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For the purpose of this chapter, the following definitions shall apply:

“Board” means the Drainage Board of Jasper County and any subordinate employee to whom they shall specifically delegate a responsibility authorized by this chapter.

“Capacity of a storm drainage facility” means the maximum flow that can be conveyed or stored by a storm drainage facility without causing damage to public or private property.

“Channel” means a natural or artificial watercourse which periodically or continuously contains moving water or which forms a connecting link between two bodies of water. It has defined bed and banks which serve to confine the water.

“Compensatory storage” means an artificial volume of storage within a floodplain used to balance the loss of natural flood storage capacity when artificial fill or structures are placed within the floodplain.

“Contiguous” means adjoining or, in actual contact with.

“Culvert” means a closed conduit used for the passage of surface drainage water under a roadway, railroad, canal, or other impediment.

“Detention basin” means a facility constructed or modified to restrict the flow of storm water to a prescribed maximum rate, and to detain concurrently the excess waters that accumulate behind the outlet. “Detention basin” also means a basin designed to be completely dewatered after having provided its planned detention of runoff during a storm event.

“Detention storage” means the temporary detaining or storage of storm water in storage basins, in streets, parking lots, school yards, parks, open spaces, or other areas under predetermined and controlled conditions, with the rate of drainage therefrom regulated by appropriately installed devices.

“Drainage area” means the area from which water is carried off by a drainage system; a watershed or catchment area.

“Drop manhole” means a manhole having a vertical drop pipe connecting the inlet pipe to the outlet pipe. The vertical drop pipe shall be located immediately outside the manhole.

“Duration” means the time period of a rainfall event.

“Erosion” means wearing away of the land by running water, waves, temperature changes, ice or wind.

“Flood elevation” means the elevation at all locations delineating the maximum level of high waters for a flood of given return period and rainfall duration.

“Flood or flood waters” means the water of any watercourse which is above the banks of the watercourse. It also means the water of any lake which is above and outside the banks thereof.

“Flood hazard area” means any floodplain, floodway, floodway fringe, or any combination thereof which is subject to inundation by the regulatory flood; or any floodplain as delineated by Zone A on a Flood Hazard Boundary Map on FIRM as adapted by the Jasper County Commissioners.

“Floodplain” means the area adjoining the river or stream which has been or may hereafter be covered by floodwaters.

“Flood protection grade” means the elevation of the lowest floor of a building. If a basement is included, the basement floor is considered the lowest floor.

Floodway. See “Regulatory floodway” in this section.

“Floodway fringe” means that portion of the floodplain lying outside the floodway, which is inundated by the regulatory flood.

“Footing drain” means a drain pipe installed around the exterior of a basement wall foundation to relieve water pressure caused by high groundwater elevation.

“Grade” means the inclination or slope of a channel, canal, conduit, etc., or natural ground surface usually expressed in terms of the percentage the vertical rise (or fall) bears to the corresponding horizontal distance.

“Impact areas” means areas defined and mapped by the Board which are unlikely to be easily drained because of one or more factors including but not limited to any of the following: soil type topography, land where there is not adequate outlet, a floodway or floodplain, land within 75 feet of each bank of any regulated drain or within 75 feet from the centerline of any regulated tile ditch.

“Impervious” means a term applied to material through which water cannot pass, or through which water passes with difficulty.

“Inlet” means an opening into a storm sewer system for the entrance of surface storm water runoff, more completely described as a storm sewer inlet.

“Junction chamber” means a converging section of conduit, usually large enough for a person to enter, used to facilitate the flow from one or more conduits into a main conduit.

“Lateral storm sewer” means a sewer that has inlets connected to it but has no other storm sewer connected.

“Major drainage system” means drainage system carrying runoff from an area of one or more square miles.

“Manhole” means storm sewer structure through which a person may enter to gain access to an underground storm sewer or enclosed structure.

“Minor drainage systems” means drainage systems having an area of less than one square mile.

“Off site” means everything not on site.

“On site” means located within the controlled area where runoff originates.

“Outfall” means the point or location where storm runoff discharges from a sewer or drain. Also applies to the outfall sewer or channel which carries the storm runoff to the point of outfall.

“Peak flow” means the maximum rate of flow of water at a given point in a channel or conduit resulting from a particular storm or flood.

“Radius of curvature” means length of radius of circle used to define a curve.

“Rainfall intensity” means the cumulative depth of rainfall occurring over a given duration, normally expressed in inches per hour.

“Reach” means any length of river, channel or storm sewer.

“Regulated area” means all of the land under the jurisdiction of the Jasper County Drainage Board.

“Regulatory flood” means that flood having a peak discharge which can be equaled or exceeded on the average of once in a 100-year period, as calculated by a method and procedure which is acceptable to the Board. If a permit from the National Resource Commission for construction in the floodway is required (see JCC 16.10.090), then the regulatory flood peak discharge should be calculated by a method acceptable to the Board and the Natural Resources Commission. This regulatory flood is equivalent to a flood having a probability of occurrence of one percent in any given year.

“Regulatory floodway” means the channel of a river or stream and those portions of the floodplains adjoining the channel which are reasonably required to carry and discharge the peak flow of the regulatory flood of any river or stream.

“Release rate” means the amount of storm water release from a storm water control facility per unit of time.

“Retention basin” means a basin designed to retain a permanent pool of water after having provided its planned detention of runoff during a storm event.

“Return period” means the average interval of time within which a given rainfall event will be equaled or exceeded once. A flood having a return period of 100 years has a one percent probability of being equaled or exceeded in any one year.

“Runoff coefficient” means a decimal fraction relating the amount of rain which appears as runoff and reaches the storm drainage system to the total amount of rain falling. A coefficient of 0.5 implies that 50 percent of the rain falling on a given surface appears as storm water runoff.

“Sediment” means material of soil and rock origin, transported, carried or deposited by water.

“Siphon” means a closed conduit or portion of which lies above the hydraulic grade line, resulting in a pressure less than atmospheric and requiring a vacuum within the conduit to start flow. A siphon utilizes atmospheric pressure to effect or increase the flow of water through a conduit. An inverted siphon is used to carry storm water flow under an obstruction such as a sanitary sewer.

“Spillway” means a waterway in or about a hydraulic structure, for the escape of excess water.

“Stilling basin” means a basin used to slow water down or dissipate its energy.

“Storage duration” means the length of time that water may be stored in any storm water control facility computed from the time water first begins to be stored.

“Storm sewer” means a closed conduit for conveying collected storm water.

“Storm water drainage system” means all means, natural or manmade, used for conducting storm water to, through or from a drainage area to any of the following: conduits and appurtenant features, canals, channels, ditches, streams, culverts, streets and pumping stations.

“Storm water runoff” means the water derived from rains falling within a tributary basin, flowing over the surface of the ground or collected in channels or conduits.

“Tributary” means contributing storm water from upstream land areas.

“Urbanization” means the development, change or improvement of any parcel of land consisting of one or more lots for residential, commercial, industrial, institutional, recreational or public utility purposes.

“Watercourse” means any river, stream, creek, brook, branch, natural or manmade drainageway in or into which storm water runoff or floodwaters flow either regularly or intermittently.

Watershed. See “drainage area” in this section. [Ord. 12-1-97C § 5.]