[Ord. No. 2994 §1, 3-15-2005]
A. This
Chapter provides minimum standards, controls and criteria for stormwater
management. The principal design consideration in this Chapter is
to minimize the harmful physical and economic effects of erosion,
sedimentation and flooding from stormwater runoff. This is to be accomplished
through the requirement of special measures to mitigate erosion both
during and after construction, the detention and controlled discharge
of the differential runoff from the development, and a well designed
stormwater conveyance system.
B. The
developer shall provide stormwater calculations that indicate that
the stormwater flows generated from the developed conditions does
not exceed the stormwater flows generated from the undeveloped condition.
[Ord. No. 2994 §1, 3-15-2005]
A. The
provisions of this Chapter further supplement other City ordinances
regulating:
1. The subdivision, layout and improvement of lands located within the
corporate limits of the City of Sullivan, Missouri.
2. The excavating, filling and grading of lots, and other parcels or
areas.
3. The construction of buildings, and the drainage of the sites on which
those structures are located, to include parking and other paved areas.
4. The design, construction and maintenance of stormwater drainage facilities
and systems.
[Ord. No. 2994 §1, 3-15-2005]
A. Before
starting any activities regulated by this Chapter, an applicant shall
comply with the requirements set forth in other applicable ordinances
with respect to submission of preliminary subdivision plats, improvement
plans, building and zoning permits, inspections, appeals and similar
matters, along with those set forth in this Chapter and as may be
required by State Statutes (Missouri Clean Water Laws).
B. NPDES Stormwater Permit. Construction sites where the area
to be disturbed is one (1) acre or more must apply for a stormwater
discharge permit and/or land disturbance permit from the Missouri
Department of Natural Resources.
[Ord. No. 2994 §1, 3-15-2005]
For the purposes of this Chapter, the following definitions
are adopted:
ADVERSE IMPACTS
Any deleterious impact on water resources or wetlands affecting
their beneficial uses including recreation, aesthetics, aquatic habitat,
quality and quantity.
BASE FLOOD ELEVATION
The elevation of all locations delineating the level of flooding
resulting from the 100-year frequency flood event.
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 STORMWATER 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 City Engineer.
CHANNEL
Any river, stream, creek, brook, branch, natural or artificial
depression, ponded area, flowage, slough, ditch, conduit, culvert,
gully, ravine, wash, natural or manmade drainageway, or shoreline
in or into which surface or ground water flows, either perennially
or intermittently.
CHANNEL MODIFICATION
Alteration of a channel by changing the physical dimensions
or materials of its bed or banks. Channel modification includes damming,
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.
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.
CONTROL STRUCTURE
The facility constructed to regulate the volume of stormwater
that is released during a specific length of time.
CULVERT
A closed conduit for the passage of surface drainage water
under a roadway, railroad, canal or other impediment.
DESIGN STORM EVENT
A storm of a specific duration expected to occur with a specific
frequency.
DETENTION BASIN
A facility constructed or modified to provide for the temporary
storage of stormwater runoff and the controlled release of this runoff
at a prescribed rate during and after a flood or storm.
DETENTION STORAGE
The temporary detaining or storage of stormwater in storage
basins on 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.
DEVELOPMENT
Any manmade change to real estate including: construction,
reconstruction or placement of a building, or any addition to a building;
installation of a manufactured home on a site, preparing a site for
a travel trailer; 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.
DEWATERING TIME
The time which it takes to drain the temporary flood storage
in a detention facility.
DIFFERENTIAL RUNOFF
The difference in peak flow rate of water anticipated to
shed from a parcel of land between the undeveloped and post-developed
surface condition for each rainfall event.
DRAINAGE AREA
The area from which water is carried off by a drainage system;
a watershed or catchment area above a given point.
DRAINAGE EASEMENT
Authorization by a property owner allowing use of a designated
portion of his/her property by others for drainage purposes.
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.
DRY BOTTOM DETENTION BASIN
A facility constructed or modified to provide for the temporary
storage of stormwater runoff and the controlled release of this runoff
at a prescribed rate during and after a flood or storm.
DURATION
The time period over which precipitation is measured.
EXCESS STORMWATER PASSAGEWAY
A channel on the surface of the soil to carry excess stormwater
runoff through a specific area from dominant to subservient estates.
FLOODPLAIN
That land adjacent to a body of water, stream, watercourse
or channel with ground surface elevations at or below the base flood
or the 100-year frequency flood elevation.
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 top of the detention
basin berm and the design surface water elevation, or the difference
in elevation between the maximum water surface and the top of any
structure, or lowest floor elevation, whichever is appropriate.
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
A term applied to material through which water cannot pass,
or through which water passes with great difficulty or at a very slow
rate.
INFILTRATION
The passage or movement of water into soil surfaces.
INLET
An opening into a stormwater system for the entrance of surface
storm runoff, more completely described as a storm sewer inlet.
MAJOR DRAINAGE SYSTEM
That part of a drainage system needed to store and convey
flows beyond the capacity of the minor drainage system.
MINOR DRAINAGE SYSTEM
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.
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.
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.
POSITIVE GRAVITY OUTLET
A term used to describe the drainage of an area in a manner
that will ensure complete removal of all surface water by means of
gravity.
REGULATORY FLOODWAY
The channel, including onstream lakes, and that part of the
floodplain adjacent to a stream or watercourse, as designated by the
appropriate regulatory body, which is needed to store and convey the
existing and anticipated future 100-year frequency flood discharge
with no more than a one-tenth (.1) foot increase in stage caused by
the loss of flood conveyance or storage and no more than a ten percent
(10%) increase in velocities.
STORMWATER CHANNEL
A natural or manmade watercourse with definite bed and banks
which periodically or continuously contain moving water or form a
connecting link between two (2) bodies of water.
STORMWATER DRAINAGE SYSTEM
All natural or manmade means used for conducting stormwater
to, through or from a drainage area to the point of final outlet from
a property. The stormwater drainage system includes, but is not limited
to, any of the following: conduits and appurtenance features, canals,
channels, ditches, streams, culverts, streets, storm sewers, detention
basins, swales and pumping stations.
STORMWATER RUNOFF
Water that results from precipitation which is not absorbed
by soil or plant material; which does not evaporate and flow over
the surface of the ground; or is collected in channels, conduits or
ponds.
SURCHARGING
To fill to excess or beyond normal capacity.
TIME OF CONCENTRATION
The elapsed time for stormwater to flow from the most hydraulically
remote point in a drainage basin to a particular point of interest
in that watershed.
WATERCOURSE
Any stream, creek, brook, branch, natural or artificial depression,
slough, gulch, reservoir, lake, pond, or natural or manmade drainageway
in or into which stormwater runoff and floodwaters flow either regularly
or intermittently.
100-YEAR RAINFALL
A precipitation event having a one percent (1%) chance of
occurring in any one (1) calendar year.