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N <br />GME CONSULTANTS. INC. <br />CONSULTING ENGINEERS <br />14000 21 St Ave No / Minneapolis. MN 55447 <br />Phone (612) 559-1859 / Fax (612) 559-0720 <br />March 20, 1997 <br />N <# ' <br />N <br />• •) <br />Mr. Stephen G. Spartz <br />Landview Landscaping <br />3670 Highway 7 <br />Excelsior, Minnesota 55331 GME Project No. 6721 <br />RE; Boulder placement for erosion protection at the Vochko <br />residence in Orono, Minnesota <br />Lear Mr. Spartz: <br />The owner, Mr. Joe Vochko, has requested our opinion concerning the <br />stability of the boulders placed at the toe of the slope leading to <br />Lake Minnetonka. This was pursuant to concerns raised by the City of <br />Orono and the City Engineer, Bonestroo Rosene Anderlik & Associates. <br />On March 19, 1997, we met Mr. Vochko on-site and observed the boulder <br />placement. We understand these boulders were placed during the fall <br />and winter of 1996-1997. The boulders were randomly stacked to form a <br />relatively steep angle approximately 4 to 5 feet high. There is a <br />horizontal separation or terrace between the boulders and the rock <br />riprap placed for shore line protection. We understand that the voids <br />between the boulders will be filled with topsoil and a vegetative <br />growth will be established between the boulders, to prevent piping and <br />erosion of the retained earth through the voids between the boulders. <br />To our knowledge, there is no accurate way to quantify the stability of <br />the existing boulders. Howev'er, based on our experience, we offer the <br />following opinions. In our judgement, the boulders should be stable in <br />their current configuration provided that good boulder to boulder <br />contact was established during construction. Please note, however, <br />that over time some isolated boulders may loosen and become unstable. <br />If this should occur, then additional boulders should be placed, or the <br />boulders should be replaced to their original position. <br />If this is unacceptable, then in our judgement, one method of <br />increasing the stability would be to place additional boulders in front <br />of the existing boulders to form a flatter angle. However, this would <br />result in the loss of some area (terrace) separating the boulders from <br />the shore line riprap which, to our understanding, is not acceptable to <br />the owner. <br />WILLIAM C. KWASNY. RE. <br />GREGORY R. REUTER. RE. <br />MARK D. MILLSOR R6. <br />THOMAS PAUL VENEMA. PE. <br />CHARLES M. ALLGOOD, RE. <br />SANDRA J. FORREST. RG. <br />V.'ILLIAM E. BLOEMENDAL. RE. <br />MERVYN MINDESS. RE. <br />STEVEN J. RUESINK. RE. <br />An Equal Opportunity Employer