(a) Erosion Control Practices: The Storm Water Control Plan must make use of erosion controls that are capable of providing cover over disturbed soils unless an exception is approved by the City of Middleburg Heights in accordance with Section 1367.16. A description of control practices designed to restabilize disturbed areas after grading or construction shall be included in the Storm Water Control Plan. The Storm Water Control Plan must provide specifications for stabilization of all disturbed areas of the site and provide guidance as to which method of stabilization will be employed for any time of the year. Such practices may include: temporary seeding, permanent seeding, mulching, matting, sod stabilization, vegetative buffer strips, phasing of construction operations, use of construction entrances and use of alternative ground cover.
(1) Stabilization - Disturbed areas must be stabilized as specified in the tables below:
Table 1: Temporary Stabilization
Area Requiring Temporary Stabilization
|
Time Frame to Apply Erosion Controls
|
Any disturbed areas within 50 feet of a stream and not at final grade | Within two days of the most recent disturbance if the area will remain idle for more than 21 days |
For all construction activities, any disturbed areas that will be dormant for more than 21 days but less than one year, and not within 50 feet of a stream | Within seven days of the most recent disturbance within the area For residential subdivisions, disturbed areas must be stabilized at least seven days prior to the transfer of permit coverage for the individual lot(s) |
Disturbed areas that will be idle over the winter | Prior to the onset of winter weather |
Table 2: Permanent Stabilization
Area Requiring Permanent Stabilization
|
Time Frame to Apply Erosion Controls
|
Any areas that will lie dormant for one year or more | Within seven days of the most recent disturbance |
Any areas within 50 feet of a stream and at final grade | Within two days of reaching final grade |
Any other areas at final grade | Within seven days of reaching final grade within that area |
(2) Permanent stabilization of conveyance channels- Person(s) implementing the Storm Water Management Plan shall undertake special measures to stabilize channels and outfalls and prevent erosive flows. Measures may include seeding, dormant seeding (as defined in the most recent edition of Rainwater and Land Development), mulching, erosion control matting, sodding, riprap, natural channel design with bioengineering techniques or rock check dams.
(b) Runoff Control Practices. The Storm Water Control Plan shall incorporate measures that control the flow of runoff from disturbed areas so as to prevent erosion. Such practices may include rock check dams, pipe slope drains, diversions to direct flow away from exposed soils and protective grading practices. These practices shall divert runoff away from disturbed areas and steep slopes where practicable.
(c) Sediment Control Practices. The Storm Water Control Plan shall include a description of structural practices that shall store runoff, allowing sediments to settle and/or divert flows away from exposed soils or otherwise limit runoff from exposed areas. Structural practices shall be used to control erosion and trap sediment from a site remaining disturbed for more than 14 days. Such practices may include, among others: sediment settling ponds, silt fences, storm drain inlet protection, and earth diversion dikes or channels which direct runoff to a sediment settling pond and storm inlet protection. All sediment control practices must be capable of ponding runoff in order to be considered functional. Earth diversion dikes or channels alone are not considered a sediment control practice unless used in conjunction with a sediment settling pond.
(d) Structural Practices: The Storm Water Control Plan must contain detail drawings for all structural practices. The structural practices shall also meet the following requirements:
(1) Timing. Sediment control structures shall be functional throughout the course of earth disturbing activity. Sediment basins and perimeter sediment barriers shall be implemented prior to grading and within seven (7) days from the start of grubbing. They shall continue to function until the up Slope development area is restabilized. As construction progresses and the topography is altered, appropriate controls must be constructed or existing controls altered to address the changing drainage patterns.
(2) Sediment settling ponds. Concentrated storm water runoff and runoff from drainage areas that exceed the design capacity of silt fence or inlet protection, as determined in Table 3 below, shall pass through a sediment settling pond. For common drainage locations that serve an area with 10 or more acres disturbed at one time, a temporary (or permanent) sediment settling pond must be provided until final stabilization of the site. The applicant may request approval from the City of Middleburg Heights to use alternative controls if it can demonstrate the alternative controls are equivalent in effectiveness to a sediment settling pond and Ohio EPA approved the alternative control. For drainage locations serving less than 10 acres, smaller sediment basins and/or sediment traps should be used.
The sediment-settling pond shall be sized to provide at least 67 cubic yards of storage per acre of total contributing drainage area. When determining the total contributing drainage area, off-site areas and areas which remain undisturbed by construction activity must be included unless runoff from these areas is diverted away from the sediment settling pond and is not co-mingled with sediment-laden runoff. The depth of the sediment-settling pond must be less than or equal to five (5) feet. The configuration between the inlets and the outlet of the basin must provide at least two units of length for each one unit of width (> 2:1 length: width ratio). Sediment must be removed from the sediment-settling pond when the design capacity has been reduced by 40 percent. This limit is typically reached when sediment occupies one-half of the basin depth. When designing sediment settling ponds, the applicant must consider public safety, especially as it relates to children, as a design factor for the sediment basin and alternative sediment controls must be used where site limitations would preclude a safe design. The use of a combination of sediment and erosion control measures in order to achieve maximum pollutant removal is encouraged.
(3) Silt fence and diversions. Sheet flow runoff from denuded areas shall be intercepted by silt fence or diversions to protect adjacent properties, water resources, and wetlands from sediment transported via sheet flow. Where intended to provide sediment control, silt fence shall be placed on a level contour. Other sediment barriers designed to control sheet flow runoff may be used if approved by the City of Middleburg Heights and allowed by Ohio EPA. The relationship between the maximum drainage area to silt fence for a particular slope range is shown in Table 3 below. Stormwater diversion practices shall be used to keep runoff away from disturbed areas and steep slopes. Such devices, which include swales, dikes or berms, may receive storm water runoff from areas up to 10 acres.
Table 3
Maximum drainage area (in acres) to 100 linear feet of silt fence | Range of slope for a particular drainage area (in percent) |
0.5 | <2% |
0.25 | >2% but <20% |
0.125 | >20% but <50% |
(4) Inlet protection. Other erosion and sediment control practices shall be installed to minimize sediment-laden water entering active storm drain systems, unless the storm drain system drains to a sediment settling pond.
(5) Stream protection. If construction activities disturb areas adjacent to streams, structural practices shall be designed and implemented on site to protect all adjacent streams from the impacts of sediment runoff. No structural sediment controls (e.g., tile installation of a silt fence or a sediment settling pond in-stream) shall be used in a stream. For all construction activities immediately adjacent to surface waters of the State, the applicant must comply with applicable setback requirements.
(6) Modifying controls. If periodic inspections or other information indicates a control has been used inappropriately or incorrectly, the applicant shall replace or modify the control for site conditions.
(7) Non-Sediment Pollutant Controls: No solid (other than sediment) or liquid waste, including building materials, shall be discharged in storm water runoff. The applicant must implement site best management practices to prevent the discharge of non-sediment pollutant to the drainage system of the site or surface waters of the State. Under no circumstances shall concrete trucks wash out directly into a drainage channel, storm sewer or surface waters of the State. No exposure of storm water to waste materials is recommended.
(8) Off-Site traffic. Off-site vehicle tracking of sediments and dust generation shall be minimized.
(9) Compliance with other requirements. The Storm Water Control Plan shall be consistent with applicable State and/or local waste disposal, sanitary sewer, or septic system regulations, including provisions prohibiting waste disposal by open burning, and shall provide for the proper disposal of contaminated soils located within the development area.
(10) Trench and ground water control. There shall be no turbid discharges to surface water or wetlands resulting from dewatering activities. If trench or ground water contains sediment, it must pass through a sediment-settling pond or other equally effective sediment control device, prior to being discharged from the construction site. Alternatively, sediment may be removed by settling in place or by dewatering into a sump pit, filter bag or comparable practice. Ground water dewatering which does not contain sediment or other pollutants is not required to be treated prior to discharge. However, care must be taken when discharging ground water to ensure that it does not become pollutant-laden by traversing over disturbed soils or other pollutant sources.
(Ord. 2008-18. Passed 2-26-08.)