(A) For the purposes of this chapter, the following definitions are adopted.
ADMINISTRATOR. The Village of Mahomet Administrator or other person specifically designated by the President of the Board of Trustees to enforce the provisions of this chapter.
BOARD OF TRUSTEES. The Board of Trustees of the Village of Mahomet.
CAPACITY OF A STORMWATER DETENTION FACILITY. The maximum volume that can be stored by a stormwater detention facility without causing damage to the public or encroachment upon private property. The capacity of a stormwater detention facility is generally determined utilizing average end area or similar volume calculation methods.
CAPACITY OF A STORMWATER DRAINAGE FACILITY. The maximum flow at atmospheric pressure that can be conveyed by the facility without causing damage to the public or encroachment upon private property. The capacity of a stormwater drainage facility is determined utilizing “Mannings Equation” or similar approved formula.
CHANNEL. A natural or artificial watercourse of perceptible extent which periodically or continuously contains moving water, or which forms a connecting line between two bodies of water. It has a definite bed and banks which serve to confine the water.
CONTROL STRUCTURE. A facility constructed to regulate the volume and rate of stormwater that is released during a specific length of time.
CULVERT. A closed conduit for the passage of surface drainage water under a roadway, railroad, or other surface impediment.
DETENTION STORAGE. Temporary detention or storage of stormwater in storage basins, on rooftops, in parking lots, school yards, parks, open space, lakes, ponds, or other areas under predetermined and controlled conditions, with the rate of drainage therefrom regulated by appropriately installed devices.
DEVELOPMENT. Any man-made change to improved or unimproved real estate, including, but not limited to, construction of or substantial improvements to buildings or other structures, the placement of mobile homes, paving, mining, filling, or other similar activities.
DISCHARGE. The rate of outflow of water from a stormwater drainage or stormwater detention facility.
DIVERSION. The deflection of storm or stream waters in such a way that those waters flow into a watercourse to which they are not naturally tributary or that the point of discharge of these waters within a natural watershed is changed.
DRAINAGE AREA. The area from which water is carried off by a drainage system; a watershed or catchment area above a given point.
DRAINAGE EASEMENT. Authorization by a property owner allowing use of a designated portion of his/her property by others for drainage purposes.
DRY BOTTOM STORMWATER DETENTION BASIN. A facility that is designed to be normally dry and which accumulates stormwater runoff only during periods when the restricted stormwater runoff release rate is less than the stormwater inflow rate.
DRY WEATHER WATER OUTLET. A dry weather water outlet is an outlet from a sump pump, footing tile, field tile, or other source which may discharge at times other than during periods of rainfall and pursuant to direct surface runoff.
EXCESS STORMWATER PASSAGEWAY. A channel formed on the surface of the soil to carry excess stormwater runoff through a specific area from dominant to servient land areas.
EXCESS STORMWATER RUNOFF. That portion of stormwater runoff which exceeds the transportation capacity of storm sewers, swales, ditches or natural drainage channels serving a specific watershed.
FLOOD ELEVATION. The elevation of all locations delineating the maximum level of high waters for a flood of a given return period.
FLOODPLAIN. The special flood hazard lands adjoining a watercourse or channel, the surface elevation of which is lower than the flood elevation and which are subject to periodic inundation during floods.
FLOODWAY. A channel of a watercourse and those portions of the adjoining floodplain which are reasonably required to carry and discharge the design flood.
GRADE. The inclination or slope of a channel, canal, conduit, etc., or natural ground surface, usually expressing in terms of percentage of the vertical rise (or fall) as compared to the corresponding horizontal distance.
ILLINOIS URBAN MANUAL. This term shall mean “A Technical Manual designed for Urban Ecosystem Protection and Enhancement”, published by the United States Department of Agriculture, Natural Resources Conservation Service, latest edition thereof.
IMPERMEABLE. A term applied to material through which water cannot pass.
IMPERVIOUS. A term applied to material through which water cannot pass, or through which water passes with great difficulty or at a very slow rate. For purposes of this chapter, any surface which
would typically be assigned a Rational Method “C” value of 0.60 or greater shall be considered impervious.
INLET. An opening into a storm drainage system for the entrance of surface storm runoff, more completely described as a storm drainage inlet.
NATURAL DRAINAGE. Water flow by gravity in channels formed by the true surface topography of the earth prior to changes made by the efforts of man.
NATURAL DRAINAGE CONDITION. The situation whereby water flows by gravity in channels formed by the true surface topography of the earth prior to changes made by the efforts of man or as defined by the Illinois Compiled Statutes.
NATURAL SAFE STORMWATER DRAINAGE CAPACITY. The quantity of stormwater runoff that can be transported by means of a channel, passage, conduit, tube, duct, or combination thereof, in such a manner that the elevation of the water does not rise significantly above the level of the adjacent soil surface, and cause damage or encroachment upon public or private property. For the purposes of this chapter, it is presumed that the maximum NATURAL SAFE STORMWATER DRAINAGE CAPACITY for downstream stormwater drainage systems is the capacity required to carry the rate of stormwater runoff from a five year return period storm prior to December 14, 1981.
OWNER. The record title holder or a beneficiary of a land trust which is the record title holder, and includes singular or plural; if the owner is other than an individual, the term includes beneficiaries, agents, shareholders, officers and directors, partnerships, associations, firms, trusts, clubs, companies, or corporations.
PEAK FLOW. The maximum rate of flow of water at a given point in a channel or conduit resulting from a predetermined storm or flood.
PERSON. An individual, public or private corporation, unit of government, partnership, or unincorporated association.
POSITIVE GRAVITY OUTLET. A term used to describe the drainage of an area in a manner that will ensure complete removal of all surface water by means of gravity.
RECOGNIZED AGENCY. A governmental unit or agency which has statistically and consistently examined local, climatic, and geologic conditions and maintained records as they apply to stormwater runoff, e.g. National Weather Service, University of Illinois Engineering Experiment Station, and the Illinois State Water Survey.
RETENTION BASIN. A structure of feature design to retain stormwater over a period of time, with its release being positively controlled over a longer period of time than a typical stormwater “detention” storage facility.
RETURN PERIOD. The average interval of time within which a given rainfall event will be equaled or exceeded once. As an example, a flood having a return period of 50 years has a 2% probability of being equaled or exceeded in any one year.
RUNOFF COEFFICIENT. A decimal fraction relating the amount of rain which appears as runoff and reaches the storm sewer system to the total amount of rain falling. For example, a coefficient of 0.50 implies that 50% of the rain falling on a given surface appears as stormwater runoff.
STANDARD SPECIFICATIONS. The Standard Specifications for Road and Bridge Construction published by the State of Illinois Department of Transportation, latest edition.
STORM DRAIN. A closed conduit for conveying collected stormwater runoff.
STORMWATER DRAINAGE SYSTEM. All means, natural or man-made, used for conducting stormwater to, through or from a drainage area to the point of final outlet, including but not limited to any of the following: conduits, storm drains, swales, canals, channels, ditches, streams, culverts, street gutters and pumping stations.
STORMWATER RUNOFF. The water that results from precipitation which is not absorbed by soil or plant material, which does not evaporate and which flows over the surface of the ground or is collected in channels, conduits or ponds.
STORMWATER RUNOFF RELEASE RATE. The rate at which stormwater runoff is released from dominant to servient land.
STORMWATER STORAGE AREA. An area designated to temporarily accumulate excess stormwater.
STRUCTURE. Anything which is constructed or erected with a fixed location on the ground or attached to something having a fixed location on the ground. Among other things, structures include buildings, fences, signs, mobile homes, swimming pools, and walls.
TIME OF CONCENTRATION. The time required for stormwater runoff from the remotest part of the drainage basin to reach the point being considered. Minimum time of concentration requirements for design of stormwater drainage systems shall be 15 minutes.
TRADITIONAL AGRICULTURAL USES. Uses commonly classes as agricultural or horticultural, including forestry, crop farming, truck gardening, wholesale nursery operations, animal husbandry, the operation of any machinery or vehicles incidental to said uses, and the construction of a single-family dwelling and other farm structures incidental to and typically associated with said uses. The terms does not include commercial feed lots, commercial grain storage/processing facilities or other similar agriculturally related commercial and industrial land uses.
TRIBUTARY WATERSHED. The entire catchment area that contributes stormwater runoff to a given point.
VILLAGE. The Village of Mahomet, Champaign County, Illinois and its staff and elected officials.
WATERCOURSE. Any stream, creek, brook, branch, natural or artificial depression, slough, gulch, reservoir, lake, pond or natural or man-made drainageway in or into which stormwater runoff and flood waters flow either regularly or intermittently.
WET BOTTOM STORMWATER STORAGE AREA. A facility that contains a body of water and which accumulates excess stormwater during periods when the restricted stormwater runoff release rate is less than the stormwater inflow rate.
(B) Words not defined shall be interpreted in accordance with the definitions contained in Webster’s New Collegiate Dictionary.
(Ord. 15-12-02, passed 12-15-2015)