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Hennepin Conservation District <br />TO: City of Orono <br />FROM-, James Piegat, Ph.D. <br />DATE: 16 November, 1987 <br />Memorandum <br />SUBJECT: Proposed repairs to the John Waldron property <br />Mr. John Waldron has asked the Hennepin Conservation District to comment on his <br />proposal to repair damage done to his property during the heavy rains of July of this <br />year. The District has three concerns to Xis matter: 1) aesthetic considerations, 2) <br />effects on water quality, and 3) prevention of recurrence. <br />1. Aes•hetic Considerations <br />W.- believe that slopes vegetated with native species of plants would present the <br />most aesthetically pleasing landscape to neighbors and users of the lake. The use of <br />retaining walls should be minimized for aesthetic reasons. Mr. Wa!dron's proposal <br />would regrade the ex;stin& slope and vegetate it. This is the best remedy to alleviate <br />the existing problem provided tivtt the concerns mentioned below are sc:tisfied. <br />2. Effects on Water Quality <br />We are not convinced that enough is known about the effects of urban and suburban <br />land uses on water quality, although considerable money has been spent toward that <br />end. <br />In terms of surface runoff, a balance must be struck between the filtering effect of <br />grass during low intensity rainfalls and the erosion of physical and chemical <br />materials during higher intensity events. 1'lte key threshold is whether the surface <br />produces runoff that reaches the lake. A surprisingly small percentage of land <br />actually contributes to surface runoff. <br />Also, a balance must be struck between the transport of solids and dissolved <br />substances by surface water to the lake and the transport of dissolved substances by <br />ground water. <br />We believe that Mr. Waldron has already taken a positive stepp in dealing with <br />runoff from his rooftop. By piping that water directly to the lake, he has avoided all <br />of the materials that runoff could entrain if it were diverted to the st-eets or even his <br />lawn. Mr. Waldron must maintain the cleanliness of this systr n to prevent <br />expensive clogging of the underground pipes and will thereby remove most of the <br />material that would otherwise be carried to the lake. <br />20`j Fudge Plaza t3tdq 12450 Wayzata &xjlevard MmnWonka. Wnesc4a 55343 Telephone +612! 544 8572 <br />