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NOV-28-ee TUE ll;14 AM Me I»h <br />BARR <br />9S2 4T25663 <br />Barr Engineering Company <br />47CX) West 77th Street • Minneapolis. MN 55435-4803 <br />Phone: 952-832-2600 • Fax 952-832-2601 <br />P.12 <br />Minneapolis. MN • Hibbl.ig, MN • Duluth. MN • Ann Arbor. Ml • Jefferson City, MO <br />September 7,2000 <br />w <br />i <br />Mr. Mike Gaffron <br />City of Orono <br />2750 Kelley Parkway <br />PO Box 66 <br />Civslal Bay, MN 55323 <br />Re: Brensheli Homes Development Proposal <br />Dear Mr. Gaffron: <br />At the request of Mr. Gary Welsh and other concerned citizens of Orono, Barr Engineering Company <br />is providing additional i^ormation for your consideration in evaluating the proposed Brensheli <br />Homes proposed subdivision. On September 6,2000, we inspected the proposed development site to <br />further evaluate the potential for erosion and drainage problems as a result of the development. <br />We observed numerous, large, healthy maple trees uiihin and surrounding the entire ravine in the <br />southeast comer of the development parcel. It appears that some of these trees would be removed in <br />order to construct the southernmost pond. Currently, these trees provide a number of bet efits b <br />protecting the ravine includbg: <br />1.The complete canopy over the area reduces the erosive potential of raindrops by interception, <br />2.The trees help promote infiltration and reduce surface runoff by keepbg the soil porous (with <br />macropoics created by roots and soil organisms), <br />3.Trees have high evapotranspiration rates which reduces soil water content between rainfall events <br />and provides more storage for rainfall and lessens runoff, and <br />4.The expansive root systems provide stability to the soils and slopes to prevent slope failure. <br />Once these large trees are removed ^d their root systems begin to decay, the stability of the slopes <br />will decrease and the lack of protective cover may berease the raindrop erosion potential and surface <br />runoff resulung in increased erosion, formation of gullies, and sediment transport to Forest Lake. <br />As wc discussed yesterday, the home Ideations on Lots 2 and 3 are shown within or immediately <br />adjacent to 18% slopes with no useabb, flat back yard areas. The proximity of these house pads on <br />the steep slopes raises serious erosion concerns due to roof runoff; the additional grading that is <br />expected to create small, useable back yards; and estabUshraent of turf which generally results in <br />increased runoff over native vegetation. It would be helpful to stake the limits of the proposed pond <br />on Lo I and the house pad areas on Lots 2 and 3 in order to properly evaluate the porential for