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,Irpe Am — <br />Hennepin Conservation District Memorandum <br />TO: City of Orono <br />FROM: James Piegat, Ph.D. <br />DATE: 16 November, 1987 <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 in this matter: 1) aesthetic considerations, 2) <br />effects on water quality, and 3) prevention of recurrence. <br />1. Aesthetic Considerations <br />We 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. Waldron's proposal <br />would regrade the existin& slope and vegetate it. This is the best remedy to alleviate <br />the existing problem provided that the concerns mentioned below are satisfied. <br />2. Effects oil 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 consi('erable money has been spent toward that <br />end. <br />In terms of su `ace runoff, a balance must be struck between the filtering effect of <br />grass during t,)w intensity rainfalls and the erosion of physical and chemical <br />materials duringhigher intensity events. The kcy threshold is whether the surface <br />produces runofthat reaches the lake. A surprisingly small percentage of nd <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 substan. es by <br />ground water. <br />We believe that Mr. Waldron has already taken a positive step 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 streets or even his <br />lawn. Mr. Waldron must maintain the cleanliness of tAis system to prevent <br />expensive cloggin of the underground pipes and will thereby remove most of the <br />material that wou d otherwise be carried to the lake. <br />2U',; Ndgie Plaza Bldg 12450 Wayzata Boulevard Mimielonka Minnesota 55343 Telephone :61 1 544 85- <br />