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� � M. <br /> �� <br /> _ , I hereby oertify$hat $2iis plan, specifi� <br /> ORONO COP �ation, or re or <br /> MmrGreen P �W�s prepared by�� ar <br /> MGSConsu/tingServiteCorp ; under my direct attpeZ•yiO3ort and that x an� <br /> a duly Regia�ered prp3�aional Enginee� <br /> 3356800neC'irNo under th� laws p� <br /> NewHope, MN 554Z7 �$�gteofMinnesota, , <br /> , ,Q. <br /> August 18,2fl15 � Date � r 9 /� <br /> Regia�ration No. 157. / <br /> Melanie Curtis -- -�-. """"�-.._ <br /> . _..--______..�._... <br /> Rlanning and Zoning Coordinator �, '� <br /> City of Onono `�"' � <br /> �i' <br /> Crystal Bay, Mn 55323 <br /> Regarding. My response to gob Bean's 5/1/15 commer� about the subterranean interiodcing grid system <br /> (Sub Grid)proposed for the Dougias Smith Project <br /> Ms.Curtis, <br /> Per my resent phone conversafion with Bob Bean,l am adding the fiollowing clarification details to the layout <br /> drawing for ifiis project. <br /> 1) Virgin or natural clay soils must be used for maximum compaction and to provide proper drainage. This clay <br /> soil must contain less than 10 per�cent fine granular material. Properly compacted soil of this type is to <br /> reduce water retention. We can expect holding forces in the range of 500 pounds per square foot against <br /> the vertical members of the grid if compacted per this requiremen�. <br /> 2) The use of treated 5 inch by 6 inch timbers are recommended for this project. Alkaline Copper Quaternary <br /> (ACCU treated timbers are required. <br /> 3) The use of Hex head steel heavy duty wood screws rated for treated�ACQ)timbers are required. Ten inch <br /> long#12 coarse thread or larger should be used. <br /> 4) Vertical posts must be set in place in 4 foot or deeper virgin or natural ctay. <br /> 5) Clear medium aggregate collection zone is required on every iayer of the grid. 4 inch drain tiles are required <br /> at the bottom of each layer to illuminate hydraulic water pressure against the walls. Each file must be <br /> connected to vertical files that lead to the shoreline rip rap. <br /> 6) Double rows of silt fence must be used by the installafion contractor prior to construction wherever possible. <br /> 7) Because of our ooncerns regarding erosion and sedimerrt control witfiin tfie project area my <br /> recommendatian is that only experienced contractors with proven successful installations should be <br /> considered for hill side restorafions of this type. <br /> Sincerely, <br /> ��Yy����2�' <br /> Max Green PE MBA <br /> RECEIVED <br /> AUG 1 9 2015 <br /> C�7Y OF ORONO <br />