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HomeMy WebLinkAboutORDINANCE - 3802 - 3/14/2023 - Amending Section A and B of Section 8-12-1B Of Municipal CodeORDINANCE NO.3802 AN ORDINANCE AMENDING SECTIONS A AND B OF SECTION 8-12-1-B OF THE OF THE MUNICIPAL CODE OF THE VILLAGE OF ELK GROVE VILLAGE NOW, THEREFORE, BE IT ORDAINED by the Mayor and Board of Trustees of the Village of Elk Grove Village, Counties of Cook and DuPage, Illinois, as follows: Section 1: That 8-1213-1-2: REQUIRED IMPROVEMENTS be amended to read as follows: A. Storm and Surface Water Runoff: 1. Storm Drains: An adequate system of storm water drainage designed for a 10-year return frequency rain shall be constructed and installed, consisting of pipes, tiles, manholes, inlets and other necessary facilities that will adequately drain the subdivision and protect roadway pavements and will prevent the accumulation of storm water at any place under normal conditions. Open ditches shall be prohibited in all residential zoning areas. Back yard swales are permitted in residential zoning areas subject to the following regulations: a. Maximum and minimum slopes and general design criteria of the Federal Housing Administration and the Department of Housing and Urban Development's "Minimum Property Requirements" will be acceptable except as herein modified. b. No continuous swale shall have a length exceeding six hundred feet (600'). (Ord. 1054, 4-13-76) c. Minimum grade of the flow line shall be one percent (1%). (Ord. 1697, 2-12-85) d. At no point in the swale shall the flow line be more than three feet (3') below the finished grade of the topsoil at the foundation of the house opposite the swale. e. No change in alignment of a back yard swale shall exceed forty five degrees (45°). 2. Open Ditches: Open ditches are allowed for rear yard drainage in the industrial and commercial zoning areas if they conform to the following regulations: a. The bottom of the ditch shall be lined with a five inch (5 ") thick concrete invert minimum of three feet (3'-0") wide. Two (2) number 6 reinforcing rods are to be equally spaced for the entire length of the invert. b. The grade of the invert shall be designed to provide a velocity of flow between three feet (3') and five feet (5') per second. c. The sides of the ditch shall not exceed a two to one (2:1) slope. d. All side slopes shall be sodded from the invert to the top of the slope. e. Any alignment change shall require concrete slope protection on the side slopes of the ditch or other erosion control measure as approved by the Director of Community Development. B. Storm Water Management: 1. The Watershed Management Ordinance (WMO) as adopted by the Metropolitan Water Reclamation District of Greater Chicago (MWRD) on May 1, 2014 and as subsequently amended, and the DuPage County Countywide Stormwater And Floodplain Ordinance adopted September 24, 1991 and as subsequently amended shall govern the design of any improvement with respect to storm water management within Cook County and DuPage County respectively in addition to the following: a. Streets, blocks, depths of lots, parks and other public grounds shall be located and laid out in such a manner as to preserve and utilize natural streams, channels and detention basins including, wherever possible, the larger streams and flood plains within parks or other public grounds. b. Storm water from a 100-year return frequency storm must be stored and/or transported from any development in such a manner that no damage results from flooding. c. A combination of storage and controlled release of storm water runoff is required for all non-residential developments, regardless of size, and for residential developments exceeding five (5) acres in area. d. The release rate of storm water from all developments requiring detention shall not exceed the storm water runoff rate from the area in its natural undeveloped state. Because of the flat conditions of the land in this area, channel configurations cut by nature are generally unable to handle the runoff from high intensity rainfalls and results in flood plain storage or spreading of runoff over the land areas during the larger storm periods. In order not to increase the runoff from such areas after development, the release rate must be limited to the carrying capacity of these natural channels. In no instance shall a release rate greater than two tenths cubic feet per second (0.2 cfs) be used. e. Drainage systems shall have adequate capacity to bypass through the development the flow from all upstream areas for a storm of design frequency assuming that the land is in a fully developed state under present zoning or zoning proposed under a Comprehensive Plan. The bypass flow rate shall be computed utilizing a runoff coefficient of not less than 0.35. An allowance will be made for upstream detention when such upstream detention and release rate has been approved by the Director of Community Development and that evidence of its construction can be shown. f. The live detention storage to be provided will be calculated on the basis of the 100-year frequency rainfall as published by the Illinois State Water Survey, Bulletin 75, for this area and as subsequently amended. The detention volume required will be that necessary to handle the runoff of a 100-year rainfall, for any and all durations, from the fully developed drainage area tributary to the reservoir, less that volume discharged during the same duration at the approved release rate. g. Sharply meandering streams or channels may be partly straightened and minor changes made in other channels, subject to approval of the Director of Community Development; provided the floodway dimensions of the stream or channel are maintained, and the volume of flood water storage outside the floodway is not reduced. h. The smaller uppermost reaches of drainage channels and swales forming the natural drainage system near the watershed divide may be relocated or eliminated and incorporated into the planned system of storm sewers upon a showing that the system is adequate and can safely handle the flood water runoff following the heavier rain storms. i. Storm sewer outfalls shall be so designed, by reason of elevation of the invert that, when the receiving stream is in full flood, the storm sewer will continue to drain the area it is designed to serve at a uniform rate. j. Cross -sections and grades of streets designed as channels shall be designed to temporarily store and convey the overflow from storm sewers and over -the -curb runoff and be provided with adequate outlets for safe disposal of such overflow. The street cross-section shall provide a lot grade for the finished floor of each adjoining building at least two feet (2') higher than the crown of the pavement, and the minimum sill elevation of openings in the outer walls of such buildings shall be at least two and one-half feet (2.5') above the crown elevation. k. The crown of street pavements hereafter built adjoining or near streams, flood water runoff channels or detention basins shall be not lower than the established high-water elevation plus two feet (2'), in the case of major streets, and plus one foot (1') in a 100-year frequency storm. 1. Waterway openings of bridges and culverts hereafter built over streams of flood water runoff channels shall be designed with a waterway opening large enough to handle the flow from a 100-year frequency storm. m. Construction, filling or other similar physical occupation of the flood plain as defined by the Department of the Interior United States Geological Survey, which is otherwise prohibited by this subsection, may be permitted if adequate compensatory storage volume is provided. This shall be accomplished by developing in the existing flood plain excavated space below the high- water elevation in an amount equal to the flood storage capacity preempted by the proposed construction. In the case of streams and channels, such excavation shall be made opposite or immediately upstream from the area to be filled. It shall be the duty of the property owner to conduct such excavation in a manner consistent with the other provisions of this subsection and may be done only after the approval by the Director of Community Development has been granted. Approval of the Director of Community Development will be contingent upon the property owner's ability to demonstrate that the compensatory storage will be adequate and satisfactory for its intended purpose. 2. Drainage Plan: A comprehensive drainage plan must be submitted to the Director of Community Development which incorporates the aforementioned rules and shall provide or be accompanied by maps or other descriptive material showing the following: a. The extent and area of each watershed tributary to the drainage channels in the subdivision. b. The street storm sewers and other storm drains to be built, the basis of their design, the outfall and outlet locations and elevations, receiving stream or channel and its high-water elevation and the functioning of the drains during high-water conditions. c. The parts of the proposed street system where pavements are planned to be depressed sufficiently to convey or temporarily store overflow from storm sewers and over -the -curb runoff resulting from the heavier rain storms and the outlets for such overflow. d. Existing streams and flood water runoff channels to be maintained, enlarged, altered otherwise and eliminated and new channels to be constructed, their locations, cross -sections and profiles. e. Existing culverts and bridges, drainage areas, elevation and adequacy of waterway openings and new culverts and bridges to be built, their materials, elevations, waterway openings and basis of design. f. Existing detention ponds and basins to be maintained, enlarged, altered otherwise and new ponds or basins to be built with dams and their design. 3. Construction Requirements for Detention Ponds: a. Detention Ponds Containing Permanent Water: (1) Detention reservoirs containing permanent water must have a water area of at least one-half (1/2) acre and a minimum depth of approximately ten feet (10') over at least twenty five percent (25%) of the total area. The remaining lake area must have an average depth of at least five feet (5') and should have no extensive shallow areas. (2) In excavated lakes, the underwater side slopes in the lakes must be stable. In the case of valley storage, natural slopes may be considered to be stable. (3) A safety ledge four feet (4') to six feet (6) in width is required and must be installed in all lakes approximately thirty inches (30") to thirty six inches (36") below the permanent water level. In addition, a ledge twelve inches (12") to eighteen inches (18") above the permanent water line must be provided. The slope between the two (2) ledges must be stable and of a material which will prevent erosion due to wave action such as stone or rip rap. (4) A safety ramp exit from the lake is required in all cases and should have a minimum width of twenty feet (20') and exit slope of six horizontal to one vertical (6:1). The ramp must be of a material that will prevent its deterioration due to vehicle use and/or wave action. (5) Periodic maintenance is required in lakes to control weed and larval growth. The reservoir must also be designed to provide for the easy removal of sediment which will accumulate in the lake during periods of reservoir operation. A means of maintaining the designed water level of the lake during prolonged periods of dry weather is also required. One suggested method is to have a water hydrant near the pond site. b. Detention Ponds Containing Permanent Water and Dry Detention Ponds: (1) All excavated spoils must be spread so as to provide for aesthetic and recreational features such as sledding hills, sport fields, etc. Slopes of six horizontal to one vertical (6:1) are required except where recreation uses call for steeper slopes. Even these features must have a slope no greater than three horizontal to one vertical (3: 1) for safety, minimal erosion, stability and ease of maintenance. (2) Safety screens must be provided for any pipe or opening to prevent children or large animals from crawling into the structures. A maximum opening of six inches (6") is required. (3) In valley storage reservoirs, an emergency spillway or other provision must be provided to allow for bypassing flood flows during periods when the design capacity of the reservoir and outlet has been exceeded. This spillway must be of such a design that its operation is automatic and does not require manual attention. (4) Sod or other suitable vegetative cover as approved by the Director of Community Development must be provided throughout the entire reservoir area. (5) Debris and trash removal and other necessary maintenance must be performed after each storm to assure continued operation in conformance to the design. c. Dry Detention Ponds: (1) Dry detention ponds must have an underdrain system to minimize the wetness of the bottom so that water does not remain standing in the bottom thereby harboring insects and limiting the potential use of the reservoir. The underdrain system could empty by gravity into the wet well of a pump station or to the receiving stream directly. (2) The dry detention pond must be designed to serve multi -purpose functions. Recreational facilities, aesthetic qualities, etc., as well as flood water storage must be considered in planning the reservoir. 4. Responsibility for Maintenance of Detention Ponds: a. The responsibility for maintenance during construction and thereafter shall be the responsibility of the land developer/ owner. b. Storm water detention and retention basins may be donated to the Village or other unit of government designated by the Village for ownership and permanent maintenance, providing: (1) The facility has been designed and constructed according to Village requirements enumerated above; (2) All improvements have been constructed, approved and accepted by the Village for the land area served by the drainage basin; (3) Detention ponds containing permanent water are located within a tract of land consisting of fifteen (15) acres or more, of which thirty percent (30%) of the area is above the high-water line, and includes a body of water of ten (10) surface acres or more, of which fifty percent (50%) is to have a minimum depth of ten feet (10'); four inch (4") size rip rap to be provided three feet (3') below and three feet (3') above normal water line; all slopes between the rip rap and high-water line are to be sodded and the remaining land area is to be hydroseeded; are equipped with electrically -driven aeration devices to maintain proper aerobic conditions to sustain aquatic life; have a four foot (4') wide crushed limestone walkway at the high water line entirely around the body of water; are situated to permit public access two hundred feet (200') wide and not less than two hundred feet (200') to the high-water line; and providing further, that the high-water line is not closer than thirty five feet (35') to any property line. (4) Dry detention ponds are located on a tract of land consisting of two (2) acres or more of land, including a minimum bottom area of two hundred seventy five feet by two hundred seventy five feet (275'x 275') or two hundred feet by three hundred seventy five feet (200'x 375'); maximum side slopes of five to one (5:1); all slopes are to be sodded to the high-water line; the bottom of the basin and areas above the high-water line are to be hydroseeded; and providing further, that the high-water line is not closer than thirty five feet (35') to any property line. (Ord. 1054, 4-13-76; 1992 Code) Section 2: That the Village Clerk is hereby authorized to publish this Ordinance in pamphlet form. Section 3: That this Ordinance shall be in full force and effect from and after its passage, approval and publication according to law. VOTE: AYES: 5 NAYS: 0 ABSENT: 0 PASSED this 14t' day of March 2023 APPROVED this 14t' day of March 2023 APPROVED: Mayor Craig B. Johnson Village of Elk Grove Village ATTEST: Loretta M. Murphy, Village Clerk PUBLISHED this 16t' day of March, 2023 in pamphlet form.