For the purpose of this chapter, the following definitions shall apply unless the context clearly indicates or requires a different meaning.
ADVERSE IMPACTS. Any negative impact on plant, soil, air or water resources 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 produce official approval of a development or permit to carry out construction of a new development or redevelopment from the county.
BASE FLOOD ELEVATION. The elevation at all locations delineating the level of flooding resulting from the 100- year frequency flood event, which has 1% chance of occurring in any given year.
BUILDING PERMIT. A permit issued by the county for the construction, erection or alteration of a structure or building and the related ground and surface preparation prior to and after completion of construction, erection or alteration of a structure or building.
BYPASS FLOWS. Storm water runoff from upstream properties tributary to a property’s drainage system but not under its control.
CERTIFY or CERTIFICATION. Formally attesting that the specific inspections and tests were performed, and that such inspections and tests comply with the applicable requirements of this chapter.
CHANNEL. Any defined river, stream, creek, brook, branch, natural or artificial depression, ponded area, on-stream lake or impoundment, karst area (sinkhole), flowage, slough, ditch, conduit, culvert, gully, ravine, wash or natural or human-made drainage way, which has a definite 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), filling, widening, deepening, straightening, relocating, lining and significant removal of bottom or woody rooted vegetation. CHANNEL MODIFICATION does not include the human-made clearing of debris or removal of trash.
CLEARING. Any activity which removes the natural vegetative ground cover.
COMPENSATORY STORAGE. An artificially excavated, hydraulically equivalent volume of storage within the floodplain used to balance the loss of natural food 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.
CUBIC YARD. A one yard by yard by one yard amount of material in excavation and or fill.
DETENTION BASIN. A facility constructed or modified to provide for the temporary storage of storm water runoff and the controlled release by gravity of this runoff at a prescribed rate during and after a flood or storm.
DETENTION TIME. The amount of time storm water is held within a detention basin.
DEVELOPMENT. Any human-made change to real estate property, including:
(1) The division or subdivision of any duly recorded parcel of property;
(2) Construction of roads, bridges or similar projects;
(3) Installation of a manufactured home on a site, preparing a site for manufactured home or installing a travel trailer on a site for more than 180 days per year;
(4) Construction of roads, bridges or similar projects;
(5) Redevelopment of a site;
(6) Filling, dredging, grading, clearing, excavating, paving or other non-agricultural alterations of a ground surface;
(7) Storage of materials or deposit of solid or liquid waste; and
(8) Any other activity that might alter the magnitude, frequency, direction or velocity of storm water flows from a property.
DRAINAGE PLAN. A plan, including engineering drawings and supporting calculations, which describes the existing storm water drainage system and environmental features, including grading, as well as proposed alterations or changes to the drainage system and environment of a property.
DRY BASIN. A detention basin designed to drain after temporary storage of storm water flows and to normally be dry over much of its bottom area.
EROSION. The general process whereby soil or earth is moved by rainfall, flowing water, wind or wave action.
EXCAVATION. Any act by which organic matter, earth, sand, gravel, rock or any other similar material, is cut into, dug quarried, uncovered, removed, displaced, relocated or bulldozed and shall include the conditions resulting from such actions.
EXCESS STORM WATER RUNOFF. The volume and rate of flow of storm water discharged from a new development or redevelopment which is or will be in excess of that volume and rate which existed before development or redevelopment.
EXISTING GRADE. The vertical location of the existing ground surface prior to excavation or filling.
FILL. Any cut which earth, sand, gravel, rock, or any other material, is deposited, placed, replaced, pushed, dumped, pulled, transported or moved by humans to a new location and shall include the conditions resulting there from.
FINAL GRADE. The vertical location of the ground surface after grading work is completed in accordance with the engineering plans.
FLOOD FRINGE. The area as designated by the Federal Emergency Management Agency (FEMA) on either side of the floodway. This area is subject to inundation from the base flood but conveys little or no flow.
FLOOD HAZARD BOUNDARY MAP (FHBM). A much generalized map prepared by the Federal Emergency Management Agency (FEMA) which shows only where floodplains are located based on very basic data. FHBMs do not include base flood elevations.
FLOOD INSURANCE RATE MAP (FIRM). A map prepared by the Federal Emergency Management Agency (FEMA) that depicts the special flood hazard area (SFHA) within a community. This map includes insurance rate zones and regulatory floodplains and may or may not depict regulatory floodways.
FLOODPLAIN. The land adjacent to a body of water with ground surface elevations at or below the base flood or the 100-year frequency flood elevation which is subject to inundation. The FLOODPLAIN as designated by the Federal Emergency Management Agency (FEMA) is also known as the special flood hazard area (SFHA). These areas can be found on the FIRM, flood boundary and floodway map or the flood hazard boundary map (FHBM) of the community. This area is the collective combination of the regulatory floodway and the flood fringe.
FLOODWAY. The channel and that portion of the floodplain, including on-stream lakes, 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 one-tenth-foot increase in stage due to any loss of flood conveyance or storage and no more than a 10% increase in velocities. FLOODWAYS are designated by FEMA on some flood insurance rate maps and flood boundary and floodway maps. However, there are floodways on all streams whether mapped by FEMA or not.
GRADING. The excavation or fill or any combination thereof and shall include the conditions resulting from any excavation or fill.
HYDROGRAPH. A graph showing for a given location on a stream or conduit, the flow rate with respect to time.
HYDROGRAPH METHOD. This method estimates runoff volume and runoff hydrographs for the point of interest by generating hydrographs for individual subareas, combining them and routing them through stream lengths and reservoir structures. Factors such as rainfall amount and distribution, runoff curve number, time of concentration and travel time are included.
IMPERVIOUS SURFACE. The area of property that is covered by materials other than soil and vegetation and that has no intended capacity to absorb water, such as parking lots, driveways, sidewalks, patios, tennis courts, roofs and other structures.
INFILTRATION. The passage or movement of water into the soil surfaces.
LOESSAL SOIL. A sediment, commonly non-stratified and un-consolidated, composed predominately of silt sized particles with accessory clay and sand.
LOT. An individual platted parcel in an approved subdivision.
MAJOR DRAINAGE SYSTEM. The portion of a drainage system needed to store and convey flows beyond the capacity of the minor drainage system.
MINOR DRAINAGE SYSTEM. That portion of a drainage system designed for the convenience of the public. It consists of street gutters, storm sewers, small open channels and swales and, where human-made, is to be designed to handle the two-year runoff event.
MITIGATION. When the prescribed controls are not sufficient and additional measures are required to offset the development, including those measures necessary to minimize the negative effects which storm water drainage and development activities might have on the public health, safety and welfare. Examples of MITIGATION include, but are not limited to, compensatory storage, soil erosion and sedimentation control, and channel restoration.
MODIFIED RATIONAL METHOD. As described in the Illinois Department of Transportation Drainage Manual is based on the principal that the maximum rate of runoff from a given drainage area occurs at that point in time when all parts of the watershed are contributing to the flow. The rainfall generating the peak flow is assumed to be of uniform intensity for the entire watershed with a rainfall duration equal to the time of concentration.
NATURAL. Conditions resulting from physical, chemical and biological processes without intervention by humans.
NATURAL DRAINAGE. Channels formed in the existing surface topography of the earth prior to changes made by unnatural causes.
ONE HUNDRED-YEAR EVENT. A rainfall, runoff or flood event having a 1% chance of occurring in any given year. A 24-hour storm duration is assumed unless otherwise noted.
PARCEL. All contiguous land in one’s ownership.
PEAK FLOW. The maximum rate of flow of water at a given point in a channel or conduit.
PERMITEE. Any person to whom a building permit is issued.
PERSON. Any individual, firm or corporation, public or private, the state and its agencies or political subdivisions, the United States of America, and its agencies or political subdivisions, and any agent, servant, officer or employee of any of the foregoing.
POSITIVE DRAINAGE. Provision for overland paths for all areas of a property including depressional areas that may also be drained by storm sewer.
PRIME FARMLAND. Land that is best suited to food, feed, forage, fiber and oilseed crops. It may be cropland, pasture, woodland or other land, but it is not urban and built up land or water areas. It is either used for food or fiber or is available for those uses. The soil qualities, growing season and moisture supply are those needed for a well managed soil to economically produce a sustained high yield of crops. PRIME FARMLAND produces the highest yields with minimum inputs of energy and economic resources, and farming it results in the least damage to the environment.
PROPERTY. A parcel of real estate.
RETENTION BASIN. A facility designed to completely retain a specified amount of storm water runoff without release except by means of evaporation, infiltration, emergency bypass or pumping.
SEDIMENTATION. The process that deposits soils, debris and other materials either on other ground surfaces or in bodies of water or storm water drainage systems.
SITE. A parcel of land, or a contiguous combination thereof, where grading work is performed as a single unified operation.
SINKHOLE, (KARST AREAS). A land surface depression or blind valley which may or may not have surface openings to cavernous underground areas and are the result of water movement through silts and jointed limestone. These conditions make such areas unstable and susceptible to subsidence and surface collapse. Fractures in the limestone may channel runoff water to public or private water supplies, making those sources especially susceptible to groundwater contamination.
SLOPE DISTURBANCE LINE. The line which delineates relatively level building areas from areas where slopes exceed 8% and where special precautions must be taken.
STORM SEWER. A closed conduit for conveying collected storm water.
STORM WATER DRAINAGE SYSTEM. All means, natural and human-made, used for conducting storm water to, through or from a drainage area to the point of final outlet from a property. The storm water drainage system includes, but is not limited to, any of the following: conduits and appurtenance features; canals; channels; ditches; streams; culverts; streets; storm sewers; detention basins; swales; and pumping stations.
STORM WATER 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.
STREAM. Any river, creek, brook, branch, flowage, ravine or natural or human-made drainage way which has a definite bed and banks or shoreline, in or into which surface or groundwater flows, either perennially or intermittently.
STRIPPING. Any activity which removes the vegetative surface cover including tree removal, by spraying or clearing, and storage removal of top soil.
TEN-YEAR EVENT. A runoff, rainfall or flood event having a 10% chance of occurring in any given year. A 24-hour storm duration is assumed unless otherwise note.
TIME OF CONCENTRATION. The elapsed time for storm water to flow from the most hydraulically remote point in a drainage basin to a particular point of interest in that watershed.
TRIBUTARY WATERSHED. All of the land surface area that contributes runoff to a given point.
TWO-YEAR EVENT. A runoff rainfall, or flood event having a 50% chance of occurring in any given year. A 24-hour storm duration is assumed unless otherwise noted.
VACANT. Land on which there are no structures or only structures which are secondary to the use or maintenance of the land itself.
WATERSHED. All land area drained by, or contributing water to, the same stream, creek, ditch, lake, marsh, storm water facility, groundwater or depressional area.
WET BASIN. A detention basin designed to maintain a permanent pool of water after the temporary storage of storm water runoff.
WETLANDS. Those areas that are inundated or saturated by surface or groundwater at a frequency and duration sufficient to support, and under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions. For general, but no inclusive locations of designated WETLANDS refer to mapping prepared jointly by the U.S. Department of Interior, Fish and Wildlife Service and the Illinois Department of Natural Resources, Office of Resource Conservation: National Wetlands Inventory Mapping, 1987. The applicant may be required to provide a field investigation by a qualified wetland delineator.
(Ord. passed 9-8-2009)