For the purpose of this chapter, the following definitions shall apply unless the context clearly indicates, or requires, a different meaning.
APPLICANT. A property owner or agent of a property owner who has filed an application for a stormwater management permit.
BEST MANAGEMENT PRACTICE (BMP). Structural and non-structural measures, practices, techniques, or devices employed to avoid or minimize sediment or other pollutants carried in runoff.
BIORETENTION. A stormwater infiltration device consisting of an excavated area that is backfilled with an engineered soil, covered with a mulch layer and planted with a diversity of woody or herbaceous vegetation.
BUILDING. Any structure having a roof supported by columns or walls for the housing or enclosure of persons or corporation, animals, or property. When any portion thereof is completely separated from every other portion thereof by a division wall without openings, then such portion shall be deemed to be a separate building.
CHANNEL PROTECTION VOLUME (CPV). The volume of runoff produced from a one-year, 24-hour design storm on a post-development site, which is detained for an extended period of time (24 hours or more).
CITY ENGINEER. The officer designated and authorized by the City Council to carry out various functions as specified in this chapter.
CLEARING. The stripping, grubbing, scalping, or removal of trees and stumps, and removing and disposing of all vegetation and debris within the site, and includes the conditions resulting therefrom.
CONSTRUCTION. The erection, alteration, repair, renovation, demolition, or removal of any building or structures; and the clearing, stripping excavating, filling, grading, and regulation of sites in connection therewith.
DESIGN STORM. Hypothetical depth of rainfall that would occur for the stated return frequency (for example, once every two years or ten years), duration (for example, 24-hours), and timing of distribution (for example, type II). All values are based on the historical rainfall records for the area.
DETENTION BASIN.
(1) A stormwater management facility designed to protect against flooding and, in some cases, downstream erosion by storing water for a limited period of a time.
(2) DETENTION BASINS do not retain a significant permanent pool of water between runoff events.
DEVELOPER. Any individual, subdivider, firm, association, syndicate, partnership, corporation, trust, or any other legal entity commencing proceedings under this chapter to effect the development of land.
DEVELOPMENT. Construction of buildings, other structures, impervious surfaces, and/or soil disturbance to the extent that peak runoff rates and volumes are increased, in a location where no such features currently exist.
DIRECTLY CONNECTED IMPERVIOUS AREA. An impervious surface that is directly connected to a storm sewer or water of the state via an impervious flow path.
DRAINAGE EASEMENT. A legal right granted by a landowner to a grantee allowing the use of private land for stormwater management purposes.
EROSION. The process of detachment, transport, and deposition of soil, sediment, or rock fragments by action of water, wind, ice, or gravity.
EXTREME FLOOD PROTECTION (QF). The controlling of post-development runoff 100-year peak flows to prevent flood damage from large storm events, maintain the boundaries of the pre-development 100-year Federal Emergency Management Agency (FEMA) and/or locally designated floodplain, and protect the physical integrity of BMP control structures.
FLOODPLAIN. A flat or nearly flat land adjacent to a stream or river that experiences occasional or periodic flooding.
HOTSPOT LAND USE.
(1) A site that produces higher concentrations of trace metals, hydrocarbons, or other priority pollutants than are normally found in urban stormwater runoff.
(2) Examples of HOTSPOTS include gas stations, vehicle service and maintenance areas, salvage yards, material storage sites, garbage transfer facilities, and commercial parking lots with high-intensity use.
HYDROLOGIC SOIL GROUP (HSG). The meaning used in the runoff calculation methodology promulgated by the United States Natural Resources Conservation Service Engineering Field Manual for Conservation Practices.
HYDROLOGY. The study of the movement, distribution, and quality of water throughout the earth.
IMPERVIOUS SURFACE.
(1) An area that releases all or a large portion of the precipitation that falls on it, except for frozen soil.
(2) Conventional rooftops and asphalt or concrete sidewalks, driveways, parking lots and streets are typical examples of impervious surfaces. For purposes of this chapter, typical gravel driveways and other examples listed shall be considered impervious unless specifically designed to encourage infiltration or storage of runoff.
INFILTRATION. The entry of precipitation or runoff into or through the soil.
KARST FEATURES. An area or surficial geologic feature subject to bedrock dissolution so that it is likely to provide a conduit to groundwater, and may include caves, enlarged fractures, mine features, exposed bedrock surfaces, sinkholes, springs, seeps, or swallets.
LAND DISTURBING ACTIVITY (OR DISTURBANCE).
(1) Any human-made alteration of the land surface that may result in a change in the topography or existing vegetative or non-vegetative soil cover, or may expose soil and lead to an increase in soil erosion and movement of sediment.
(2) LAND DISTURBING ACTIVITY includes clearing and grubbing for future land development, excavating, filling, grading, building construction, or demolition, and pit trench dewatering.
MAINTENANCE AGREEMENT. A legally recorded document that acts as a property deed restriction, and which provides for long-term maintenance of stormwater BMPs.
OVERBANK FLOOD PROTECTION (QP). The controlling of post-development runoff peak flows to prevent an increase in the frequency and magnitude of out-of-bank flooding generated by development (for example, flow events that exceed the bank-full capacity of the channel, and therefore must spill over into the floodplain).
PEAK FLOW. The maximum rate at which a unit volume of stormwater is discharged.
POST-DEVELOPMENT CONDITION. The extent and distribution of land cover types anticipated to occur under conditions of full development that will influence rainfall, runoff, and infiltration.
PRE-DEVELOPMENT CONDITION. The extent and distribution of land cover types present before the initiation of land development activity.
PRE-SETTLEMENT CONDITION. The extent and distribution of land cover types likely present before European settlement.
RAIN GARDEN. A depression area, designed and constructed as a landscape feature that is used to improve water quality and enhance infiltration.
RECHARGE VOLUME (REV). The volume of rainfall that is captured on a post-development site and directed through the soil to the groundwater table.
REDEVELOPMENT. Any construction, alteration, or improvement performed on sites where the existing site is already predominantly developed.
RUNOFF. Water from rain, snow, or ice melt, or dewatering that moves over the land surface via sheet or channelized flow.
RUNOFF CURVE NUMBER (RCN). The meaning used in the runoff calculation methodology promulgated by the United States Natural Resources Conservation Service Technical Release 55, “Urban Hydrology for Small Watersheds” (commonly known as TR-55).
SEDIMENT. Solid earth material, both mineral and organic, that is in suspension, is being transported, or has been moved from its site of origin by air, water, gravity, or ice, and has come to rest on the earth’s surface at a different site.
SITE. The entire area included in the legal description of which the land disturbing or land development activity will occur.
SOIL. All earth material of whatever origin that overlies bedrock, and may include the decomposed zone of bedrock which can be readily excavated by mechanical equipment.
SPECIFICATIONS. The general term comprising all the directions, provisions, and requirements, together with such as may be added or adopted as supplemental specifications or special provisions approved by the City Engineer.
STORMWATER. The same meaning as the term RUNOFF.
SURFACE WATERS. All lakes, bays, rivers, streams, springs, ponds, wells, impounding reservoirs, marshes, watercourses, drainage systems, and other surface water or groundwater, natural or artificial, public or private, within the city.
TIME OF CONCENTRATION (TC). The time needed for water to flow from the most remote point in a watershed to the watershed outlet. It is a function of topography, geology, and land use within the watershed.
VOLUMETRIC RUNOFF COEFFICIENT (RV). The fraction of rainfall during small storm events that becomes runoff, and can be determined by the methodologies described by Scheuler (1987) or Pitt (1994).
WATER QUALITY VOLUME (WQV). The storage needed to capture and treat the runoff from 90% of the average annual rainfall. In numerical terms, it is equivalent to the rainfall depth in inches multiplied by the volumetric runoff coefficient (Rv) for the site, and the site drainage area.
WETLANDS. An area where water is at, near, or above the land surface long enough to be capable of supporting aquatic or hydrophytic vegetation, and which has soils indicative of wet conditions.
(Prior Code, § 6-21-3)