Adams County Unincorporated
City Zoning Code

STORM DRAINAGE

CONTROL

§ 153.180 PURPOSE.

(A) The purpose of this subchapter is to reduce the hazard to public health and safety caused by excessive stormwater runoff, to enhance economic objectives, and to protect, conserve, and promote the orderly development of land and water resources within the regulatory area.

(B) This subchapter regulates:

(1) Stormwater drainage improvements related to development of lands, as defined within this subchapter, located within the county;

(2) Drainage control systems installed during new construction and grading of developments as defined within this subchapter; and

(3) The design, construction, and maintenance of stormwater drainage facilities and systems.

(Ord. 1997-16, passed 12-8-1997; Ord. 2005-01, passed 2-17-2005)

§ 153.181 CONFLICT AND COMPLIANCE WITH OTHER REGULATIONS.

(A) The provisions of this subchapter shall be deemed as additional requirements to minimum standards required by other ordinances of the county. In case of conflicting requirements, the most restrictive shall apply.

(B) In additions to the requirements of this subchapter, compliance with the requirements set forth in this chapter and other applicable ordinances with respect to submission and approval of preliminary and final subdivision plats, improvement plans, building and zoning permits, construction, inspections, appeals and similar matters, and compliance with applicable state statues and regulations shall be required.

(Ord. 1997-16, passed 12-8-1997; Ord. 2005-01, passed 2-17-2005)

§ 153.182 DEFINITIONS.

For the purpose of this subchapter, the following definitions apply unless the context clearly indicates or requires a different meaning.

ACRE-FOOT (AF). A measure of water volume equal to the inundation of a flat one-acre area to a depth of one foot (43,560 cubic feet).

ADAMS COUNTY DRAINAGE BOARD. The Drainage Board of the county and any subordinate employee to whom they shall specifically delegate a responsibility authorized by this subchapter.

AMORTIZATION PERIOD. The length of time used to repay a debt or mortgage to depreciate an initial cost.

ANTECEDENT RUNOFF CONDITION. The index of runoff potential before a storm event. The index, developed by the Soil Conservation Service (SCS), is an attempt to account for the variation of the SCS runoff curve number (CN) from storm to storm. The ANTECEDENT MOISTURE CONDITION is the moisture found within a soil due to a previous storm event.

BACKFLOW PREVENTER. A device that allows liquids to flow in only one direction in a pipe. BACKFLOW PREVENTERS are used on sewer pipes to prevent a reverse flow during flooding situations.

BACKWATER. The rise in water surface elevation caused by some obstruction such as a narrow bridge opening, buildings, or fill material that limits the area through which the water shall flow. BACKWATER may also be considered as that water elevation found in a tributary that is based on the receiving stream’s existing water elevation.

BASE FLOOD ELEVATION (BFE). The water surface elevation corresponding to a flood having a 1% probability of being equaled or exceeded in a given year.

BASEMENT. Any area of the building having its floor subgrade on all sides.

BENCHMARK. A marked point of known elevation from which other elevations may be established.

BEST MANAGEMENT PRACTICES. Design, construction, and maintenance practices and criteria for stormwater facilities that minimize the impact of stormwater runoff rates and volumes, prevent erosion, and capture pollutants.

BUILDING. See STRUCTURE.

CAPACITY OF A STORM DRAINAGE FACILITY. The maximum flow that can be conveyed or stored by a storm drainage facility without causing damage to public or private property.

CENTERLINE OF CHANNEL. The middle point or baseline of a channel.

CHANNEL. 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 a defined bed and banks which serve to confine the water.

CHANNEL MODIFICATION. Alteration of a channel by changing the physical dimensions or materials of its bed or banks. CHANNEL MODIFICATION includes damming, rip-rapping, or other armoring, widening, deepening, straightening, relocating, lining and significant removal of bottom or woody vegetation. CHANNEL MODIFICATION does not include the clearing of dead or dying vegetation, debris, or trash from the channel. CHANNELIZATION is a severe form of channel modification typically involving relocation of the existing channel (e.g., straightening).

COMPENSATORY STORAGE. An excavated volume of storage within a floodplain used to balance the loss of natural flood storage capacity when fill or substructures are placed within the floodplain. Such excavated volume has to be available for inundation by and accessible to the floodwaters.

CONTIGUOUS. Adjoining or in actual contact with.

CONTOUR. Imaginary line on the earth’s surface which connects points of equal elevation.

CONTOUR LINE. Line on a map which represents a contour or points of equal elevation.

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.

CONVOLUTION. The process of translating precipitation excess into a runoff hydrograph.

CRAWL SPACE. Low space below first floor of a house where there has not been excavation deep enough for a basement, but where there is often access for pipes, ducts, and utilities.

CROWN OF PIPE. The elevation of top of pipe.

CROSS-SECTION. A graph or plot of ground elevation across a stream valley or a portion of it, usually along a line perpendicular to the stream or direction of flow.

CUBIC FEET PER SECOND (CFS). Used to describe the amount of flow passing a given point in a stream channel. One cubic foot per second is equivalent to approximately seven and one-half gallons per second.

CULVERT. A closed conduit used for the conveyance of surface drainage water under a roadway, railroad, canal, or other impediment.

CURVE NUMBER (CN). The Soil Conservation Service index that represents the combined hydrologic effect of soil, land use, land cover, hydrologic condition, and antecedent runoff condition.

DAM. All obstructions, wall embankments, or barriers, together with any abutments and appurtenant works, constructed to store, direct water, or create a pool (not including underground water storage tanks).

DAMAGE. Measurable rise in flood heights on buildings currently subject to flooding, flooding of buildings currently not subject to flooding, and increases in volume or velocity to the point where the rate of land lost to erosion and scour is substantially increased.

DATUM. Any level surface to which elevations are referred, usually using mean sea level.

DEPRESSIONAL STORAGE AREAS. Non-riverine depressions in the earth where stormwater collects. The volumes are often referred to in units of acre-feet.

DESIGN STORM. A selected storm event, described in terms of the probability of occurring once within a given number of years, for which stormwater or flood control improvements are designed and built.

DETENTION FACILITY. A facility designed to detain a specified amount of stormwater runoff assuming a specified release rate. The volumes are often referred to in units of acre-feet.

DETENTION STORAGE. The temporary detaining of storage of stormwater in storage facilities, on rooftops, in streets, parking lots, school yards, parks, open spaces, or other areas under predetermined and controlled conditions, with the rate of release regulated by appropriately installed devices.

DEVELOPMENT.

(1) Any human-made change to improved or unimproved real estate as defined below:

(a) A major subdivision as defined by §§ 153.140 through 153.165;

(b) All new business, commercial, and industrial developments more than one acre and up to three acres in size and exceeding 33% impervious surface;

(d) Any new highway, street, or road construction that adds impervious surface over and above the existing condition and in the opinion of the County Surveyor adds significantly to the stormwater runoff so as to require the application of this subchapter.

(2) DEVELOPMENT does not include activities such as the maintenance of existing buildings and facilities such as painting, re-roofing, resurfacing roads, or gardening, plowing, and similar agricultural practices that do not involve filling, grading, excavation, or the construction of permanent buildings. In addition, DEVELOPMENT does not include the reconstruction or maintenance of regulated drains or replacement of existing stream crossings by the County Drainage Board, the County Highway Department, the State Department of Transportation, or other governmental agencies.

DISCHARGE. Normally, the rate of flow into or out of a sewer, stormwater storage facility, or from a land surface. DISCHARGES are customarily measured in cubic feet per seconds (CFS).

DRAINAGE AREA. The area from which water is carried off by a drainage system, a watershed, or catchment area.

DROP MANHOLE. 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.

DRY BOTTOM DETENTION FACILITY. A facility designed to be completely dewatered after having provided its planned detention of runoff during a storm event.

DURATION. The time period of a rainfall event.

ELEVATION CERTIFICATE. A form published by Federal Emergency Management Agency that is used to certify the 100-year or base flood elevation and the lowest elevation of usable space to which a building has been constructed.

ELEVATION REFERENCE MARK (ERM). Elevation benchmark tied to the National Geodetic Survey Map (NGSM) and identified during the preparation of a flood insurance study prepared for the Federal Emergency Management Agency.

ENERGY DISSIPATOR. A device to reduce the energy of flowing water.

EROSION. Wearing away of the land by running water and waves, abrasion, temperature changes, ice, and wind.

EXTRATERRITORIAL JURISDICTION (ETJ). Areas located outside the corporate limits of a community over which the community has statutory development authority.

FARM OR FIELD TILE. A small diameter clay, plastic, or pipe of some other accepted material installed in an agricultural area to allow drainage of farmland.

FEMA. The Federal Emergency Management Agency.

FLOOD or FLOODWATERS. A general and temporary condition of partial or complete inundation of normally dry land areas from the overflow, the unusual and rapid accumulation, or the runoff of surface waters from any source.

FLOOD BOUNDARY AND FLOODWAY MAP (FBFM). A map prepared by the Federal Emergency Management Agency that depicts the FEMA designated floodways within a community. This map also includes the delineation of the 100-year and 500-year floodplain boundaries and the location of the flood insurance study cross-sections.

FLOOD CREST. The maximum stage or elevation reached or expected to be reached by the waters of a specific flood at a given location.

FLOOD DURATION. The length of time a stream is above flood stage or overflowing its banks.

FLOOD EASEMENT. Easement granted to identify areas inundated by the 100-year flood and prohibit or severely restrict development activities.

FLOOD ELEVATION. The elevation at all locations delineating the maximum level of high waters for a flood of given return period.

FLOOD FIGHTING. Actions taken immediately before or during a flood to protect human life and to reduce flood damages such as evacuation, emergency sandbagging, and diking.

FLOOD FORECASTING. The process of predicting the occurrence, magnitude, and duration of an imminent flood through meteorological and hydrological observations and analysis.

FLOOD FREQUENCY. A statistical expression of the average time period between floods equaling or exceeding a given magnitude. For example, a 100-year flood has a magnitude.

FLOOD HAZARD BOUNDARY MAP (FHBM). A map prepared by the Federal Emergency Management Agency that depicts special flood hazard areas as a zone A within a community. There are no study text, base flood elevations, or floodways associated with this map.

FLOOD INSURANCE RATE MAP (FIRM). A map prepared by the Federal Emergency Management Agency that depicts special flood hazard areas within a community. This map also includes the 100-year or base flood elevation at various locations along the watercourses. More recent versions of the FIRM may also show the FEMA designated floodway boundaries and the location of the flood insurance study cross-sections.

FLOOD INSURANCE STUDY (FIS). A study prepared by the Federal Emergency Management Agency to assist a community participating in the National Flood Insurance Program in its application of the program regulations. The STUDY consists of a text which contains community background information with respect to flooding, a floodway data table, a summary of flood discharges, flood profiles, a flood insurance rate map, and a flood boundary and floodway map.

FLOODPLAIN. The channel proper and the areas adjoining any lake or watercourse which have been or hereafter may be covered by the regulatory or 100-year flood. The FLOODPLAIN includes both the floodway and the floodway fringe districts.

FLOODPLAIN MANAGEMENT. The operation of a program of corrective and preventive measures for reducing flood damage, including, but not limited to, flood control projects, floodplain land use regulations, flood-proofing of buildings, and emergency preparedness plans.

FLOODPLAIN REGULATIONS. General term applied to the full range of codes, ordinances, and other regulations relating to the use of land and construction within floodplain limits. The term encompasses zoning ordinances, subdivision regulations, building and housing codes, encroachment laws, and open area (space) regulations.

FLOOD PROFILE. A graph showing the relationship of water surface elevation to a specific location, the latter generally expressed as distance above the mouth of a stream of water flowing in an open channel. It is generally drawn to show surface elevation for the crest of a specific magnitude of flooding, but may be prepared for conditions at any given time or stage.

FLOOD PROTECTION GRADE (FPG). The elevation of the regulatory or 100-year flood plus two feet at any given location in the special flood hazard area or 100-year floodplain.

FLOOD RESISTANT CONSTRUCTION (FLOOD-PROOFING). Additions, changes, or adjustments to structures or property that are designed to reduce or eliminate the potential for flood damage.

FLOOD STORAGE AREAS. Depressions, basins, or other areas that normally stand empty or partially empty, but fill with rainfall runoff during storms to hold the runoff and reduce downstream flow rates. The volumes are often referred to in units of acre-feet.

FLOODWAY. The channel of a river or stream and those portions of the floodplains adjoining the channel which are reasonably required to carry and discharge efficiently the peak flow of the regulatory flood of any river or stream.

FLOODWAY FRINGE. Those portions of the floodplain lying outside the regulatory floodway.

FOOTING DRAIN. A drain pipe installed around the exterior of a basement wall foundation to relieve water pressure caused by high groundwater elevation.

FREEBOARD. An increment of height added to the base flood elevation to provide a factor of safety for uncertainties in calculations, unknown local conditions, wave actions, and unpredictable effects such as those caused by ice or debris jams. (See FLOOD PROTECTION GRADE).

FRENCH DRAIN. A drainage trench backfilled with a coarse, water-transmitting material; may contain a perforated pipe.

GABION. An erosion control structure consisting of wire cage filled with rocks.

GRADE. The inclination or slope of a channel, canal, conduit, and the like, or natural ground surface usually expressed in terms of the percentage the vertical rise (or fall) bears to the corresponding horizontal distance.

GROUNDWATER RECHARGE. The infiltration of water into the earth. It may increase the total amount of water stored underground or only replenish supplies depleted through pumping or natural discharge.

HIGH WATER. Maximum designed, permitted, or regulated water level for an impoundment.

HYDRAULICS. A branch of science that deals with the practical application of the mechanics of water movement. A typical hydraulic study is undertaken to calculate water surface elevations.

HYDRAULIC GRADE LINE (HGL). For open channel flow, the HGL is equal to the water surface whereas for pressure flow, it is the piezometric surface.

HYDRODYNAMIC LOADS. Forces imposed on structures by floodwaters due to the impact of moving water on the upstream side of the structure, drag along it sides, and eddies or negative pressures on its downstream side.

HYDROGRAPH. For a given point on a stream, drainage basin, or a lake, a graph showing either the discharge, stage (depth), velocity, or volume of water with respect to time.

HYDROLOGY. The science of the behavior of water, its dynamics, composition, and distribution in the atmosphere, on the surface of the earth, and underground. A typical hydrologic study is undertaken to compute flow rates associated with specified flood events.

HYDROMETEOROLOGIC. Water-related meteorologic date such as rainfall or runoff.

HYDROSTATIC LOADS. Those loads or pressures resulting from the static mass of water at any point of floodwater contact with a structure. They are equal in all directions and always act perpendicular to the surface on which they are applied. HYDROSTATIC LOADS can act vertically on structural members such as floors, decks, and roofs, and can act laterally on upright, structural members such as walls, piers, and foundations.

IMPACT AREAS. Areas defined or mapped by the County Surveyor 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 center line or any regulated tile ditch.

IMPERVIOUS SURFACE. Any hard-surfaced, human-made area that does not readily absorb or retain water, including, but not limited to, building roofs, parking and driveway areas, graveled areas, sidewalks, and paved recreation areas.

IDNR. Indiana Department of Natural Resources.

INFILTRATION. Passage or movement of water into the soil.

INFILTRATION SWALES. A depressed earthen area that is designed to promote infiltration.

INLET. An opening into a storm sewer system for the entrance of surface stormwater runoff, more completely described as a STORM SEWER INLET.

JUNCTION CHAMBER. 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.

LAND SURVEYOR. A person licensed under the laws of the state to practice land surveying.

LATERAL STORM SEWER. A sewer that has inlets connected to it but has no other storm sewer connected.

LIFE CYCLE COST. Cost based on the total cost incurred over the system life including research, development, testing, production, construction, operation, and maintenance. Costs are normally determined on present worth or equivalent annual cost basis.

LOW ENTRY ELEVATION. The elevation in a structure where overbank flooding can enter the structure.

LOWEST FLOOR. Refers to the lowest of the following:

(1) The top of the basement floor;

(2) The top of the garage floor, if the garage is the lowest level of the building;

(3) The top of the first floor of buildings constructed on a slab or of buildings elevated on pilings or constructed on a crawl space with permanent openings; or

(4) The top of the floor level of any enclosure below an elevated building where the walls of the enclosure provide any resistance to the flow of floodwaters unless:

(a) The walls are designed to automatically equalize the hydrostatic flood forces on the walls by allowing for the entry and exit of floodwaters; or

(b) Such enclosed space shall be usable only for the parking of vehicles or building access.

MAJOR DRAINAGE SYSTEM. Drainage system carrying runoff from the drainage area of one or more square miles.

MANHOLE. Storm sewer structure through which a person may enter to gain access to an underground storm sewer or enclosed structure.

MANNING ROUGHNESS COEFFICIENT or MANNING’S “N” VALUE. A dimensionless coefficient (“n”) used in the Manning’s equation to account for channel wall frictional losses in steady uniform flow.

MINOR DRAINAGE SYSTEM. Drainage system carrying runoff from a drainage area less than one square mile.

NATIONAL FLOOD INSURANCE PROGRAM (NFIP). A federal program enabling property owners to purchase flood insurance. The Federal Emergency Management Agency administers the NFIP in communities throughout the United States. The NFIP is based on an agreement between local communities and the federal government which states that if a community will implement floodplain management measures to reduce future flood risks to new construction and substantially improved structures in flood hazard areas, the federal government will make flood insurance available within the community as a financial protection against flood losses that do occur.

NATIONAL POLLUTION DISCHARGE ELIMINATION SYSTEM (NPDES). Permit system under the authority of the U.S. Environmental Protection Agency regarding point and nonpoint sources of water pollution.

NONPOINT SOURCE POLLUTION. Pollution that enters a water body from diffused origins on the watershed or drainage basin and does not result from discernible, confined, or defined conveyances or discharge points.

OFFSITE. Everything not located at or within a particular site.

OFFSITE LAND AREAS. Those areas which by virtue of existing topography must outlet through the developing property.

100-YEAR FREQUENCY FLOOD. See REGULATORY FLOOD.

ONSITE. Located within the controlled or urbanized area where runoff originates.

OPEN CHANNELS. Include not only those channels which are completely open overhead, but also closed conduits which are flowing partly full. Examples of such closed conduits are tunnels, storm sewers, sanitary sewers, and various types of pipelines. Flow in OPEN CHANNELS involves a free surface.

ORIFICE. A device which controls the rate of flow from a detention basin.

OUTFALL. 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.

OVERLAND FLOW. Consists of sheet flow, shallow concentrated flow, and open channel flow.

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.

PLANIMETRIC DATA. Horizontal measurements involving distances or dimensions on a diagram, map, plat of survey, or topographic map. Normally in units of feet.

PLAT OF SURVEY. A scaled diagram showing boundaries of a tract of land or subdivision. This may constitute a legal description of the land and be used in lieu of a written description.

PROBABLE MAXIMUM FLOOD. The most severe flood that may be expected from a combination of the most critical meteorological and hydrological conditions that are reasonably possible in the drainage basin. It is used in designing high-risk flood protection works and siting of structures and facilities that shall be subject to almost no risk of flooding. The PROBABLE MAXIMUM FLOOD is usually much larger than the 100-year flood.

PROFESSIONAL ENGINEER. A person licensed under the laws of the state to practice professional engineering.

RADIUS OF CURVATURE. Length of radius of a circle used to define a curve.

RAINFALL INTENSITY. The cumulative depth of rainfall occurring over a given duration, normally expressed in inches per hour. In the Rational Formula, this represents the average rainfall intensity over a duration equal to the time of concentration for the catchment.

REACH. Any length of river, channel, or storm sewer.

RECURRENCE INTERVAL. A statistical expression of the average time between floods equaling or exceeding a given magnitude.

REDEVELOPMENT. See the definition for DEVELOPMENT.

REGULATED AREA. All of the county, except for land areas lying within incorporated areas of the county.

REGULATED DRAIN. A drain subject to the provisions of the State Drainage Code, I.C. 36-9-27.

REGULATORY OR 100-YEAR FLOOD. The flood having a 1% probability of being equaled or exceeded in any given year, as calculated by a method and procedure which is acceptable to and approved by the State Department of Natural Resources and the Federal Emergency Management Agency. If a permit from the State Department of Natural Resources - Division of Water (IDNR-DOW) for construction in the floodway is required, then the regulatory flood peak discharge should be calculated by a method acceptable to the IDNR-DOW. The REGULATORY FLOOD is also known as the BASE FLOOD.

REGULATORY FLOODWAY. See FLOODWAY.

RELEASE RATE. The amount of stormwater released from a stormwater control facility per unit of time.

RESERVOIR. A natural or artificially created pond, lake, or other space used for storage, regulation, or control of water. May be either permanent or temporary. The term is also used in the hydrologic modeling of storage facilities.

RETENTION FACILITY. A facility designed to completely retain a specified amount of stormwater runoff without release except by means of evaporation, infiltration, or pumping. The volumes are often referred to in units of acre-feet.

RETURN PERIOD. 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 1% probability of being equaled or exceeded in any one year.

RIGHT-OF-WAY FOR A COUNTY DRAIN. Land over which a regulated county drain passes and is controlled without restriction or interruption by the property owner.

RIPRAP. Large rock that, when installed along an erodible surface, reduces the erosion potential.

RIVERINE. Relating to, formed by, or resembling a stream (including creeks and rivers).

RUNOFF. The waters derived from melting snow or rain falling within a tributary drainage basin that exceed the infiltration capacity of the soils of that basin, flow over the surface of the ground, or are collected in channels or conduits.

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. A COEFFICIENT of one- half implies that 50% of the rain falling on a given surface appears as stormwater runoff.

SANITARY BACKUP. The condition where a sanitary sewer reaches capacity and surcharges into the lowest area, normally a basement.

SCOUR. The clearing and digging action of flowing water.

SEDIMENT. Material of soil and rock origin transported, carried, or deposited by water.

SEDIMENTATION. The process that deposits soils, debris, and other materials either on the ground surfaces or in bodies of water or watercourses.

SEEPAGE. The passage of water or other fluid through a porous medium, such as the passage of water through an earth embankment or masonry wall.

SILT SCREEN FENCE. A fence constructed of wood or steel supports and either natural (e.g. burlap) or synthetic fabric stretched across area of flow during site development to trap and retain onsite sediment due to rainfall runoff.

SIPHON. 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 stormwater flow under an obstruction such as a sanitary sewer.

SPECIAL FLOOD HAZARD AREA (SFHA). Those lands within the jurisdiction of a community which are subject to inundation by the regulatory or 100-year flood. SPECIAL FLOOD HAZARD AREAS are usually designated on a flood hazard boundary map as zone A. After detailed evaluation of local flooding characteristics, the flood insurance rate map will refine this categorization into zones A, AE, AH, AO, and A1-30.

SPILLWAY. A waterway in or about a hydraulic structure, for the escape of excess water.

STANDARD PROJECT FLOOD. A term used by the U.S. Army Corps of Engineers to designate a flood that may be expected from the most severe combination of the meteorological and hydrological conditions that are considered reasonable characteristics of the geographical area in which the drainage basin is located, excluding extremely rare combinations. The peak flow for a STANDARD PROJECT FLOOD is generally 40% to 60% of the probable maximum flood for the same location.

STILLING BASIN. A basin used to slow water down or dissipate its energy.

STORM DURATION. The length of time that water may be stored in any stormwater control facility, computed from the time water first begins to be stored.

STORM SEWER. A closed conduit for conveying collected stormwater.

STORMWATER FACILITY. All ditches, channels, conduits, levees, ponds, natural and human-made impoundments, wetland, tiles, swales, sewers, and other natural or artificial means of draining surface and subsurface water from land.

STORMWATER RUNOFF. The water derived from rains falling within a tributary basin, flowing over the surface of the ground, or collected in channels or conduits.

STRUCTURE. Refers to a structure that is principally above ground and is enclosed by walls and a roof. The term includes a gas or liquid storage tank, a manufactured home, or a prefabricated building. The term also includes recreational vehicles to be installed on a site for more than 180 days.

STRUCTURAL ENGINEER. A person licensed under the laws of the state to engage in the designing or supervising of construction, enlargement, or alteration of structures or any part thereof, for other, to be constructed by persons other than himself or herself.

STRUCTURAL FLOODPLAIN MANAGEMENT MEASURES. Those physical or engineering measures employed to modify the way floods behave, e.g., dams, dikes, levees, channel enlargements, and diversions.

SUBAREA/SUBBASIN. Portion of a watershed divided into homogenous drainage units which can be modeled for purposes of determining runoff rates. The SUBAREAS/SUBBASINS have distinct boundaries, as defined by the topography of the area.

SUBSTANTIAL IMPROVEMENT. Any reconstruction, rehabilitation, addition, or other improvement of a structure, the cost of which equals or exceeds 50% of the market value of the structure at the time of the “start of construction” of the improvement. This term includes structures which have incurred “substantial damage” regardless of the actual repair work performed. The term does not include improvements of structures to correct existing violations of state or local health, sanitary, or safety code requirements, or any alteration of a “historic structure,” provided that the alteration will not preclude the structures continued designation as a “historic structure.”

SUMP FAILURE. A failure of the sump pump that results in inundation of a crawl space or basement.

SUMP PUMP. A small pump that discharges seepage from foundation footing drains.

SURCHARGE. Backup of water in a sanitary or storm sewer system in excess of the design capacity of the system.

TAILWATER. The water surface elevation at the downstream side of a hydraulic structure, i.e. culvert, bridge, weir, dam, and the like.

THALWEG. The deepest point of a channel.

TIME OF CONCENTRATION. The travel time of a particle of water from the most hydraulically remote point in the contributing area to the point under study. This can be considered the sum of an overland flow time and times of travel in street gutters, storm sewers, drainage channels, and all other drainage ways.

TOPOGRAPHIC MAP. Graphical portrayal of the topographic features of a land area, showing both the horizontal distances between the features and their elevations above a given datum.

TOPOGRAPHY. The representation of a portion of the earth’s surface showing natural and human-made features of a given locality such as rivers, streams, ditches, lakes, roads, buildings, and most importantly, variations in ground elevations for the terrain of the area.

TP-40 RAINFALL. Design storm rainfall depth data for various durations published by the National Weather Services in their Technical Paper 40 dated 1961.

TRANSITION SECTION. Reaches of the stream or floodway where water flows from a narrow cross-section to a wide cross-section or vice-versa.

TRIBUTARY. Based on the size of the contributing drainage area, a smaller watercourse which flows into a larger watercourse.

UNDERDRAIN. A small diameter perforated pipe that allows the bottom of a detention basin to drain.

UNIT HYDROGRAPH. The hydrograph that results from one inch of precipitation excess generated uniformly over the watershed at a uniform rate during a specified period of time.

URBANIZATION. 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. Any river, stream, creek, brook, branch, natural or human-made drainage way in or into which stormwater runoff or floodwaters flow either regulatory or intermittently.

WATERSHED. The land area drained by contributing water to a specific point that could be along a stream, lake, or other stormwater facilities. WATERSHEDS are often broken down into subareas for the purpose of hydrologic modeling.

WATERSHED AREA. The total area from which surface runoff is carried away by a drainage system.

WEIR. A device which is used to restrict the flow of water thereby limiting the discharge rates. A WEIR can also facilitate calculation or measurement of the discharge rates. These are often used to control the rate of flow out of stormwater storage facilities.

WET BOTTOM RETENTION FACILITY. A facility designed to retain a permanent pool of water after having provided its planned detention of runoff during a storm event.

WETLANDS. Areas that are inundated or saturated by surface water or groundwater at a frequency and duration sufficient to support and that under normal circumstances do support a prevalence of vegetation typically adapted for line in saturated soil conditions.

(Ord. 1997-16, passed 12-8-1997; Ord. 2005-01, passed 2-17-2005)

§ 153.183 ABBREVIATIONS.

For the purpose of this subchapter, the following abbreviations apply unless the context clearly indicates or requires a different meaning.

BFE. Base flood elevation.

CFS. Cubic feet per second.

CLOMR. Conditional letter of map revision (from FEMA).

CLOMR-F. Conditional letter of map revision based on fill (from FEMA).

CN. Curve number.

COE. United States Army Corps of Engineers.

ERM. Elevation reference mark.

ETJ. Extraterritorial jurisdiction.

FBFM. Flood boundary and floodway map.

FEMA. Federal Emergency Management Agency.

FHBM. Flood hazard boundary map.

FIRM. Flood insurance rate map.

FIS. Flood insurance study.

FPG. Flood protection grade.

FPS. Feet per second.

HGL. Hydraulic grade line.

IDEM. Indiana Department of Environmental Management.

IDNR. Indiana Department of Natural Resources.

LAG. Lowest adjacent grade.

LOMA. Letter of map amendment (from FEMA).

LOMR. Letter of map revision (from FEMA).

LOMR-F. Letter of map revision based on fill (from FEMA).

NFIP. National Flood Insurance Program.

NAVD. North American Vertical Datum of 1988.

NGVD. National Geodetic Vertical Datum of 1929.

NPDES. National Pollution Discharge Elimination System.

SFHA. Special flood hazard area.

TC. Time of concentration.

(Ord. 1997-16, passed 12-8-1997; Ord. 2005-01, passed 2-17-2005)

§ 153.184 STORMWATER CONTROL POLICY.

(A) It is recognized that the watercourses serving the county do not have sufficient capacity to receive and convey stormwater runoff resulting from continued urbanization. Accordingly, the storage and controlled release rate of excess stormwater runoff shall be required for the following instances:

(1) All new business, commercial, and industrial developments more than one acre and up to three acres in size and exceeding 33% impervious surface;

(2) All new business, commercial, and industrial developments over three acres in size;

(3) Developments, as defined above; and

(4) Any new highway, street, or road construction that adds impervious surface over and above the existing condition and in the opinion of the County Surveyor adds significantly to the stormwater runoff so as to require the application of this subchapter.

(B) The release rate of stormwater from developments and redevelopments may not exceed the peak five-year return period stormwater runoff from the land area in its present state of development.

(C) The developer shall submit to the County Surveyor and the County Drainage Board detailed computations of runoff before and after development or redevelopment which demonstrates that runoff will not be increased. These computations shall show that the peak runoff rate after development for the 100-year return period storm of 24-hour duration shall not exceed the five-year return period pre-development peak runoff rate.

(D) The method for computations as applied to this subchapter for development sites shall be approved by the County Surveyor.

(Ord. 1997-16, passed 12-8-1997; Ord. 2005-01, passed 2-17-2005) Penalty, see § 153.999

§ 153.185 INFORMATION REQUIREMENTS.

The following information and data prepared by a licensed professional engineer or land surveyor engaged in storm drainage design shall accompany plans for each regulated development lying within the regulated area prior to final plat approval by the County Plan Commission as follows in §§ 153.186 through 153.191.

(Ord. 1997-16, passed 12-8-1997; Ord. 2005-01, passed 2-17-2005) Penalty, see § 153.999

§ 153.186 TOPOGRAPHIC SURVEY MAP.

(A) A topographic map of the land to be subdivided and such adjoining land whose topography may affect the layout or drainage of the development. The contour intervals shall be one foot when slopes are less than 2% and shall be two feet when slopes exceed 2%.

(B) On this map, the following shall be shown:

(1) The location of streams and other floodwater runoff channels, the extent of the floodplains at the established 100-year flood elevation where available and the limits of the regulatory floodway, all properly identified and sources noted. Note: the regulatory floodway may be measured from the effective FEMA map. However, floodplain boundaries shall be determined based on the 100-year flood elevation/profile and the topographic survey map prepared according to this section;

(2) The normal shoreline of lakes, ponds, swamps, and detention/retention facilities, their floodplains, and direction of inflow and outflow, if any;

(3) The location of regulated drains, farm drains, inlets, and outfalls, if any of record;

(4) Storm, sanitary, and combined sewers and outfalls, if any of record;

(5) Septic tank systems and outlet, if any of record;

(6) Seeps, springs, flowing, and other wells, that are visible or of record; and

(7) Soil names and their hydrologic classification for the proposed development when hydrologic methods requiring soils information are used.

(Ord. 1997-16, passed 12-8-1997; Ord. 2005-01, passed 2-17-2005) Penalty, see § 153.999

§ 153.187 PRELIMINARY DRAINAGE PLANS.

(A) A comprehensive plan, in preliminary form (or in combined preliminary and final form), designed to safely handle the stormwater runoff and detain the increased stormwater runoff.

(B) The plan shall provide or be accompanied by maps or other descriptive material indicating the feasibility of the drainage plan and showing the following:

(1) The extent and area of each upstream, offsite watershed tributary to the subject site. Required materials for preliminary review include:

(a) Exhibit showing each upstream, offsite drainage area tributary to the subject site on USGS Quandrangle Maps or other more detailed topographic maps; and

(b) Preliminary plan to convey upstream, offsite runoff through the subject property, shown on the preliminary drainage plan for the site.

(2) The capacity of the downstream, offsite receiving system (outlet). Information must be submitted to show that the downstream, offsite drainage system has the capacity to convey the expected runoff from the subject property and any upstream, offsite areas. The County Surveyor may also determine the capacity of the downstream drainage system;

(3) The general drainage plan for the subject property must include the following items:

(a) The extent and area of each watershed on the subject property in the existing condition. Calculations to determine the allowable release rate from the subject property should also be included;

(b) The extent and area of each watershed affecting the design of detention facilities as shown on USGS Quadrangle Maps or other more detailed topographic maps;

(c) Elevations in either National Geodetic Vertical Datum of 1929 (NGVD) or North American Vertical Datum of 1998 (NAVD);

(d) The estimated location and percentage of impervious surfaces expected to be constructed when the development is completed;

(e) Existing detention/retention facilities to be maintained, enlarged, or otherwise altered and new ponds or basins to be built and the basis of their design;

(f) The estimated depth and amount of storage required by design of the new facilities;

(g) The preliminary layout and design of street storm sewers, where proposed, and other storm drains to be built, the outfall and outlet locations and approximate elevations, the receiving stream or channel, and its 100-year return period water elevation;

(h) The preliminary layout of swales which collect runoff from onsite and/or offsite watersheds;

(i) Proposed culverts and bridges to be built, their material, elevations, waterway openings, and basis of their design; and

(j) Identification of overland flow routes to detention/retention facilities;

(4) Existing streams and floodplains to be maintained, and new channels to be constructed, their locations, cross-sections, and profiles;

(5) Any interim drainage plan which is to be incorporated into the development pending completion of the development and the final drainage plan;

(6) A copy of the effective FEMA map, annotated to show the project location and property boundaries in relation to the regulatory floodplain and floodway;

(7) The location of any regulatory wetlands on the subject property; and

(8) A report summarizing the hydraulic design parameters and detailing how this design satisfies this subchapter.

(Ord. 1997-16, passed 12-8-1997; Ord. 2005-01, passed 2-17-2005) Penalty, see § 153.999

§ 153.188 VALLEY CROSS-SECTIONS.

One or more typical cross-sections of all existing and proposed channels or other open drainage facilities carried into the overbank to a point above the 100-year flood elevation. These shall also show the elevation of the existing land and the proposed changes thereto, together with the high water elevations expected from the 100-year flood under the controlled conditions called for by this subchapter and the relationship of structures, streets, and other facilities. Cross-sections must be represented perpendicular to the expected flow path.

(Ord. 1997-16, passed 12-8-1997; Ord. 2005-01, passed 2-17-2005) Penalty, see § 153.999

§ 153.189 SITE ENGINEERING PLAN.

(A) Site engineering plans shall be drawn to scale and show the dimensions and features of the proposed development.

(B) The requirements for the site plan contents and format are as follows:

(1) The set of plans shall contain the following sheets as a minimum:

(a) Title sheet, with project name and location map. The title sheet shall also include the name, address, telephone number, and seal of the registered professional engineer or the licensed/registered land surveyor preparing the plans;

(b) Topographic survey map;

(c) Geometric plan showing all dimensions of existing property boundaries, and necessary data to layout the proposed development; and

(d) Grading/drainage plan which identifies all existing and proposed drainage characteristics such as swales, drainage break points, and storm sewers and detention facilities.

(2) Each plan sheet shall include:

(a) A title block located in the lower right hand corner that includes the project name job number, sheet title (geometric, grading, and the like), sheet number, date of preparation, and latest revision date and description;

(b) North arrow;

(d) A legend clearly identifying all symbols indicated on that plan sheet;

(e) Plan sheets shall be 24 inches by 36 inches in size;

(f) An adequate number of benchmarks shown with elevations referenced to NGVD or NAVD to facilitate checking of elevations without more than one setup of a surveyor’s level, except for large development sites where additional setups may be warranted; and

(g) Delineation of all existing and proposed easements for underground and overhead utilities and drainage.

(Ord. 1997-16, passed 12-8-1997; Ord. 2005-01, passed 2-17-2005) Penalty, see § 153.999

§ 153.190 FINAL DRAINAGE PLANS.

(A) Upon approval of the preliminary drainage plans by the County Drainage Board, final drainage plans shall be submitted to the Drainage Board.

(B) In addition to data provided on the preliminary drainage plans, the final plans shall provide or be accompanied by calculations, maps, and other descriptive material, including the following:

(1) A set of plan drawings stamped by a state registered professional engineer or a state registered land surveyor showing all proposed detention areas, storm sewers, inlets, outfall structures, open ditches, culverts (including driveway crossings), and bridges. At the minimum, these plan drawings should show or accompany the following:

(a) The extent and area of each watershed area tributary to the drainage channels in the development;

(b) Elevations in the National Geodetic Survey Map (NGSM);

(d) The street storm sewers and other storm drains to be built, the basis of their design, outfall and outlet locations, and invert elevations, receiving stream or channel, and its 100-year flood conditions;

(e) The parts of the proposed street system where pavements are planned to be depressed sufficiently to convey or temporarily store overflow from storm sewers and over the curb runoff resulting from the heavier rainstorms and the outlets for such overflow;

(f) Existing streams and 100-year floodplains to be maintained, and new channels to be constructed, their locations, cross-sections, and profiles;

(g) Proposed culverts, and bridges to be built, their materials, elevations, waterway openings, and basis of their design;

(h) Existing detention/retention facilities to be maintained, enlarged, or otherwise altered and new facilities to be built and the basis of their design;

(i) The estimated location and percentage of impervious surfaces existing and expected to be constructed when the development is completed; and

(j) The slope, type, and size of all sewers and other waterways.

(2) A written report stamped by a state registered professional engineer or a state registered land surveyor shall be included with each preliminary and final drainage plan. The report will contain a summary description of the following:

(a) The significant drainage problems associated with the project;

(b) The analysis and procedure used to evaluate these problems and propose solutions;

(c) Any assumptions or special conditions associated with the use of these procedures, especially the hydrologic or hydraulic methods;

(d) The proposed design of the drainage control system;

(e) The results of the analysis of the proposed drainage control system showing that it does solve the project’s drainage problems;

(f) As an appendix to the report, a hydraulic report detailing existing and proposed drainage patterns on the subject site. The report should include a description of the present land use as well as proposed land use. Any offsite drainage entering the site should also be addressed. This report should be comprehensive and detail all the steps which the design engineer took during the design process. All hydrologic and hydraulic computations should be included in the submittal. These calculations should include, but not be limited to: development of runoff curve numbers or runoff coefficients; runoff calculations; stage-discharge relationships for detention/retention facility outfalls; times of concentration; and storage volume. A map showing any drainage subareas used in the analysis shall accompany the report;

(g) Copies of the computer models used in the drain analyses may be obtained using disks, USB flash drives, or other means of electronic information transfer and storage devices commonly used; and

(h) For all detention/retention facilities, a plot or tabulation of storage volumes with corresponding water surface elevations and a plot or tabulation of the facility outflow rates for those water surface elevations.

(3) In addition to the criteria and requirements set in this subchapter, the plans and calculations should also meet the following criteria:

(a) If roadside ditches are used rather than storm sewers, the bottom of the ditch should be low enough to install adequately sized driveway culverts without creating “speed bumps;”

(b) Driveway culvert inverts shall be designed to adequately consider upstream and downstream culvert elevations;

(d) Maximum yard slopes are three to one unless otherwise approved by the Plan Commission;

(e) Top of foundation no less than one-half foot above finished grade;

(f) Spot elevations shown at the drainage break points;

(g) Pipes have adequate slope to maintain two and one-half feet per second (fps) velocity (cleaning velocity);

(h) When changing pipe size from a smaller to a larger pipe, match crowns of pipes; and

(i) Inlets are placed such that the tributary flows are in accordance with the grate capacity (i.e., depth of inundation above rim is tolerable in ten-year and 100-year storms).

(Ord. 1997-16, passed 12-8-1997; Ord. 2005-01, passed 2-17-2005) Penalty, see § 153.999

§ 153.191 SUBMITTAL AND CONSIDERATION OF PLANS.

(A) Preliminary and final drainage plans and/or construction plans shall be submitted to the County Drainage Board 20 days prior to their regularly schedule meeting. All preliminary plans, final plans, and construction plans in compliance with the standards of this subchapter shall be approved by the Drainage Board. The Drainage Board or the County Surveyor shall stamp such approval on a copy of such plans and deliver the same to the applicant. The Drainage Board shall approve or disapprove any preliminary plans, final plans, and construction plans within 60 days of submission unless the applicant consents to a continuance or extension. All approvals and disapprovals with written reasons shall be incorporated into the Drainage Board minutes.

(B) The County Surveyor is authorized to either review or appoint someone to review engineering summaries of projects and based upon the same, grant exemptions from any and all requirements of this subchapter and/or waive any requirements of this subchapter upon approval of the Drainage Board. Any applicant may appeal the decision of the County Surveyor to the Drainage Board which shall also be authorized to grant exemptions from any and all requirements of this subchapter and/or waive any requirements of this subchapter in its discretion.

(Ord. 1997-16, passed 12-8-1997; Ord. 2005-01, passed 2-17-2005)

§ 153.192 RUNOFF QUANTITIES.

(A) Runoff quantities shall be computed for the area of the parcel under development plus the area of the watershed flowing into the parcel under development. The quantity of runoff which is generated as the result of a given rainfall intensity shall be computed by a method, as approved by the County Surveyor.

(B) Various parts of a drainage facility shall accommodate runoff water as follows:

(1) The minor drainage system such as inlets, catch basins, street gutters, swales, sewers, and small channels which collect stormwater shall accommodate, at a minimum, peak runoff from a ten-year return frequency storm.

(2) These minimum requirements shall be satisfied:

(a) The allowable spread of water on collector streets is limited to maintaining two clear ten-foot moving lanes of traffic. One lane is to be maintained on local roads, while other access lanes (such as a subdivision cul-de-sac) can have a water spread equal to one-half of their total width.

(b) Open channels carrying greater than 30 cubic feet per second shall be capable of accommodating peak runoff for a 24-hour, 50-year return frequency storm within the drainage easement.

(c) Culverts shall be capable of accommodating peak runoff from a 24-hour, 50-year return frequency storm when crossing under a road which is part of the INDOT rural functional classification system.

(d) Rear and side lot swales shall not carry more than four cfs and only two cfs if a swale crosses a sidewalk.

(3) Major drainage systems are defined in § 153.182 and shall be designed in a method approved by the County Surveyor.

(Ord. 1997-16, passed 12-8-1997; Ord. 2005-01, passed 2-17-2005) Penalty, see § 153.999

§ 153.193 LEVEL OF PROTECTION.

(A) The lowest floor elevations of all residential, commercial, or industrial buildings shall be such that all floors, including basement, shall be at the flood protection grade and therefore have two feet of freeboard above the 100-year flood, whichever is greater, together with a freeboard of two feet, as applies to ponds and swales. Pad elevations shall be a minimum of 15 inches above an adjacent road elevation.

(B) The low entry elevation for residential buildings outside the 100-year floodplain shall be based upon the maximum flood of record or upon the 100-year flood, whichever is greater, together with a freeboard of two feet, as applies to ponds and swales. Pad elevations shall be a minimum of 15 inches above an adjacent road elevation.

(Ord. 1997-16, passed 12-8-1997; Ord. 2005-01, passed 2-17-2005) Penalty, see § 153.999

§ 153.194 STORM SEWER DESIGN STANDARDS.

(A) Design standards.

(1) All storm sewers, whether private or public, and whether constructed on private or public property, shall conform to the design standards and other requirements contained herein.

(2) The minimum diameter of all storm sewers shall be 12 inches. The rate of release for detention storage shall be controlled by an orifice plate or other device, subject to approval of the Drainage Board, when the minimum 12-inch diameter pipe will not limit the rate of release to the required amount.

(3) Sewer grade shall be such that, in general, a minimum of one and one-half feet of cover is maintained over the top of the pipe. If the pipe is to be placed under pavement, then the minimum pipe cover shall be two feet. Pipe cover less than the minimum may be used only upon approval of the Drainage Board. All pipe crossings involving a county highway, street, or road shall require the approval of the County Engineer. Uniform slopes shall be maintained between inlets, manholes, and inlets to manholes. Final grade shall be set with full consideration of the capacity required, sedimentation problems, and other design parameters. Minimum and maximum allowable slopes shall be those capable of producing velocities of between two and one-half and 15 feet per second, respectively, when the sewer is flowing full.

(4) Storm sewers shall be straight between manholes.

(5) Manholes shall be installed to provide access to continuous underground storm sewers for the purpose of inspection and maintenance. Manholes shall be provided at the following locations:

(a) Where two or more storm sewers converge;

(b) Where pipe size changes;

(d) Where a change in grade occurs; and

(e) At intervals in straight sections of sewer, not to exceed the maximum allowed.

(6) The maximum distance between storm sewer manholes shall be as follows:

Size of Pipe (Inches)	Maximum Distance (Feet)
12 through 42	400
48 and larger	600

(7) Inlets or drainage structures shall be utilized to collect surface water through grated openings and convey it to storm sewers, channels, or culverts. The inlet grate opening provided shall be adequate to pass the culverts. The inlet grate opening provided shall be adequate to pass the design ten-year flow with 50% of the sag inlet areas clogged. An overload channel from sag inlets to the overflow channel or basin shall be provided at sag inlets, so that the maximum depth of water that might be ponded in the street sag shall not exceed seven inches. Inlet design and spacing may be done using the hydraulic equations by manufacturers or orifice/weir equations. Gutter spread on continuous grades may be determined using equations or methods approved by the County Surveyor.

(B) Workmanship and materials.

(1) The specifications for the construction of storm sewers shall not be less stringent than those set forth in the latest edition of the State Department of Transportation “Standard Specifications.” Additionally, ductile iron pipe shall be laid in accordance with American Water Works Association (AWWA) C-600 and clap pipe shall be laid in accordance with either American Society of Testing Materials (ASTM) C-12 or the appropriate American Association of State Highway and Transportation Officials (AASHTO) specifications.

(2) (a) Storm sewer manholes and inlets shall be constructed of masonry, cast in place concrete, or precast reinforced concrete. Material and construction shall conform to the State Department of Transportation “Standard Specifications,” § 720.

(b) Pipe and fittings used in storm sewer construction shall be extra-strength clay pipe (ASTM C-76). Other pipe and fittings not specified herein may be used only when specifically authorized by the Drainage Board. Pipe joints shall be flexible and watertight and shall conform to the requirements of § 715.02 - Materials, of the latest edition of the State Department of Transportation “Standard Specifications.”

(c) Special hydraulic structures required to control the flow of water in storm runoff drainage systems include junction chambers, drop manholes, inverted siphons, stilling basins, and other special structures. The use of these structures shall be limited to those locations justified by prudent planning and by careful and thorough hydraulic engineering analysis.

(Ord. 1997-16, passed 12-8-1997; Ord. 2005-01, passed 2-17-2005) Penalty, see § 153.999

§ 153.195 OPEN CHANNEL DESIGN STANDARDS.

(A) Design standards.

(1) All open channels, whether private or public, and whether constructed on private or public land, shall conform to the design standards requirements of the County Surveyor.

(2) The required channel cross-section and grade are determined by the design capacity, the material in which the channel is to be constructed, and the requirements for maintenance. A minimum depth may be required to provide adequate outlets for subsurface drains, tributary ditches, or streams. The channel grade shall be such that the velocity in the channel is high enough to prevent siltation but low enough to prevent erosion. Velocities less than one and one-half feet per second should be avoided since siltation will take place and ultimately reduce the channel cross-section. The maximum permissible velocities in vegetal-lined channels are shown in Table 1. Developments through which the channel is to be constructed shall be considered in the design of the channel section.

(3) Earthen channel side slopes shall be no steeper than two horizontal to one vertical. Flatter slopes may be required to prevent erosion and for ease of maintenance. Where channels will be lined, side slopes shall be no steeper than one and one-half horizontal to one vertical with adequate provisions made for weep holes. Side slopes steeper than one and one-half horizontal to one vertical may be used for lined channels, provided that the sidelining is designed and constructed as a structural retaining wall with provisions for live and dead load surcharge.

Table 1
Maximum Permissible Velocities in Vegetal-Lined Channels*
Cover	Side Slope Range*** (Percent)	Permissible Velocity**	Permissible Velocity**
Cover	Side Slope Range*** (Percent)	Erosion Resistant Soils (ft. per sec.)****	Easily Eroded Soils (ft. per sec.)****
Alfalfa	5-10	3.4	2.5
Bahia Buffalo Grass	0-5	7	5
Bermuda Grass	0-5	8	6
	5-10	7	5
	Over 10	6	4
Canary Grass	5-10	4	3
Common Lespedeza*****	******0-5	3.5	2.5
Grass Mixture Reed	***0-5	5	4
Kentucky Bluegrass	5-10	6	4
Lespedeza Sericea	5-10	3.4	2.5
Red Fescue	5-10	3.4	2.5
Redtop	5-10	3.4	2.5
Smooth Brome Blue Grama	Over 10	5	3
Sudangrass*****	******0-5	3.5	2.5
Weeping Lovegrass	****0-5	3.4	2.5
Yellow Bluestem	5-10	3.4	2.5
Notes to table: * From Soil Conservation Service, SCS-TP-61, “Handbook of Channel Design for Soil and Water Conservation.” Use velocities exceeding five feet per second only where good channel ground covers and proper maintenance can be obtained. * Do not use on slopes steeper than 10% except for vegetated side slopes in combination with a stone, concrete, or highly resistant vegetative center section. ** Do not use on slopes steeper than 5% except for vegetated side slopes in combination with a stone, concrete, or highly resistant vegetative center section. * Annuals- use on mild slopes or as temporary protection until permanent covers are established. **** Use on slopes steeper than 5% is not recommended.

(4) (a) Characteristics of a stable channel are as follows.

1. It neither promotes sedimentation or degrades the channel bottom and sides beyond tolerable limits.

2. The channel banks do not erode to the extent that the channel cross-section is changed appreciably.

3. Excessive sediment bars do not develop.

4. Excessive erosion dos not occur around culverts, bridges, outfalls, or elsewhere.

5. Gullies do not form or enlarge due to the entry of uncontrolled flow to the channel.

(b) Channel stability shall be determined for an aged condition and the velocity shall be based on the design flow or the bank full flow, whichever is greater. In no case shall it be necessary to check channel stability for discharges greater than that from a 100-year frequency storm.

(5) Vegetated waterways that are subject to low flows of long duration or where wet conditions prevail shall be drained with a tile system or by other means such as paved gutters. Tile lines may be outletted through a drop structure at the ends of the waterway or through a standard tile outlet.

(6) When the Drainage Board determines it is necessary to establish a new regulated drain, each developer shall provide the necessary information and meet the requirements of the 1965 Indiana Drainage Code, being I.C. 36-9-27, as amended, for the establishment of a new regulated drain. The Drainage Board shall determine necessary easements for adequate maintenance of any new regulated drain.

(7) (a) The design of channels will include provisions for operation and maintenance and the proper functioning of all channels, laterals, travelways, and structures associated with the project. Recessed inlets and structures needed for entry of surface and subsurface flow into channels without significant erosion or degradation shall be included in the design of channel improvements. The design will also provide for necessary flood gates, water level control devices, and any other appurtenance structure affecting the functioning of the channels and the attainment of the purpose for which they are built.

(b) The effects of channel improvements on existing culverts, bridges, buried cables, pipelines, and inlet structures for surface and subsurface drainage on the channel being improved and laterals thereto shall be evaluated to determine the need for modification or replacement. Culverts and bridges which are modified or added as part of channel improvement projects shall meet reasonable standards for the type of structure and shall have a minimum capacity equal to the design discharge or governmental agency design requirements, whichever is greater.

(8) Spoil material resulting from clearing, grubbing, and channel excavation shall be disposed of in such a manner which will:

(a) Minimize overbank wash;

(b) Provide for the free flow of water between the channel and floodplain boundary unless the valley routing and water surface profiles are based on continuous dikes being installed;

(d) Leave the right-of-way in the best condition feasible, consistent with the project purposes, for productive use by the owner;

(e) Improve the aesthetic appearance of the site to the extent feasible; and

(f) Be approved by the IDNR or U.S. Army Corps of Engineers (whichever is applicable), if deposited in the floodway.

(B) Construction and materials.

(1) Specifications shall be in keeping with the proceeding standards and shall describe the requirements for proper installation of the project to achieve its intended purpose.

(2) (a) Materials acceptable for use as channel lining are:

1. Grass;

2. Revetment riprap;

3. Concrete;

4. Hand laid riprap;

5. Precast cement concrete riprap;

6. Grouted riprap;

7. Gabions; and

8. Mattins.

(b) Other lining materials shall receive specific approval of the County Surveyor. Materials shall comply with the latest edition of the State Department of Transportation “Standard Specifications.”

(Ord. 1997-16, passed 12-8-1997; Ord. 2005-01, passed 2-17-2005) Penalty, see § 153.999

§ 153.196 STORMWATER DETENTION.

The following shall govern the design of any improvement with respect to the detention of stormwater runoff.

(A) Acceptable detention methods. The increased stormwater runoff resulting from a proposed development should be detained onsite by the provisions of appropriate wet bottom retention or dry bottom detention facilities, storage on flat roofs, parking lots, streets, lawns, or other acceptable techniques. Measures which retard the rate of overland flow and the velocity in runoff channels shall also be used to partially control runoff rates. Detention/retention facilities shall be sized to store excess flows from storms with a 100-year return period. Control devices shall limit the discharge to a rate no greater than that prescribed by this subchapter.

(B) Design storm. Design of stormwater detention/retention facilities shall be based on a storm with a 1% chance of occurrence every year, also know as a 100-year storm. The storage volume and outflow rate shall be sufficient to handle stormwater runoff from a 24-hour duration storm.

(1) Only methods approved by the County Surveyor shall be used to determine the five-year return period pre-development release rate for development sites controlled by this subchapter.

(2) In the event the natural downstream channel or storm sewer system is inadequate to accommodate the release rate provided above, then the allowable release rate shall be reduced to that rate permitted by the capacity of the receiving downstream channel or storm sewer system and additional detention as determined by the County Surveyor.

(3) If more than one detention/retention facility is involved in the development of the area upstream of the limiting restriction, the allowable release rate off of the site from any one detention basin shall be in direct proportion to the ratio of its drainage area to the drainage area of the entire watershed upstream of the restriction.

(D) Drainage system overflow design. Drainage systems, including all ditches, channels, conduits, swales, and the like, shall have adequate capacity to convey the stormwater runoff from all upstream tributary areas (offsite land areas) through the development under consideration for a 100-year return period design storm calculated on the basis of the upstream land in its present state of development. Swales between privately owned residential lots shall not be used to convey the above referenced stormwater runoff unless the discharge paths are confined within the drainage easements and/or common areas. An allowance, equivalent to the reduction in flow rate provided, may be made for upstream detention when such upstream detention and release rate have previously been approved by the Drainage Board and evidence of its construction and maintenance can be shown.

(E) Acceptable outlet.

(1) Design and construction of the stormwater facility shall provide for the discharge of the stormwater runoff from offsite land areas as well as the stormwater from the area being developed (onsite land areas) to an acceptable outlet(s) having capacity to receive upstream (offsite) and onsite drainage.

(2) The acceptable outlet for stormwater discharge shall be a regulated open (ditch) drain or a “Blue Line” open drain as shown on the USGS Quadrangle Maps. “Blue Line” open drains shall have adequate available capacity to handle design runoff; Roadside ditches may be acceptable provided permission is granted from right-of-way owner, roadside ditch is in a maintained condition, and the outlet for the roadside ditch is a regulated open drain or “Blue Line” open drain.

(3) In case of extreme hardship, the Drainage Board has final authority over the acceptable outlet.

(4) Where the outfall from the stormwater drainage system of any developer flows through real estate owned by others prior to reaching a regulated drain or natural waterway, no approval shall be granted for such stormwater drainage system until all impacted owners consent in writing to such use of their real estate or are notified of such use in writing of a hearing by the Drainage Board to review such use. The notification shall include the time and place of a hearing and be delivered, either personally or by certified mail, at least five days prior to the hearing thereon, and proof of such notice to each landowner shall be filed with the Drainage Board prior to such hearing, which proof shall be by affidavit.

(F) Determination of storage volume. The required volume of stormwater storage for development sites shall be approved by the County Surveyor.

(G) General detention basin design requirements. Basins shall be constructed to temporarily detain the stormwater runoff which exceeds the maximum peak release rate authorized by this subchapter. The volume of storage provided in these basins, together with such storage as may be authorized in other onsite facilities shall be sufficient to control excess runoff from the 100-year storm. The following design principles shall be observed.

(1) The maximum volume of water stored and subsequently released at the design release rate shall not result in a storage duration in excess of 48 hours from the start of the storm unless additional storms occur within the period.

(2) All stormwater detention facilities shall be separated by not less than 25 feet from any building or structure to be occupied.

(3) All excavated excess spoil to be spread onsite shall be spread so as to provide for aesthetic and recreational features such as sledding hills, sports fields, decorative mounds, and the like. Slopes no steeper than six horizontal to one vertical for safety, erosion control, stability, and ease of maintenance shall be permitted.

(4) Safety screens having a maximum opening of four inches shall be provided for any pipe or opening to prevent children or large animals from crawling into the structures.

(5) Outlet control structures shall be designed to operate as simply as possible and shall require little or no maintenance and/or attention for proper operation. They shall limit discharges into existing or planned downstream channels or conduits so as not to exceed the predetermined maximum authorized peak flow rate.

(6) Emergency overflow facilities such as a weir or spillway shall be provided for the release of at least 100-year storm runoff (or, if applicable, the minimum required under the IDNR dam safety criteria) or in emergency conditions should the normal discharge devices become totally or partially inoperative. The overflow facility shall be of such design that its operation is automatic and does not require manual attention.

(7) Grass or other suitable vegetative cover shall be provided throughout the entire detention storage basin area. Grass should be cut regularly at approximately monthly intervals during the growing season or as required to maintain the facility.

(8) Debris and trash removal and other necessary maintenance shall be performed on a regular basis to assure continued operation in conformance to design.

(9) Hydraulic calculations shall be submitted to substantiate all design features.

(10) No detention facility or other water storage area, permanent or temporary, shall be constructed under or within ten feet of any pole or high voltage electric line. Likewise, poles or high voltage electric lines shall not be placed within ten feet of any detention facility or other water storage area.

(11) No residential lots or any part thereof, shall be used for any part of a detention basin or for the storage of water, either temporary or permanent.

(H) Dry bottom facility design requirements. Detention facilities which will not contain a permanent pool of water shall comply with the following requirements.

(1) Provisions shall be incorporated into facilities for complete interior drainage of dry bottom facilities, including the provisions of natural grades to outlet structures, longitudinal and transverse grades to perimeter drainage facility, paved gutters, or the installation of subsurface drains.

(2) The detention facility may, whenever possible, be designed to serve as a secondary or multipurpose function. Recreational facilities, aesthetic qualities (open spaces), or other types of use shall be considered in planning the detention facility.

(3) In excavated detention facilities, a minimum side slope of three to one shall be provided for stability. In the case of valley storage, natural slopes may be considered to be stable.

(I) Wet bottom facility design requirements. Where part of a detention facility will contain a permanent pool of water, all the items required for detention storage shall apply except that the system of drains with a positive gravity outlet required to maintain a dry bottom facility will not be required. A controlled positive outlet will be required to maintain the design water level in the wet bottom facility and provide required detention storage above the design water level. However, the following additional conditions shall apply.

(1) Facilities designed with permanent pools or containing permanent lakes shall, if fish are to be used to keep the pond clean, have a minimum depth of approximately eight feet over at least 25% of the pond area.

(2) In excavated ponds, the underwater side slopes in the lake shall be stable. In the case of valley storage, natural slopes may be considered to be stable.

(3) A safety ledge four to six feet in width at a slope of five to one is required and shall be installed in all ponds.

(4) Periodic maintenance is required in lakes to control weed and larval growth. The facility shall also be designed to provide for the easy removal of sediment which will accumulate during periods of reservoir operation.

(5) For emergency use, facility cleaning, or shoreline maintenance, additional facilities may have to be provided or plans prepared for auxiliary equipment to permit emptying and drainage.

(J) Rooftop storage. Detention storage requirements may be met in total or in part by detention on flat roofs. Details of such design to be included in the building permit application shall include the depth and volume of storage, details of outlet devices and downdrains, elevations of emergency overflow provisions, and certification of the structural portion of the building design plans by a structural engineer.

(K) Parking lot storage. Paved parking lots may be designed to provide temporary detention storage of storm waters on all or a portion of their surfaces. Outlets will be designed so as to empty the stored waters slowly. Depths of storage shall be limited to a maximum depth of seven inches so as to prevent damage to parked vehicles and so that access to parked vehicles is not impaired. Ponding should in general be confined to those positions of the parking lots farthest from the area served.

(L) Facility financial responsibilities. The construction cost of stormwater control systems and required facilities which are identified in the Stormwater Ordinance of the county shall be accepted as part of the cost of land development.

(M) Facility maintenance responsibilities. Maintenance of detention/retention facilities during construction and thereafter, shall be the responsibility of the land developer/owner. Assignment of responsibility for maintaining facilities serving more than one lot or holding shall be documented by appropriate covenants to property deeds, unless responsibility is formally accepted by a public body, and shall be determined before the final drainage plans are approved.

(N) Inspections. All public and privately owned detention storage facilities may be inspected during construction by representatives of the county.

(O) Corrective measures. If deficiencies are found by the inspector prior to final approval of the drainage facility, the owner of the detention/retention facility will be required to take the necessary measurements to correct such deficiencies. If the owner fails to do so, the Drainage Board will undertake the work and collect the cost of maintenance or repair from the owner using lien rights if necessary.

(P) Joint development of control systems. Stormwater control systems may be planned and constructed jointly by two or more developers as long as compliance with this subchapter is maintained.

(Q) Detention facilities in floodplains. If detention storage is provided within a 100-year floodplain, only the net increase in storage volume above that which naturally existed on the floodplain shall be credited to the development. No credit will be granted for volumes below the elevation of the regulatory flood at the location unless compensatory storage is also provided.

(Ord. 1997-16, passed 12-8-1997; Ord. 2005-01, passed 2-17-2005) Penalty, see § 153.999

§ 153.197 CERTIFICATIONS REQUIRED.

(A) After completion of the project and before final approval and acceptance can be made, a professionally prepared and certified “as built” set of plans shall be submitted to the Drainage Board for review. These plans shall include all pertinent data relevant to the completed storm drainage system and shall include as a minimum:

(1) Pipe size and pipe material;

(2) Invert elevations;

(3) Top rim elevations;

(4) Lengths of all pipe structures;

(5) Submittal of the data and calculations showing detention basin storage volume; and

(6) Certified statement on plans saying the completed storm drainage system substantially complies with construction plans as approved by the Drainage Board.

(B) All such submitted plans shall be reviewed for compliance within 30 days after submission to the Drainage Board or the County Surveyor.

(Ord. 1997-16, passed 12-8-1997; Ord. 2005-01, passed 2-17-2005) Penalty, see § 153.999

§ 153.198 POST-CONSTRUCTION PLAN SUBMITTAL.

(A) Changes in plan. Any significant change or deviation in the detailed plans and specifications after granting formal approval shall be filed in duplicate with and approved by the Drainage Board prior to the land development involving the change. Copies of the changes, if approved, shall be attached to the original plans and specifications.

(B) Other requirements.

(1) Sump pumps. Sump pumps installed to receive and discharge groundwaters or other stormwaters shall be connected to the storm sewer where possible or discharged into a designated storm drainage channel. Sump pumps installed to receive and discharge floor drain flow or other sanitary sewage shall be connected to the sanitary sewers. A sump pump shall be used for one function only, either the discharge of stormwaters or the discharge of sanitary sewage.

(2) Down spouts. All down spouts or roof drains shall discharge onto the ground or be connected to the storm sewer. No down spouts or roof drains shall be connected to the sanitary sewers.

(3) Footing drains. Footing drains shall be connected to storm sewers where possible or designated storm drainage channels. No footing drains or drainage tile shall be connected to the sanitary sewer.

(4) Basement floor drains. Basement floor drains shall be connected to the sanitary sewers.

(Ord. 1997-16, passed 12-8-1997; Ord. 2005-01, passed 2-17-2005) Penalty, see § 153.999

§ 153.199 LIMITATIONS.

The degree of protection required by this subchapter is considered reasonable for regulatory purposes and is based on historical records, engineering, and scientific methods of study. Larger storms may occur or stormwater runoff depths may be increased by human-made or natural causes. This subchapter does not imply that land uses permitted will be free from stormwater damage. This subchapter shall not create liability on the part of the county or any officer or employee thereof for any damage which may result from reliance on this subchapter or on any administrative decision lawfully made thereunder.

(Ord. 1997-16, passed 12-8-1997; Ord. 2005-01, passed 2-17-2005)

§ 153.200 CORRECTIVE ACTION.

Nothing herein contained shall prevent the county by and through the Drainage Board, County Surveyor, Plan Commission, Plan Commission Director, or other county official or officials from taking such other lawful action as may be necessary to prevent or remedy any violation. All costs connected therewith shall accrue to the person or persons responsible.

(Ord. 1997-16, passed 12-8-1997; Ord. 2005-01, passed 2-17-2005)

§ 153.201 EXEMPTIONS.

All residential, commercial, or industrial subdivision (major or minor) or construction project thereon, which has had its drainage plan approved by the Drainage Board prior to the effective date of this subchapter shall be exempt from all of the requirements of the subchapter.

(Ord. 1997-16, passed 12-8-1997; Ord. 2005-01, passed 2-17-2005)

§ 153.202 NO PRIVATE RIGHTS CONFERRED.

Notwithstanding any provision as contained herein, this subchapter shall not be construed to confer any private enforceable rights upon any private person, firm, or corporation for enforcement of this subchapter, for damages, for injunctive relief, or for any cause of action whatsoever resulting of non-compliance herewith. All rights to enforcement of this subchapter shall be exclusively delegated to the county acting in its public capacity.

(Ord. 1997-16, passed 12-8-1997; Ord. 2005-01, passed 2-17-2005)

§ 153.999 PENALTY.

(A) Any person, whether as principal agent, owner, lessee, tenant, contractor, builder, architect, engineer, or otherwise, who violates any provisions of this chapter shall be guilty of a zoning ordinance violation and shall, upon conviction, be punished by a fine of not less than $100 nor more than $500 for each offense. Each day of the existence of any violation of this chapter shall be a separate offense. In addition, the court may award a reasonable attorney fee in favor of the county against any person violating any provision of this chapter which shall be deemed an additional penalty hereunder.

(B) The erection, construction, enlargement, conversion, moving, or maintenance of any building or structure; and the use of any land or structure which is continued, operated, or maintained contrary to any provision of this chapter is hereby declared to be a nuisance and a violation of this chapter in addition to the penalties provided for herein. The Zoning Administrator may institute a suit for injunction in the Circuit or Superior Court of the county, to restrain any person or governmental unit from violating any provision of this chapter and to cause any such violation to be prevented, abated, or removed. Such action may be instituted by any property owner who may be especially damaged by the violation of any provision of this chapter, except that the attorney fees provision herein shall not apply to a suit instituted by a private person.

(C) In addition to the penalties provided for herein, the county shall be entitled to recover its costs and expenses in enforcing this chapter including reasonable attorney fees which may be awarded by the court against any person violating any of the provisions of this chapter. Such assessment of costs and attorney fees shall be in addition to the fines and penalties provided for herein except that such expenses of enforcement and attorney fees shall not apply, to any action instituted by any private citizen instituting an action for enforcement of this chapter.

(D) Failure to obtain a floodplain development permit in the SFHA or failure to comply with the requirements of a floodplain development permit or conditions of a variance shall be deemed a violation of §§ 153.105 through 153.129. All violations shall be considered a common nuisance and be treated as such in accordance with the provisions of the Zoning Code for the county. All violations shall be punishable by a fine not exceeding $2,500 per day.

(1) A separate offense shall be deemed to occur for each day the violation continues to exist.

(2) The County Plan Commission by and through the Floodplain Administrator shall inform the owner that any such violation is considered a willful act to increase flood damages and therefore may cause coverage by a standard flood insurance policy to be suspended.

(3) Nothing herein shall prevent the county from taking such other lawful action to prevent or remedy any violations. All costs connected therewith shall accrue to the person or persons responsible.

(E) The remedies provided for in this section shall be cumulative and not exclusive, and shall be in addition to any other remedies provided by law.

(Ord. 2005-01, passed 2-17-2005; Ord. 2020-7, passed 6-30-2020)