11/28/2007 Env Bd Packet - Laserfiche WebLink

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Biofiltration areas planted with the transitional seed mix should have a low- profile height associated with the forbes (native flowering plants). All Native seed mix areas should be planted by a contractor on the Minnesota Department of Natural Resources list of contractors. The native areas should be maintained for a minimum of 3 years by the approved contractor and if possible burned at the end of 3 years. Recommendations: 1. All Stormwater volume and flow designs must be evaluated for conformance to RCWD and AUAR standards. 2. Site Access for surface water treatment areas must be shown on the map. 3. Slopes of the wetland mitigation area be changed to conform to the AUAR 4. Recommend 1 -2 inch scrapping the wetland soils in a freeze /thaw situation to control reed canary grass. Also recommend the scraped soils in wetland fill areas be salvaged and stockpiled for use in the wetland mitigation area. 5. In general, there should be a narrative to the Boards and the City Council addressing all of the mitigation strategies presented in the AUAR that effect this development. 6. All infiltration areas and wetland mitigation areas should be seeded with the city native seed mix. The City transitional mix is shown on the plan and this is a good mix between cultural areas and wetland /pond areas. The BWSR U8 mix is shown on the wetland mitigation slopes. A better mix selection from the BWSR choices would be the W1 mix. However, I would again recommend the City native pond seed mix for this area, supplemented with flowering native plugs every 10 feet. All biofiltration areas should also be supplemented with flowering plugs. Biofiltration areas planted with the transitional seed mix should have a low- profile height associated with the forbes. All Native seed mix areas should be planted by a contractor on the Minnesota Department of Natural Resources list of contractors. The native areas should be maintained for a minimum of 3 years by the approved contractor and if possible burned at the end of 3 years. 7. More trees should be planted particularly in type C and D soils. The C type soils intersect biofiltration pond number 9 and wetland mitigation area 10 on the North side, East side, South side and South west corner. Salix `Golden Curls' is a marginally hardy plant and non - native. The AUAR recommends that water infiltration areas be augmented with large herbaceous woody plant materials such as Aspen and Cottonwoods. Therefore substituting more of these types of species and more abundant in the type C soil areas in accordance with the AUAR recommendations. Cottonwoods must be of the non - seeding types. Recommend one tree per 25' O.C. in these type C soil areas. • • •