6307 36TH AVE W Geotech Report 2025-07-29

1 ' August 13,2008 - Project No.T-624I 5.9 Pavements Pavements should be constructed on subgrades, as described in Section 5.2 of this report. Regardless of the degree of relative compaction achieved, the subgrade must be firm and relatively unyielding before paving. Proofrolhng the subgrade with heavy construction equipment should be completed 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 occasional 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. 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) ' • Two inches of(HMA)over three inches of asphalt-treated base(ATB) Heavy Traffic: • Three inches of HMA over six inches of CRB • Three inches of HMA over three inches of ATB HMA should conform to 2008 WSDOT specifications for 1/2-inch class HMA. Crushed surfacing base course ' material should conform to 2008 WSDOT 9-03.9(3)"Crushed Surfacing"specifications. 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 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. 6.0 ADDITIONAL SERVICES ' Terra Associates, Inc. should review the final design and specifications in order to verify that earthwork and foundation recommendations have been properly interpreted and incorporated in project design. We should also provide geotechnical services during construction in order to observe compliance with our design concepts, ' specifications, and recommendations. This will also allow for design changes if subsurface conditions differ from those anticipated prior to the start of construction. I Page No. 11 I