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► , <br /> Conclusions: <br /> Based on the results from the GSLOPE i_imit Equilibrium Slope Stability, the proposed design <br /> prepared by Concept Landscaping includin�; burying a newly constructed retaining wall slope yields <br /> a minimum safety factor of 1.63, which exceeds the minimum industry safety factor requirement of <br /> 1.3. In addition, burying the existi�g retaining wall with fill to reach the proposed finish grade <br /> yields a minimum safety factor of 1.61, which also exceeds the minimum industry safety factor of <br /> 1.3. <br /> Therefore it is my professional opinion that the design plans originally submitted to the City of <br /> Orono are structurally sound and can safely resist any future deep seated global stability failure. It is <br /> also my opinion that the constructing a new retaining wall is not necessary to saiisfy global safety <br /> requirements. Simply burying the existing retaining wall with fill to finished grade also safely <br /> resists any future �ieep seated blobal stability failure because the slope is stable under its o�vn <br /> strength without the retaining wall as shown in the GSLOPE results. In addition, there are tree roots <br /> and vegetation that further he(p stabilize thc existing slope. However, the slope in the fill area must <br /> be bench cut, and all organics and unstable surface material removed. The fill material must then be <br /> strong enough to resist a surface failure. <br /> Surface s{ope stability is beyond the scope of this report. The method of stabilizinb the surface slope <br /> was not addressed in the original plans submitted by Concept Landscaping. <br /> Gray's analysis revealed a much lesser safety factor due to their use af a very conservative assumed <br /> soil strength due to their lack of information. When inputting soil parameters that are reflective of <br /> the actual strength of the soil, an increased safety factor of global stability results, whieh exceeds <br /> minimum industry standards. <br /> The conclusions retained are based o<i my professional opinion. These opinions are arrived in <br /> accordance with accepted engineeri��g practices in this time and location. Na other warranty is <br /> implied or intended. Should additional inf'armation become available, this report may be modificd <br /> based on the new data. If you have any auestions, please feel free to give me a call. <br /> Since cly <br /> Michael R. Johnson, PE <br /> 1 hereby certify that this plan, specification, or mport was prepared by me or under my direct <br /> supervision an that I a duly Licensed Professional Engineer under the laws of the state of <br /> Minnesota. <br /> 1� � �2 �11 <br /> Datc: <br /> _._____-------- ___.._� _ <br /> Michael R. Johnson, P. . License #25493 <br /> Gvd Des�gn Professiona�s • 8009 tynda/e Ave. 5.,Su�te�QO BloomMgton, MN 55420 • Office 952-303-5311 • www.cdp-us.com <br /> 5 <br />