06-11-09 Planning Comm. Agenda - Laserfiche WebLink

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Planning Commission May 29, 2009 Page Two Utility Plan 1. The sanitary sewer line to the north of the development that is being used for sanitary sewer extension is currently owned and operated by the Metropolitan Council. The specific details on the connection and a permit for the connection will need to be coordinated with their representatives; however it is our recommendation that a new manhole structure be added over the existing line to allow adequate maintenance of the new line by City crews. The location of the connection to this line may need to be moved to ensure access to the manhole with maintenance equipment. 2. A drop conforming to the City details must be utilized for Sanitary Manhole 2. 3. Any work within the Edgerton Street right-of-way will need to be permitted through Ramsey County. If the bituminous surface is disturbed full lane replacement will be required. Details should be provided on required pavement removals and other impacts to existing features. 4. At the time of platting for Lots 3, 4, and 5 a drainage and utility easement will be required over the 8" sanitary sewer mainline. This easement should be a minimum of 3 times as wide as the pipe is deep centered over the pipe. This easement width will be required in the area of MH-2. 5. A profile view must be provided with the final plans for the sanitary sewer extension. 6. All storm sewer culverts should be labeled with proposed elevations and slopes. Storm Sewer Calculations 1. Routing should be completed over a time span from 0 to 24 hours. 2. The routing diagram provided for the post-development HydroCAD report is inaccurate and should be revised for the area that is discharging to the north. 3. Time of concentrations for the post-development Subcatchments should be reviewed. Items that would be called into question include the length of sheet flow due to actual conditions that would result in concentrated flow due to swales, structures, or driveways and that the post development times should be close to the existing when the area has not changed or has been reduced. 4. The outlet invert for the culvert from Pond 3P would result in a top of pipe that is above the gutter line of Little Canada Road. This should be reviewed and revised. 5. The proposed discharge rate exceeds the existing rate for the Existing Catchbasin on the south side of the property for the 100 year event and for Pond P-2 for the 10 year and 100 year event. This should be addressed. 6. Soil borings and infiltration rate determination will be needed in the areas proposed for infiltration. 7. The area on the Post-Development drainage areas plan sheet for P1 should be corrected to match the HydroCAD. ~1r-052909-PC 10062 Flanders Court NE, Blaine, MN 55449 -Phone: (763) 780-0450 -Fax: (763) 780-0452