[Ord. No. 11-2I 86 §§1 — 2, 7-30-2012]
Unless specifically defined elsewhere in this Title, words or
phrases shall be interpreted so as to give them the meaning they have
in common usage and to give this Chapter its most reasonable application:
2-YEAR STORM
Rainstorms of varying duration and intensity having a fifty
percent (50%) probability of being equaled or exceeded in any given
year.
10-YEAR STORM
Rainstorms of varying duration and intensity having a ten
percent (10%) probability of being equaled or exceeded in any given
year.
25-YEAR STORM
Rainstorms of varying duration and intensities having a four
percent (4%) probability of being equaled or exceeded in any given
year.
100-YEAR STORM
Rainstorm of varying duration and intensity having a one
percent (1%) probability of recurring in any one (1) year.
ADVERSE IMPACT
Any modifications, alterations or effects on a feature or
characteristic of surface waters including their quality, quantity,
hydrodynamics, surface area, species composition, living resources,
aesthetics or usefulness for human or natural uses which are or may
potentially be harmful or injurious to human health, welfare, safety
or property, to biological productivity, diversity or stability, or
which unreasonably interfere with the enjoyment of life or property,
including outdoor recreation. The term includes secondary and cumulative,
as well as direct impacts.
APPEAL
As defined in Title IV of this Code.
APPLICANT
The owner of record, or his/her authorized representative,
of a tract of land that is the site of development, or development
activity within the scope of this Chapter.
BASE FLOOD ELEVATION
The elevation at any location delineating high waters having
a one percent (1%) probability of being equaled or exceeded in any
given year (also known as the 100-year flood).
BEST MANAGEMENT PRACTICES (BMPs)
The Best Management Practices referenced in this Chapter
are thoroughly described in the publication "Protecting Water Quality
— A field guide to erosion, sediment and stormwater best management
practices for development sites in Missouri and Kansas". It is available
free of charge at: http://www.dnr.mo.gov/env/wpp/wpcp-guide.htm.
BYPASS FLOWS
Stormwater runoff from an upstream property's tributary to
a property's drainage system, but not under the control of the drainage
system.
CAPACITY OF A STORM DRAINAGE FACILITY
The maximum flow at atmospheric pressure that can be conveyed
by the facility without causing damage to the public or encroachment
upon private property. The capacity of a stormwater drainage facility
is determined utilizing "Manning's Equations" or other methods acceptable
to the Administrative Officer.
CHANNEL
A natural or artificial open watercourse with definite bed
and banks which periodically or continuously contains moving water
or which forms a connecting link between two (2) bodies of 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, widening, deepening, straightening, relocating, lining,
and significant removal of bottom or woody rooted vegetation. Channel
modification does not include the clearing of debris or removal of
trash.
COMMON PROMOTIONAL PLAN
A plan, undertaken by one (1) or more persons, to offer lots
for sale or lease; where the land is offered by sale by a person or
group of persons acting in concert and the land is contiguous or is
known, designated or advertised as a common unit or by a common name
or similar names, the land is presumed, without regard to the number
of lots covered by each individual offering, as being offered for
sale or lease as part of a common promotional plan.
COMPENSATORY STORAGE — FLOODPLAIN
An artificially excavated, hydraulically equivalent volume
of storage within the floodplain used to balance the loss of natural
flood storage capacity when fill or structures are placed within the
floodplain.
COMPENSATORY STORAGE — UPLAND DEPRESSIONAL
An artificial storage provided to balance the loss of natural
flood storage capacity when fill or structures are placed within natural
upland depressional storage areas.
CONDUIT
Any channel, pipe, sewer or culvert used for the conveyance
or movement of water, whether open or closed.
CONSTRUCTION
Any activities including, but not limited to, the erection,
installation, or significant modification of any dwelling, structure,
building, sewer system, water contaminant source or point source.
Construction commences with any preparatory activity including, but
not limited to, trenching, excavation for any building or structure,
but shall not include interior remodeling of residential, commercial,
industrial, or institutional buildings or structures, which will not
result in a substantial change in wastewater volume, nature or change
in the nature or strength of the discharge therefrom.
CONTROL DEVICE
An element of a discharge structure which allows the gradual
release of water under controlled conditions.
CONTROL ELEVATION
Design elevation of a discharge structure at which, or below
which, water is contained behind the structure.
CULVERT
A closed conduit for the passage of surface drainage water
under a roadway, railroad, canal or other impediment.
DETENTION
The delay of storm runoff prior to discharge into receiving
waters.
DETENTION BASIN
A facility constructed or modified to restrict the discharge
of stormwater to a prescribed maximum rate and to concurrently detain
the excess waters that accumulate behind the outlet. A wet-bottom
detention basin is a structure designed to retain a permanent pool
of water after having provided its planned detention of runoff during
a storm event. A dry-bottom detention basin is designed to be completely
dewatered after having provided its planned detention of runoff during
a storm event.
DETENTION BASIN, OFF-SITE
A feature or structure for temporarily storing excess stormwater
originating at two (2) or more sites having devices for controlling
the rate of release of the stored water and located downstream of
all sites where the runoff originates.
DETENTION BASIN, ON-SITE
A feature or structure for temporarily storing excess stormwater,
having devices for controlling the rate of release of the stored waters,
and located within the sites where the runoff originates.
DETENTION STORAGE
The temporary detaining or storage of stormwater in storage
basins, or rooftops, in streets, parking lots, school yards, parks,
open space, or other areas under predetermined and controlled conditions,
with the rate of drainage therefrom regulated by appropriately installed
devices.
DETENTION TIME
The mean residence time of stormwater in a detention basin.
DETENTION VOLUME
The volume of water required to be detained to allow the
post-construction peak runoff rate leaving a site or subdivision to
be less than or equal to the pre-construction peak runoff rate.
DEVELOPER
Any person who, directly or indirectly, sells, leases or
offers to sell or lease or advertises for sale or lease any lots in
a subdivision, but shall not include any licensed broker or licensed
salesman who is not a shareholder, director, officer or employee of
a developer and who has no legal or equitable interest in the land.
DEVELOPMENT
Any man-made change to real estate including: construction,
reconstruction or placement of a structure, building, or any addition
to a structure or building; installation of a manufactured home or
modular structure on a site, preparing a site for a recreational vehicle;
construction of roads, bridges or similar projects; redevelopment
of a site; filling, dredging, grading, clearing, excavating, paving,
or other non-agriculture alterations of the ground surface; storage
of materials or deposit of solid or liquid waste; any other activity
that might increase the magnitude, frequency, deviation, direction
or velocity of stormwater flows from a property.
DIFFERENTIAL RUNOFF
The difference in rate and volume of stormwater runoff from
a parcel or project in its undeveloped natural condition and its developed
condition.
DISCHARGE
The causing or permitting of one (1) or more water contaminants
to enter waters of the State.
DISCHARGE STRUCTURE
Structural control device, usually made of concrete, through
which water is discharged from a project to the receiving water.
DRAINAGE AREA
The area from which water is carried off by a drainage system;
a watershed or catchment area above a given point of study.
DRAINAGE FACILITY
An element in a drainage system which includes, but is not
limited to, any of the following: conduits and appurtenant features,
canals, channels, detention basins, ditches, streams, culverts, streets
and pumping stations.
DRAINAGE PLAN
A plan, including engineering drawing and supporting calculations,
which describes the existing stormwater drainage system and environmental
features, as well as the drainage system and environmental features
which will be in place after development of a property.
DRAINAGE SYSTEM
The surface or subsurface system which conveys water from
or over the land including all watercourses, water bodies and wetlands
(also referred to as the stormwater management system).
DRAINAGE SYSTEM, MAJOR
That part of a drainage system needed to store and convey
flows beyond the capacity of the minor drainage system.
DRAINAGE SYSTEM, MINOR
That part of a drainage system designed for the convenience
of the public. It consists of street gutters, storm sewers, small
open channels and swales and is usually designed to handle the 25-year
runoff event or less.
EASEMENT
A grant by a property owner to the public, a corporation
or a person of the use of land for a specific purpose.
EASEMENT, DRAINAGE
Authorization by a property owner allowing use of a designated
portion of his/her property by others for drainage purposes.
ELEVATION
Height in feet above mean sea level according to a National
Geodetic Vertical Datum (NGVD).
ELEVATION, HIGH-WATER
The elevation of floodwaters of a flood of specified frequency
or occurrence at any given point.
EMERGENCY SPILLWAY
Saddle or low point facility located around the rim of a
dammed impoundment such as a detention or retention basin for providing
an efficient and safe means of conveying the maximum design flood
discharge through the impoundment, without overtopping the dam.
EROSION
The wearing away of the land surface by the action of the
wind, water, ice, gravity or any combination thereof.
EXCESS STORMWATER RUNOFF
The volume and rate of flow of stormwater discharged from
a drainage area which is or will be in excess of that volume and rate
which is specified in this Chapter.
FINAL STABILIZATION
All soil disturbing activities at the site have been completed
and a uniform perennial vegetative cover with a density of seventy
percent (70%) of the cover for unpaved areas not covered by permanent
structures has been established or equivalent permanent stabilization
measures (such as the use of riprap, gabions or geotextiles) have
been employed.
FLOODPLAIN
The special flood hazard land adjoining a watercourse, the
surface elevation of which is equal to or lower than the base flood
elevation [the 100-year flood/one percent (1%) chance per year], which
is subject to periodic inundation during floods.
FLOODWAY
The channel and that part of the floodplain adjacent to a
stream or watercourse which is needed to store and convey the anticipated
existing and future 100-year frequency flood discharge with no more
than a one-tenth (0.1) foot increase in stage caused by any loss of
flood conveyance or storage and no more than a ten percent (10%) increase
in velocities.
FLOODWAY FRINGE
That part of the floodplain outside of the regulatory floodway.
FREEBOARD
The difference in elevation between the maximum design surface
water elevation and the top of the channel, detention basin berm,
top of stormwater control structure, or the finished floor of a structure.
FREQUENCY
An expression or measure of how often a hydrologic event
of given size or magnitude should, on an average, be equaled or exceeded.
GRADE
The inclination or slope of a channel, canal, conduit, etc.,
or natural ground surface, usually expressed in terms of the percentage
the vertical rise (or fall) bears to the corresponding horizontal
distance.
HYDROGRAPH
A graph showing, for a given location on a stream or conduit,
the flow rate with respect to time.
IMPERVIOUS SURFACE
A surface which has been compacted or covered with a layer
of materials so that it is highly resistant to infiltration of water.
The term includes most conventionally surfaced streets, roofs, sidewalks,
parking lots and similar structures.
IMPROVEMENT
A building or structure on, or other addition or alteration
of, land on a given site including, but not limited to, grading, street
surfaces and/or pavements, sanitary and storm sewers, water mains,
and utilities and all other appropriate improvements required to render
land suitable for the use proposed.
LAND DISTURBANCE
Any construction, development, or improvement activity which
changes the physical condition of a land form, vegetation, hydrology,
or otherwise may cause erosion or sedimentation by any means including,
but not limited to: land clearing and grubbing, grading, excavation
or filling, removing and replacing soil, contouring, cutting, topsoil
stripping, blading, trenching, sidecutting, overburden and spoil disposal,
ground leveling, land development, timber harvesting activities, paving,
quarrying, mining, blasting, or the construction or alteration of
earth dams or embankments; and the construction, realignment, or widening
of streets, roadway or access routes, parking or loading/unloading
areas, parking or loading dock facilities, railways, and similar features,
facilities, or activities. It excludes agricultural cultivation and
domestic gardening, the digging of holes for the erection of posts
or poles, the planting of trees or similar landscaping activities
not listed above, and the general maintenance of existing improvements,
infrastructure, or facilities.
LOSING STREAM
A stream which distributes thirty percent (30%) or more of
its flow during low flow conditions through natural processes, such
as through permeable geologic materials into a bedrock aquifer within
two (2) miles' flow distance downstream of an existing or proposed
discharge. Flow measurements to determine percentage of water loss
must be corrected to approximate the seven (7) day Q10 stream flow.
If a streambed or drainage way has an intermittent flow or a flow
insufficient to measure in accordance with this rule, it may be determined
to be a losing stream on the basis of channel development, valley
configuration, vegetation development, dye tracing studies, bedrock
characteristics, geographical data and other geological factors. Losing
streams are listed in Table J of 10 CSR 20-7.031; additional streams
may be determined to be losing by the Division of Geology and Land
Survey.
NATURAL DRAINAGE
Water flow by gravity along the true surface topography of
the earth or in channels prior to development.
NATURAL SAFE STORMWATER DRAINAGE CAPACITY
The quantity of stormwater runoff that can be transported
by means of a channel, passage, conduit, tube, duct, or combination
thereof in such a manner that the elevation of the water does not
rise significantly above the level of the adjacent soil surface and
cause damage or encroachment upon public or private property.
OVERFLOW ELEVATION
Design elevation of a discharge structure at which point,
or above which point, water leaks out, or bleeds out, through a control
device down to the control elevation.
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.
POINT SOURCE
Any discernible, confined and discrete conveyance including,
but not limited to, any pipe, ditch, channel, tunnel, conduit, well,
discrete fissure, container, rolling stock, concentrated animal feeding
operation, separate storm sewer or vessel or other floating craft
from which pollutants are, or may be, discharged.
POLLUTANT
Dredged spoil, solid waste, incinerator residue, sewage,
garbage, sewer sludge, munitions, chemical waste, biological materials,
radioactive materials, heat, wrecked or discarded equipment, rock,
sand, cellar dirt, filter backwash or industrial, municipal or agricultural
waste discharged into water.
POST-DEVELOPMENT CONDITIONS
Those conditions which are expected to exist, or do exist,
after alteration, resulting from human activity, of the natural topography,
vegetation and rate, volume or direction of surface or subsurface
flow.
PRE-DEVELOPMENT CONDITIONS
Those conditions which existed at the time this Chapter becomes
effective in terms of topography, vegetation and rate, volume or direction
of surface or subsurface flow, as indicated by the best available
historical date.
RATIONAL METHOD
An empirical formula for calculating peak rates of runoff
resulting from rainfall. Expressed mathematically, the formula is:
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CIA
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Q
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Peak flow in cubic feet per second (c.f.s.).
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C
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Runoff coefficient, or fraction of runoff to rainfall, dependent
on type of surface cover and topography.
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I
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Rainfall intensity, in inches per hour, for a specific storm
and duration.
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A
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Watershed area, in acres.
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REGISTERED DESIGN PROFESSIONAL
A professional engineer registered with the Missouri Board
for Architects, Professional Engineers, Professional Land Surveyors
and Landscape Architects.
RESIDENCE, SINGLE-FAMILY
Any structure or dwelling which is intended for or is used
by a single household complying with the provisions of this Title
and Title V.
SEDIMENTATION
The process by which suspended solids from erosion are transported
and deposited.
STORMWATER RUNOFF
The waters derived from rain falling or snow melting within
a tributary drainage basin flowing over the surface of the ground
or collected in a stormwater drainage system, storm sewer or watercourse.
TIME OF CONCENTRATION
The elapsed time for stormwater to flow from the most distant
point in a drainage basin to the outlet or point in question.
WATER CONTAMINANT
Any particulate matter or solid matter or liquid or any gas
or vapor or any combination thereof or any temperature change which
is in or enters any waters of the State either directly or indirectly
by surface runoff, by sewer, by subsurface seepage or otherwise, which
causes or would cause pollution upon entering waters of the State
or which violates or exceeds any of the standards, regulations or
limitations under the Missouri Clean Water Law or the Federal Clean
Water Act or is included in the definition of pollutant in the Federal
Act.
WATERCOURSE
Any stream, creek, brook, branch, natural or artificial depression,
slough, gulch, reservoir, lake, pond or natural or man-made drainageway
in or into which stormwater runoff and floodwaters flow either regularly
or intermittently.
WATERS OF THE STATE
All rivers, streams, lakes and other bodies of surface and
subsurface water lying within or forming a part of the boundaries
of the State which are not entirely confined and located completely
upon lands owned, leased or otherwise controlled by a single person
or by two (2) or more persons jointly or as tenants in common. These
waters also include waters of the United States lying within or adjacent
to the State.
[Ord. No. 11-2I 86 §§1 — 2, 7-30-2012]
This Chapter shall not in any way limit or modify the vested
rights of any person to complete any development or improvement to
lands based upon prior law where a previous permit or authorization
has been granted or applied for and where such previous permit or
authorization remains in effect. The City may acknowledge vested rights
in other circumstances where it is equitable and just.
[Ord. No. 11-2I 86 §§1 — 2, 7-30-2012]
In case of conflicts within this Chapter or any part thereof
and the whole or part of any other existing or future ordinance or
Code of the City, the most restrictive in each case shall apply.
[Ord. No. 11-2I 86 §§1 — 2, 7-30-2012]
In the interpretation and application of this Chapter, the provisions
expressed herein shall be held to be the minimum requirements and
shall be liberally construed in favor of the City and shall not be
deemed a limitation or repeal of any other powers granted by State
Statutes.
[Ord. No. 11-2I 86 §§1 — 2, 7-30-2012]
It is not intended by this Chapter to repeal, abrogate or impair
any existing easements, covenants or deed restrictions. However, where
this Chapter imposes greater restrictions, the provision of this Chapter
shall prevail.
[Ord. No. 11-2I 86 §§1 — 2, 7-30-2012]
The performance standards and design criteria set forth herein
establish minimum requirements which must be implemented with good
engineering practice and workmanship. Use of the requirements contained
herein shall not constitute a representation, guarantee or warranty
of any kind by the municipality or its officers and employees of the
adequacy or safety of any drainage management structure or use of
land. Nor shall the approval of a stormwater management plan and the
issuance of a permit imply that land use permitted will be free from
damages caused by stormwater runoff. The degree of protection required
by these regulations 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 heights may
be increased by man-made or natural causes. Enforcement of these provisions,
therefore, shall not create liability on the part of the municipality
or any officer of the municipality with respect to any legislative
or administrative decision lawfully made hereunder, nor shall compliance
relieve an owner, developer and/or permittee from responsibility under
any circumstances where liability would otherwise exist.