(A) Submission requirements for subdivisions. Plans, profiles and supporting documentation to verify conformance with this chapter shall be submitted along with the usual plan submissions required in Chapter 151 - Subdivision Rules and Regulations.
(1) Preliminary plans. In addition to the requirements of Chapter 151, a plan showing the total area contributing runoff to the subdivision or project area being considered shall be submitted with the preliminary plans. This plan shall contain, but is not limited to, the following information:
(a) A contour plan showing the outline of all areas outside the project area that contributes runoff to it;
(b) Estimated runoff (Q) before and after development for terminal points along natural streams, proposed open channels, and other strategic points such as existing storm sewers or culverts;
(c) Location of proposed detention/retention areas; and
(d) Location of proposed stormwater quality control measures and BMPs.
(e) Any other information required by the city to clarify intent.
(2) Improvement plans. In addition to the requirements of Chapter 151, the improvement plan for the project area shall contain, but is not limited to, the following information:
(a) Diameter, length, slope, type pipe (ODOT designation for concrete pipe), and class (if other than Class II), of all storm sewers, culverts, and subsurface drainage;
(b) Invert elevations on profiles of all pipes at terminal points such as manholes, inlets and catch basins, and headwalls;
(c) Top of grate elevations of manholes and grate flowlines of catch basins and inlets located outside the public right-of-way. This information shall be submitted for structures within the right-of-way when required by the City Engineer;
(d) Type of catch basin, inlet and manhole;
(e) Headwall type;
(f) Actual existing and proposed cross sections of open channels showing width of bottom, depth of water, erosion control measures and limits, and side of slopes at each point of design along with a profile indicating the longitudinal slope and bottom elevations at the terminal points of design;
(g) High and low points indicating the direction of runoff flow along the profile of a roadway;
(h) Structural details and design data for detention/retention facilities and stormwater quality BMPs;
(i) Details of construction for all structures not included in the city standard construction drawings, this chapter or other referenced standards;
(j) Easements;
(k) Other requirements of this chapter; and
(l) Any other information required by the City Engineer to clarify intent or design features.
(3) Drainage and grading plans. In addition to the improvement plan, a drainage plan shall be submitted. This plan may be the improvement plan required above or a similar plan at a scale of 1 inch = 100 feet or larger showing at least the following additional information:
(a) Contours indicating the existing and final grading at vertical increments of no more than two feet;
(b) Discharge (Q), coefficient of runoff (c) and drainage area (A) along with the outline of the drainage area for each inlet, catch basin, culvert, and open channel point of design and other locations designated by the City Engineer. Drainage areas that lie partially outside the limits of the drainage and grading plan may be delineated on any contour map acceptable to the City Engineer;
(c) Discharge (Q) before and after development, in accordance with the design requirements, at strategic points within and at the extremities of the project area;
(d) Delineation of the boundaries and contour elevation, along with the track, of the major drainage system through downstream areas to an adequate outlet - though the outlet may be outside the project area;
(e) Delineation of the horizontal limits of ponding areas at low points (sags) in the street profile and low points outside the street right-of-way including, but not limited to, culvert headwater, natural stream water surfaces, and sump type inlets for storms with frequencies of 25 years and 100 years;
(f) High and low water horizontal limits and contour elevation of detention/retention/ sedimentation facilities along with water surface and control weir elevations, outlet structures, and the like;
(g) Areas outside the project area susceptible to sediment deposits or to erosion caused by accelerated runoff;
(h) Location of soils that may be limited for the proposed use;
(i) All requirements of this chapter; and
(j) Any other information required by the City Engineer to clarify intent, specified design requirements, or design features.
(4) Stormwater quality control measure. A plan showing the location of the required stormwater quality control measure is necessary. All developed areas are to be treated with an acceptable post-construction storm water quality best management practice. Practices chosen must be sized to treat the water quality volume (WQv) and to ensure compliance to the maximum extent practicable with Ohio EPA Water Quality Standards (Ohio Administrative Code Chapter 3745-1) and latest version of the Ohio EPA Construction General Storm Water NPDES discharge permit requirements applicable to the property.
(5) Supporting data. All data and design information used for the design of drainage facilities and for determining downstream flood information shall be submitted with the drainage and grading plan. To facilitate review and avoid confusion, legends, descriptions, and structure numbering, used on design forms or other calculations shall be identical to those used on the improvement plans and the drainage and grading plan. These data shall include but are not limited to:
(a) Weighted runoff coefficient calculations for each contributing area;
(b) Pavement drainage calculations;
(c) Storm sewer computations;
(d) Culvert design computations;
(e) Open channel computations;
(f) Detention/retention facilities computations;
(g) Major drainage system computations unless specifically not required by the City Engineer;
(h) Post construction water quality volume calculations; and
(i) Any other information required by the City Engineer to clarify intent or design features.
(6) As-built plans. Amended improvement plans specifying the locations, dimensions, elevations, and capacities of designated facilities as constructed shall be submitted to the city upon construction completion of the project. These shall include all required design features except those waived by the City Engineer.
(B) Submission requirements for land developments other than subdivisions shall be the same as the requirements for subdivisions but may be altered by the City Engineer for specific project areas.
(Ord. 04-1990, passed 3-5-90; Am. Ord. 14-2021, passed 8-2-21)