A. Channels and adjoining properties shall be protected from erosion and sedimentation. Where concentrated flow leaves a development site, effective energy dissipation shall be placed on site at discharge locations.
B. Erosion control blanket shall be required on all interior site runoff storage facilities side slopes between normal water level and high water level.
C. Erosion control blanket to be placed in wetland or buffer shall be one hundred percent (100%) biodegradable, unless an alternative material is approved by the director or administrator. This requirement does not include turf reinforcement mats or other structural materials necessary for high erosion or scour areas.
D. Land disturbance activities in streams shall be avoided, where possible. If disturbance activities are unavoidable, the following requirements shall be met:
1. Temporary stream crossings shall be constructed of nonerosive material.
2. The time and area of disturbance of a stream shall be kept to a minimum. The stream, including bed and banks, shall be restabilized within forty eight (48) hours after channel disturbance is completed.
E. Soil erosion and sediment control measures shall be placed where there is a potential for erosion and sized appropriately for the tributary drainage area, and disturbed areas draining less than one acre shall, at a minimum, be protected by a filter barrier (including filter fences, which at a minimum, meet the applicable sections of the AASHTO standard specification 288-00, or equivalent control measures) to control all off site runoff from disturbed areas. The filter barrier shall be designed in accordance with the following:
1. The use of straw bales as a filter barrier or ditch check is prohibited.
2. Silt fences can be used to intercept sheet flow only. Silt fences cannot be used as velocity checks in ditches or swales, nor can they be used where they will intercept concentrated flows.
3. Ditch checks shall be constructed using nonerodible materials or prefabricated devices. Straw or hay bales are not acceptable.
4. Reinforced silt fences (normal silt fence reinforced with woven wire fencing) can be used to intercept sheet flow runoff from disturbed areas greater than one acre.
5. All undisturbed wetland, floodplain, waters and buffer areas shall, at a minimum, have a barrier of protection. The barrier shall be placed at the limits of soil disturbance and consist of:
a. A dual row of silt fence, and a row of orange construction fence, or
b. A dual silt fence barrier, with one of the fences being of high visibility material.
c. Alternative practices offering comparable protection to wetland, floodplain, waters, and buffer areas may be used to prevent impact where applicable.
d. Additional soil erosion and sediment control measures may be required to adequately protect these sites.
F. Disturbed areas with drainage areas of one acre or greater, but fewer than five (5) acres shall, at a minimum, be protected by a sediment trap or equivalent control measure at a point downslope of the disturbed area.
G. Disturbed areas with drainage areas of five (5) acres or greater, shall, at a minimum, be protected by a sediment basin, in accordance with subsection H of this section, with a perforated filtered riser pipe or equivalent control measure at a point downslope of the disturbed area.
H. Sediment basins shall have both a permanent pool (dead storage) and additional volume (live storage) with each volume equal to the runoff amount of a 2-year, 6-hour event over the on site hydrologically disturbed tributary drainage area to the sediment basin. The available sediment volume below normal water level, in addition to the dead storage volume, shall be sized to store the estimated sediment load generated from the site over the duration of the construction period. For construction periods exceeding one year, the one year sediment load and a sediment removal schedule may be submitted. If the site runoff storage basin for the proposed development condition of the site is used for sediment basin, the above volume requirements will be explicitly met. Until the site is finally stabilized, the basin permanent pool of water shall meet the above volume requirements and have a filtered perforated riser protecting the outflow pipe.
I. Pumping sediment laden water into any stormwater facility that is not designated to be a sediment control measure, sediment trap, or sediment basin either directly or indirectly without filtration is prohibited.
J. Water removed from traps, basins and other water holding depressions or excavations must first pass through a sediment control or filtration device. When dewatering devices are used, discharge locations shall be protected from erosion. Discharges shall be routed through an effective sediment control measure (e.g., sediment trap, sediment basin or other appropriate measure).
K. All discharges to undisturbed area, stabilized area or watercourse shall be designed at a nonerosive velocity corresponding to the soil and vegetative cover of the undisturbed area.
L. All storm sewers, storm drain inlets and culverts that are, or will be functioning during construction shall be protected by sediment and erosion control measures. The sediment and erosion control measures shall be maintained until the site is stabilized.
M. A stabilized construction entrance of aggregate underlain with filter cloth, or graveled road, or access drive, or parking area of sufficient width and length, and/or vehicle wash down facilities, shall be provided to prevent soil from being tracked or deposited onto public or private roadways. Any soil reaching a public or private roadway shall be removed immediately, or as warranted, and transported to a controlled sediment disposal area.
N. All temporary and permanent stormwater conveyance channels, including ditches, swales, diversions, and the outlets of all channels and pipes shall be designed and constructed to withstand velocities that have the potential to cause damage or soil erosion.
O. Earthen embankments with constructed side slopes steeper than 3H:1V must be constructed with appropriate stabilization as approved by the director or the administrator.
P. Temporary diversions shall be constructed, as necessary, to direct all runoff through an effective sediment control measure (e.g., sediment trap, sediment basin or other appropriate measure).
Q. To the extent possible, soil stockpile locations shall be shown on the soil erosion and sediment control plan.
R. Soil stockpiles shall not be located in a drainageway, floodplain area or a designated buffer, unless otherwise approved, under specific conditions to be established by the director or administrator.
S. Stockpiles to remain in place more than three (3) days shall be provided with soil erosion and sediment control measures.
T. The applicant shall provide adequate receptacles for the deposition of all construction debris generated during the development process. The applicant shall not cause, or permit, the dumping, depositing, dropping, throwing, blowing, discarding or leaving of construction material debris upon or into any development site, channel, pond, lake, wetland, buffer or waters of DuPage County. The applicant shall maintain the development site free of uncontrolled construction debris. Construction site operators shall implement appropriate soil erosion and sediment control, and control waste such as, discarded building materials, concrete truck washout, chemicals, litter, and sanitary waste that may cause adverse impacts to water quality.
U. All temporary erosion and sediment control measures shall be removed within thirty (30) days after final stabilization is achieved. Trapped sediment and other disturbed soils resulting from temporary measures shall be properly disposed of prior to permanent stabilization.
V. Design criteria, standards and specifications for erosion and sediment control shall be taken from one of the following sources:
1. Handbooks: Standards and specifications contained in the "Illinois Urban Manual", as amended, DuPage appendix E "Water Quality Best Management Practices Technical Guidance Manual" and the IDOT "Standard Specifications For Road And Bridge Construction".
2. Other: Other design criteria, standards and specifications, provided prior written approval is obtained from the administrator or director.
W. Applicant with land disturbing activities greater than one acre shall provide a statement acknowledging that the site complies with the IEPA NPDES ILR10 permit, if applicable. (Ord. G-976, 7-24-2012; Ord. G-1003, 6-11-2013)