[Ord. No. 95-12 §3.1, 3-7-1995]
No development equal to or greater than ten thousand (10,000) square feet shall increase the quantity and rate of stormwater emanating from said land areas except in accordance with an approved Stormwater Management Plan as provided in these regulations. The Stormwater Management Plan shall be prepared by a licensed professional engineer in the State where the development occurs. No building permits shall be issued until and unless the Stormwater Management Plan has been approved by the City Building Inspector.
[Ord. No. 95-12 §3.2, 3-7-1995]
A. 
The Preliminary Stormwater Management Plan for any proposed development shall contain, but not be limited to, the following information and date:
1. 
Topographic map outlining the limits of the contributing area. Topographic maps should be the best available U.S.G.S. 7.5 minute quandrange topographic maps with a ten (10) foot contour interval will be accepted as a minimal requirement;
2. 
Site plan suitable scale and contour interval, showing the land to be developed and such adjoining land whose topography may affect the layout or drainage patterns for the development;
3. 
The location of streams and other flood water runoff channels, the extent of flood plains at the established high water elevations, the limits of the floodway, if pertinent, and any additional information, all of which shall be properly identified;
4. 
The normal shoreline of lakes, ponds, swamps, and detention basins including their flood plains and inflow and outflow structures if such structures exist;
5. 
The location and calculated flow rates of other existing storm drains, inlets and outfalls;
6. 
The location and calculated flow rates of any existing storm, sanitary and combined sewers which occur within the proposed project site or adjacent thereto within a distance of approximately five hundred (500) feet from the perimeter of said site;
7. 
The location and observed flow rates of any flowing springs, existing wells or any existing seepage areas as determined by means of a field inspection of the property;
8. 
General information regarding the type and characteristics of soils which will be encountered within the project;
9. 
Concepts which will be considered within the development to handle safely all stormwater runoff, including the methods for detention or control of increased stormwater runoff generated by the project development;
10. 
A general plan showing the extent and nature of the storm drainage facilities which will be planned to serve the proposed project including preliminary calculations indicating the runoff which must be handled by such facilities, the methods and criteria which have been utilized in calculating such runoff, and basic information regarding the receiving stream channel into which such drainage facilities will discharge;
11. 
Calculations supporting the method and capacity needed for safe and temporary storage of increased runoff resulting from the proposed development, if temporary storage is needed;
12. 
Basic information regarding the receiving stream or channel into which proposed storm drainage facilities will discharge including the channel location, general cross-section, existing downstream culverts and bridges and other waterway openings, any existing detention basins or lakes and other information required to determine, in preliminary form, the effect which the proposed development will have on downstream drainage conditions;
13. 
A general plan indicating the exterior perimeter of the site, the general development proposed for the project, and an indication by means of rough contours showing the terrain after grading the site.
[1]
Note — The information required in Section 430.120 shall be submitted in accordance with existing subdivision plat approval procedures.
[Ord. No. 95-12 §3.3, 3-7-1995]
Following receipt of the Preliminary Stormwater Management Plan, and information to be included with such plan, the general drainage concepts and planning proposals will be reviewed by the City Building Inspector. A review meeting then will be scheduled by the City Building Inspector with representatives of the developer, including the developer's engineer, to review the overall concepts included in the Preliminary Stormwater Management Plan. The purpose of this review shall be to jointly agree upon an overall Stormwater Management Concept for the proposed development and to review criteria and design parameter which shall apply to final design of the project.
[Ord. No. 95-12 §3.4, 3-7-1995]
A. 
Following review of the Preliminary Stormwater Management Plan and after the concept review meeting and general approval of the preliminary plan by the City Building Inspector, a Final Stormwater Management Plan shall be prepared for each phase of the proposed project as each phase is developed. The final plan shall constitute a refinement of the concepts approved in the Preliminary Stormwater Management Plan with preparation and submittal of the following additional detailed information unless specifically excluded during the preliminary concept review meeting:
1. 
A topographic map of the project site and adjacent areas, of suitable scale and contour interval, which shall define the location streams, the extent of flood plans and calculated high water elevations, the shoreline of lakes, ponds, swamps and detention basins including their inflow and outflow structures, if any;
2. 
The location and flowline elevation of all existing sanitary, storm or combined sewers, and the location of any existing sewage treatment facilities, which fall within the project limits and within a distance of two hundred fifty (250) feet beyond the exterior boundaries of said project;
3. 
Detailed determination of runoff anticipated for the entire project site following development indicating design volumes and rates of proposed runoff for each portion of the watershed tributary to the storm drainage system, the calculations used to determine said runoff volumes and rates and restatement of the criteria which have been used by the project engineer throughout his/her calculations;
4. 
A refined layout of the proposed stormwater management system including the location and size of all drainage structures, storm sewers, channels and channel sections, detention basins, and analyses regarding the effect said improvements will have upon the receiving channel and its high water elevation;
5. 
The slope, type, size and flow calculations for all existing and proposed storm sewers and other waterway;
6. 
For all detention basins, if any, a plot or tabulation of storage volumes with corresponding water surface elevations and of the basin outflow rates for those water surface elevations;
7. 
For all detention basins, if any, peak inflow and outflow flowrates for the 2-, 10-, and 100-year storm events, for both pre-development and proposed conditions. Proposed peak flowrates leaving the site must not exceed corresponding pre-project peak flowrates.
[Ord. No. 481-2024, 2-7-2024]
8. 
A refined grading plan for the entire project site drawn at a suitable scale and contour interval, or the terrain within the proposed project site including contours of the existing terrain along with contours indicating final grades which will be established during completion of the project. The grading plan shall also include a plotting of the line defining the high water elevation to be expected under one hundred (100) year peak flow conditions produced by the projected development of the contributing watershed based on the best available land use information;
9. 
A profile and one (1) or more cross-sections of all existing and proposed channels or other open drainage facilities, showing existing conditions and the proposed changes thereto, together with the high water elevations expected from stormwater runoff under the controlled conditions called for by these regulations and the relationship of structures, streets, and other utilities to such channels.
[Ord. No. 95-12 §3.5, 3-7-1995]
A. 
Final Stormwater Management Plans shall be reviewed by the City Building Inspector. If it is determined according to present engineering practice that the proposed development will provide control of stormwater runoff in accordance with the purposes, design criteria and performance standards of these regulations and will not be detrimental to the public health, safety and general welfare, the City Building Inspector shall approve the plan or conditionally approve the plan, setting forth the conditions thereof. If approved, a drainage permit for the development shall be granted.
B. 
If it is determined that the proposed development will not control stormwater runoff in accordance with these regulations, the City Building Inspector shall disapprove the Final Stormwater Management Plan.
C. 
If disapproved, the application and data shall be returned to the applicant for resubmittal.
[1]
Note — Time frames for filing, review and approval of Stormwater Management Plans should coincide with time periods applicable in existing subdivision regulations.