7500 HARDESON RD Geotech Report 2022-10-25

' Geotechnical Engineering Report SSGC Hardeson Road Retail Everett,Washington SSGC Project No. 18072 September 18,2018. ' Table 4.CEC and Organic Content Results Organic Organic Test Location and Sample CEC Results CEC Required* Number (milliequivalents) (milliequivalents) Content Content Results(%) Required* (%) PIT-1, S-1 8.5 >5 2.88 >1.0 *Per the 2014 DOE Stormwater Management Manual for Western Washington Organic content and CEC test results of the upper native soils satisfy DOE requirements. . Conventional Asphalt Pavement Sections Subgrades for conventional pavement areas should be prepared as described in the "Subgrade Preparation" and "Structural Fill" sections of this report. Subgrades below pavement sections should be graded or crowned to promote drainage and not allow for ponding of water beneath the section. If drainage is not provided and ponding occurs, subgrade soils could become saturated, lose strength, and result in premature distress or failure of the section. In addition, the pavement surfacing should also be graded to promote drainage and reduce the potential for ponding of water on the pavement surface. We understand removal of all fill in pavement areas could potentially increase earthwork construction costs substantially. The lateral limits and overall thickness of fill can only be determined at the time of ' earthwork. If the owner is willing to accept the risk of reduced pavement life and additional maintenance in these area (and if allowed by the city),some of the existing fill could be left in place with a structural ' fill pad placed above to attempt to bridge the lower portions of existing fill. We recommend a minimum of 2 feet of existing fill (below the bottom of the design pavement section) is ' removed from pavement areas, where encountered. The lateral limits of excavation should extend a minimum of 5 feet outside the edge of pavement. Exposed subgrades should be proofrolled as described in the "General Subgrade Preparation"section. Alternatively, finish site grades could be lowered so fill is removed from all planned development areas. Minimum recommended pavement sections for conventional asphalt pavements are presented in Table 5. ' Note that expected pavement life will depend on whether subgrades consist of native or fill soil and construction preparation methods. I I 1 10