11-21-2005 Planning Commission Packet

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�Bonestroo 0 Rosene e m o �Anderlik& Associates Englneers 6 Architec[s Project Name: Mackinnon Hill Client: City of Orono To: Mike Gaffron, Planning Director File No: 139-05-000 From: John Smyth, Senior Scientist Date: 11/17/05 Re: Wetland Review Remarks: Site Summary The development was reviewed for wetland impacts. Currently a wetland is located within the southern portion of the site. A small creek flows into the wetlands under Watertown Road via a culvert. The creek flows through the northwest side of the wetland. There is a drainage easement shown on the plan however the easement location on the southern portion of the property does not reflect the location of the creek and in one location is shown on a slope. I would recommend that the centerline of the creek be surveyed and the drainage easement be modified to more accurately reflect the drainage through the site and also assist in the pond location as discussed in the paragraph below. Proposed Wetland Impacts and Ponding The impacts to the wetland are from a proposed treatment pond. It is my understanding the goal of locating this pond within the wetland was to preserve the wooded area within the site. I have reviewed the pond location with our Water Resource Engineer and here are some items to be considered to further preserve trees on this site. 1) Shift pond slightly to southwest to further avoid trees and potentially the creek. 2) Currently a pipe from catch basin 2 and 3 cut across the wooded area to a manhole and then the treatment pond. It is recommended that these catch basins be routed along the proposed road to catch basin 7 so only one pipe crosses the wooded area. Realignment of a pipe from catch basin 7 to the pond could also reduce impacts to the wooded area and could be aligned to discharge at the upstream portion of the pond to provide better treatment. 3) Consideration will need to be made in the pond design and location to insure that the creek does not flow into the pond and reduce its treatment efficiency by flushing it with clean water. Bonestroo, Rosene,Anderlik and Associates, Inc. www.bonestroo.com ❑St.Paul Office: O Milwaukee Office: O Rochester Office: ❑Willmar Office: O St.Cloud Office: O Grayslake Office: 2335 West Highway 36 1516 West Mequon Road 112 7`h Street NE 205 5th Street SW 3721 23r°Street S 888 East Belvidere Road St.Paul.MN 55113 Mequon,WI 53092 Rochester,MN 55906 Willmar,MN 56201 5t.Cloud,MN 56301 Grayslake,IL 60030 Phone:651-636-4600 Phone:262-241-4466 Phone:507-282-2100 Phone:320-214-9557 Phone:320-251-4553 Phone:847-548-6774 Fax:651-636-1311 Fax:262-241-4901 Fax:507-282-3100 Fax:320-214-9458 Fax:32�-251-6252 Fax:847-548-6979