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v <br /> March 24, 2021 Earth Solutions NW LLC <br /> ES-6516.09 Geotechnical Engineering,Construction <br /> Observation/Testing and Environmental Services <br /> Heartland Construction, LLC <br /> 10900 Northeast 8t" Street, Suite 1200 <br /> Bellevue, Washington 98004 <br /> Attention: Mr. Dalton Arndt <br /> Subject: Geotechnical Assessment <br /> BMP Infeasibility <br /> Proposed Four Corners <br /> 8102 Evergreen Way <br /> Everett, Washington <br /> Reference: Earth Solutions NW, LLC <br /> Geotechnical Engineering Report <br /> Project No. ES-6516, dated April 1, 2019 <br /> Dear Mr. Arndt: <br /> At the request of CPH Consultants, Earth Solutions NW, LLC (ESNW) has prepared this letter <br /> and geotechnical assessment of site BMP implementation. In preparing this letter, we reviewed <br /> recent City of Everett comments requesting an evaluation of BMP feasibility. Specifically, <br /> evaluation of BMP T5.15 (pervious pavement) and BMP T5.10C (perforated stub-outs) were <br /> requested. <br /> BMP T5.15 (Pervious Pavement) — Based on the findings of the geotechnical investigation <br /> (referenced above) the following infeasibility criteria are applicable to the identified subsurface <br /> conditions: <br /> "Where seasonal high ground water or an underlying impermeable/low permeable layer would <br /> create saturated conditions within one foot of the bottom of the lowest gravel base course." <br /> The dense to very dene glacial till deposits identified near surface and at-depth throughout the <br /> site will effectively function as an underlying impermeable/low permeable layer below the site <br /> pavement areas. As such, saturated conditions within one foot of the bottom of the lowest gravel <br /> base course would be expected to develop if pervious pavement applications were implemented. <br /> 15365 N.E.90th Street,Suite 100 • Redmond,WA 98052 • (425)449-4704 • FAX(425)449-4711 <br />