In order to control sediment pollution of water resources, the owner or person responsible for the development area shall use conservation planning and practices to maintain the level of conservation established in the following standards:
(A) (1) The plan shall include measures that control the flow of runoff from disturbed areas so as to prevent soil erosion from occurring;
(2) All sediment control practices must be capable of ponding runoff in order to be considered functional;
(3) Clearing and grubbing will be done in two or more phases. The first phase will include only those locations necessary to install the perimeter soil erosion, sediment and storm water control BMPs. After the perimeter controls are in place and functioning, the remaining phase(s) of clearing and grubbing may continue; and
(4) Structural practices shall be used to control erosion and trap sediment from areas remaining disturbed for more than 14 days.
(B) Sediment barriers.
(1) Sheet flow runoff from denuded areas shall be intercepted by silt fence or diversions to protect adjacent properties and water resources from sediment. Where intended to provide sediment control, silt fence shall be placed on a level contour. The relationship between the maximum drainage areas to silt fence for a particular slope is shown in the table below.
Table 1: Sill Fence Applicability
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% |
(2) This does not preclude the use of other sediment barriers designed to control sheet flow runoff. The total runoff flow treated by a sediment barrier shall not exceed the design capacity for that sediment barrier. Straw bale barriers are not acceptable.
(C) Stormwater diversion practices. Stormwater diversion practices shall be used to keep runoff away from disturbed areas and steep slopes where practicable. Such practices, which include swales, dikes or berms, pipe slope drains and diversions, may receive stormwater runoff from areas up to ten acres. Stormwater diversion practices alone are not considered a sediment control practice unless those are used in conjunction with a sediment settling pond.
(D) Timing of sediment trapping practices. Sediment control practices shall be functional throughout all phases of up slope earth disturbing activity. Settling facilities, perimeter controls and other practices intended to trap sediment shall be implemented prior to grading and within seven days from the start of grubbing. They shall continue to function until the up slope development area is permanently restabilized. As construction progresses and the topography is altered, appropriate controls must be constructed or existing controls altered to address the changing drainage patterns.
(E) Stabilization of denuded areas.
(1) Disturbed areas must be stabilized as specified in the tables below:
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 |
Table 3: 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 transfer of NPDES permit coverage - For the individual lot(s). Proof of permit coverage transfer must be submitted to the city. The city shall then inspect the lot to ensure that the temporary seeding has been done. |
Disturbed areas that will be idle over winter | Prior to the onset of winter weather |
(2) Where vegetative stabilization techniques may cause structural instability or are otherwise unobtainable, alternative stabilization techniques must be employed.
(F) Sediment settling ponds. Stormwater runoff that exceeds the design capacity of sediment barriers and concentrated stormwater flows shall pass through a sediment settling facility.
(1) Where storm sewer drainage areas include ten or more acres disturbed at one time, a temporary (or permanent) sediment settling pond must be provided and maintained until final stabilization of the site. In single-family residential construction, final stabilization is after the houses are built and permanent landscaping is done.
(a) Alternative equivalent controls may be used if approved by the appropriate city officials.
(b) It is recommended that for drainage locations of less than ten acres, smaller sediment settling basins and/or sediment traps be used.
(2) Each facility's storage capacity shall be no less than 67 cubic yards per acre of total contributing drainage area. The storage volume will be measured from the bottom of the basin to the top of the primary (principal) spillway.
(3) Permanent stormwater management ponds that are designed to trap sediment during construction shall be designed to provide for a slow release of sediment-laden water. The draw down time must be at least 72 hours, or meet the criteria in the Indiana Storm Water Quality Manual whichever is most stringent. If the ponds are designed to provide final runoff control, pre-development and post-development runoff calculations certified by a professional engineer registered in Indiana shall be provided with discharge rate requirements established by the city. The pond shall also be cleaned of construction debris and sediment following permanent erosion control establishment.
(4) The design configuration between inlet(s) and the outlet of settling ponds must provide at least two units of length for each one unit of width (> 2:1 length to width ratio).
(5) The depth of the sediment settling pond must be less than or equal to five feet.
(6) Sediment must be removed from the sediment settling ponds when the design capacity has been reduced by 40%.
(7) Public safety, especially as it relates to children, must be considered in the design. Alternative sediment controls must be used where site limitations would preclude a safe design.
(8) Temporary sediment settling ponds will not be constructed in any stream channel. Permanent settling or retention/detention ponds will only be allowed in streams if permitted and approved by IDEM, IDNR and any other regulatory agency with review authority.
(G) Storm sewer inlet protection.
(1) All storm sewer inlets that accept water runoff from the development area shall be protected so that sediment-laden water will not enter the storm sewer, unless the storm drain system drains to a sediment settling pond and is exempted in writing by the city. In areas where construction will be ongoing, such as subdivisions, the storm sewer protection shall be maintained until all up slope areas reach final stabilization, as determined by the city.
(2) At the end of this period the site owner shall hydraulically clean the storm sewers to the satisfaction of the city. All sediments shall be removed from the system and shall not be flushed downstream.
(H) Storm sewer and other drainage outlets. Where practical, all storm sewers, footer drains, roof gutter drains and all other drains will be outlet at the bottom of the slope. Structural measures will be taken so that the slope below the outlet will be able to control the water being drained through the storm sewer or other drains without causing erosion of the stream or channel banks or channel bottom or other areas that the water is outletted on.
(I) Working near, or crossing streams and wetlands.
(1) Construction vehicles shall avoid water resources, wetlands, riparian areas, and their setbacks. If construction vehicles must cross these areas during construction, an approved temporary crossing shall be constructed. Streams, including intermittent streams with a defined bed and banks, shall be restabilized immediately after in-channel work is completed, interrupted, or stopped. Erodible materials will not be used in making stream crossings.
(2) No soil, rock, debris, or any other material shall be dumped or placed into a water resource or into such proximity that it may slough, slip, or erode into a water resource unless such dumping or placing is authorized by the approving authority and, when applicable, the US Army Corps of Engineers and IDEM, for such purposes as, but not limited to, constructing bridges, culverts, and erosion or sediment control structures.
(3) If construction activities disturb areas adjacent to streams, structural practices shall be designed and implemented on site to protect the adjacent streams from the impacts of sediment runoff.
(4) No temporary or permanent sediment controls will be constructed in a stream channel.
(5) Streams and wetland setbacks required by the city will be implemented. As a minimum a setback of 25 feet, as measured from the ordinary high water mark of the surface water, will be maintained in its natural state as a permanent buffer.
(J) Construction entrance.
(1) Measures shall be taken to prevent soil transport onto public roads, or surfaces where runoff is not checked by sediment controls.
(2) Stone with geotextile construction entrance(s) shall be implemented as required by the city. These will be planned and installed according to the requirements in the most recent edition of the Indiana Stormwater Quality Manual.
(3) Where soil is transported onto a public road surface, the roads shall be cleaned thoroughly at the end of each day, or more frequently, in order to ensure public safety. Soil shall be removed from paved surfaces by shoveling or sweeping. Street washing shall be allowed only after shoveling or sweeping has removed most of the sediment and street sewer inlet protection is properly installed unless end of sewer sediment ponds exist and are properly functioning.
(4) Erodible material ramps in streets will not be used to enable equipment to cross curbs. Non-erosive materials (e.g. wood and stone) can be used.
(K) Unstable soils.
(1) Unstable soils will be as determined by the local county soil survey or by a detailed soil report.
(2) The city may require detailed soil reports when deemed necessary.
(3) Unstable soils prone to slipping or land sliding shall not be graded, excavated, filled or have loads imposed upon them unless the work is performed in accordance with a qualified professional engineer's recommendations to correct, eliminate, or adequately address the problems.
(L) 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. The minimum final unreinforced soil slopes will have a horizontal to vertical ratio of 2:1 (the horizontal will be two times the vertical).
(M) Stabilization of outfalls and channels. Outfalls and constructed or modified channels shall be designed and constructed to withstand the expected velocity of flow from the planned post-development frequency storm without eroding. The planned post-construction velocity and flow shall include the entire contributing watershed.
(N) Establishment of permanent vegetation. A permanent vegetative cover shall be established on denuded areas not otherwise permanently stabilized. Permanent vegetation shall not be considered established until ground cover is achieved which, in the opinion of the city, has 80% vegetative density over the entire disturbed area and provides adequate cover, and is mature enough to satisfactorily control soil erosion and survive adverse weather conditions.
(O) Disposition of temporary practices. All temporary soil erosion and sediment control practices shall be disposed of immediately after final site stabilization is achieved or after the temporary practices are no longer needed, unless otherwise required by the city. Trapped sediment shall be permanently stabilized to prevent further erosion. The construction maintenance guarantee shall not be released by the city until all temporary soil erosion and sediment control practices that are no longer needed have been removed, properly disposed of and any trapped sediment has been stabilized.
(P) Underground utility construction. The construction of underground utility lines, pipes, etc. shall be subject to the following criteria:
(1) Trenches shall remain open for no more than five days;
(2) There shall be no turbid discharges to surface waters resulting from dewatering activities. If trench or groundwater 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 or to waters of the state; and
(3) When discharging clean groundwater care must be taken to ensure that it does not become pollutant laden by crossing over disturbed soils or other pollutant sources.
(Q) Inspections.
(1) If inspections or other information indicates a control has been used inappropriately or incorrectly or it has failed, it must be replaced or modified for the site conditions.
(2) The owner of the development area shall have the site inspected for soil erosion, sediment control and other environmental concerns every seven calendar days, and within 24 hours of one-half inch or greater rainfall event until the MS4 Operator or appointed representative certifies the site as being stable and all permanent facilities are established.
(3) The owner, or his or her designated representative, shall keep a written log of each inspection and any subsequent improvements to the soil erosion, sediment control or other environmental controls. The inspections shall include the date of the inspection, the name of the inspector, weather conditions, and the actions needed to correct the identified problems.
(4) The inspection log will include the date and actions taken to correct problems noted in past inspection logs.
(5) A copy of all of the required inspection logs will be submitted to the MS4 Operator within three working days of the date that the inspection was conducted.
(6) 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.
(7) Erosion and sediment controls identified in the comprehensive stormwater management plan shall be observed to ensure that they are operating correctly.
(8) Discharge locations shall be inspected to ascertain whether erosion and sediment control measures are effective in preventing significant impacts to the receiving waters.
(9) Locations where vehicles enter or exit the site shall be inspected for evidence of off-site vehicle tracking.
(10) If the inspection reveals that a control practice is in need of repair or maintenance, with the exception of sediment settling ponds, it must be repaired or maintained within three days of the inspection. Sediment settling ponds must be repaired or maintained within ten days of the inspection.
(11) If any inspection reveals that a control practice fails to perform its intended function and that another, more appropriate control practice is required, the comprehensive stormwater management plan must be amended by the owner and the new control practice must be installed within ten days of the inspection.
(12) If the inspection reveals that a control practice has not been implemented in the time required by this chapter it must be installed within ten days from the date of inspection.
(13) If the inspection reveals that a planned control practice is not needed, the record must contain a statement of explanation as to why the control practice is not needed.
(R) Control of materials and debris. Site management practices shall be implemented to prevent toxic materials, hazardous materials, or other debris from entering the city's and state's water resources or wetlands. These practices shall include, but are not limited to, the following:
(1) A covered dumpster shall be made available for the proper disposal of construction site waste materials, garbage, plaster, drywall, grout, gypsum and etc. A second covered dumpster will be provided for the proper disposal of toxic and hazardous wastes.
(2) The washing of excess 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 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. IDEM can provide guidance on these issues.
(5) On a site with a prior industrial landuse or a site that is contaminated with gasoline, fuel oil, hydrocarbon based chemicals or other IDEM or RCRA regulated contaminates, the stormwater is considered wastewater. Discharge of pollutants to the city sewer system must be approved by city wastewater personnel. The city may elect to refuse such contaminated discharge.
(6) Proper permits shall be obtained for development projects on solid waste landfill sites.
(7) 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 groundwaters.
(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.
(8) Restroom facilities will be provided for site workers at all times that workers are present on the site and during all phases of the construction.
(9) All required permits from appropriate federal, state, or local agencies are required to develop land with a previous industrial or commercial use or another use that may have led to soil contamination by a regulated pollutant.
(S) Pre-winter stabilization. If the development area will, or is planned to remain, active through the winter months, the owner of the development area shall hold a pre-winter stabilization meeting. The meeting will be held before October 1. The owner shall invite the operator, developer, engineer, contractor, MS4 Operator and anyone else requested by the city to the meeting.
(T) Stormwater basins.
(1) Pool geometry. The minimum length-to-width ratio for the pond is 3:1 (the length will be three times the width).
(2) Riser in embankment. The riser shall be located within the embankment for purposes of maintenance access. Access to the riser will be by manholes.
(3) Water drains. Each retention basin shall have a drainpipe that can completely drain the pond. The drain shall have an elbow, stone filtration barrier or other mechanism within the pond to prevent sediment deposition from plugging the drain.
(4) Adjustable valves. Both the stormwater management and water quality basin drains shall have adjustable valves. Valves shall be located inside the riser at a point where they will remain dry and can be operated in a safe and convenient manner. During the annual inspections the valves shall be fully opened and closed at least once, and the certifying official shall attest to this on the inspection form. To prevent vandalism, the handwheel shall be chained to a ringbolt or manhole step.
(5) Principal spillway. Each principal spillway shall have the capacity to pass the 100-year design storm flow. The inlet or riser size for the pipe drops shall be designed so that the flow through the structure goes from weir flow control to pipe flow control without going into orifice control in the riser. The crest elevation of the primary spillway shall be no less than one foot below the emergency spillway crest. Pressure joint pipe is required and a removable trash rack shall be installed at each location. Anti-seep collars shall be provided for all pipe conduits through an embankment.
(6) Emergency spillway. An emergency spillway shall be provided on each stormwater management basin. Emergency spillways shall convey flood flows safely past the embankment. Emergency spillways shall have a 100-year design storm capacity unless exempted in writing by the city.
(7) Embankments. Anti-seep collars shall be provided for all pipe conduits through an embankment.
(8) Safety features.
(a) The primary spillway opening shall not permit access to the public and other non-maintenance personnel.
(b) The perimeter of all water pool areas that are deeper than three feet shall be surrounded by benches that meet the following:
1. A safety bench, with a maximum slope of 3%, which extends outward, on dry land, from the shoreline. This bench will be a minimum of 25 feet wide to provide for the safety of individuals and maintenance vehicles that are adjacent to the water pool. The safety bench may be landscaped, without the use of structures, to prevent access to the water pool.
2. Side slopes between the safety bench and the aquatic bench shall not be steeper than 3:1 (three feet horizontal for every one foot vertical).
3. An aquatic bench that extends inward from the shoreline far enough to ensure public safety and has a maximum depth of 15 inches below the normal water surface elevations. The aquatic bench may be landscaped to prevent access to the deeper water pool.
4. Side slopes beyond the aquatic bench and below the permanent water level shall not be steeper than 2:1 (two feet horizontal for every one foot vertical).
5. The contours of the pond will be designed and managed to eliminate drop-offs and other hazards.
6. Side slopes getting to the pond shall not exceed 3:1 and shall terminate on a safety bench.
7. Soil erosion and sediment control practices used to satisfy these standards shall meet the standards and specifications in the current edition of the Indiana Stormwater Quality Manual.
(c) Alternative safety features including fencing and other access restrictions may also be considered as acceptable by the city.
(U) These standards are general guidelines and shall not limit the right of the city to impose at any time additional, more stringent requirements, nor shall the standards limit the right of the city to waive, in writing, individual requirements.
(V) Soil limitations shall be determined by using the current edition of the county soil survey written by the NRCS, USDA.
(W) Methods for controlling increases in stormwater runoff peaks and volumes may include, but are not limited to:
(1) Retarding flow velocities by increasing friction; for example, grassed road ditches rather than paved street gutters where practical, discharging roof water to vegetated areas, or grass and rock-lined drainage channels;
(2) Grading and use of grade control structures to provide a level of control in flow paths and stream gradients;
(3) Induced infiltration of increased stormwater runoff into soil, where practical; for example, constructing special infiltration areas where soils are suitable, retaining topsoil for all areas to be vegetated, or providing good infiltration areas with proper emergency overflow facilities; and
(4) Provisions for detention and retention, for example, permanent retention ponds and lakes, dry detention basins, and subsurface detention tanks.
(Ord. 3436, passed 9-6-05) Penalty, see § 156.99