Agenda - Council - 04/13/2021 - Laserfiche WebLink

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• Best management practices (BMP's) including infiltration/filtration sites, storm water ponds, etc. shall be clearly labeled on the pre and post project watershed maps. • Plan sheets submitted as watershed maps shall be evaluated as such. They shall be readable and legible and meet all the same requirements including clear delineation of watershed boundaries, readable map scale, and land use shown by an aerial photo background map, or that is clearly depicted based on details on the plan sheet or sheets submitted. • Project plan sheets relevant to the Drainage Permit are required and include: existing site conditions, the proposed grading plan as well as proposed site drainage system plans and profiles. The plans shall include applicable wetland impact/mitigation features and temporary sediment and erosion control measures for the project. In addition, erosion control blanket will be used to stabilize disturbed area on MnDOT right-of-way unless other methods such as rip -rap treatment are called for in the plans and approved by MnDOT. • Pond and basin special structures including weirs and orifices shall be consistent with what is used in the HydroCAD or XPSWMM models submitted and include relevant calculations/details. • A table summary of existing versus proposed site discharge to MnDOT drainage system/right-of-way is required for the 2-year, 10-year and 100-year Atlas 14 rainfall events. • Post project storm water discharge to MnDOT ditches or other open channel shall be limited to flow velocities of 6 fps or less for a 50-year Atlas 14 rainfall event. • Project discharge points that will connect to MnDOT ditch or channel shall be located such that they do not cause erosion or conflict with the grade of the existing ditch or channel. • Proposed access road culverts on MnDOT right-of-way shall be designed for the 10-year Atlas 14 rainfall event unless they are part of a significant drainage ditch along the roadway in which case a 100-year or 50-year design will apply. • Direct connections to MnDOT storm system shall be avoided. Connection to open ditch, or channel is preferred. If direct storm sewer connections cannot be avoided, it is the applicant's responsibility to provide a good connection typically via a new structure. Furthermore, MnDOT offers no warranty that there will not be a hydraulic backwater effects on the new storm line upstream that is connected to MnDOT's existing storm sewer. April 2014