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Planning Commission <br />November 2, 2007 <br />Page Two <br />3. The current hydrant spacing is insufficient to meet city standards and it appears that the <br />addition of a hydrant will be necessary. We would recommend that a hydrant be added <br />between Lots 1 and 2. <br />4. All utilities should be shown in a profile view. The minimum storm sewer pipe size for <br />pipe runs other than leads to single catchbasins is 15-inches. <br />5. Standard detail plates should be included in the final plan set including specifics on the <br />pond outlet structure. <br />Drainage Calculations <br />1. The pond contours for Pond 1 P and 3P scaled from the plans don't appear to match the <br />area information noted in the HydroCAD calculations. The scale may be off when <br />printed so please submit the AutoCAD base drawing so that they can be directly <br />measured. <br />2. For Pond 1 P a detail will be required for the outlet structure. If it will be utilized as an <br />inlet, additional detailed information should be entered into the HydroCAD calculations <br />for the outlet. <br />3. The slope of the storm sewer run provided in the pipe sizing calculations does not match <br />the preliminary plans. Please update the calculations and resubmit. <br />Preliminary Plat <br />1. Infiltration area 2 should be covered by a drainage and utility easement, which covers <br />the ponding area up to 1-foot above the 100-year high water level. <br />2. Additional drainage and utility easement may be necessary on Lots 6 and 7 depending <br />on proposed contours that are added. All drainage from Lot 7 across Lot 6 should be <br />covered. <br />Miscellaneous <br />1. A Stormwater Pollution Prevention Plan should be submitted for review and approval. <br />2. All required permits should be provided including the Watershed Permit, Minnesota <br />Department of Health, and Minnesota Pollution Control Permit for the sanitary sewer <br />extension. <br />The above comments should be addressed and plans should be resubmitted for review. If you <br />have any questions concerning this information, please call me at (763) 780-0450 ext. 13. <br />Sincerely, <br />Elfering & Associates <br />Lee Elfering, P.E. <br />City Engineer <br />2 <br />7:\PROJ\120101G -Whispering Pines\ID'ainage Submittal 103007\Itr-110207-PC.doc <br />