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HomeMy WebLinkAboutG57-85 Ordinance No. G57-85 AN ORDINANCE AMENDING CHAPTER 18.36 ENTITLED STORMWATER CONTROL OF THE ELGIN MUNICIPAL CODE, 1976 BE IT ORDAINED BY THE CITY COUNCIL OF THE CITY OF ELGIN, ILLINOIS: Section I . That Chapter 18.36 of Title 18 of the Elgin Municipal Code, 1976, as amended, be and is hereby further amended by adding the following: "I8.36.060 Development permit. No person, firm, or corporation shall commence any development in the SFHA without first obtaining a development permit from the city engineer. The city engineer shall not issue a development permit if the proposed development does not meet the requirements of this chapter. A. Application for a development permit shall be submitted to the city engineer and shall be accompanied by drawings of the site, drawn to scale showing property line dimensions; and I. Existing grade elevations and all changes in grade resulting from excavation or filling; 2. The direction of flow of surface drainage and flood flows; 3. The location of all watercourses and drainage facilities; 4. The location and dimensions of all buildings and additions to buildings; and 5. The elevation of the lowest floor (including basement) of all buildings subject to the requirements of Section 18.36.070 of this chapter. B. Upon receipt of an application for a development permit, the city engineer shall compare the elevation of the site to the base flood elevation. Any development located on land higher than the base flood elevation is not in the SFHA and therefore not subject to the requirements of this chapter. C. The city engineer shall inform the applicant of any and all other local, state, and federal permits that may be required for this type of development activity. The development permit will only be issued on the condition that the other specified permits are obtained. The city engineer shall not approve a certificate of occupancy unless all required permits have been obtained. D. All new development proposals in the special flood hazard areas shall be reviewed and approved by the city engineer. The city engineer's review is to ensure the following: I. New developments will not change the flow of flood or other surface drainage waters so that other properties become more susceptible to damage; 2. New developments will not create special hazards or nuisances when flooded; and 3. New buildings and major improvements to existing buildings will not be subject to damage by the base flood. E. No development in the SFHA shall create a damaging or poten- tially damaging increase in flood heights or velocity. I. For development proposals located in an identified floodway or within a riverine SFHA where the floodway has not yet been identified, the following rule shall apply: The city engineer shall review the develop- ment plans to discern if: a. A new obstruction to flood flows would be created; b. The project will involve a channel crossing such as a bridge or pipeline; or c. The project will modify the shape of the channel. If any of these three situations will result from the project, the applicant shall be required to obtain a permit from the Illinois Depart- ment of Transportation, Division of Water Resources, issued pursuant to III. Rev. Stat., Ch. 19, sec. 70. The city engineer shall not issue a development permit unless the applicant has obtained either a Section 70 permit or a "waiver of permit required" from the Division of Water Resources. 2. For development proposals located in a flood fringe, "AO zone", or "AH zone" identified as such on a SFHA map or in a lake- front floodplain, ponding area, area of sheet flow, or other SFHA not subject to overbank flooding from an identified channel, the requirement of subsection E.l of this section shall not apply. F. No development in the SFHA shall include locating or storing chemicals, explosives, buoyant materials, flammable liquids, pollutants, or other hazardous or toxic materials below the FPE unless such materials are stored in a storage tank or flood proofed building constructed according to the requirements of this chapter. G. New replacement sanitary sewer lines and on-site waste disposal system may be permitted providing all manholes or other aboveground openings located below the FPE are watertight. I8.36.070 Building regulations. A. In addition to the damage prevention requirement of Section 18.36.060, all buildings to be located in the SFHA shall, except where provided herein, be constructed at an elevation not lower than the base flood elevation plus one foot, otherwise known as the flood protection elevation (FPE) and shall be protected from flood damage below the FPE. This building protection requirement applies to the following situations: I. Construction or placement of a new building valued at more than one thousand dollars; 2. Improvements made to an existing building that increase the first floor area by more than fifty percent; 3. Reconstruction, repairs or improvements made to a damaged building that are valued at or more than fifty percent of the value of the building before the damage occurred; and 4. Installing a mobile home on a new site or a new mobile home on an existing site. This building protection requirements does not apply to returning a mobile home to the same site it formerly lawfully occupied. B. This building protection requirement may be met by any one of the following methods: I. A building may be constructed on permanent land fill in accordance with the following: a. The area to be filled shall be cleared of all standing trees, brush, down timber, trash, and other growth or objects unsuitable for use as foundation material. b. The fill shall be placed in layers no greater than one foot deep before compaction. c. The surface of the fill shall be at or above the FPE. The fill shall extend at least ten feet beyond the foundation of the building before sloping below the FPE. d. The fill shall be protected against erosion and scour during flooding by vegetation cover, rip rap, or bulkheading. If vegetative cover is used, the slopes shall be no steeper than three horizontal to one vertical. e. The fill shall not adversely affect the flow of surface drainage from or onto neighboring properties. f. The city engineer shall maintain a record of the as-built elevation of the lowest floor of the building. 2. A building may be elevated in accordance with the follow- ing: a The building or improvements shall be elevated on stilts, piles, walls, crawl space, or other foundation that is permanently open to floodwaters and not subject to damage by hydrostatic pressures. b. The foundation and supporting members shall be anchored, shooed and aligned so as to minimize exposure to known hydrodynamic forces such as current, waves, and floating debris. All mobile homes to be placed within Zone A on the Flood Insurance Rate Map (FIRM) shall be anchored to resist flotation, collapse, or lateral movement by providing over-the- top and frame ties to ground anchors. Specific requirements shall be that: I. Over-the-top ties be provided at each of the four corners of the mobile home, with two additional ties per side at intermediate locations and mobile homes less than fifty feet long requiring one additional tie per side; 2. Frame ties to be provided at each corner of the home with five additional ties per side at intermediate points and mobile homes less than fifty feet long requiring four addi- tional ties per side; 3. All components of the anchoring system be capable of carrying a force of four thousand eight hundred pounds; and 4. Any additions to the mobile home be similarly anchored. c. All arens below the FPE shall be constructed of materials resistant to flood damage. The bottom of the joists of the lowest floor and all utility meters shall be located at or above the FPE. d. The city engineer shall maintain a record of the as-built elevation of the lowest floor. e. No area below the FPE shall be used for storage of items or materials subject to flood damage unless such items or materials are declared "property not covered" by a Standard Flood Insurance Policy of the National Flood Insurance Program. f. Any future alteration of the area below the FPE that violates the requirements of subsection B2 of this section shall be deemed a violation of this chapter. The city engineer shall inform the applicant that any such alteration is considered a willful act to increase flood damages and therefore will cause coverage by a Standard Flood Insurance Policy to be suspended. g. No mobile home may be placed on a new site located within an identified floodway. 3. A nonresidential building may be floodproofed in accordance with the following: a. A registered professional engineer shall certify that the building has been designed so that below the FPE, the structure and attendant utility tacilities are watertight and capable of resisting the affects of the base flood. The building design shall take into account flood velocities, duration, rate of rise, hydro- static and hydrodynamic forces, the effects of buoyancy, and impacts from debris or ice. b. Floodproofing measures shall be operable without human intervention and without an outside source of electricity. c. The city engineer shall maintain the engineer's certifi- cate and a record of the as-built elevation to which the building was floodproofed. C. The city council shall take into account flood hazards to the extent that they are known, in all official actions related to land manage- ment, use and development: I. The city council shall not approve any annexation agreement or plat of subdivision located outside the corporate limits unless such agreement or plat is in accordance with the provisions of this chapter. The city engineer shall obtain the best available SFHA maps and data for the unincorporated areas. 2. New subdivisions, mobile home parks, and planned unit developments (PUDs) shall meet the requirements of this chapter. Plats or plans for new subdivision, mobile home parks, and planned unit develop- ments (PUDs) shall include a signed statement by a registered professional engineer that the plat or plans account for changes in the drainage or surface waters in accordance with the Plat Act (III. Rev. Stat., 1979, Ch. 109, par. 2). 3. Plats or plans for new subdivisions, mobile home parks, and planned unit developments (PUDs) shall display the following flood data: a. The boundary of the SFHA; b. The boundary of the floodway, if shown on available SFHA maps; c. Easements of lands dedicated to the city for access for channel maintenance purposes; and d. The FPE for each building site. Where the base flood elevation is not available from an existing study filed with the Illinois State Water Survey, the applicant shall be responsible for calculating the FPE and submitting it to the State Water Survey for review and approval as best available elevation data. 4. Plans for the development activities to be undertaken by the city in the SFHA shall be reviewed by the city engineer to ensure that they comply with this chapter. Except as exempted by law, no other local government shall commence any development activity in the SFHA without first ubluiiiiiiy u development permit from the city engineer. 5. The planning department shall take the following into con- sideration when preparing or revising the comprehensive plan, community development program, housing assistance plan, and other land use or development programs: a. Preserving SFHA land for open space uses such as farming or recreation; b. Acquiring and removing frequently flooded buildings; c. Prohibiting hospitals, water treatment plants, natural gas storage and other critical or especially hazardous facilities from locating in the SFHA; d. Identifying the elevations of the base flood and past floods at entrances to public buildings, on street signs, or other prominent locations; and e. Other flood hazard mitigation or floodplain management activities that could help accomplish the purposes of this chapter. 18.36.08u Stormwater detention areas--Purpose and findings. A. It is recognized that many of the receiving streams and lowland areas within the city do not have the capacity to receive and convey the increased stormwater runoff resulting from urbanization occurring in many areas. These receiving streams or lowlands are subject to periodic inunda- tion which results in a growing rate of property damage. B. It is the intent of this section to require developers to partici- pate in providing detention area storage to eliminate excessive runoff during heavy storm periods. Other control methods which would be accept- able to regulate the rate of stormwater discharge include detention on flat roofs, parking lots, streets, lawns, underground storage, and oversized storm sewers with restricted outlets. C. It is recognized that in order to better serve the long-range interests of the city, comprehensive basin-wide planning for stormwater control shall be followed as determined by the city engineer. This compre- hensive drainage plan may require that a single large detention area serve several parcels as determined by the city engineer. Comprehensive basin- wide drainage planning is far more beneficial than individual on-site deten- tion, although on-site detention does provide protection and is acceptable for compliance with this chapter. 18.36.090 Stormwater detention areas--Requirements. Pursuant to the provisions of this chapter, no final plat shall be approved unless detention of stormwater runoff is provided as set forth in the fol!o\e'inn criteria: A. A combination of storage and controlled release of stormwater runoff is required for all commercial developments exceeding two acres in area; and for all residential developments exceeding five acres in area. However, a residential development of five acres or less must have an adequate outlet as determined by the city engineer. If the outlet is not adequate, then detention, as determined by the city engineer, will be required to store that portion of the runoff exceeding the outlet capacity. B. The release rate of stormwater from all developments requiring detention shall not exceed the stormwater runoff rate from the area in its natural undeveloped state. The city will accept a release rate of not greater than that calculated from a storm of five-year frequency with a runoff coefficient of 0.15. C. Drainage systems shall have adequate capacity to bypass through the development the flow from all upstream areas for a storm of five-year 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 0.45. An allowance will be made for upstream detention when such upstream detention and release rate has previously been approved by the city and that evidence of its construction can be shown. D. The detention storage volume to be provided will be calculated on the basis of the one-hundred-year storm, for any and all durations, from the fully developed drainage area tributary to the reservoir, less that volume discharged during that same duration at the approved release rate. E. Sample calculations reflecting the provisions of this section will be furnished by the city engineer upon request." Section 2. That all ordinances or parts of ordinances in conflict with the provi- sions of this ordinance be and are hereby repealed. Section 3. That this ordinance shall be in full force and effect ten days after its passage and publication in the manner provided by law. s/ Richard L_ Verhir Richard L. Verbic, Mayor Presented: July 22 , 1985 Passed: July 22 , 1985 Vote: Yeas 7 Nays 0 Recorded: Published: Attest: s/ Marie Yearman Marie Yearman, City Clerk ,