(a) SMPs are intended to provide information on all soil erosion, sediment and runoff control activities, storm water control measures (SCMs), and best management practices (BMPs) to be used and incorporated on the site both during and after site development. This information includes, but is not limited to, site grading, storm water management facilities and practices, erosion, sediment and runoff control information, maintenance plans, and other measures that focus on managing the effects of earth-disturbing activities that occur as a result of site development.
(b) No earth-disturbing activity subject to regulation under this chapter shall be undertaken for any land disturbance equal to or greater than one acre or less than one acre, but part of a larger common plan of development disturbing one or more acres of land, without an approved Site Development Plan as required under Section 1050.52 and a Storm Water Management Plan (SMP) as required under this section. Soil disturbing activities shall not begin and permits will not be issued without the installation of erosion and sediment controls.
(c) Each SMP shall provide site designs that meet the performance standards required by this section.
(d) An SMP shall specifically include all the following:
(1) The minimum elements required in the Site Development Plan described this chapter.
(2) The contents of the Storm Water Pollution Prevention Plan (SWP3) required by Ohio EPA Permit No. OHC000005 and incorporated herein by reference including the following:
A. Methods to minimize the exposure of building materials and products, construction wastes, trash, landscape materials such as fertilizers and herbicides, sanitary waste exposure to precipitation, storm runoff, or snow melt;
B. Measures to handle chemical spills or leaks possibly referencing other spill prevention plans and procedures;
C. Minimize pollutants from vehicle and wheel wash water. Detergents are not to be used, treatment in a sediment basin is required or other equivalent treatment before wash water is discharged.
(3) A determination of runoff co-efficients for both the pre-construction and post construction site conditions.
(4) For all disturbances of five or more acres of land (or less than five acres, but part of a larger common plan of development or sale which will in total disturb five or more acres of land), a description of post construction BMP(s) chosen and designed to detain and treat a water quality volume (WQv) equivalent to the volume of runoff from a 0.75-inch rainfall in accordance with the methodology outlined in Ohio EPA Permit Number OHC000005, Part III.G.2.e., Large Construction Activities.
(5) Post construction BMPs shall be designed such that the drain time is long enough to provide treatment, but short enough to provide storage available for successive rainfall events as described in Table A. The developer must provide the Village Engineer with written approval from the Ohio EPA to use any post-construction BMP not listed in Table A.
(6) The BMPs and SCMs are available to approach the EPA's guidelines and TMDL requirements for the appropriate watershed.
Table A Target Draw Down (Drain) Times for Structural Post-Construction Treatment Control Practices | |
Storm Water Control Measures (SCMs) | Drain time of WQv |
Table A Target Draw Down (Drain) Times for Structural Post-Construction Treatment Control Practices | |
Storm Water Control Measures (SCMs) | Drain time of WQv |
Infiltration | 48 hours |
Extended detention basins (dry basins) | 48 hours |
Extended detention basins (permeable pavement) | 24 hours |
Retention basins (wet basins) | 24 hours* |
Constructed wetlands (above permanent pool) | 24 hours |
Media filtration/bioretention | 24 hours |
* Provide both a permanent pool and an extended detention volume above the permanent pool, each size at 0.75 * WQv. | |
(7) For all disturbances of more than one acre but less than five acres of land and is not a part of a larger common plan of development or sale which will disturb five or more acres of land, a description of measures that will be installed during the construction process to control pollutants in storm water discharges that will occur after construction operations have been completed. Structural practices must comply with the requirements of the Ohio Environmental Protection Agency (EPA) Permit No. OHC000005: Authorization for Storm Water Discharges Associated with Construction Activity under the National Pollutant Discharge Elimination System (NPDES) Part III.G.2.e.
(8) An implementation schedule which describes the sequence of major construction operations (e.g., grubbing, excavating, grading, utilities and infrastructure installation) and the implementation of erosion, sediment and storm water management practices or facilities to be employed during each operation of the sequence.
(9) A detail drawing of a typical individual lot showing standard individual lot erosion and sediment control practices.
(10) A detailed description of the storm water controls to be incorporated into the SMP and explaining how such controls meet or exceed the appropriate performance standards required by this chapter.
(11) A detailed maintenance plan that describes procedures for inspections, cleaning, maintenance, repair, and replacement needed to ensure the continued performance of control practices by the managing organization responsible for implementing the SMP along with a log documenting grading and stabilization activities as well as amendments to the SWP3 that occur after the commencement of construction. Amendments shall be made if there is a change in design, construction, operation, or maintenance that has a significant effect on the potential discharge of pollutants to surface waters of the state or if the SWP3 is proved to be ineffective at controlling pollutants. Such plans must ensure that pollutants collected within structural post construction practices, be disposed of in accordance with local, State, and Federal regulations.
(12) A Site Map including:
A. Limits of earth-disturbing activity of the site including associated off-site borrow or spoil areas.
B. Soil types on the site, including locations of unstable or highly erodible soils.
C. Existing and proposed elevations and contours. A delineation of drainage watersheds expected during and after major grading activities as well as the size of each drainage watershed, in acres.
D. Existing and planned locations of buildings, roads, parking facilities and utilities.
E. The location of all erosion and sediment control practices, including areas likely to require temporary stabilization during site development.
F. Sediment and storm water management basins, noting their required and provided sediment storage and dewatering/settling volume and contributing drainage area in addition to the weir length or skimmer size as applicable/provided.
G. Permanent storm water management practices to be used to control pollutants in storm water after completion of the construction project.
H. Areas designated for the storage or disposal of solid, sanitary, and toxic wastes, including dumpster areas, cement truck washout areas, and vehicle fueling and maintenance.
I. The location of designated construction entrances where vehicles will access the site.
J. The location of any in-stream activities, including stream crossings.
K. Surface water locations of springs, wetlands, streams, lakes, water wells, etc., on or within 100 feet of the site, and including the boundaries of wetlands or stream channels and first subsequent named receiving water(s) the permittee intends to fill or relocate for which the permittee is seeking approval from the U.S. Army Corps of Engineers and/or Ohio EPA. For discharge to a municipal separate storm sewer system (MS4), the point of discharge to the MS4 and the location where the MS4 discharges should be included.
L. The location of permanent SCMs to be used to control pollutants in storm water after construction operations have been completed.
(13) A copy of the written notification from the director of the Ohio EPA that the developer or permittee has been granted permit coverage and is authorized to discharge storm water associated with construction activity under the conditions of the permit and a copy of the Ohio EPA permit under which the permittee has been granted coverage or a copy of the permit requirements.
(14) The permittee's Ohio EPA Facility Permit Number.
(15) The identity of all subcontractors engaged in activities that could impact storm water runoff.
(16) Signatures from all of the identified subcontractors indicating that they have been informed and understand their roles and responsibilities in complying with the SMP.
(17) Determination of post-development runoff.
A. Each SMP shall include a comparison that quantifies the volume and rate of runoff from the site by subdrainage areas for pre-development conditions and proposed conditions. This evaluation shall be prepared according to methods prescribed in the current edition of Rainwater and Land Development or other appropriate sources. The evaluation shall:
1. Show delineation and sequence of subdrainage units which comprise the area proposed for development.
2. Indicate the hydraulic length of slope per individual subdrainage unit and the length of the natural or man-made watercourse which accommodates the surface runoff from each subdrainage unit.
3. Indicate within the legend the average percent slope, erosion factor (K) and runoff curve number (CN) per the individual subdrainage areas.
4. Include a hydrograph using the TR55, Type II Rainfall Distribution Pattern over a 24-hour period for the following return intervals: 1, 2, 5, 10, 25, 50, and 100-year storms. Hydrographs for each of the recurrence intervals shall be produced for both the existing and proposed conditions.
5. The 24-hour rainfall depths in Table B shall be utilized to quantify the storm water runoff for the existing and proposed conditions.
Table B Sectional Mean Frequency Distributions for Storm Period of 24 Hours and Recurrence Intervals of 1 Year to 100 Years in Ohio | |
Return Period (years) | Rainfall (inches) for given recurrence interval |
Table B Sectional Mean Frequency Distributions for Storm Period of 24 Hours and Recurrence Intervals of 1 Year to 100 Years in Ohio | |
Return Period (years) | Rainfall (inches) for given recurrence interval |
1 | 2.00 inches |
2 | 2.40 inches |
5 | 2.98 inches |
10 | 3.46 inches |
25 | 4.16 inches |
50 | 4.74 inches |
100 | 5.36 inches |
Source: NOAA Atlas 14, Precipitation Frequency Estimates, Extracted Feb. 2011 | |
(18) Calculations for the design of storm water management facilities shall demonstrate the following for each subdrainage unit:
A. The peak rate of runoff from the critical storm and all more frequent storms occurring on the site does not exceed the peak rate of runoff from a one-year frequency, 24-hour storm occurring on the same site under pre-development conditions.
B. Storms of less frequent occurrence (greater return periods) than the critical storm, shall have a proposed peak rate of runoff less than the existing peak rate of runoff.
C. The overflow spillway elevation shall be set one foot above the 100-year storm elevation and the surrounding berm elevation shall set minimally one foot higher than the overflow spillway.
(19) Calculation of a critical storm for each subdrainage unit of the site shall be determined as follows:
A. Calculate by appropriate hydrologic methods, such as the NRCS Technical Release 55 (TR55) the total volume of runoff from a one-year frequency, 24-hour storm occurring on the development area before and after development. For redevelopment sites, the pre- developed condition for existing impervious surfaces shall be defined as grassland in good hydrologic condition for the pre-developed peak discharge rates, critical storm and volume storage calculations.
B. From the volumes determined in above, determine the percentage increase in volume of runoff due to the proposed development, and using this percentage, select the 24-hour critical storm from Table C.
Table C 24-Hour Critical Storm Runoff Rate | ||
If the percentage of increase in runoff volume is: | ||
Equal to or greater than | And less than | The critical storm runoff rate will be limited to: |
Table C 24-Hour Critical Storm Runoff Rate | ||
If the percentage of increase in runoff volume is: | ||
Equal to or greater than | And less than | The critical storm runoff rate will be limited to: |
0 | 10 | 1 year |
10 | 20 | 2 years |
20 | 50 | 5 years |
50 | 100 | 10 years |
100 | 250 | 25 years |
250 | 500 | 50 years |
500 | - | 100 years |
C. The Village Engineer shall approve or reject any calculation method based on its technical validity for the given situation. Downstream capacity may further reduce maximum discharge requirements.
D. When calculating runoff for post construction areas, assume an impervious surface such as asphalt or concrete except in the instances of engineered permeable pavement systems. When a combination of impervious area reduction and storm water quality control facilities are used, ensure a 20% reduction of the site impervious area, provide for treatment of at least 20% of the WQv, or a combination of the two.
(20) List TMDLs applicable for the site and demonstrate that appropriate BMPs or storm water control measures (SCMs) have been selected to address these TMDLs. (A TMDL identifier for Northeast Ohio communities is available at http://www.neohiostormwater.coin/)
(21) For subdivided developments, a detail drawing of a typical individual lot showing standard individual lot erosion and sediment control practices. This does not remove the responsibility to designate specific erosion and sediment control practices in the SWP3 for areas such as steep slopes, stream banks, drainage ways, and riparian zones.
(e) Storm Water Management Facility Design Criteria.
(1) Runoff from all drainage area tributary to the storm water management facility must be conveyed to the facility for all design storms up to and including the 100-year storm.
(2) A vehicular access drive and permanent easements must be provided from a public roadway to the outlet control device as approved by the Village Engineer.
(3) While implementing SCMs, attempt to preserve natural existing vegetative buffer strips, and phase construction operations to disturb minimal land at any one time. Designate tree preservation areas or other similar protected areas.
(f) Storm Water Basins.
(1) The outlet structure and/or riser shall be located in the embankment for maintenance purposes.
(2) An emergency spillway is to be provided on all storm water basins. Emergency spillways must be designed to convey flood flows safely past the embankment, and shall be designed in accordance with NRCS standards and specifications. The emergency spillway shall have a 100-year design storm capacity unless exempted in writing by the Village Engineer.
(3) All embankments shall be designed in accordance with the specifications in the current edition of the Ohio Rainwater and Land Development manual, the NRCS Field Office Technical Guide for Cuyahoga County, and the Ohio EPA standards.
A. All pond grading shall have a maximum slope of 3:1 and shall incorporate safety features to ensure public safety.
B. The primary spillway opening shall be constructed so as to not permit access to the public and other non-maintenance personnel.
(g) Off-Site Storm Water Control Facilities.
(1) Exceptions to requiring permanent on-site runoff control on the site may be considered by the Village Engineer provided the applicant can prove that:
(2) The intent and standards of this chapter for runoff control can be best achieved by the utilization of off-site storm water control facilities.
(3) Runoff from the site can be conveyed to off-site storm water facilities in a manner and by means which satisfy or surpass the standards of this chapter.
(4) The applicant has ownership of or the right to use the off-site facility in question.
(h) Underground Storm Water Facilities.
(1) Underground storm water control facilities may be constructed to provide storm water management for development sites as approved by the Village Engineer.
(2) Voids in the stone aggregate around underground pipes or chambers are not to be included in the volume calculations for underground detention storm water management facilities.
(Ord. 2015-3-5. Passed 4-7-15; Ord. 2017-3-16. Passed 5-2-17; Ord. 2021-6-7. Passed 6-8-21; Ord. 2022-4-6. Passed 4-5-22; Ord. 2022-5-3. Passed 5-2-22.)