired 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 that 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) Heavy Traffic: • Three inches of HMA over six inches of CRB The paving materials used should conform to the Washington State Department of Transportation (WSDOT) specifications for 1/2-inch class HMA and CRB. Long-term pavement performance will depend on surface drainage. A poorly-drained pavement section will be subject to premature failure as a result of surface water infiltrating into the subgrade soils and reducing their supporting capability. For optimum pavement performance,we recommend surface drainage gradients of at least. two percent. Some degree of longitudinal and transverse cracking of the pavement surface,should be expected over time. Regular maintenance should be planned to seal cracks when they occur. Page No. 12