The SWP3 must contain a description of the controls appropriate for each construction operation and the applicant must implement such controls. The SWP3 must clearly describe for each major construction activity the appropriate control measures; the general sequence during the construction process under which the measures will be implemented. The SWP3 shall identify all subcontractors engaged in activities that could impact storm water runoff. The SWP3 shall contain signatures from all of the identified subcontractors indicating that they have been informed and understand their roles and responsibilities in complying with the SWP3.
(a) Erosion and Sediment Kept on Site. Using BMPs, erosion and sedimentation caused by accelerated wind or storm water runoff over the site shall be stabilized within the boundaries of the development site to the maximum extent practicable.
(b) Structural and Nonstructural Best Management Practices. Nonstructural storm water management practices shall be encouraged. 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.
(c) Stream and Wetland Riparian Buffers. The site owner and/or applicant shall leave a riparian buffer on sides of and/or surrounding surface waters of the state, except for crossings and other riparian area impacts approved by the City Engineer. Buffer area shall equal all identified FEMA floodways and floodplains, or revised floodplain via FEMA unless otherwise approved by the City Engineer. The buffer that operators shall leave undisturbed along a surface water of the state is 25 feet as measured from the top of bank of the surface water.
(d) Channel Protection. To protect stream channels from degradation, specific channel protection criteria shall be provided as prescribed in Rainwater and Land Development or in a manner approved by the City Engineer.
(e) Temporary Stabilization of Disturbed Areas and Soil Stockpiles.
(1) A temporary vegetative cover shall be established on disturbed areas as specified in the table below.
Table 916.05(e)(1): Temporary Stabilization Requirements
Area Requiring Temporary Stabilization | Time Frame To Apply Erosion Controls |
Any disturbed areas within 50 feet of a stream but not at final grade. | Within two days of the most recent disturbance if that area will remain idle for more than 21 days. |
For all construction activities, any disturbed area, including soil stockpiles that will be dormant for more than 21 days but less than one year. | Within seven days of the most recent disturbance within the area. |
Disturbed areas that will be idle over winter | Prior to November 1 |
(2) Application practices include vegetation 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 shall be maintained in a usable condition for sustaining vegetation and reused on the site.
Note: Where vegetative stabilization techniques may cause structural instability or are otherwise unobtainable, alternative stabilization techniques must be employed. These techniques may include mulching or erosion matting.
(f) Permanent Stabilization.
(1) A permanent vegetative cover shall be established on disturbed areas as specified in the table below.
Table 916.05(f)(1): Permanent Stabilization Requirements
Area Requiring Permanent Stabilization | Time Frame to Apply Erosion Controls |
Any area that will lie dormant for one (1) year or more. | Within seven days of the most recent disturbance. |
Any areas within 50 feet of any stream and at final grade. | Within two days of reaching final grade. |
Any area at final grade. | Within seven days of reaching final grade within that area. |
(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 and constructed in a manner that will minimize erosion and slippage. Consideration shall be given to the length and steepness of the slope, soil type, up-slope drainage area, groundwater conditions, and slope stabilization.
(h) Protection of Adjacent Properties/Public Right-of-Ways. Properties, public right-of-ways, 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 whenever possible, by installing perimeter controls such as sediment barriers, filters, dikes, sediment basins, or by a combination of such measures as applicable.
(h-1) Preservation of Wetland Hydrology. Concentrated storm water runoff from BMPs to wetlands shall be converted to diffuse flow before the runoff enters a wetland in order to protect the natural hydrology, hydroperiod, and wetland flora. The flow shall be released such that no erosion occurs down slope. Practices such as level spreaders, vegetative buffers, infiltration basins, conservation of forest covers, and the preservation of intermittent streams, depressions, and drainage corridors may be used to maintain the wetland hydrology. If the applicant proposes to discharge to natural wetlands, a hydrological analysis shall be preformed to demonstrate that the proposed discharge matches the pre-development hydroperiods and hydrodynamics.
(i) Control Structures.
(1) rosion and sediment control practices, and storm water management practices used to satisfy the performance standards should meet the standards and specifications in Rainwater and Land Development or other standards acceptable to the Ohio EPA. This does not preclude the applicant from proposing an alternate solution as approved by the City Engineer. The engineer shall design and implement control practices which comply with these and the minimum requirements by the Ohio EPA.
(2) Sediment control structures shall be used to control erosion and trap sediment on a site remaining disturbed for more than 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.
(3) Sediment control structures shall be set up within seven days from the start of grubbing and shall be made functional before other 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 and until the site is stabilized with permanent vegetation.
(4) Sheet flow runoff from disturbed areas of the site shall be intercepted by silt fence or diversions. Silt fence shall be placed on a level contour and shall be capable of temporarily ponding runoff. Placing silt fence in parallel does not extend the permissible drainage area to the silt fence. The relationship between the maximum drainage area to silt fence for a particular slope range is shown in Schedule 916.05(i)(1).
Schedule 916.05(i)(1) Maximum Drainage Area For Silt Fence
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% |
(5) Concentrated storm water runoff from denuded areas flowing at rates that exceed the design capacity of sediment barriers shall pass through a sediment-settling facility. The applicant may use alternative controls to a sediment-settling pond only if approval is granted by Ohio EPA. If the applicant proposes to use an alternative control to a sediment-settling facility, the applicant shall provide the City Engineer with documentation from Ohio EPA which indicates approval of the alternative controls proposed for the applicant's development. This documentation shall be provided at the time of SWM Plan or site development plan submittal.
(6) Storm water 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 ten acres.
(7) A centralized sedimentation basin shall be utilized for common drainage areas equal to or greater than ten acres.
(8) The City Engineer may require sediment basins or traps for smaller disturbed areas where deemed necessary.
(9) If the City Engineer determines that site conditions do not warrant its construction, based upon hydrological and hydraulic data, the storm water detention requirement may be modified.
(10) Sediment settling ponds. A sediment settling pond, or equivalent best management practice upon approval from the Engineer, is required for any one of the following conditions:
A. Concentrated storm water runoff.
B. Runoff from drainage areas that exceeds the design capacity of silt fence or inlet protection.
C. 10-acres of disturbed land.
The sediment-settling pond shall provide both a sediment storage zone and a dewatering zone. The volume of the dewatering zone shall be at least 67 cubic yards of storage per acre of total contributing drainage area and have a minimum of 48-hour drain time for sediment basins serving a drainage area over 5 acres. The volume of the sediment storage zone shall be calculated by one of the following methods:
A. The volume of the sediment storage zone shall be 1000ft^3 per disturbed acre within the watershed of the basin.
B. The volume of the sediment storage zone shall be the volume necessary to store the sediment as calculated with a generally accepted erosion prediction model.
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 comingled with sediment-laden runoff. The depth of the dewatering zone 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), however a length to width ration of 4:1 is recommended. 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.
(j) Stabilization of Waterways and Outlets. All on-site storm water conveyance channels shall be designed and constructed to withstand the expected velocity of flow. Methods adequate to minimize erosion shall also be provided at the outlets of all pipes and paved channels.
(k) Storm Sewer Inlet Protection.
(1) Unless otherwise provided for on the approved Stormwater Management Plan, 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, unless otherwise approved by the City Engineer. All inlets receiving runoff from drainage areas of one or more acres will require a sediment settling pond.
(2) There shall be no sediment-laden discharges to drainage channels resulting from dewatering activities. If any sediment-laden ground water is encountered during trenching activities, then the sediment-laden ground water must pass through an effective sediment control device prior to being discharged from the construction site.
(3) Areas designated for the storage or disposal of solid, sanitary, and toxic wastes, dumpsters, concrete truck washout pits, and fuel tanks shall be shown on the Storm Water Management (SWM) plan.
(l) Working In or Crossing Streams.
(1) Construction activities shall be kept out of streams to the maximum 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 and all disturbed area stabilized immediately after in-channel work is completed.
(2) Where a stream will be crossed regularly during construction, a non- erodible temporary stream crossing shall be provided.
(m) Construction Access Routes.
(1) Measures shall be taken to prevent soil transport onto surfaces where runoff is not checked by sediment controls, such as public roads. Stone construction entrance(s) shall be implemented as soon as possible. The entrances shall be planned and installed according to the requirements in the most recent edition of the Ohio Rainwater and Land Development manual or as directed by the City Engineer.
(2) Where soil is transported onto public road surfaces, the roads shall be cleaned thoroughly by either sweeping or scraping at the end of each work day or more frequently, in order to ensure public safety. Street washing shall be allowed only after shoveling or sweeping has removed most of the sediment.
(3) Erodible material ramps in streets to enable equipment to cross curbs shall be properly removed immediately after use.
(n) Maintenance and Removal of Temporary Measures.
(1) All temporary erosion and sediment control practices shall be maintained and repaired to assure continued performance.
(2) All temporary erosion and sediment control measures shall be removed within 30 days of achieving final site stabilization 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.
(o) Control of Construction Site Debris and Wastes. All owners, applicants, contractors and developers shall control wastes such as discarded building materials, concrete truck washout, chemicals, litter, and sanitary waste on debris from the site to the extent practical. Site management practices shall be implemented to prevent toxic materials, hazardous materials, or other debris from entering drainage channels. These practices shall include, but are not limited to, the following:
(1) If applicable, a dumpster shall be made available for the proper disposal of construction site waste materials, garbage, plaster, drywall, grout, gypsum, and etc. If applicable, a second covered dumpster will be provided for the proper disposal of toxic and hazardous wastes.
(2) The washing of any concrete material into a street, catch basin, or other public facility or natural resource shall not occur. A designated area for concrete washouts shall be made available and used for all concrete washouts.
(3) All fuel tanks and drums shall be stored in a marked storage area. A dike shall be constructed around this storage area with a minimum capacity equal to 110% of the volume of the largest container in the storage area. All additional containment requirements of the local fire authority must be followed. If the fuel tanks have a self-contained dike, the plug will be kept in the dike tank at all times.
(4) Any toxic or hazardous wastes and/or contaminated soils must be disposed of according to all applicable environmental laws and statutes. Local health districts and Ohio EPA can provide guidance on these issues.
(5) Paint, paint washing liquids, excess paints and other paint wastes are considered solid wastes and shall be disposed of in accordance with applicable state regulations. Appropriate handling of these wastes shall occur at the site so as to prevent the discharge of these wastes into surface or ground waters.
A. Water-based paint washing liquids and small quantities of excess water-based paints may be disposed of by flushing down a connected sanitary sewer but may not be disposed of in an on-lot disposal system.
B. All other paints, paint thinners, and paint cleaning materials will be disposed of in the site's hazardous waste disposal dumpster.
(p) Use, Safety and Maintenance of Storm Water Practices.
(1) Storm water management practices shall be designed for the ultimate use of the site and function safely and with minimal maintenance. Areas developed for a subdivision shall provide a storm water management system for the ultimate development of all the subdivided lots.
(2) If an inspection by a representative of the City reveals that a control practice is in need of repair or maintenance, upon proper notice, the permittee shall repair same according to the Timeline Correction Table as identified in Section 916.08(g).
(q) Inspection of Storm Water Controls. All on-site and off-site (if applicable) control practices shall be periodically inspected by both the permittee and/or permittee's representative and a representative of the City to ensure proper function and to identify failures in accordance with the requirements of subsection 916.08(h). All controls on the site shall be inspected at least once every seven calendar days and within 24 hours after any storm event greater than one-half inch of rain per 24 hour period. The inspection frequency may be reduced to at least once every month if the entire site is temporarily stabilized or runoff is unlikely due to weather conditions (e.g., site is covered with snow, ice, or the ground is frozen). A waiver of inspection requirements is available until one month before thawing conditions are expected to result in a discharge if prior written approval has been attained from the City of Amherst Engineer and all of the following conditions are met:
(1) The project is located in an area where frozen conditions are anticipated to continue for extended periods of time (i.e. more than one (1) month).
(2) Land disturbance activities have been suspended, and temporary stabilization is achieved.
(3) The beginning date and ending dates of the waiver period are documented in the SWP3.
The applicant shall assign qualified inspection personnel to conduct these inspections to ensure that the control practices are functional and to evaluate whether the SWP3 is adequate, or whether additional control measures are required. Qualified inspection personnel are individuals with knowledge and experience in the installation and maintenance of sediment and erosion controls. These inspections shall meet the following requirements:
(1) Disturbed areas and areas used for storage of materials that are exposed to precipitation shall be inspected for evidence of or the potential for, pollutants entering the drainage system.
(2) Erosion and sediment control measures identified in the SWP3 shall be observed to ensure that they are operating correctly. The applicant shall utilize an inspection form provided by the City of Amherst or an alternate form acceptable to the City of Amherst Engineer. The inspection form shall include:
A. The inspection date.
B. Names, titles and qualifications of personnel making the inspection.
C. Weather information for the period since the last inspection, including a best estimate of the beginning of each storm event, duration of each storm event and approximate amount of rainfall for each storm event in inches, and whether any discharges occurred.
D. Weather information and a description of any discharges occurring at the time of inspection.
E. Locations of:
1. Discharges of sediment or other pollutants from site.
2. BMPs that need to be maintained.
3. BMPs that failed to operate as designed or proved inadequate for a particular location.
4. Where additional BMPs are needed that did not exist at the time of inspection.
F. Corrective action required including any necessary changes to the SWP3 and implementation dates.
(3) Discharge locations shall be inspected to determine whether erosion and sediment control measures are effective in preventing significant impacts to the receiving water resource or wetlands.
(4) Final Stabilization shall be determined by The City of Amherst Engineer. Once a definable area has achieved final stabilization, the applicant may note this on the SWP3 and no further inspection requirement applies to that portion of the site.
(5) A copy of all of the inspection log sheets must be submitted to the City of Amherst Building Department within five working days of the date that the inspection was conducted. Inspections shall be documented in a format deemed acceptable by the City Engineer.
(Ord. 11-35. Passed 7-25-11.)