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(A) Specifications for erosion control measures shall be in accordance with the Illinois Urban Manual (2002) or latest edition. Sediment and erosion control planning shall be in accordance with Procedures and Standards for Urban Soil Erosion and Sedimentation Control in Illinois (revised July, 1988) by the Urban Committee of the Association of State Soil and Water Conservation Districts (The Green Book) Chapters 1 through 5. Where the Illinois Urban Manual supersedes sections of The Green Book, the Illinois Urban Manual shall prevail.
(B) All projects that will result in the development of one acre or more, except for agricultural projects regulated solely under § 164.024, shall be required to obtain coverage under an appropriate NPDES permit and shall submit an application for a NPDES permit or a notice of intent (NOI) to be covered under a general NPDES permit. The developer shall certify to the Chief Subdivision Engineer that all required permits, plans and inspections have been prepared and maintained in accordance with the NPDES permit. Specifically, the developer shall prepare and adhere to a stormwater pollution prevention plan (SWPPP) prepared for the development project and shall meet the conditions in the permit for SWPPPs. A copy of such plan shall be provided to the Chief Subdivision Engineer prior to commencement of development activities and a copy shall be maintained on the construction site at all times.
(Ord. 10-164, passed 6-17-2010)
The runoff from disturbed areas shall not leave the development site without first passing through sediment control facilities. This requirement shall apply to all phases of construction and shall include an ongoing process of implementation of measures and maintenance of those measures during both the construction season and any construction shut down periods.
(Ord. 10-164, passed 6-17-2010)
The condition of the construction site for the winter shut down period shall address proper sediment and erosion control early in the fall growing season so that slopes and other bare earth areas may be stabilized with temporary and/or permanent vegetative cover. All open areas that are to remain idle throughout the winter shall receive temporary erosion control measures including temporary seeding, mulching and/or erosion control blanketing prior to the end of the fall growing season. The areas to be worked beyond the end of the growing season must incorporate soil stabilization measures that do not rely on vegetative cover such as erosion control blankets and heavy mulching.
(Ord. 10-164, passed 6-17-2010)
(A) In the hydraulic and hydrologic design of major erosion control measures (those whose tributary drainage area is greater than three acres) such as sediment basins and traps, diversions and the like, the design frequency shall be commensurate with the risk of the design event being exceeded.
(B) The following design frequencies shall be regarded as minimum design frequencies for the construction period.
(1) For those projects whose construction period is less than six months, then the storm event having a 50% chance (two-year event) of being exceeded in any year shall be used for design purposes.
(2) For those projects whose construction period is greater than six months but less than one year, the design frequency for major sediment basins shall be a rainfall event with a 20% (five-year event) chance of being exceeded in any one year.
(3) For those construction projects expected to last more than one year, major sediment basins shall be designed for a rainfall event with a 10% (ten-year event) chance of being exceeded in any one year.
(Ord. 10-164, passed 6-17-2010)
(A) The sediment and erosion control plan shall designate a series of practices which shall be implemented either at the direction of the permittee or the permittee’s representative on-site or at the direction of the Chief Subdivision Engineer should an inspection of the site indicate a deficiency in soil and sediment erosion control measures.
(B) As a minimum, these measures shall include the following:
(1) Sedimentation basins;
(2) Sediment traps;
(3) Diversion swales;
(4) Silt fences;
(5) Temporary seeding;
(6) Mulching; and
(7) Erosion control blankets.
(Ord. 10-164, passed 6-17-2010)
(A) Detailed construction phasing plan identifying sediment and erosion control measures to be in place for each phase shall be submitted prior to stripping the site of existing vegetation or cover.
(B) Sediment and erosion control measures to be installed initially prior to stripping existing vegetation or mass grading shall be indicated on the plans.
(C) Permanent stabilization measures shall be indicated on a separate plan.
(D) The expected two-year and ten-year runoff rates from all off-site areas draining into the site shall be identified on the plan.
(E) Methods for conveying flows through the site during construction shall be indicated. These methods must include the temporary and permanent stabilization measures to be used to reduce velocity and erosion from flow through the construction zone.
(F) A maintenance schedule of each measure used shall be indicated on the plan. As a minimum, all sediment and erosion control measures on-site shall be inspected weekly and also by the applicant’s designee or after a one-half inch or greater rainfall event and any required repairs shall be made to keep these measures functional as designed. All plan modifications shall be reviewed by the Chief Subdivision Engineer or his or her designee. A record of all repairs and modifications shall be maintained by the applicant and available for review by the Chief Subdivision Engineer or his or her designee.
(Ord. 10-164, passed 6-17-2010)
(A) To the extent practicable, proposed ditches and waterways that are to convey off-site flows through the site shall be stabilized upon construction.
(B) Where new waterways are constructed, they shall be stabilized to the extent practicable prior to their use to convey flood flows.
(Ord. 10-164, passed 6-17-2010)
(A) Stockpiles of soil and other erodable or floatable building materials (sand, limestone and the like) shall not be located in floodplains, overflow routes or areas subject to frequent inundation.
(B) If a stockpile is to remain in place for more than three days, then sediment and erosion control shall be provided for the stockpile.
(Ord. 10-164, passed 6-17-2010)
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