3800 RIVERFRONT BLVD Geotech Report 2023-05-04

March 26, 2019 HWA Project No. 2015-061-21 Task 600-7 We recommend that the asphaltic layers consist of HMA Class 1/2 inch. The maximum lift thickness for HMA Class 1/2-inch is 0.3 feet (3.6 inches) for the wearing course and 0.35 feet (4.2 inches) for all other courses, as stipulated by WSDOT (WSDOT, 2018). In areas where a more rigid section is need, particularly in areas where large trucks and busses are anticipated to be starting, stopping or turning, a rigid pavement section may be more appropriate. Based on the anticipated ESAL counts for the roadway construction and soil conditions a section consisted of a minimum of 9 inches concrete over 4 inches of CSBC should be utilized. All pavement materials and construction procedures should conform to Washington Department of Transportation(WSDOT), or appropriate local requirements 4.5.5 Concrete Design Considerations Concrete design parameters include a 28-day mean modulus of rupture of 600 pounds per square inch (psi) and a 28-day mean modulus of elasticity of approximately 3,600,000 psi. The concrete mix design should consist of a normal weight concrete with a minimum 28-day compressive strength of 4,000 psi when tested in accordance to ASTM C39. The concrete should contain an air entraining admixture to resist the effects of freezing and thawing. The design of joints,joint spacing, doweling and steel/wire mesh reinforcement was not included in HWA's Scope-of- Services, but should conform to the applicable local or WSDOT requirements 4.5.6 HMA Design Considerations The following design considerations should be noted and implemented: • The pavement will likely require a functional overlay after about 10 to 12 years because of non-structural associated distress caused by environmental factors such as degradation of the asphalt surface and rutting. 4.5.7 HMA Binder Selection The selection of the optimum asphalt binder type for the prevailing climate is critical to ensure long-term pavement performance. Use of the wrong binder can result in low temperature cracking or permanent deformation at high temperatures. Based on the climate in Everett, we recommend Superpave Performance Grade binder PG 64-22 be used. 4.5.8 Placement of HMA Placement of HMA should be in accordance with Section 5-04 of the WSDOT Standard Specifications (WSDOT, 2018). Particular attention should be paid to the following: • HMA should not be placed until the engineer has accepted the previously constructed pavement layers. • HMA should not be placed on any frozen or wet surface. 111 Geotechnical Report Revision 3 26 2019.doc 20 HWA GEOSCIENCES INC.