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