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<br />3 of 4 <br /> <br /> <br />10062 Flanders Court NE – Blaine, MN 55449 – Ph: (763) 780-0450 Fax (763) 780-0452 <br /> <br />the development. However, the narrative indicates that a filtration volume of <br />6,026 cf is provided and as such the infiltration practice will not drain down <br />within the 48 hour period based on the calculations. Either the volume to be <br />filtrated should be reduced to 4,692 or more infiltration area must be <br />provided. <br />2. The time of concentration paths for the existing conditions should be <br />reviewed as the exhibit does not match in the inputs into the HydroCAD <br />model for E1 and E2. <br />3. The elevation of the existing boulevard inlet off Rice Street is shown as 941.0 <br />on the plans, but the inputs for Pond P2 indicate an elevation of 941.40. This <br />discrepancy should be addressed. <br />4. The proposed condition HydroCAD model should start at 0 hours as was <br />done on the existing conditions. <br />5. The time of concentration paths should be added to the proposed condition <br />drainage map. <br />6. The proposed condition drainage areas P4 and OS-1 should be revised. P-4 <br />should include all of the proposed street and boulevard north of the proposed <br />street that is west of the high point as it will directly discharge to Rice Street. <br />OS-1 should be reduced by the appropriate area and should then be modeled <br />as a Pond just as it was in the existing conditions. <br />7. The devices for Pond 2P:FILT2 should be revised for the pipe type, slopes, <br />and inverts. <br />8. The pond for OS-1 and the pond for P1 should be routed into the existing <br />outlet pipe to determine the effects of the existing pipe. <br /> <br />Landscape Plan <br />1. The landscaping plan meets the general tree replacement quantity, but there <br />have been significant concerns from residential property owners to the south <br />about the need for screening. An evergreen row is proposed along the south <br />boundary. As the Planning Commission is aware additional plantings were <br />requested of Developers as part of previously submitted townhome plan for <br />this particular site. The current Developer should be made aware of this <br />concern and a discussion held if the current level of planting is adequate. <br />2. The slopes of the pond above the normal water level of the proposed pond <br />are called out to be seeded with MnDOT seed mix 33-262. This is a seed mix <br />consisting of 42% native grasses, 1% forbes (native flowering plants), and <br />57% oat cover crop. Establishment of these native mixes, especially the <br />forbes portion can take several years. Due to the relatively small area of the <br />pond slopes we would recommend that some plug plantings or large plants <br />be used to supplement the seeding to make the pond more of an amenity to <br />the site. The Watershed provides assistance with planting plans of this <br />nature and would likely assist the Owner with a planting design.