(a) All Erosion and Sediment Kept on Site. Erosion and sedimentation caused by accelerated wind or stormwater runoff over the site due to earth disturbing activities shall be stabilized and confined to the boundaries of the development site.
(b) Structural and Nonstructural Best Management Practices.
(1) Nonstructural stormwater management practices shall be used to the maximum extent practicable. Such practices may include, but not be limited to, preserving riparian areas, preserving existing vegetation and vegetative buffer strips, phasing of construction, and designation of tree preservation areas.
(2) Nonstructural and structural stormwater management practices shall be designed in accordance with requirements and standards specified in this Section or by the City's Authorized Agent.
(3) Structural and nonstructural stormwater management practices shall be placed in easements and recorded on the property deeds on which they are located and shall remain unaltered unless first approved by the City's Authorized Agent.
(4) Specific types of structural stormwater management practices, including detention and retention facilities, shall be designed and constructed to meet both stormwater detention requirements for flood control and water quality protection requirements as approved by the City's Authorized Agent.
(c) Stream and Wetland Riparian Buffers. The site owner or applicant shall leave an undisturbed riparian buffer on both sides of and/or surrounding water resources, except for crossings and other riparian area and wetland impacts approved by the City's Authorized Agent. Buffer width will be determined by Section 2.5, Stream Setback Area of the Rainwater and Land Development Manual.
(d) Channel Protection. To protect stream channels from instability and erosion during and after construction activities, temporary and permanent runoff control practices shall be designed and constructed as defined in the latest edition of Rainwater and Land Development.
(e) Temporary Stabilization of Disturbed Areas and Soil Stockpiles.
(1) A temporary vegetative cover shall be established on disturbed areas as specified in the NPDES Construction Activity General Permit Number #OHC000004 or current permit.
(2) Application practices shall include vegetative establishment, mulching, and the early application of gravel base on areas to be paved. Soil stabilization measures should be appropriate for the time of year, site conditions and estimated time of use.
(3) Topsoil removed shall be stored on site and shall be stabilized with quick growing plants or other means, so that it is protected from wind and water erosion. Topsoil shall be maintained in a usable condition for sustaining vegetation and reused on the site. Temporary vegetation shall also be maintained.
(f) Permanent Stabilization.
(1) A permanent vegetative cover shall be established on disturbed areas as specified in In the NPDES Construction Activity General Permit Number #OHC000004 or current permit.
(2) Permanent vegetation shall not be considered established until a ground cover is achieved which is mature enough to control soil erosion and will survive severe weather conditions.
(g) Cut And Fill Slopes. Cut and fill slopes shall be designed, constructed and stabilized in a manner which will minimize erosion. Consideration should be given to the length and steepness of the slope, the soil type, upslope drainage area, groundwater conditions and other applicable factors. If, after final grading, excessive erosion takes place, additional slope stabilizing measures will be required by the owner, developer or builder until the problem is corrected. The following guidelines are provided to aid in developing an adequate design.
(1) Roughened soil surfaces are generally preferred to smooth surfaces on slopes.
(2) Diversions should be constructed at the top of long steep slopes which have significant drainage areas above the slope. Diversions or terraces may also be used to reduce slope length.
(3) Concentrated stormwater should not be allowed to flow down cut or fill slopes unless contained within an adequate channel, flume or slope drain structure.
(4) Wherever a slope face crosses a water seepage plane which endangers the stability of the slope, adequate drainage or other protection should be provided.
(h) Protection of Adjacent Properties and Public Right-of-Ways. Properties, public right-of-way's, and thoroughfares adjacent to the site of an earth disturbing activity shall be protected from sediment deposition. This may be accomplished by preserving a well-vegetated buffer at the perimeter of the site, by installing perimeter controls such as sediment barriers, filters, dikes, sediment basins, or by a combination of such measures.
(i) Sediment Control Structures.
(1) Sediment control structures shall be used to control erosion and trap sediment on a site remaining disturbed for more than fourteen (14) days. Such structures may include, but are not limited to, silt fences, storm drain inlet protection, sediment basins and diversions or channels which direct runoff to a sediment basin. All sediment control practices must be capable of ponding runoff in order to be considered functional.
(2) Sediment control structures shall be constructed as a first step in grading and be made functional before earth disturbing activities take place. Earthen structures such as dams, dikes, and diversions shall be seeded and mulched as soon as the installation is complete. Sediment control structures shall be functional throughout the course of earth disturbing activity until the site is stabilized with permanent vegetation.
(3) Sheet flow runoff from the site shall be intercepted by silt fence or diversions. A silt fence shall be placed on a level contour and shall be capable of temporarily ponding runoff. The relationship between the maximum drainage area to silt fence for a particular slope range is shown in Table 1 below.
Table 1: Maximum Drainage Area to Silt Fence
Maximum drainage area (in acres) to 100 linear feet of silt fence | Range of slope for a particular drainage area (percent) |
0.5 | <2% |
0.25 | > 2% but < 20% |
0.125 | > 20% but < 50% |
(4) 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 stormwater runoff from areas up to ten (10) acres.
(5) Whenever stormwater detention is required, the stormwater runoff from the site shall pass through a sediment basin or other suitable sediment trapping facility before discharge to a receiving water body. The City's Authorized Agent may require sediment basins or traps for smaller disturbed areas where deemed necessary.
(j) Stabilization of Waterways And Outlets. All on-site stormwater conveyance channels shall be designed and constructed to withstand the expected velocity of flow without creating erosion. Methods adequate to prevent erosion shall also be provided at the outlets of all pipes and paved channels.
(k) Storm Sewer Inlet Protection. All storm sewer inlets shall be protected so that sediment-laden water will not enter the conveyance system without first being filtered or otherwise treated to remove sediment.
(l) Working In or Crossing Watercourses.
(1) All activities shall be kept out of watercourses to the extent possible. Where in-channel work is necessary, precautions shall be taken to stabilize the work area during construction to minimize erosion. The channel (including bed and banks) shall be restored to its original cross-section and all disturbed area stabilized immediately after in-channel work is completed.
(2) Where a watercourse will be crossed regularly during construction, a temporary stream crossing shall be provided, used for the shortest period practical, removed following site construction, and restored as described in these Subdivision Regulations.
(m) Maintenance and Removal of Temporary Measures.
(1) All temporary erosion and sediment control practices shall be maintained and repaired to assure continual performance.
(2) All temporary erosion and sediment control measures shall be removed within thirty (30) days after final site stabilization is achieved or after the temporary measures are no longer needed. Trapped sediment and other disturbed soil areas resulting from the removal of temporary measures shall have the final grade re-established and be permanently stabilized to prevent further erosion and sedimentation.
(n) Control of Construction Site Debris and Wastes. All owners, applicants, contractors and developers shall control waste such as discarded building materials, concrete truck washout, chemicals, litter, and sanitary waste on construction sites and shall keep streets and gutters clear of all sediment and debris from the site.
(o) Use, Safety, and Maintenance of Stormwater Practices.
(1) Stormwater management practices shall be designed for the ultimate use of the site and function safely with minimal maintenance.
(2) If an inspection reveals that a control practice is in need of repair or maintenance, with the exception of a sediment settling pond, it must be repaired or maintained within three days of the inspection. Sediment settling ponds must be repaired or maintained within ten (10) days of the inspection.
(p) Inspection of Stormwater Controls Required by the Developer.
(1) All on-site control practices shall be periodically inspected to ensure proper function and to identify failures.
(2) On-site and off-site discharge locations shall be inspected to ascertain whether erosion and sediment control measures are effective in preventing significant impacts to the receiving waters.
(3) Detailed records of inspections shall be maintained for three (3) years following the final stabilization of the site.
(q) Accessibility of Easements. All permanent stormwater management measures shall have easements sufficient to cover the facility and to provide access for inspection and maintenance.
(r) Status of Standards. The standards identified in this Section are general guidelines. Each application shall be reviewed on a case by case basis and some may require additional and more stringent requirements, while others may have individual requirements waived by the City's Authorized Agent. (Ord. 73-2021. Passed 1-18-22.)