2015-01353 - land alteration - Laserfiche WebLink

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y • Max Green MGS Consulting Service Corp 3356 Boone Cir No New Hope, MN 55427 August 18,2015 Melanie Curtis Pianning and Zoning Coordinator City of Orono Crystal Bay,Mn 55323 Regarding: My response to Bob Bean's 5/1/15 comments about the subterranean interlocking grid system (Sub Grid)proposed for the Douglas Smith Project Ms.Curtis, Per my resent phone conversation with Bob Bean,I am adding the following clarification details to the layout drawing for this project. 1) Virgin or natural clay soils must be used for maximum compaction and to provide proper drainage. This clay soil must contain less than 10 percent fine granular material. Properly compacted soil of this type is to reduce water retention. We can expect holding forces in the range of 500 pounds per square foot against the vertical members of the grid if compacted per this requirement. 2) The use of treated 5 inch by 6 inch timbers are recommended for this project. Alkaline Copper Quaternary (ACQ)treated timbers are required. 3) The use of Hex-head steel heavy duty wood screws rated for treated(ACQ)timbers are required. Ten inch long#12 coarse thread or larger should be used. 4) Vertical posts must be set in place in 4 foot or deeper virgin or natural clay. 5) Clear medium aggregate collection zone is required on every layer of the grid. 4 inch drain tiles are required at the bottom of each layer to illuminate hydraulic water pressure against the walls. Each tile must be connected to vertical tiles that lead to the shoreline rip rap. 6) Double rows of silt fence must be used by the installation contractor prior to construction wherever possible. 7) Because of our concerns regarding erosion and sediment control within the project area my recommendation is that only experienced contractors with proven successful installations should be considered for hill side restorations of this type. Sincerely, Max Green PE MBA