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■ff‘ ; -1 f ^ i. NOV-28-00 TUE 11;12 AM Me Ish 952 4725663 BARR Barr Engineering Company 4700 West 77th Street • Minneapolis. MN 55435-4803 Phone; 952-832-2600 • Fax: 952-832-2601 P.lO Minneapolis, MN • Hiboing, MN • Duluth, MN • Ann Arbor, Ml • Jefferson City, MO September II, 2000 Mr. Paul Weinberger City of Orono 2750 Kelley Parkway PO Box 66 Crystal Bay, MN 55323 J Re: Brenshell Homes Development Proposal Dear Mr. Weinberger: At the reque*- of h;:. G'^ry Welsh and other concerned citizens of Orono, Barr Engineering Company has reviewed the revised develo^/mcnt plans received today in support of the proposed Brenshell Homes subdivision at 1181 Wildburst Trail in Orono. We are providing comments for your consideration in evaluating the proposed subdivision at your September 11,2000 city council meeting. Based on our latest review, we continue to have concerns regarding the steep slopes and wetland losses. Steep Slopes and Erosion Concerns The revised development plans include a reconfiguration of the lot line between Lots 2 and 3 and a minor reduction in the cul-de-sac length as recommended by city staff. However, the plans do not adequately protect the slopes and ravine from erosion due to concentrated runoff from the backs and sides of the homes. Unfortunately, approximately one-half of the bouse pad on Lot 2 and approximately one-sixth of the house pad on Lot 3 lie within areas defined as “steep slopes ” (slopes steeper than 12%). The current plans have not altered the drainage to ensure that concentrated runoff does not cause erosion in the south ravine and on the steep slopes leading to Wildburst Trail. The south stormwater pond is also planned for construction within the south ravine in areas currently containing slopes steeper than 18 percent. The construction of the south pond would require the removal of numerous large maple trees which are currently providing stability in the ravine. The steep slopes on Lots 2 and 3 arc currently protected from erosion by: 1.The full tree and shrub canopy which intercepts rainfall, maintains a more permeable soil structure and wicks away moisture from within the soils by evapotranspiration, and 2.1 he natural surface roughness and small dcpressional areas in the upstream drainage area slows any runoff that does occur so runoff within the ravine is spread out and maintained at lower rates. As the city staff recommended at our meeting on September 6, 2000, a conservation easement should be provided over the steeper slopes on Lots 2 and 3 to protect the existing vegetative cover and ground elevations. The pend would also create a new slope into the rav^e which would be steeper than 20 percent. Constructing ;hc por4 within a flatter area would eliminate smaller trees and create less of an erosion concern. ■—T-n■■■