(A) General. The following information shall either accompany or be presented on the plans of all development projects. All plan sheets and other information and data prepared shall be stamped by a licensed professional engineer or land surveyor engaged in storm drainage design.
(B) Existing condition information (to be shown on submitted plans):
(1) A title sheet shall be included with the following information: project name and location map, name, address, telephone number and seal of the registered professional engineer or licensed/registered land surveyor preparing the plans;
(2) Legal description of site;
(3) A topographic map of the land to be developed and adjoining land whose topography may affect the layout or drainage of the development. The contour intervals shall be 1 foot when slopes are less or equal to than 2% and shall be 2 feet when slopes exceed 2%. All elevations shall be given in either National Geodetic Vertical Datum of 1929 (NGVD) or North American Vertical Datum of 1988 (NAVD);
(a) If the project site is less than or equal to 2 acres in total land area, the topographic map shall include all topography of land surrounding the site to a distance of at least 100 feet; and
(b) If the project site is greater than 2 acres in total land area, the topographic map shall include all topography of land surrounding the site to a distance of at least 200 feet.
(4) Adequate number of benchmarks shown with elevations referenced to NGVD, NAVD, to facilitate checking of elevations without more than 1 setup of a surveyor's level, except for large development sites where additional setups may be warranted;
(5) The location of existing streams and other stormwater runoff channels;
(6) One or more typical cross sections of all existing channels or other open drainage facilities. Cross sections must be represented perpendicular to the expected flow path and the location indicated on the map;
(7) Spot elevations shown at drainage break points;
(8) Normal shoreline of lakes, ponds, swamps and detention/retention facilities, their floodplains and direction of inflow and outflow;
(9) The size and location of regulated drains, farm drains, inlets and outfalls, if any of record. Include the elevations of tile outlet inverts;
(10) Storm, sanitary and combined sewers and outfalls, if any of record;
(11) Septic tank systems, disposal field and outlet, if any of record;
(12) Seeps, springs, flowing and other wells, that are visible or of record;
(13) Roads, rights-of-way, building set backs, drainage, regulated drain and overhead or underground utility easements;
(14) The extent of the floodplains for any stream or channel (draining more than 640 acres or 1 square mile) at the established 100-year flood elevation per FEMA maps, IDNR Recommendation Letter, or engineer's calculations and the limits of the regulatory floodway, all properly identified and sources noted. NOTE: The regulatory floodway may be measured from the effective FEMA map; however, floodplain boundaries shall be determined based on the 100-year flood elevation/ profile and the existing topography on the map (flood insurance will still be required on those portions of the FEMA designated floodplain until the applicant requests and receives a LOMR/LOMA from FEMA);
(15) The extent and location of any current wetlands area located on the subject property. A plan must be submitted which details how the wetland loss will be mitigated. The developer is responsible for all necessary coordination and compliance with IDNR or COE regulations; and
(16) Each plan sheet shall be 24 inches by 36 inches in size and include the following:
(a) A title block located in the lower right hand corner of each sheet that includes the project name, job number, sheet title (geometric grading and the like), sheet number, date of preparation and latest revision date and description;
(b) Map scale (preferably with a scale between 1 inch=20 feet and 1 inch=100 feet);
(c) A legend clearly identifying all symbols indicated on each sheet; and
(d) North arrow.
(C) Existing condition information (to be included within a report or as a separate exhibit):
(1) Soil names and their hydrologic classification for the proposed development when hydrologic methods requiring soils information are used;
(2) Each upstream, off-site drainage area tributary to the subject site on USGS quadrangle maps or other more detailed topographic maps;
(3) Watershed boundary delineation for each stormwater facility (storm sewer, culvert, swale, detention basin and the like) on the subject property; and
(4) Copy of the effective FEMA map, annotated to show the project location and property boundaries in relation to the regulatory floodplain and floodway.
(D) Proposed condition information to be shown on submitted plans (in addition to previous plan requirements):
(1) Plan to convey upstream, off-site runoff through or around the subject property;
(2) Proposed contours and where they tie into existing contours;
(3) Location and percentage of impervious surfaces expected when the development is completed;
(4) Depth and amount of storage required by design of the new facilities;
(5) Proposed layout and design of storm sewers, other storm drains including the outfall and outlet locations and (approximate) invert elevations, the receiving stream or channel and its 100-year return period water elevation;
(6) Layout of swales which collect runoff from on-site and/or off-site watersheds;
(7) Existing detention/retention facilities to be maintained, enlarged or otherwise altered and new ponds or basins to be built;
(8) Proposed culverts and bridges; include elevations, waterway openings;
(9) Identification of overland flow routes to detention/retention facilities;
(10) New channels or other open drainage facilities to be constructed, their locations, cross sections and profiles. Cross sections should be represented perpendicular to the expected flow path;
(11) Interim drainage plan which is to be incorporated into the development pending completion of the development and the final drainage plan;
(12) All proposed underground and overhead utility and drainage easements;
(13) Parts of the proposed street system where pavements are planned to be depressed sufficiently to convey or temporarily store overflow from storm sewers and over the curb runoff resulting from the heavier rainstorms and the outlets for overflow;
(14) Slope, type and size of all sewers and other waterways. Plan and profile of all storm sewers and culverts must also be submitted; and
(15) Erosion control plan.
(E) Proposed condition information (to be included within a report or as a separate exhibit). The report should be comprehensive and detail all the steps which the designer took during the design process and how the design satisfies the requirements of this chapter. The report should include:
(1) A description of the present land use as well as proposed land use;
(2) Hydrologic and hydraulic information detailing existing and proposed drainage patterns on the subject site, along with any off-site drainage entering the site. All hydrologic and hydraulic computation should be included in the report. These calculations should include, but not be limited to: development of runoff curve numbers or runoff coefficients, runoff calculations, stage-discharge, relationships for detention/retention facility outfalls, storage volume, times of concentration;
(3) Watershed boundary delineation for each proposed stormwater facility (storm sewer, culverts, swale, detention basin and the like);
(4) For all detention/retention facilities, a plot or tabulation of storage volumes with corresponding water surface elevations and a plot or tabulations of the facility outfall rates for those water surface elevations;
(5) Copies of all computer model runs used in the drainage analyses. These computer runs should include both the model inputs and the outputs. A floppy diskette with input files may expedite the review process; and
(6) Discussion of significant drainage problems associated with the project and assumptions associated with procedures used to evaluate and propose solutions to these problems.
(Ord. 01-2000, passed 7-18-2000)