(A) Design and operation standards and requirements.
(1) Each applicant shall submit the information as regulated to ensure that the provisions of this chapter are met. The submittal shall include sufficient information to evaluate the environmental characteristics of the property, the potential adverse impacts of the development related to erosion both on-site and off-site, and the effectiveness of the proposed erosion and sediment control plan in reducing sediment loss.
(2) Submissions shall be prepared in accordance with the standards and requirements contained in the “Illinois Urban Manual,” most current update, prepared by the U.S. Department of Agriculture, Natural Resources Conservation Services (formerly Soil Conservation Service) for the Illinois Environmental Protection Agency and recognized by the Madison County Soil and Water Conservation District, which standards and requirements are hereby incorporated into this chapter by reference.
(3) Properties and channels adjoining development sites shall be protected from erosion and sedimentation. At points where concentrated flow leaves a development site, energy dissipation devices shall be placed at discharge locations and along the length of any outfall channel as necessary to provide a non-erosive velocity of flow from the structure to the watercourse so that the natural physical and biological characteristics and functions are maintained and protected.
(4) Disturbed areas shall be stabilized with temporary or permanent measures within 14 calendar days following the end of active hydrologic disturbance, or re-disturbance, consistent with the following criteria or using an appropriate measure as approved by the code enforcement official.
(a) Appropriate temporary or permanent stabilization measures shall include seeding, mulching, sodding, and/ or non-vegetative measures.
(b) Areas of embankments having slopes greater than or equal to three horizontal to one vertical shall be stabilized with staked-in-place sod, mat, or blanket in combination with seeding.
(c) Erosion control blankets shall be required on all interior detention basin side slopes between the normal water level and the high-water level.
(d) The 14-day stabilization requirement may be precluded by snow cover or where construction activity will resume within 21 days from when the active hydrologic disturbance ceased, then stabilization measures do not have to be initiated on that portion of the site by the fourteenth day after construction activity temporarily ceased, given that portion of the site has appropriate soil erosion and sediment controls.
(5) Land disturbance activities in streams shall be avoided, where possible. If disturbance activities are unavoidable, the following requirements shall be met:
(a) Where stream construction crossings are necessary, temporary crossings shall be constructed of non-erosive material.
(b) 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 48 hours after channel disturbance is completed or interrupted.
(6) Soil erosion and sediment control measures shall be appropriate with regard to the amount of tributary area as follows:
(a) Disturbed areas draining greater than 5,000 square feet but less than one acre shall, at a minimum, be protected by a filter barrier (including filter fences) which at a minimum, meet the applicable specification sections in the IDOT “Illinois Standard Specifications for Road and Bridge Construction” and “Illinois Urban Manual” to control all off-site runoff. Vegetated filter strips, with a minimum width of 25 feet, in the direction of flow, may be used as an alternative only where runoff in sheet flow is expected.
(b) Disturbed areas draining more than one but fewer than five acres shall, at a minimum, be protected by a sediment trap and a filter barrier or equivalent control measure at a point downslope of the disturbed area.
(c) Disturbed areas draining more than five acres shall, at a minimum, be protected by filter barrier and a sediment basin with a perforated filtered riser pipe or equivalent control measures at a point downslope of the disturbed area.
(d) 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 two-year, 24-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. A detention basin may serve as the sediment basin if a filtered perforated riser pipe protects the outflow pipe.
(e) The maximum drainage area for overland flow to a silt fence shall not exceed half-acre per 100-feet of fence. In addition, the maximum allowable slope distances contributing runoff to a silt fence are as follows:
Slope (%) | Max Spacing Along Slope (ft) |
25 | 50 |
20 | 75 |
15 | 125 |
10 | 175 |
Flatter than 10 | 200
|
(7) All storm sewers that are or will be functioning during construction shall be protected by an inlet protection control measure and cleaned once the site has been stabilized.
(8) If dewatering services are used, adjoining properties and discharge locations shall be protected by erosion. Discharges shall be routed through an effective sediment control measure (e.g., sediment trap, basin, erosion fence, or other appropriate measures).
(9) All temporary soil erosion and sediment control measures shall be removed within 30 days after final site stabilization is achieved or after the temporary measures are no longer needed. Trapped sediment and other disturbed soil areas shall be permanently stabilized. Typically, a site is stabilized when permanent vegetation is established over at least 75% of the area or when otherwise approved by the city.
(10) A stabilized mat of aggregate under laid with filter cloth shall be located at any point where traffic will be entering or leaving a construction site of a major development to or from a public right-of-way, street, alley, or parking area. Any sediment or soil reaching an improved public right-ow-way, street, alley, or parking area shall be removed by scraping or street cleaning as accumulations warrant and transported to a controlled sediment disposal area. The code enforcement official may require additional stabilized construction entrance methods.
(11) Earthen embankments shall be constructed with side slopes no steeper than three horizontal to one vertical. Steeper slopes may be constructed with appropriate stabilization as recommended by a geotechnical engineer and approved by the City Engineer.
(12) Stormwater conveyance channels, including ditches, swales, and diversions, and the outlet of all channels and pipes shall be designed and constructed to withstand the expected flow velocity from the two-year frequency storm without erosion. All constructed or modified channels shall be stabilized within 48 hours.
(13) Temporary diversions shall be constructed, as necessary, to direct all runoff from hydrologically disturbed areas to the appropriate sediment trap or basin.
(14) Soil stockpiles shall not be located in a flood-prone area or a designated buffer protecting Waters of the United States. Soil stockpiles are defined as having greater than 100 cubic yards of soil and will remain in place for more than seven days. Soil stockpiles locations shall be shown on the soil erosion and sediment control plan and shall have the appropriate measures to prevent erosion of the stockpile.
(15) A concrete wash-out pit shall be located on-site to control concrete waste from trucks for projects that include concrete work.
(16) Handbooks. Standards and specifications contained in the “Illinois Urban Manual,” as amended, and the planning procedures sections of the “Illinois Procedures and Standards for Urban Soil Erosion and Sedimentation Control,” as amended, are referenced in this ordinance as guidance for presenting soil erosion and sediment control plan specifications and delineating procedures and methods of operation under site development for soil erosion and sediment control. In the event of conflict between provisions of said manuals and this ordinance, this chapter shall govern.
(17) The applicant shall provide adequate receptacles for the deposition of all construction material debris generated during the development process. The applicant shall not cause or permit the dumping, depositing, dropping, throwing, discarding or leaving of construction material debris upon or into any development site, channel, or waters of the United States. The applicant shall maintain the development site free of construction material debris.
(B) Plan submittal requirements. An “Erosion and Sediment Control Plan” shall be submitted for both existing and proposed property conditions; new developments or redevelopments meeting the requirements of § 156.002. The plan shall show/contain the following information:
(1) All erosion and sedimentation control measures necessary to meet the objectives of this chapter throughout all phases of construction and permanently after completion of development of the site.
(2) Outfalls, drainage tributary areas, and two-year, 24-hour storm frequency volumes required to evaluate whether the requirements in division (A)(6) are being met.
(3) Location of the slope disturbance lines.
(4) The proposed phasing of development of the site, including stripping and clearing, rough grading and construction, and final grading and landscaping. Phasing should identify the expected date on which clearing will begin, the estimated duration of exposure of cleared areas, and the sequence of clearing, installation of temporary sediment control measures, installation of storm drainage, paving streets and parking areas, and establishment of permanent vegetative cover. All design and related work, where required by law, shall be prepared under the direct supervision of an Illinois Licensed Professional Engineer.
(5) Seeding mixtures and rates, types of sod, method of seed-bed preparation, expected seeding dates, type and rate of lime and fertilizer application, and kind and quantity of mulching for both temporary and permanent vegetative control measures.
(6) Construction details for all erosion and sedimentation control measures used on the project (e.g., ditch checks, inlet protection, sediment basins, stone riprap, construction entrances, erosion control blanket, concrete wash-out pits, etc.). Appropriate construction details are included herein in Appendix A, and may be supplemented by the IDOT “Highway Standards” for Temporary Erosion Control Systems or the “Illinois Urban Manual” practice standards.
(7) Provisions for maintenance of control facilities, including easements and estimates of the cost of maintenance.
(8) Identification of the person(s) or entity which will have legal responsibility for maintenance of erosion control structures and measures after development is completed.
(9) The applicant shall certify and sign on the drawing that all clearing, grading, drainage and construction shall be accomplished in strict conformance with the erosion and sediment control plan.
(Ord. 2017-03, passed 3-6-2017)