§ 30-162. Definitions.
The following words, terms and phrases, when used in this division, shall have the meanings ascribed to them in this section, except where the context clearly indicates a different meaning. Words not defined shall be interpreted in accordance with definitions contained in Merriam Webster's New Collegiate Dictionary, Ninth Edition.
Administrator: The person designated by the county to administer and enforce this article. The planning director and county engineer shall jointly administer this article.
Adverse impacts: Any deleterious impact on water resources or wetlands affecting their beneficial uses including recreation, aesthetics, aquatic habitat, quality, and quantity.
Applicant: Any person, firm or governmental agency who executes the necessary forms to procure official approval of a development or permit to carry out construction or a development from the county.
Base flood: The flood having a one percent probability of being equaled or exceeded in any given year. The base flood is also known as the 100-year frequency flood.
Base flood elevation: The elevation at all locations delineating the level of flooding resulting from the base flood event.
Best management practice (BMP): A measure used to control the adverse stormwater-related effects of development. BMPs include structural devices (e.g. swales, filter strips, infiltration trenches, and detention basins) designed to remove pollutants, reduce runoff rates and volumes, and protect aquatic habitats. BMPs also include non-structural approaches, such as public education efforts to prevent the dumping of household chemicals into storm drains.
Buffer area: An area of predominantly vegetated land to be left open, adjacent to wetlands, drainage ways, lakes, ponds, or other surface waters for the purpose of eliminating or minimizing adverse impacts on such areas.
Channel: Any river, stream, creek, brook, branch, natural or artificial depression, ponded area, flowage, slough, ditch, conduit, culvert, gully, ravine, wash, or natural or manmade drainage way, which has a defined bed and bank or shoreline, in or into which surface or groundwater flows, either perennially or intermittently.
Channel modification: Alteration of a channel by changing the physical dimensions or materials of its bed or banks. Channel modification includes damming, riprapping (or other armoring), widening, deepening, straightening, relocating, lining, and significant removal of bottom or woody rooted vegetation. Channel modification does not include the clearing of debris or removal of trash.
Compensatory storage: An artificially excavated, hydraulically equivalent volume of storage within the floodplain used to balance the loss of natural flood storage capacity when fill or structures are placed within the floodplain.
Conduit: Any channel, pipe, sewer or culvert used for the conveyance or movement of water, whether open or closed.
Control structure: A structure designed to control the rate of flow that passes through the structure, given a specific upstream and downstream water surface elevation.
County: Unless otherwise identified, the County of DeKalb, Illinois.
County engineer: The county superintendent of highways or a professional engineer, registered in the state, who has been duly appointed as the county engineer of the County of DeKalb, or who has been hired by the county as its consulting engineer.
Critical duration: The duration of a storm or flood event that results in the greatest peak runoff or high water elevation.
Deed or plat restriction: Easements, covenants, deed restricted open spaces, outlets dedicated to a public entity, reserved plat areas, conservation easements, or public road rights-of-way that contain any part of the stormwater management system of a development.
Depressional storage: A non-riverine depression where stormwater collects. The depressional storage volume is the volume contained in a depression below the high water level of the critical duration 100-year flood through the site in the pre-developed condition.
Detention basin: A facility constructed or modified to provide for the temporary storage of stormwater runoff and the controlled release by gravity of this runoff at a prescribed rate during and after a flood or storm.
Detention time: The mean residence time of stormwater in a detention basin.
Development: Any man-made change to real estate, including:
(1)
Preparation of a plat of subdivision;
(2)
Construction, reconstruction or placement of a building or any addition to a building;
(3)
Installation of a manufactured home on a site, preparing a site for a manufactured home, or installing a travel trailer on a site for more than 180 days;
(4)
Drilling, mining, installation of utilities, construction of roads, bridges, or similar projects;
(5)
Filling, dredging, grading, construction of levees, clearing, excavating, paving, or other non-agricultural alterations of the ground surface;
(6)
Storage of materials or deposit of non-agricultural solid or liquid waste; and
(7)
Any other activity that might alter the magnitude, frequency, deviation, or velocity of stormwater flows from a property.
"Development" does not include maintenance of existing buildings and facilities such as resurfacing of roadways when the road elevation is not increased, or gardening, plowing, and traditional agricultural practices that do not involve filling, grading, or construction of levees. Additionally, development does not include fence installation, pole placement, drilling or other minor auxiliary construction activity, which does not affect stormwater runoff rates or volumes.
Director: The county planning director.
Drainage district: A special district created by petition or referendum and court approval having the power to construct and maintain drainage improvements and to pay for improvements with assessments on the land within the district boundaries.
Dry detention basin: A detention basin designed to drain completely after temporary storage of stormwater flows and to normally be dry over the majority of its bottom.
Emergency overflow: The structure in a stormwater management system designed to protect the system in event of a malfunction of the primary flow structure or a storm event greater than the system design. The emergency overflow capacity initiates at the facility design high water level or base flood elevation.
Erosion: The general process whereby soil is detached by the action of water or wind.
Excess stormwater runoff: The volume and rate of flow of stormwater discharged from an urbanized area which is or will be in excess of that volume and rate which pertained before urbanization.
Exempt municipality: A municipality located entirely or partially within the boundaries of the county that has adopted and enforces its own stormwater management ordinance, said ordinance being consistent with and at least as stringent as the countywide stormwater management ordinance, based on the finding of the stormwater management planning committee in accordance with section 30-168 herein.
FEMA: Federal Emergency Management Agency and its regulations codified as 44 CFR 59-79, effective September 29, 1989, as amended.
Floodplain: That land adjacent to a body of water with ground surface elevations at or below the base flood or the 100-year frequency flood elevation. The floodplain is also known as the special flood hazard area (SFHA).
Flood fringe: That portion of the floodplain outside of the regulatory floodway.
Flood rate insurance map (FIRM): A map prepared by the Federal Emergency Management Agency of HUD that depicts the special flood hazard area (SFHA) within a community. The map includes insurance rate zones and floodplains and may or may not depict regulatory floodways.
Floodway: The channel and that portion of the floodplain adjacent to a stream or watercourse which is needed to store and convey the anticipated existing and future 100-year frequency flood discharge with no more than a 1.0 foot increase in stage due to any loss of flood conveyance or storage and no more than ten percent increase in velocities. Municipality should reference the FIRMs applicable to the municipality and the surrounding areas.
Freeboard: An increment of height added to the base flood elevation, groundwater table, or 100-year design water surface elevation to provide a factor of safety for uncertainties in calculations, unknown local conditions, wave action, and unpredictable effects.
GIS Maps: The digital maps created and maintained by the information management office of the county.
Hydrograph: A graph showing the flow with respect to time for a given location on a stream or conduit.
Illinois Urban Manual: Technical design manual by the Natural Resource Conservation Service for best management practices (BMPs) for controlling non-point source pollution.
Impervious surface: Any hard-surfaced, man made area that does not readily absorb, retain, or infiltrate water, including but not limited to building roofs, parking and driveway areas, graveled areas, sidewalks and paved recreation areas.
Infiltration: The passage or movement of water into the soil surfaces.
Lowest adjacent grade: The lowest finished grade adjacent to a structure, not including the bottom of window wells.
Major drainage system: That portion of a stormwater management system needed to store and convey flows beyond the capacity of the minor drainage system. Where manmade, it is designed to handle stormwater runoff from the 100-year frequency event.
Minor drainage system: That portion of a stormwater management system designed for the convenience of the public. It consists of street gutters, storm sewers, small open channels, and swales. Where manmade, the minor conveyance system is designed to handle stormwater runoff from the ten-year frequency event. It also consists of crossroad culverts, which shall be designed to handle stormwater runoff from the 50-year frequency event.
Mitigation: Mitigation includes those measures necessary to minimize the negative effects, which stormwater drainage and development activities might have on the public health, safety and welfare. Examples of mitigation include compensatory storage, soil erosion and sediment control, and channel restoration.
Natural: Conditions resulting from physical, chemical, and biological processes without intervention by man.
New impervious area: Impervious surface area created after the effective date of this article.
One hundred-year return frequency event: A rainfall, runoff, or flood event having a one percent change of occurring or being exceeded in any given year.
On-stream detention: Any detention facility to which runoff from upstream tributary areas flow.
Overland flow route: An area of land, which conveys stormwater runoff for all events up to, and including the base flood event.
Peak flow: The maximum rate of flow of water at a given point in a channel or conduit.
Person: An individual, public or private corporation, government, partnership, or unincorporated association.
Planning and zoning committee: The planning and zoning committee of the county board, it's successors or assigns.
Plat officer: The plat officer of the county.
Positive drainage: Provision for overland paths for all areas of a property including depressional areas that may also be drained by storm sewers.
Property: A parcel of real estate.
Redevelopment: Any activity, alteration, or change in land use that is undertaken on previously developed land.
Registered professional engineer: An engineer in the State of Illinois, under the Professional Engineer Act of 1989, 225 ILCS 325/1-49.
Regulatory floodway: The channel, including on-stream lakes, and that portion of the floodplain adjacent to a stream or watercourse as designated by the Illinois Department of Natural Resources, Office of Water Resources (IDNR-OWR), which is needed to store and convey the existing and anticipated future 100-year frequency flood discharge with no more than a 1.0 foot increase in stage due to loss of flood conveyance or storage, and no more than ten percent increase in velocities. To locate the regulatory floodway boundary on any site, the regulatory floodway boundary shall be scaled off the regulatory floodway map and located on a site plan, using reference marks common to both maps. Where interpretation is needed to determine the exact location of the regulatory floodway boundary, the IDNR-OWR should be contacted for the interpretation.
Release rate: The rate at which stormwater runoff leaves the property.
Retention basin: A facility designed to completely retain a specified amount of stormwater runoff without release except by means of evaporation, infiltration, emergency bypass or pumping.
Riverine: Relating to, formed by, or resembling a stream (including creeks and rivers).
Sedimentation: The process that deposits soils, debris, and other materials either on other ground surfaces or in bodies of water or stormwater drainage systems.
Special flood hazard area (SFHA): Any area subject to inundation by the base flood from a river, creek, stream, or any other identified channel or ponding and shown on the FEMA flood insurance rate map. The SFHA is also known as the floodplain.
Storm sewer: A closed conduit for conveying collected stormwater.
Stormwater management planning committee: The committee appointed by the county board and charged with the development of the countywide stormwater management plan and ordinance and other duties as set forth in 55 ILCS 5/5-1062.2
Stormwater management plan: The countywide stormwater management plan, which describes the existing stormwater drainage system and environmental features, as well as the stormwater management system and environmental features in the county.
Stormwater management system: The collection of natural features and man-made facilities, which define the stormwater management for a development. Examples include major and minor drainage systems, stormwater storage facilities, BMPs, etc.
Stormwater runoff: The waters derived from melting snow or rain falling within a tributary drainage basin which are in excess of the infiltration capacity of the soils of that basin, which flow over the surface of the ground or are collected in channels or conduits.
Structure: The results of man-made change to the land constructed at or below the ground, including the construction, reconstruction or placement of a building or any addition to a building; installing a manufactured home on a site; preparing a site for a manufactured home or installing a recreational vehicle on a site for more than 180 days.
Time of concentration: The elapsed time for stormwater to flow from the most hydraulically remote point in a drainage basin to a particular point of interest in that watershed.
Traditional agriculture uses: Uses commonly classified 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 single-family dwellings and other farm structures incidental to and typically associated with said uses. Agribusiness uses are not considered to be traditional agricultural uses and include but are not limited to commercial grain elevators, commercial facilities for grain storage, drying or other processing; commercial feed, seed or fertilizer manufacturing, processing or sales; or any other agricultural-related use, which substantially increases the size of impervious surface areas which may cause significant or measurable increases in stormwater runoff.
Tributary: A stream or river that flows into a main stem (or parent) river.
Two-year return frequency event: A runoff, rainfall, or flood event having a 50 percent chance of occurring or being exceeded in any given year.
Watershed: An area of land where all of the water that drains off of it goes into the same place. Watershed boundaries in the county are as depicted on the GIS maps, as may be amended by additional studies of greater detail.
Wet detention basin: A detention basin designed to maintain a permanent pool of water after the temporary storage of stormwater runoff.
Wetland: Wetlands are land that is inundated or saturated by surface or ground water at a frequency and duration sufficient to support, under normal conditions, a prevalence of vegetation adapted for life in saturated soil conditions (known as hydrophilic vegetation). A wetland is identified based upon the three attributes:
(1)
Hydrology;
(2)
Soils; and
(3)
Vegetation as mandated by the current federal wetland determination methodology.
(Ord. 2006-28, § 3, 11-15-06; Ord. No. 2010-18, § 3, 9-15-10)