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How will the drainage be addressed? Under traditional practice of storm water management, rainwater is allowed to flow out into the street and into storm sewers. Eventually it flows into Lake Owasso. This storm water carries pollutants such as sand, chemicals, and fertilizers from our lawns and driveways. By infiltrating the rainwater as close as possible to where it falls, we can reduce the impact on our lakes, as well as the local wildlife. As part of the project, we will construct Best Management Practices (BMPs) to improve storm water quality and collect runoff. Through the design process, we will be identifying locations on the project suited for a BMP. The proposed BMPs would be constructed within the City right-of-way, which extends approximately 16 feet behind the edge of the road. The cost will be paid for with city storm water funds. Rainwater is routed to the BMP and allowed to percolate down into the ground and be filtered by the plants. This trapping of water and the filtration process removes nutrients and pollutants. By acting as amicro-detention pond, the plants and soils provide an easy, natural way of reducing the amount of water that flows from rooftops, lawns, and driveways. Then, using the concept of bio- retention, these gardens remove pollutants from storm water and help restore natural infiltration. BMPs are design to overflow into the storm sewer system during larger rain events. Storm water best management practices are tools that can be used to address water volume and quality. Like any tool, they should only be used where they will be effective. Factors that can impact their success are; soils, topography, and property owner support. Some brief descriptions of the types of BMPs we are considering with this project: • Rain Garden: A rain garden is a relatively small area of plantings near a paved area. Rain water is routed to the garden where it is used by the plants and infiltrates naturally into the soil of the garden. • Biofiltration Basin: A biofiltration basin is similar to a rain garden in that it is a relatively small area of plantings near a paved area. However, these are constructed in areas where the soils do not infiltrate into the ground quickly. Rainwater is routed to the garden and filtered naturally by plants, but there is an overflow to the storm sewer system. Rain garden in City street boulevard Infiltration trench: An infiltration trench is located underground. This shallow excavation is filled with porous material to create an underground reservoir for storm water runoff. The runoff gradually percolates through the bottom and the sides of the trench into the surrounding subsoil over a period of days. Would you like a rain garden? Rain gardens constructed in conjunction with reconstruction projects are a partnership between the property owners and the City of Roseville. All costs for materials, excavation and backfill are paid for by the City. The size, location, and planting plan are coordinated with the homeowner. The City's contractor will prepare the site for the garden (excavate and make sure suitable soils are within the proposed rain garden) and deliver the plants. We ask that the homeowner plant and maintain the rain garden. We find this most effective, because the homeowner can modify the design if they want, and they learn what each plants look like when planting them. This way, they know what to leave and what to pull when weeding. Homeowners are asked to sign a maintenance agreement for the rain gardens that are installed by the City. The City is looking for volunteers. If you are interested in having the City construct a rain garden in your boulevard, please contact Deb Bloom at 651-792-7042 or deb.bloomCa~ci.roseville.mn.us . Dale Street Reconstruction June 10, 2010 Page 3 T `F~S~'~T. • ~.~i~. } . y ~e',1 c Pt 5'W".,~'!Y ~~4 y~ I~{j C{~gff