Section
51.01 Title, purpose, intent and policy
51.02 Applicability
51.03 Exemptions
51.04 Definitions
51.05 Drainage system components
51.06 Permits and applications
51.07 Drainage plan submittal requirements
51.08 Design requirement
51.09 Maintenance responsibility
51.10 Inspections
51.11 Approval of constructed facilities
51.12 Performance guarantee
51.13 Dry weather water outlets
51.14 Variances
51.15 Enforcement
51.16 Severability
51.17 Penalties
51.18 Appeals
51.19 Disclaimer of liability
51.20 Retroactivity
51.21 Administrative rules
51.22 Savings and applicability
(A) Title. This chapter shall be known, cited and referred to as the, “Stormwater Management Ordinance of the Village of Mahomet, Champaign County, Illinois”.
(B) Purpose. The purpose of this chapter is to guide developer’s attempts to control the transportation or movement of stormwater so as to reduce the likelihood of damage to property; prevent injury to persons; protect the public health, safety, and general welfare of the community; and to promote the orderly development of land and water resources within the Village of Mahomet.
(C) Intent. The intent of this chapter is to require temporary storage of stormwater runoff, to control the rate of release of stormwater runoff by implementation of “reasonable provisions” and “in accordance with generally accepted engineering practices”, to provide for adequate drainage of development sites and surrounding areas, and to protect existing agricultural drainage system. Further, it is intended that this chapter complement and coordinate with the Village of Mahomet Subdivision Ordinance and the Village of Mahomet Zoning Ordinance.
(D) Policy. This chapter establishes a stormwater management policy for the future control of stormwater runoff within the jurisdictional limits of the village. Accordingly, a combination of temporary storage and the controlled release of stormwater runoff shall generally be required for all new commercial and industrial developments, residential subdivisions, planned unit developments, and any redevelopment or other new construction, as further defined in this chapter.
(Ord. 15-12-02, passed 12-15-2015)
(A) Scope of application. A combination of stormwater storage and controlled release of stormwater runoff is required for all non-agricultural development activities within the boundaries of the village involving:
(1) All non-agricultural developments greater than two acres in size.
(2) All non-agricultural developments between 20,000 square feet and two acres in size with greater than 35% impervious surface area.
(3) All new or expanded subdivisions which require approval of the village pursuant to the provisions of the Village of Mahomet Subdivision Ordinance, as amended.
(4) Generally, any new construction within the village’s area of zoning jurisdiction, pursuant to the provisions of the Village of Mahomet Zoning Ordinance, that increases the amount of pervious area of the lot or parcel of land upon which it is constructed.
(5) Except as may otherwise be provided herein, all structures erected hereafter, all uses of land or structures established hereafter, all improvements to water courses, all structural alterations or relocation of existing structures occurring hereafter, and all enlargement of, or additions to, existing uses which increase the amount of pervious area, occurring hereafter, shall be subject to the provisions of this chapter. Therefore, except as provided in § 51.03, no building permit may be issued, no subdivision or plat of land may be approved or recorded; no mobile home, independent travel trailer, or recreational travel trailer park permit may be issued; no planned unit development may be approved; no watercourse, stormwater drainage system, storm sewer, or stormwater control structure may be constructed; and no paved or compacted area designed to be used for loading, open storage, or the parking or movement of vehicles may be constructed without first having complied with the applicable provisions of this stormwater management chapter.
(B) Whenever storage and controlled release of stormwater is required for existing developed parcels, and where improvements upon such parcels were constructed prior to 1972, such storage and the required controlled release rate shall apply to the net increase in the amount of runoff since January 1, 1972.
(C) Any area proposed for development, consisting of a tract of land of three or more acres in common ownership or interest and upon which phased development is proposed, shall be required to provide a combination of storage and controlled release of stormwater runoff for future development of the entire tract.
(1) Where phased development is proposed, the owner may construct, after receiving site specific approval from the Administrator, one stormwater detention facility which is built larger than initially needed in order to anticipate subsequent phases of development and/or is designed to be enlarged at later dates as additional portions of the overall site are developed. Phased construction shall include implementation of sufficient and enforceable covenants upon the land to properly document the phased implementation. The form of covenant shall be approved by the Village Attorney, and the substance of the covenant shall reflect the approved overall stormwater detention plan for the site.
(2) Where a subdivision plat or a planned unit development involves new lots which are more than three acres in size that are zoned for commercial or industrial purposes, the developer/owner may provide for storage and controlled release of stormwater runoff for the developed lots by sufficient and enforceable covenant upon the individual lots. The covenant shall require construction of on-site stormwater detention facilities upon each lot at the time of subsequent development of that lot. The form of covenant shall be approved by the Village Attorney, and the substance of the covenant shall require construction of on-site stormwater runoff storage and controlled release of stormwater runoff from each lot in a manner approved by the Administrator, and in accordance with the provisions of this chapter.
(D) Any property or development falling within the scope of the provisions of this chapter shall be subject to review by the Administrator in order to establish and determine, in the opinion of the Administrator,that no adverse consequences will arise downstream as a result of construction of improvements under the sought-after permit. Any property located within floodplain areas, as defined in the flood hazard area development ordinance of the village shall be governed by such ordinance in the event of and to the extent of conflict with the provisions of this stormwater management ordinance.
(E) All applications for building permits shall contain a statement that such buildings or structures and appurtenances connected therewith include facilities for the orderly runoff or detention of rain and melting snow, as required herein. Plans submitted with said application shall include a signed statement issued by the owner and by an Illinois professional engineer that the plans include facilities adequate to prevent hazardous runoff, as required herein. For single family dwellings to be located in a subdivision meeting the requirement of this chapter, the signed statement may, in lieu of the above procedure, be placed on the face of the final plat or upon the required subsidiary drainage plat for the entire subdivision.
(F) Existing conditions.
(1) It is anticipated in this chapter that a land owner shall be allowed to pass through existing excess stormwater runoff from tributary areas upstream from that owner’s land without storage or controlled release of such runoff. It is further anticipated that this chapter will require the controlled release of excess stormwater runoff resulting from development on an owner’s land. The controlled release rate of excess stormwater runoff from an owner’s land shall not exceed the rate of runoff which would have occurred from that owner’s land prior to the development or redevelopment of that owner’s land.
(2) It is presumed by this chapter that prior to development, the owner’s land had a traditional agricultural use. It is further presumed that the maximum safe stormwater drainage capacity for downstream stormwater drainage systems is the capacity required to carry the peak rate of stormwater runoff from a five year return period storm event prior to December 14, 1981.
(Ord. 15-12-02, passed 12-15-2015)
(A) The provisions of this chapter shall not apply to the following developments:
(1) Any development constructed totally upon a lot or parcel of land, recorded prior to December 14, 1981, that contains less than 20,000 square feet of land area, provided the development has less than 35% impervious surface area; or
(2) Any single-family residential or two-family residential development on any lot or parcel of land, which was recorded prior to December 14, 1981; or
(3) Modification of single-family residential or two-family residential structures which will continue to be used as single-family or two-family dwellings; or
(4) Modification of existing structures or appurtenances, other than a single-family dwelling or two-family dwelling, which do not increase the amount of impervious area of the lot or parcel upon which it is constructed; or
(5) Traditional agricultural land uses; or
(6) Improvement of any existing roadways which do not increase the number of traffic lanes in the typical cross-section of the roadway; or
(7) Any development greater than two acres in size which the total impervious area is less than 15% of the total area of the site.
(8) New development in which the total impervious area, including the area of the existing, adjacent public or private streets, is less than 20% of the total area or is less than 10,000 square feet, whichever is less.
(B) The exemptions set forth above shall not apply to the installation, repair, or replacement of dry weather water outlets.
(Ord. 15-12-02, passed 12-15-2015)
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