(A) Development and re-development. Single family residential development shall generally be exempt from permanent water quality, rate control, and volume reduction practices. However, if the City Engineer deems that previous documented flooding or related storm water issues exist or the increased imperviousness resulting from new residential construction totals 0.25 acres or more, this development shall be subject to appropriate permanent storm water management practices. Commercial, industrial development, or redevelopment projects equal to or exceeding a 0.25 acre threshold of new impervious surfaces or located in areas where flooding or related storm water issues exist shall be subject to appropriate permanent storm water management requirements. Construction projects shall be developed and in compliance with a storm water management plan that includes the following:
(1) Two sets of clearly legible copies of plans and required information shall be submitted to the city and shall be accompanied by all applicable fees.
(2) Drawings shall be prepared to a scale appropriate to the site of the project and suitable for the review to be performed. At a minimum, the scale shall be one inch equals 50 feet.
(3) Included on all plan submissions shall be the project name and the date of preparation.
(4) Also included on all plan submissions:
(a) Names, addresses, and phone numbers of the land surveyor and engineer;
(b) Property boundaries;
(c) Area(s) to be disturbed;
(d) Spot elevations of proposed grades in relation to existing grades on the subject property and adjacent properties;
(e) Drainage arrows depicting water movement;
(f) Areas where finished slope will be steeper than 5:1 shall be noted;
(g) Location and type of erosion/sediment control devices. The use of innovative practices and new technologies on a performance basis is encouraged. Information and resources include the Minnesota Drainage Manual, current edition;
(h) Location of storm drains, wetlands, sediment ponds, and lakes;
(i) Location of material stockpiles;
(j) Plan for temporary site stabilization. The use of innovative practices and new technologies on a performance basis is encouraged. Information and resources include the Minnesota Drainage Manual, current edition;
(k) Plan for final site stabilization;
(l) Temporary stabilized construction entrance location;
(m) Name of individual responsible for installation and maintenance of control devices;
(n) Any other information pertinent to the particular project that, in the opinion of the city, is necessary for the review of the project.
(B) Permanent storm water management requirements: development/re-development resulting in 0.25 or more acres of new impervious surface.
(1) Hydrologic calculations shall be done for volume runoff, velocities, and peak flow rates by watershed for the two-year, ten-year, and 100-year 24-hour storm events. These shall include: pre-existing peak flow rates, assumed runoff curve numbers, time of concentration used in calculations, and the 100-year flood elevation provided by an engineer licensed to practice in Minnesota.
(2) Proposed conditions. A complete site plan and specifications, signed by the person who designed the plan, shall be drawn to an easily legible scale, shall be clearly labeled with a north arrow and a date of preparation, and shall include, at a minimum, the following information. This submittal shall also include a narrative report summarizing design assumptions, procedures, and tabulated results.
(3) All proposed storm water practices, hydrologic models, and design methodologies shall be reviewed by the city for ordinance compliance.
(Ord. 7, passed 5-10-2016)