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Geotechnical Engineering Report <br /> Community Transit Merrill Creek Operating Base <br /> 7100 Hardeson Road <br /> Everett, Washington <br /> February 28, 2018 <br /> RN File No. 3224-002A <br /> Page 10 <br /> • "Observations of areal extent and time of surface ponding, including local <br /> government or professional observations of high water tables, frequent or <br /> long durations of standing water, springs, wetlands and/or frequent <br /> flooding." <br /> The photos below were taken on June 21, 2017 after an extended period of dry weather. As <br /> you can see, there is water on the pavement surface. <br /> �'. �!:r-,.,ry awl <br /> ��11 f . t;i�4. <br /> d _^. <br /> µ/ <br /> 1 <br /> ti 't Y v <br /> 2r's .YY 3S.*Ir_ { vi.•Y'-Di ,Mtu c d4 <br /> In addition, the DOE present Site Suitability Criteria (SSC) in section 3.3.7 of Volume III. SSC-6 <br /> states "Waste fill materials shall not be used as infiltration soil media nor shall such media be <br /> placed over uncontrolled or non-engineered fill soils." The entire site is underlain by <br /> approximately 14 to 19 feet of uncontrolled fill as shown on the boring logs in Figures 4 through <br /> 21 of this report. In our opinion, the site is therefore not suitable for infiltration. <br /> Rain Gardens/Bioretention BMP 15.14: The infeasibility criteria for rain gardens are the same <br /> as for bioretention. This is discussed in DOE Section 7.4 in Volume V. Infeasibility criteria <br /> include: <br /> • "Where professional geotechnical evaluation recommends infiltration not be used due <br /> to reasonable concerns about erosion, slope failure, or downgradient flooding." <br /> o The reason behind this study was to find a solution to the water that is ponded <br /> on the asphalt surface year round. In our opinion, rain gardens should not be <br /> used because there are reasonable concerns about downgradient flooding from <br /> the rain gardens onto the adjacent pavement. <br /> Robinson Noble, Inc. <br />