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Wetland Re�lacement and Enhancement-It is anticipated that wetland alteration(i.e.,grading for the <br /> stormwater pond)will require on-site replacement. Due to the poor quality of the existing wetland <br /> (especially the western portion),there are opportunities to provide a net improvement in the ecological <br /> health of this habitat and enhance its aesthetics. The southern portion of the site wetland is situated just <br /> north of Watertown Road. Enhancing this location would provide an attractive amenity for the <br /> development to be enjoyed by both residents and passers-by. Our recommendations for wetland <br /> replacement and enhancement include: <br /> • Provide wetland replacement in the old field area just east and/or north of the existing stand of <br /> black willows. These already low-lying areas are adjacent to the e�cisting wetland and could be <br /> converted to wetland with minimal grading. The wetland replacement design could allow for <br /> relatively flat slopes to provide gradual transition zones for a variety of wetland and upland <br /> plants. Replacement wetland areas should be seeded and planted with appropriate,local ecotype <br /> native vegetation(e.g.,fox sedge,river bulrush,marsh milkweed,golden Alexanders,New <br /> England aster,wool grass,iris). Care will need to be taken to prevent invasion of reed canary <br /> grass into the replacement area. <br /> • Remove all non-native vegetation(e.g.,mostly reed canary grass). This should be done using <br /> appropriate methods(e.g.,using an aquatic-approved herbicide,such as Rodeo). <br /> � Seed and/or plant areas where reed canary grass was reznoved with appropriate,local ecotype <br /> native vegetation. <br /> Vegetated Buffer Establishment-Vegetated buffers can provide many ecological and aesthetic benefits <br /> including stormwater management,wildlife habitat,and visual screening, Generally,the wider the buffer, <br /> the greater the benefits. Buffers are particularly important around wetlands for water quality protection. <br /> Vegetated buffers should be established by removing non-native or invasive plant species and re-planting <br /> with appropriate,local ecotype perennial native species. Selecting the appropriate species depends on the <br /> soil,moisture regime,amount of sunlight,adjacent vegetation,and aesthetic desires. <br /> Stormwater l�ianagement-Ecologically sound stormwater management is important to protect the <br /> existing on-site wetland as well as downstream receiving waters,including Stubbs Bay of Lake <br /> Minnetonka. Protection of aquatic resources often requires techniques beyond or in place of standard <br /> curb and gutter collecrion systems and stormwater ponds. The proposed plan provides for the new <br /> roadway and stormwater pipes to convey runoff into a treatment pond partially located in the willow sta�d <br /> of the existing wetland. Recommendations for stormwater rrianagement include: <br /> � Ivlinimize impervious surfaces throughout the development. This can be accomplished by using <br /> narrower streets and limiting roof,driveway,and other hard surface areas on individuallots. <br /> o Employ rain gardens or other types of uafiltration systems where appropriate. This requires� <br /> source of water and slopes that allow for gravity flow of runoff into management areas. <br /> Management areas preferably have upland soils with higher infiltration rates. 1Chese types of soils <br /> exist on the site, Rain gardens can be lacated and designed to intercept and manage runoff from <br /> individual lots,reducing the capacity required by other stormwater management areas on the site. <br /> This approach c�n result ua not only a sm�ller pond,but more effective and more natural <br /> stormwater anaayagernent,which can greatly benefit aquatic resources both on site and <br /> downstream. <br /> o �,stablish permanent natYVe v�getation ir�the pr�posed rear-1ot sv�ales. tWhile grassed swales <br /> provide conveyance af Yvnoff,nativ�vegetation in these swales would aflso provide greater <br /> opportumity for runoff infiltration,reducing the amount of water that may reach the starinwater <br /> pond. <br /> �= As men�4c�ned preva�ti�s�Y,astace�E��s±or�:v��ater mardageanent g�cand along the�r✓ester�edge of'th� <br /> sout�ern wetland a�ea. T'his would e�eduee forest impacts as wefl�as avoic�impacts���the sfigh�ly <br /> more diverse portions of the wetland. <br /> 050929:111�05 4 of 5 MacKinnon Hill <br />