Editor's Note — Ord. no. 11-2I 86, adopted July 30, 2012,
repealed ch. 420 and enacted new provisions set out herein. Ord. no.
11-2I 92 §§2 — 3, adopted December 17, 2012, also
amended section 420.080(A). Former ch. 420 derived from ord. no. 3-40
§1, 10-20-1997; ord. no. 3-40-1 §1, 2-19-1998; ord. no.
11-2I 14 §§4 — 6, 5-17-2004; ord. no. 11-2I 27 §§1
— 2, 3-21-2005; ord. no. 11-2I 32 §§1 — 8, 7-18-2005;
ord. no. 11-2I 57 §1, 4-25-2007.
[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:
Rainstorms of varying duration and intensity having a fifty
percent (50%) probability of being equaled or exceeded in any given
year.
Rainstorms of varying duration and intensity having a ten
percent (10%) probability of being equaled or exceeded in any given
year.
Rainstorms of varying duration and intensities having a four
percent (4%) probability of being equaled or exceeded in any given
year.
Rainstorm of varying duration and intensity having a one
percent (1%) probability of recurring in any one (1) year.
The duly appointed City Administrator or his/her designated
representative.
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.
As defined in Title IV of this Code.
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.
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).
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.
As defined in Chapter 410 of this Code.
Stormwater runoff from an upstream property's tributary to
a property's drainage system, but not under the control of the drainage
system.
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.
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.
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.
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.
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.
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.
Any channel, pipe, sewer or culvert used for the conveyance
or movement of water, whether open or closed.
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.
An element of a discharge structure which allows the gradual
release of water under controlled conditions.
Design elevation of a discharge structure at which, or below
which, water is contained behind the structure.
A closed conduit for the passage of surface drainage water
under a roadway, railroad, canal or other impediment.
The delay of storm runoff prior to discharge into receiving
waters.
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.
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.
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.
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.
The mean residence time of stormwater in a detention basin.
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.
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.
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.
The difference in rate and volume of stormwater runoff from
a parcel or project in its undeveloped natural condition and its developed
condition.
The causing or permitting of one (1) or more water contaminants
to enter waters of the State.
Structural control device, usually made of concrete, through
which water is discharged from a project to the receiving water.
The area from which water is carried off by a drainage system;
a watershed or catchment area above a given point of study.
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.
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.
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).
That part of a drainage system needed to store and convey
flows beyond the capacity of the 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.
A grant by a property owner to the public, a corporation
or a person of the use of land for a specific purpose.
Authorization by a property owner allowing use of a designated
portion of his/her property by others for drainage purposes.
Height in feet above mean sea level according to a National
Geodetic Vertical Datum (NGVD).
The elevation of floodwaters of a flood of specified frequency
or occurrence at any given point.
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.
The wearing away of the land surface by the action of the
wind, water, ice, gravity or any combination thereof.
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.
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.
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.
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.
That part of the floodplain outside of the regulatory floodway.
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.
An expression or measure of how often a hydrologic event
of given size or magnitude should, on an average, be equaled or exceeded.
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.
A graph showing, for a given location on a stream or conduit,
the flow rate with respect to time.
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.
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.
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.
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.
Water flow by gravity along the true surface topography of
the earth or in channels prior to development.
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.
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.
The maximum rate of flow of water at a given point in a channel
or conduit resulting from a predetermined storm or flood.
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.
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.
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.
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.
Includes major waterways and appurtenant structures or systems
whose total tributary area from origin to outfall exceeds or equals
fifty (50) acres.
An empirical formula for calculating peak rates of runoff
resulting from rainfall. Expressed mathematically, the formula is:
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Q
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=
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CIA
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Q
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=
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Peak flow in cubic feet per second (c.f.s.).
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C
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=
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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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=
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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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=
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Watershed area, in acres.
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Any water body or stream into which surface waters flow.
A professional engineer registered with the Missouri Board
for Architects, Professional Engineers, Professional Land Surveyors
and Landscape Architects.
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.
The process by which suspended solids from erosion are transported
and deposited.
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.
As defined in Chapter 410 of this Code.
The elapsed time for stormwater to flow from the most distant
point in a drainage basin to the outlet or point in question.
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.
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.
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]
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
for each discharge point of the property.
[Ord. No. 11-2I 86 §§1 — 2, 7-30-2012]
A.
A development
permit shall be required for any of the following:
1.
Land disturbance. Any land disturbance as defined
by this Title.
2.
Stormwater point sources. The operation, use or
maintenance of existing stormwater point sources or disturbing land
which would result in a stormwater point source.
3.
Exemptions. The following is a list of activities
that may be exempt from permit requirements, if otherwise exempt from
obtaining a State land disturbance permit.
a.
Certain linear strip or ribbon construction or maintenance operations
such as regrading existing roadways or cleaning existing road ditches
as long as best management practices are utilized.
b.
Trenches less than two (2) feet in width, along with any emergency
repairs or replacement to any existing facilities as long as best
management practices are employed.
c.
Farmlands, domestic gardens or lands used for sludge management where
domestic sludge is beneficially used and which are not physically
located in the confines of a producing facility.
d.
Mowing, brush hog clearing, tree cutting or similar activities which
do not grade, dig, excavate or otherwise remove or kill the surface
growth and root system of the ground cover.
e.
Agricultural stormwater discharges and irrigation return flows. For
purposes of this permit, land disturbance activities from Class I
Concentrated Animal Feeding Operations (CAFO) are not considered an
agricultural activity and therefore are not exempted.
4.
Other permit requirements. Activities exempt from
permits shall not cause any violations of water quality standards
or other provisions of this Title. Any activity which is exempt from
a development permit shall conform to the requirements of this Title
for Best Management Practices.
[Ord. No. 11-2I 86 §§1 — 2, 7-30-2012]
A.
The
owner or an authorized agent of the owner shall submit an application
and obtain a permit prior to commencement of any work requiring a
permit.
1.
Applications. A complete application shall consist
of the following:
a.
Application form. The application form shall contain
information including, but not limited to, the following:
(1)
The name, address, and telephone number of the applicant and
the owner if different from the applicant.
(2)
Name, address, and telephone number of the registered design
professional.
(3)
The location of the property.
(4)
A description of the work to be performed.
(5)
Signature of the property owner or owner's authorized representative.
b.
At least three (3) copies of a Storm Water Pollution Prevention Plan
(SWPPP) complying with this Chapter.
c.
At least three (3) copies of a Stormwater Management Plan complying
with this Chapter and one (1) copy of supporting calculations.
d.
At least three (3) copies of construction plans complying with this
Chapter.
e.
All required fees.
2.
Process. The Administrative Officer shall review
all applications to determine if they are complete.
a.
Complete application shall be submitted to the Administrative Officer
or other persons with special technical expertise as needed.
b.
The application shall be approved, denied or conditionally approved
within a reasonable time.
c.
All reasons for denial or conditions of approval shall be clearly
stated with the denied application or permit as applicable.
[Ord. No. 11-2I 86 §§1 — 2, 7-30-2012]
A.
Stormwater
management plans shall be submitted to the Administrative Officer
or his/her designated representative by the owner, or owner's representative,
of any proposed residential, commercial, industrial, or institutional
development unless the Administrative Officer accepts an alternative
in writing for one (1) of the following reasons:
1.
Off-site facility, two (2) or more developments. If two (2) or more developments, including that of the applicant,
have provided for a common system meeting the requirements and intent
of this Chapter.
2.
Off-site facility by City. If an off-site stormwater management system has been either constructed or programmed, or identified for construction by the City or if, as a result of the topographical conditions present at the development site, there exists in the opinion of the Administrative Officer a suitable natural retention area and the applicant has agreed to either contribute to a stormwater management fund or participate in the construction of an off-site system as part of a City project. The applicant must agree in writing to contribute to the City fund in accordance with Subsection (4) of this Section.
3.
Other management techniques. Management techniques
other than detention facilities may be utilized by the development
provided the techniques proposed meet the intent of this Chapter and
provide a benefit to the watershed that equals or exceeds the benefit
that a detention facility would provide.
4.
Stormwater Management Fund. A Stormwater Management
Fund is hereby created and established by City. Said fund shall be
used exclusively by City for programs and projects designed to help
control the effects of stormwater within the City limits. Any contribution
made by an applicant in lieu of constructing an on-site facility shall
be deposited into said fund with any interest income on such funds
to remain a part of such fund. In order to participate in such fund,
the following shall apply:
a.
Eligibility. It is determined that no adverse effects
will result to adjacent property, and a contribution is made to the
Stormwater Management Improvements Fund. Residential development of
four (4) acres or less and commercial/industrial developments of two
(2) acres or less will be considered as prime candidates for a contribution
in lieu of on-site detention. It is the City's desire that regional
detention storage be utilized to accommodate these smaller developments.
b.
Contribution. The contribution shall be an amount equal to a cost estimate prepared by a professional engineer for site specific improvements necessary to provide detention as provided herein. All cost estimates for site specific detention facilities shall be subject to review and approval by the Administrative Officer. The cost estimate must include the value of the land which otherwise would have been used as part of the system with the value of the subject land determined by an independent appraiser paid for by the developer. Alternatively, the procedure detailed in Section 420.140 can be used to determine contribution.
[Ord. No. 11-2I 86 §§1 — 2, 7-30-2012]
A.
A Stormwater
Pollution Prevention Plan (SWPPP) as required for the DNR land disturbance
permit shall be submitted as a part of any application for a development
permit for a land disturbance activity. A SWPPP shall be prepared
by a registered design professional.
1.
General. Drawn and written descriptive materials
shall be provided which contain information including, but not limited
to, the following:
a.
A site and physical condition description.
b.
How the drainage area will be protected from erosion and discharge
of sediment.
c.
Description of Best Management Practices (BMP) that will be used.
d.
Locations at the site where BMP will be installed.
e.
A description of the types of temporary and permanent structural
and non-structural BMP that will be used.
f.
Location of the sedimentation basin for each drainage area with ten
(10) or more acres disturbed at one time, with sizing and overflow
calculations as outlined in the DNR NPDES permit.
g.
Additional site management BMP to be used, such as solid and hazardous
waste management, provision of portable toilets, proper storage of
construction materials, installation of containment berms and use
of drip pans at petroleum product and liquid storage tanks and containers.
2.
Drawings. The drawn portion of the overall plan
shall also conform to the following requirements:
a.
Shall be of sufficient clarity to clearly indicate proposed buildings,
structures or uses or other features shown on the plan.
b.
Shall be drawn to scale not greater than one (1) inch equals twenty
(20) feet nor less than one (1) inch equals two hundred (200) feet.
c.
Shall identify property by lot lines and location, including dimensions,
angles and size, correlated with the legal description of said property.
d.
Shall show the scale, north point, boundary dimensions, natural features
such as woods, streams, rivers, lakes, drains, topography [contour
interval shall be two (2) foot] and similar features.
e.
Shall show existing man-made features such as buildings, structures,
easements, high tension towers, pipelines, existing utilities such
as water and sewer lines, etc., excavations, bridges, culverts and
drains and shall identify adjacent properties within one hundred (100)
yards and their existing uses.
f.
Shall show the location, proposed finished floor and grade line elevations,
size of proposed main and accessory buildings, their relation one
to another and to any existing structures to remain on the site and
the height of all buildings and structures, as well as building elevations
and materials proposed for the structures under consideration.
g.
Shall show the existing and proposed public and private streets,
driveways, sidewalks, and other vehicular and pedestrian circulation
features within and adjacent to the site; also the location, size
and number of parking spaces in the off-street and on-street parking
areas and identification of service lands, service parking, and loading
zones required or provided in conformance with the requirements set
forth in this Title.
h.
Shall show the location and size of all existing utilities serving
the property as well as the location and size of all proposed utilities
to serve the property.
i.
Shall show existing and proposed topography of the subject property
and adjacent properties within fifty (50) feet of the subject property
and gutter line or edge of pavement of existing public or private
streets, access roadways, or drives adjacent of the subject property.
Any proposed alterations to the topography and other natural features
shall be indicated.
j.
Shall show the existing and post-developed site information.
k.
Shall show the location of vegetative cover and soil types and characteristics
representative of the design conditions, where percolation or exfiltration
systems are proposed.
l.
Shall show the location of streams, their normal channels and the
extent of the floodplains at the established high water elevations
and the limits of the floodway.
m.
Shall show the location of lakes, ponds, swamps and detention basins
indicating their normal shorelines. floodplains, floodways and lines
of inflow and outflow.
n.
Shall show the location of farm drains, inlets and outfalls, storm,
and sanitary sewers and outfalls, septic tank systems and outlets,
if any, and seeps, springs and flowing and other wells.
o.
Shall show the location and description of nearby existing off-site
water management facilities such as wells, lakes, drainageways and
other similar features which are potentially directly affected by
the proposed construction or development.
p.
Shall show all existing drainage facilities which are to be maintained,
altered or enlarged as part of the stormwater management system; provide
information as to their size, slopes, depths, outfalls, receiving
waters, elevations, cross sections, profiles, construction materials
and other design details as applicable.
q.
Shall show the location of all new drainage facilities, including
detention basins, to be constructed and provide design details on
each as applicable.
r.
Shall show the location and extent of right-of-way and easements
for the stormwater management system, including all areas to be dedicated
for water management purposes.
s.
Shall identify and describe any special or required maintenance procedures
for the project to continue to function as designed.
t.
Shall include any other information required by the Administrative
Officer to determine compliance with this Title.
u.
Shall be signed and sealed by a registered design professional.
3.
Construction details. Detailed construction drawings
clearly indicating the proposed locations, materials and specifications
of any structural BMP shall be submitted.
4.
Additional requirements. Additional requirements
pertaining to the SWPPP shall be as follows:
a.
After a permit is approved, a copy of the SWPPP shall be kept on
site during the entire term of the land disturbance activity and shall
be made available to all local, State and Federal authorities having
jurisdiction upon request.
b.
The SWPPP shall be amended or updated as appropriate during the term
of the land disturbance activity.
c.
Amendments or updates shall be also be submitted to the Administrative
Officer for approval and are to be included in the permit record.
[Ord. No. 11-2I 86 §§1 — 2, 7-30-2012]
A.
A stormwater
management plan shall be designed to safely manage stormwater runoff
resulting from the critical duration storm event. The plan will identify
infrastructure improvements designed to reduce stormwater discharge
rates to pre-development levels through detention of excess runoff.
Stormwater management plans shall be prepared by a professional engineer
registered in the State of Missouri.
1.
Grading/detention plan. The minimum requirement
for a grading/detention plan are the same as those listed for the
SWPPP drawings defined in Section 420.060(2).
2.
Report. A stormwater management report shall be
provided along with the grading and detention plan. The minimum requirements
for a stormwater management report complying with this Chapter shall
be as follows:
a.
Shall include the design calculations.
(1)
Design storms used.
(2)
Calculated hydrographs of outflow of design storm's runoff from
the project site existing and developed conditions.
(3)
For all detention basins, a plot or tabulation of storage volumes
with corresponding water surface elevations and of the basin outflow
rates for those water surface elevations.
c.
Shall include runoff routing calculation showing discharge, elevations
and volumes retained and/or detained during applicable storm event.
d.
Shall include calculations required for determination of minimum
building floor and road elevations.
e.
Shall include the name of the entity responsible for operation and
maintenance of the system.
f.
The requirements for specific plan elements cited above may be waived
at the discretion of the Administrative Officer. No plan element waiver
on the part of the Administrative Officer shall have the effect of
a variance or relieve any person from complying with all other applicable
provisions of this Title.
3.
Construction details. Detailed construction drawings
clearly indicating the proposed locations, materials and specifications
of any stormwater improvements shall be submitted. The design of all
such improvements details shall comply with the subdivision regulations
in addition to this Chapter.
4.
Other construction documents. The Administrative
Officer may require other drawn or written descriptive documentation
or materials to determine compliance with the requirements of this
Chapter.
5.
Waivers. The Administrative Officer may waive specific
submittal information from time to time as deemed appropriate.
a.
Sufficient documentation shall be provided to the Administrative
Officer to determine whether a waiver is appropriate.
b.
A statement from a registered design professional certifying that
the differential runoff shall result in no adverse impact to the area
or adjoining properties.
c.
The Administrative Officer may require a review and written supportive
recommendation from a consulting engineer or other persons having
specialized technical knowledge prior to waiving such information
whenever necessary.
d.
No waiver on the part of the Administrative Officer shall have the
effect of a variance or relieve any person from complying with all
other applicable provisions of this Title.
6.
Plan adherence. The owner or authorized agent of
the applicant shall be required to adhere strictly to the stormwater
management plan as approved. Any changes or amendments to the plan
must be approved by the Administrative Officer in accordance with
the procedures set forth in this Chapter.
7.
Final inspection and approval by design professional. A final inspection by the design professional shall be required on each project to verify that all stormwater pipes, structures, basins, etc. have been built according to the approved plan and specifications. A written approval by the design professional shall be provided to the Administrative Officer (see Section 420.170).
[Ord. No. 11-2I 86 §§1 — 2, 7-30-2012; Ord. No. 11-2I 92 §§2 — 3, 12-17-2012]
A.
All
applications shall be accompanied by a fee as designated by Table
O at the end of this Title. The Zoning Administrator shall be permitted
to establish a refund policy. No fee shall be refunded for failure
to act in favor of the applicant.
B.
The
effective acreage for a project is not limited to a fractional part
of the total concept, rather if a project is developed in phases or
small plots, the total acreage of the conceptual project will be considered.
C.
The
review fee shall be collected at the time the stormwater management
plan application is submitted by the applicant to the Administrative
Officer and will reflect the cost of the administration and management
of the review process. These fees may be adjusted from time to time
by the City Council to reflect actual costs of administration and
review.
[Ord. No. 11-2I 86 §§1 — 2, 7-30-2012]
A.
A stormwater
management system shall be provided for protecting lots, roads, streets
and buildings in the project area from the potential adverse impacts
of stormwater runoff. Streets, blocks, depths of lots, parks and other
public grounds, and ultimate land usage shall be determined, located
and laid out in such a manner as to reduce the velocity of overland
flow and allow the maximum opportunity for infiltration of stormwaters
into the ground and to preserve and utilize natural streams, channels
and detention basins and, wherever possible, to include streams and
floodplains within parks or other public grounds.
B.
The maximum allowable release rate of stormwater after development at each point of discharge shall not exceed the pre-development rate for that location (see Section 420.100). The total drainage area must be used in calculating the allowable release rate.
C.
The
increased stormwater runoff resulting from the proposed development
shall be detained on-site by appropriate detention basins; by storage
on flat roofs, parking lots or streets; or by other acceptable techniques.
Control devices shall limit the discharge from storage to a rate no
greater than that prescribed by this Chapter. Downstream property,
watercourses, channels or conduits shall not receive stormwater runoff
from proposed development at a higher peak flow rate than that which
existed prior to the development.
D.
Generally
acceptable locations of the stormwater runoff channels in the design
of the project area may include the following:
1.
In a depressed median of a double roadway, street or parkway, provided
the median is wide enough to permit required roadway shoulders.
2.
In a depressed area long roadway, street or parkway, provided the
area is wide enough to permit side slopes as required in other Sections
of this Chapter and the right-of-way is widened to encompass the area
of the depression.
3.
Alternative systems such as curb and gutter and storm sewers that
discharge into an appropriate detention basin may be incorporated
into the stormwater management plan.
4.
The smaller, uppermost reaches of drainage channels and swales forming
the natural drainage system near a watershed divided may be relocated
or eliminated and incorporated into the planned system of storm sewers
and open channels designed consistent with the requirements of this
Chapter.
5.
Stormwater runoff channels will not be allowed on private lots. However,
stormwater piping systems may be centered on the rear lot lines in
a block or entirely within the rear yards of a single row of lots
or parcels, provided that in either case the lots are deep enough
to permit the drainage easement and a building site.
E.
Locations
where drainage facilities serve multiple properties are to be located
and maintained and shall have a continuous utility-drainage easement
provided. The utility-drainage easement shall be at least twenty (20)
feet wide. Within the area so designed for the passage or storage
of waters, no structure may be erected, no fences, shrubbery or trees
planted, or changes made to the prescribed grades and contours of
the specified stormwater runoff channels.
F.
All
storm sewer outfalls shall be so designed that they will continue
to drain the areas they are designed to serve unless the provision
is made for sewer backups into planned storage locations.
G.
All
sanitary sewer manholes constructed in a floodplain or in an area
designed for the storage or passage of floodwater or stormwater shall
be provided with either a water-tight bolted manhole cover, a water-tight
concealed pick-hole cover, or be constructed with a rim elevation
at or above the high-water elevation of the 100-year flood or the
high-water elevation of the design storm, whichever is applicable
to the specific area.
H.
Projects
that are to be developed in phases will require the submission of
a master plan of the applicant's contiguous land holdings. Applications
for individual project phases may be considered only when the phases
are totally independent of, or make sufficient provisions for, adjacent
lands.
I.
The
plan shall include provisions for any off-site development activity
related to the project. All land within the City on which development
activity related to a project is proposed shall be identified and
included in the plan. All owners of property where development activity
related to the project is proposed shall be identified and included
in the application.
[Ord. No. 11-2I 86 §§1 — 2, 7-30-2012]
A.
Rainfall Frequency. All conduit facilities shall be designed to carry a twenty-five (25) year storm while maintaining a minimum of one (1) foot of freeboard between the hydraulic grade line and the gutter or other surcharge point. All channels shall be designed to carry a twenty-five (25) year storm while maintaining a minimum of one (1) foot of freeboard. All stormwater detention facilities shall be designed as required in Chapter 420. The Administrative Officer may require a different design storm if there are downstream flooding problems or, in the opinion of the Administrative Officer, a public health or safety issue would exist otherwise. All systems shall be designed to allow for a one-hundred (100) year storm to pass through the development without destroying or damaging property or inundating dwellings. Sufficient design information shall be provided by the developer to verify that the requirements of this section have been met.
[Ord. No. 4-38 §1, 10-28-2013]
B.
Calculation Of Runoff. The method of calculating and routing
stormwater runoff shall be a generally accepted stormwater management
practice. The drainage area shall consider all on- and off-site lands
contributing to the proposed development's drainage system. Capacity
for such facilities shall be based on the maximum potential water
shed development permitted by current zoning. In the case of most
development, hydrograph routing will be required. Hydrograph routing
requires that time be taken into account in the hydrologic model.
Hydrograph Modeling using HEC-I (or HEC-HMS) and the Kinematic Wave
Method is the preferred method for most complex urban runoff conditions.
Other allowable methods include Pond Pack and EPA-SWMM. Additional
methods may be approved by the Administrative Officer. For instances
where hydrograph routing is not required and land use in the watershed
is homogeneous (i.e. calculating storm inlet capacity and pipe sizing),
the Rational Method for calculating stormwater runoff may be used.
C.
Runoff Coefficient. The runoff coefficient "C" is the variable in the Rational Formula least susceptible to precise determination and the one, which requires the greatest exercise of engineering judgment because of the many area characteristics, which affect the coefficient. Among the factors to be considered in influencing the runoff coefficients are the following: present and future zoning; terrain; local ponding or depressions; the amount of pavement; roofs, turf, and other areas having different degrees of imperviousness. The selection of coefficient should take into consideration the probable ultimate development of presently underdeveloped areas. Suggested values of runoff coefficients are included in "Chapter 420, Table A" at the end of this Chapter.
D.
Runoff Curve Number Determination. The determination of the Curve Number (CN) value for a watershed is a function of soil characteristics, hydrologic condition and cover or land use. CN values for undeveloped and developed areas are provided in "Chapter 420, Table B" and "Chapter 420, Table C" respectively at the end of this Chapter. For watershed with multiple soil types or land uses, an area-weighted CN should be calculated. Wheri significant differences in land use or natural control points exist, the watershed should be broken into smaller drainage areas for modeling purposes.
E.
Rainfall Intensity. Maximum intensity of rainfall of a given expectancy is greater for a short period of time than for longer periods. Therefore, it is assumed that the maximum runoff will occur as soon as all parts of the drainage area under consideration are contributing. The length of time from the beginning of rainfall until runoff from the hydraulically most remote point in the drainage area reaches the point under consideration is called the time of concentration. This may include overland flow time and channel or gutter flow time. Once the time of concentration is known, the design intensity rainfall may be determined from the rainfall intensity curves developed from the Weather Bureau data. For Rational Method analysis, rainfall intensity in inches per hour must be determined from an event with a duration equivalent to the time of concentration. "Chapter 420, Table D" and "Chapter 420, Table E" at the end of this Chapter provide depth and intensity values for various rainfall durations and frequencies in the Farmington area.
F.
Temporal Rainfall Distribution. When using the Kinematic
Wave Method or SCS Method for runoff computations, the NRCS Type II
and Huff rainfall distribution methods shall be used for the temporal
distribution. Different families of Huff distribution curves are applicable
for different drainage areas. Each family of curves consists of four
(4) storms (first-quartile, second-quartile, third-quartile, and fourth-quartile)
that correspond to the quartile within the storm event when the bulk
of the rainfall occurs. As part of the stormwater management plan,
a critical duration analysis shall be performed for all drainage facilities.
The analysis shall determine the storm duration causing the maximum
peak flow or maximum peak stage for a storm event of a given magnitude.
Storms with durations of six (6) hours or less, six (6) to twelve
(12) hours, twelve (12) to twenty-four (24) hours, and greater than
twenty-four (24) hours tend to be associated with the first- (1st),
second- (2nd), third- (3rd), and fourth- (4th) quartile storms, respectively
(Huff and Angel 1992).
G.
Open Channels. Open channels consist of swales, ditches
or depressions, both natural and man-made, that convey water. Channels
shall be protected from scour and erosion by providing a channel lining
adequate to sustain the velocity of the design storm. If velocities
in channels exceed three and one-half (3.5) feet per second during
the design storms, then erosion control other than vegetation shall
be provided in channel construction. Channels shall have the hydraulic
capacity to carry the design storm runoff within the channel bed and
banks with one (1) foot of freeboard. Out of bank flow may be permitted
on land slopes parallel to the channel where it can be shown that
no erosion damage or property damage will result. Channels that function
as part of the major drainage system shall be evaluated for the 100-year
design storm to determine the impacts of runoff on adjacent property.
The channel's hydraulic capacity shall be increased where adjustments
to channel geometry provide significant protection to adjacent properties
during the 100-year event.
H.
Closed Conduit Storm Sewers. Pipe sizes for closed conduit
flow shall be based on the design storm runoff and minimum allowable
velocities. The system shall provide for the clearing of sediment
and other deposits by maintaining a minimum velocity of two (2) feet
per second during the 2-year storm. Pipe sizes in a storm system may
not be reduced smaller than the upstream pipe section even though
the smaller pipe may have adequate flow capacity. The smallest pipe
size allowed in storm systems is eighteen (18) inches in diameter.
Manning's Equation is the most common method of estimating the capacity
and flow resistance in closed conduits, although the Kutter, Hazen-Williams,
and Darcy Weisbach formulas are also acceptable.
I.
Drainage And Storm Sewer Systems. All drainage and storm
sewer systems shall be designed and constructed in accordance with
standards and specifications of the City. All facilities shall be
designed to carry a 25-year storm while maintaining a minimum of one
(1) foot of freeboard between the hydraulic grade line and the gutter.
The developer's engineer shall verify that the 100-year storm may
be contained in the road right-of-way and/or in a dedicated drainage
easement. The engineer shall provide a stormwater report to document
meeting these requirements. Generally, pressure flow (when the hydraulic
grade line is above the crown of the pipe) occurs where the capacity
of a pipe run is exceeded by the design flow or the outfall point
controls the discharge rate. Storm sewer systems may be designed for
pressure flow. The decision to design a pressure flow system may be
based on aesthetics, the need to submerge outfalls, economics, limitations
associated with reduced pipe sizes, or grade constraints at the system
discharge point.
J.
Inlets. Calculations shall be submitted to demonstrate the capacity of all inlets, such calculations must consider the cross-slope of the pavement, depth of water at the curb face, size of opening, and the longitudinal grade of street. Street inlets and inlets in parking areas shall reduce the spread and depth of flow to acceptable levels during the 25-year design storm. Inlets located on continuous grades may be designed to permit a portion of flow to bypass the structure; however, calculations for the downstream structure must consider the bypass. Street flow shall be limited by pavement encroachment and depth of flow are included in "Chapter 420, Table F" at the end of this Chapter.
K.
Plans And Calculations. Plans and calculations shall be
in accordance with the following:
1.
A drainage map shall be developed from a base reproduction of the
site plan or grading plan. The existing and proposed contours shall
be shown, of suitable scale and one (1) foot contour interval for
the subject property, extending off-site one hundred (100) feet or
less as determined by the City for proper design of the proposed improvements.
Contour intervals other than the above may be used if approved by
the Administrative Officer.
2.
The location of existing and proposed property lines, streets, sinkholes,
railroads, areas within the tract subject to inundation by stormwater
and other significant natural features, such as wooded areas and rock
formations, etc., shall be included on the map. All existing and proposed
stormwater facilities, such as inlets, manholes, pipes, culverts,
bridges, channels, etc., and all existing and proposed improvements
required for property design review, such as pavement, buildings,
etc., shall be included on the map.
3.
The location of streams and other floodwater runoff channels, calculations
supporting the method and capacity needed for the safe and temporary
storage of increased runoff resulting from the proposed development.
4.
Basic information regarding the receiving watercourse into which
the proposed stormwater system will discharge.
5.
The runoff details shall be required showing individual flows for
each existing and proposed structure and cumulative flows in pipes
and gutters, including flow rate (Q) and area. The map shall show
all bodies of water, such as ponds or lakes (including surface area
and elevation), wetlands, and all waterways (including their names
or the names of creeks or rivers they flow into).
6.
Lots shall be laid out so as to provide positive drainage away from
all buildings. Individual lot drainage shall be shown and coordinated
with the drainage pattern for the area and designed so that runoff
from one (1) lot will not adversely affect an adjoining lot. All necessary
grading to direct stormwater runoff shall be located within a drainage
easement. A layout of the proposed stormwater management system including
the location and size of all drainage structures, storm sewers, channels,
channel sections, detention basins, and analysis regarding the effect
said improvements will have upon the receiving channel and its high
water elevation.
7.
The Administrative Officer may require alternative designs or features
to reduce the cost of long-term maintenance.
8.
In critical areas, the Administrative Officer may require additional
hydraulic capacity above the minimum set forth above, up to the 100-year
frequency design.
9.
All computations, plans, and specifications related to the implementation
of this Chapter must be prepared and sealed by a professional engineer
registered in the State of Missouri.
[Ord. No. 11-2I 86 §§1 — 2, 7-30-2012]
A.
The peak rates (pre-developed and post-developed) of runoff shall
be determined for the two (2), ten (10), twenty-five (25) and one-hundred
(100) year rainfall frequencies. The minimum storm duration shall
be twenty (20) minutes.
[Ord. No. 4-38 §2, 10-28-2013]
B.
Stormwater
shall be detained on-site or on adjacent property under agreement
and metered out at the pre-developed rate for the above frequencies
and critical duration to prevent possible flooding and erosion downstream.
C.
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 downstream channel or storm sewer system to the
fullest extent practical.
D.
Detention
basin volume will be based on hydrograph method routing of all post-developed
runoff through the detention facility while satisfying the appropriate
allowable release rate.
E.
Credit
pursuant to this Section will be given for existing impervious area.
[Ord. No. 11-2I 86 §§1 — 2, 7-30-2012]
A.
Method Of Evaluation. Differential runoff evaluation consists
of the determination of rates of runoff before and after development,
the determination of required volume of detention and verification
of adequacy of discharge and control structures.
B.
Control Structures. Detention facilities shall be provided
with obvious and effective control structures. Plan view and sections
of the structure with adequate detail shall be included in plans.
1.
The sizing of the control structure shall be by the appropriate weir
and orifice formulas.
2.
The overflow opening or spillway shall be designed to accept the
total peak runoff of the improved tributary area.
3.
Detention design criteria. Detention in the overall
system, including swales, lakes, canals, greenways, etc., shall be
provided as follows:
a.
General.
(1)
Storage volumes. The storage volume required shall be determined as outlined in Section 420.110 while maintaining a minimum of one (1) foot of freeboard for the one-hundred (100) year storm.
[Ord. No. 4-38 §3, 10-28-2013]
(2)
Outlet control structures. Outlet control structures
shall be designed to operate simply and automatically. They will limit
discharges into existing or planned downstream channels or conduits
so as not to exceed predetermined maximum authorized peak flow rates.
(3)
Emergency spillway. Emergency overflow facilities
must be provided in all instances so that stored waters will not exceed
the safe capacity of the basin. At a minimum, the emergency spillway
must be able to pass the 100-year storm without overtopping.
(4)
Appearance. Designs should result in aesthetically
pleasing configurations which will enhance public acceptability.
b.
Dry-detention facilities.
(1)
Perimeter maintenance, access, and operation easements of fifteen (15) feet minimum width beyond the top of the slope shall be provided in accordance with Section 420.160 of this Chapter.
(2)
Side slopes of the facility shall not be steeper than 3:1 (three
horizontal to one vertical). The bottom of the facility shall not
be flatter than one and one-half percent (1.5%) to facilitate complete
drainage. If retaining walls are utilized, vehicular access into the
bottom of the basin must be provided for maintenance.
(3)
The low-flow channel invert through dry detention facilities
on other than permanently flowing streams shall be concrete and have
a minimum slope of one-half percent (0.5%). Other materials for constructing
the low-flow channel invert may be considered by the Administrative
Officer.
(4)
Provisions must be incorporated to facilitate complete interior
drainage to dry-bottom basins, to include the provision of natural
grades to outlet structures, longitudinal and transverse grades to
perimeter drainage facilities, or the installation of subsurface drains.
(5)
Multi-purpose features may be designed to serve secondary purposes
for recreation, open space or other types of use which will not be
adversely affected by occasional or intermittent flooding.
(6)
The entire reservoir area shall be seeded, fertilized and mulched,
sodded or paved.
c.
Wet-detention facilities.
(1)
Perimeter maintenance, access, and operation easements of fifteen (15) feet minimum width beyond the top of the slope shall be provided in accordance with Section 420.160 of this Chapter.
(2)
Control elevations should be no higher than two and one-half
(2½) feet below the minimum road centerline elevation within
two hundred (200) feet of the detention pond to protect the road subgrade
when structures are constructed near roads.
(3)
Side slopes shall not be steeper than 3:1 (horizontal to vertical)
out to a depth of two (2) feet below the control elevation, then as
steep as soils stability will allow.
(4)
If fish are to be used to help keep the basin clean, at least
one-quarter (¼) of an area of the permanent pool must be a
minimum depth of ten (10) feet.
(5)
For emergency purposes, cleaning or shoreline maintenance, facilities
shall be provided or plans prepared for the use of auxiliary equipment
to permit emptying and drainage.
(6)
The limits of maximum ponding elevations are to be no closer
than twenty-five (25) feet horizontally from any building and no less
than two (2) feet below the lowest sill elevation of any building.
d.
Impervious areas. Paved parking lots may be designed
to provide detention storage of stormwaters on all or a portion of
their surfaces. Outlets will be designed so as to slowly empty the
stored waters, and depths of storage must be limited to a maximum
depth of six (6) inches so as to prevent damage to parked vehicles.
Ponding should be regulated to those positions of the parking lots
farthest from the area served.
e.
Rooftop storage. Detention storage requirements
may be met in total or in part by detention on flat roofs. Details
of such designs to be included in the stormwater management plan application
shall include the depth and volume of storage, details of outlet devices
and down drains, elevations of overflow scuppers, design loadings
for the roof structure and emergency overflow provisions.
f.
Underground storage. All or a portion of the detention
storage may also be provided for in underground facilities, as long
as all applicable requirements of this Chapter are met. Details of
such designs are to include type of facility, depth and volume of
storage, details of inlet and outlet devices and locations, emergency
overflow and maintenance provisions, and measures to be used for surface
water and ground water pollution control.
g.
Design alternatives. The above listing of design
criteria is not intended to preclude the use of other known state-of-the-art
methods and available best management practices and should not be
construed as a mechanism to discourage innovative design concepts.
4.
Development adjoining a floodplain. Where a development
adjoins or encompasses a portion of a FEMA designated floodplain,
the following shall apply:
a.
The applicant shall comply with the requirements contained in Chapter 415 of this Title and show the floodplain and floodway on the stormwater management plan.
b.
The applicant shall include in the stormwater management plan all
other plans, plats, specifications, etc., required by Federal, State,
County and/or municipal laws or regulations detailing such provisions
or restrictions as are necessary to comply with the following:
5.
Channel flow. The applicant shall not alter any
channel in such a way that would prohibit any section of the channel
from conveying, in its post-development state, the same amount of
flow that is conveyed in its pre-development state.
6.
Modifications of channel. The applicant shall furnish,
for the Administrative Officer's review and approval, the following
information pertaining to proposed channel modifications:
a.
Typical cross sections of the existing and proposed channel.
b.
Plan view of the channel showing the location of existing constrictions,
obstructions and other non-typical areas.
c.
Hydrographs and/or flood routing calculations and backwater curve
profiles of the proposed waterway corresponding to a storm recurrence
interval of one hundred (100) years.
d.
Engineering evaluation of all potential increases in flood hazards
to the adjacent upstream or downstream private or public lands and
facilities located thereon, showing provisions for eliminating any
and all adverse impacts on such land and facilities at no public cost.
e.
Minimum finished floor elevations shall be set at or above the maximum water surface elevation as determined by the following in accordance with Section 420.150:
(1)
"Flood Insurance Rate Map" published by the Federal Emergency
Management Agency.
(2)
Backwater curve profiles of the proposed waterway due to a 100-year
storm recurrence interval.
(3)
The slab on grade finish floor elevation or the top of foundation
of a building or structure shall be a minimum of twelve (12) inches
above the lowest elevation of the public street gutter (at the lowest
point perpendicular to the structure) plus two percent (2%) times
the distance between the public street curb face (or edge of existing
asphalt street) and the building or structure.
(4)
The minimum finish floor elevation for the allowable building
area or footprint identified on a preliminary plat, final record plat,
and boundary adjustment for a lot or subdivision shall be a minimum
of twelve (12) inches above the lowest elevation of the public street
gutter (at the lowest point perpendicular to the structure) plus two
percent (2%) times the distance between the public street curb face
(or edge of existing asphalt street) and the building setback.
(5)
Shall comply with the applicable minimum elevation requirements of the Building and Residential Code (an example has been provided in "Chapter 420, Table G").
(6)
Designation on the final plan of all areas reserved for flood
routing, detention or storage, together with the required wording
pertaining to restrictions, dedications and maintenance responsibilities
of such areas.
f.
Designation on the final plan of all areas reserved for flood routing,
detention or storage, together with the required wording pertaining
to restrictions, dedications and maintenance responsibilities of such
areas.
7.
Detention storage. If detention storage is provided
within a 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 that location unless compensatory storage
is also provided.
8.
Verification of adequacy. Analysis of all elements
of design is to be verified by the engineer of record submitting the
plan. The following outline is provided to ascertain that certain
critical elements are in workable compliance with the aims of this
Chapter and Title.
a.
Verification shall be made of:
(1)
Volume of detention for the total project.
(2)
Peak flow rate for the item being studied.
(3)
Detention routing calculations.
(4)
Sizing of all stormwater channels and conduits.
(5)
Sizing of the detention control structure.
(6)
Stability of detention dikes.
(7)
Safety features.
(8)
Maintenance features.
9.
Installation of stormwater runoff control measures. Positive stormwater runoff control shall be provided for during
development. Stormwater management plans shall include a schedule
for the installation, construction or modification of all drainage
facilities. Erosion control measures and a schedule for their installation
shall be shown on the stormwater management plan. Installation of
drainage facilities and erosion control measures shall proceed as
scheduled in the approved stormwater management plan.
10.
Best management practices. Best management practices
to prevent erosion, sedimentation and other contamination of the municipal
storm sewer system or the waters of the State shall be incorporated
into the Storm Water Pollution Prevention Plan. Such measures shall
be implemented from the time the land is disturbed until final stabilization
of the land is achieved. Permitted best management practices may include,
but are not limited to, the following.
a.
Site planning.
b.
Silt fencing.
c.
Straw bales.
d.
Rock dams.
e.
Mulching.
f.
Temporary berms.
g.
Sediment basins.
h.
Temporary seeding.
i.
Permanent seeding.
j.
Maintain vegetation.
|
|
The best management practices utilized shall be in accordance
with the publication "Protecting Water Quality" as published by the
Missouri Department of Natural Resources. Use of other State-approved
standard specifications or methods which offer a higher level of protection
may also be incorporated by the design professional.
|
[Ord. No. 11-2I 86 §§1 — 2, 7-30-2012]
A.
Storm
pipes shall be protected from excessive bearing pressures by placing
them outside the forty-five degree (45°) influence zone of building
structures unless an engineer's calculations show the pipe material
or soil condition to be adequate for the subjected load.
B.
Pipes
on twenty percent (20%) slopes or greater shall be anchored securely
with concrete anchors or their equal to prevent the pipe from creeping
downhill. The minimum allowable pipe slope is one-half percent (0.5%).
C.
Pipes
or structures constructed on fill shall be stable and protected against
settlement by compacting fill material to ninety-five percent (95%)
of the modified proctor maximum dry density.
D.
Pipes
thirty-six (36) inches or larger may be placed on a curved alignment
utilizing alignment radii established by the pipe manufacturer.
E.
The
receiving surface where pipes discharge shall be protected from erosion
by evaluating the discharge velocity for the 25-year design storm.
The use of energy-dissipating devices may be necessary to reduce the
velocity to acceptable levels for the receiving surface. The energy-dissipating
device used shall be a minimum length of ten (10) times the diameter
of the discharge pipe.
F.
A manhole,
inlet or junction box shall be located at changes in pipe size, grade,
alignment or material except for cases where the pipe size is thirty-six
(36) inches or greater.
G.
The
angle between influent and effluent pipes shall be not less than ninety
degrees (90°), and the drop between inverts shall be not less
than one-tenth (0.1) foot.
H.
Manhole
and inlet castings located in travelways shall be capable of withstanding
traffic loads and shall be constructed flush with the finished surface.
I.
All
materials and appurtenances for stormwater management systems shall
conform to current standards of the American Society for Testing and
Materials (ASTM).
J.
Manholes
shall be pre-cast or cast-in-place concrete with concrete risers and
approved manhole covers.
K.
A new
drainage channel or pipe shall intersect an existing drainage channel
at a maximum angle of sixty degrees (60°).
L.
All
trenches under roadway pavement shall be backfilled with MHTD Type
I aggregate in six (6) inch layers and compacted to ninety-five percent
(95%) of the modified proctor maximum dry density.
M.
All
piping shall be bedded per the manufacturer's requirements.
N.
Grated
inlets will not be allowed without special approval by the Administrative
Officer.
O.
All
materials used in the construction of storm sewers shall be subject
to inspection and approval of the Administrative Officer or his/her
designated representative.
P.
Acceptable
pipe material shall be reinforced concrete pipe, corrugated metal
pipe and corrugated polyethylene pipe. Reinforced concrete pipe shall
conform to the requirements of the Specifications for Reinforced Concrete
Culvert, Storm Drain and Sewer Pipe, ASTM C76. Strength class or classes
shall be as required per design specifications of the latest edition
of the Concrete Pipe Handbook as published by the American Pipe Association.
Corrugated aluminized metal pipe shall conform to the appropriate
requirements of AASHTO or Missouri Department of Transportation. Structural
design requirements shall be per the latest edition of the Handbook
of Steel Drainage and Highway Construction Products as published by
the American Iron and Steel Institute. Use of corrugated metal pipe
greater than forty-eight (48) inches in diameter shall only be allowed
after approval by the Administrative Officer. Corrugated polyethylene
pipe shall conform to the requirements of AASHTOM294 "Standard Specifications
for Corrugated Polyethylene Pipe". All polyethylene pipe should be
installed according to ASTM D 2321 "Standard Practice for Underground
Installation of Thermoplastic Pipe for Sewers and Other Gravity-Flow
Applications".
Q.
All
construction details pertaining to stormwater drainage shall be in
accordance with the City and State requirements, unless otherwise
noted herein.
[Ord. No. 11-2I 86 §§1 — 2, 7-30-2012]
A.
Whenever the stormwater analysis that is presented by the registered
design professional and accepted by the Administrative Officer shows
that detention of the one-hundred (100) year storm provides no significant
benefit, the property owner or developer may apply for a buyout of
the required detention volume. A buyout of the detention facility
construction may not be allowed if the Administrative Officer has
made a finding that there is a significant drainage problem below
the property where the buyout is proposed to occur even though the
detention facility is marginally efficient. The Administrative Officer
may consider in making such determination that the discharge of any
additional waters at an increased rate onto the properties downstream
is not desirable due to the significant drainage problems that exist
on downstream properties.
[Ord. No. 4-38 §4, 10-28-2013]
B.
Buyout
funds shall be used by the City to construct and maintain regional
detention and conveyance systems within the City.
C.
Detention
buyouts are not automatic and must be considered on a case-by-case
basis by submission of the completed Buyout Fund application form,
a copy of which is on file in the City offices. Initial determination
of approval will be made by the Administrative Officer. That decision
may be appealed in writing to the Board of Adjustment for a final
determination.
D.
When
a buyout is approved, it is the responsibility of the developer to
convey the stormwater runoff from the development to the existing
storm sewer system by making whatever modifications are necessary
to the existing system.
E.
When the detention volume is less than five thousand (5,000) cubic feet, the table shown in Chapter 420, Table H, at the end of this Chapter and a copy of which is outlined on the buyout application form, a copy of which is on file in the City offices, shall be used to determine the buyout amount.
[Ord. No. 11-2I 111 §1, 11-23-2015]
|
When the project is too large to use the table shown in Chapter 420, Table H, the buyout volume may be determined by using the formula of fifteen thousand (15,000) cf per acre of impervious area.
|
F.
The
contribution to the Stormwater Management Fund for the detention buyout
is as follows:
1.
A cost estimate shall be prepared by a professional engineer for
site specific improvements necessary to provide detention as provided
herein. All cost estimates for site specific detention facilities
shall be subject to review and approval by the Administrative Officer.
The cost estimate must include the value of the land which otherwise
would have been used as part of the system with the value of the subject
land determined by an independent appraiser paid for by the property
owner or developer.
2.
Alternately, for single- and two-family residential developments,
the contribution shall be one dollar ($1.00) for each cubic foot up
to twenty-four thousand (24,000) cubic feet and fifty cents ($0.50)
for each cubic foot above twenty-four thousand (24,000) cubic feet.
3.
For developments other than single- or two-family residential developments,
the contribution shall be two dollars ($2.00) for each cubic foot
of detention volume up to twenty-four thousand (24,000) cubic feet,
one dollar ($1.00) for each cubic foot between twenty-four thousand
(24,000) cubic feet and one hundred thousand (100,000) cubic feet,
and fifty cents ($0.50) for each cubic foot in excess of one hundred
thousand (100,000) cubic feet.
G.
The
payment in lieu of construction may be revised by the Administrative
Officer to reflect the annual percentage change in construction costs
by using the Construction Price Index, increase or decrease, from
the previous amount.
[Ord. No. 11-2I 86 §§1 — 2, 7-30-2012]
A.
Minimum
finished floor elevations shall be set at or above the maximum water
surface elevation as determined by the following:
1.
"Flood Insurance Rate Map" published by the Federal Emergency Management
Agency.
2.
Backwater curve profiles of the proposed waterway due to a 100-year
storm recurrence interval.
3.
The slab on grade finish floor elevation or the top of foundation
of a building or structure shall be a minimum of twelve (12) inches
above the lowest elevation of the public street gutter (at the lowest
point perpendicular to the structure) plus two percent (2%) times
the distance between the public street curb face (or edge of existing
asphalt street) and the building or structure.
4.
The minimum finish floor elevation for the allowable building area
or footprint identified on a preliminary plat, final record plat,
and boundary adjustment for a lot or subdivision shall be a minimum
of twelve (12) inches above the lowest elevation of the public street
gutter (at the lowest point perpendicular to the structure) plus two
percent (2%) times the distance between the public street curb face
(or edge of existing asphalt street) and the building setback.
[Ord. No. 11-2I 86 §§1 — 2, 7-30-2012]
A.
All stormwater management facilities for residential, commercial, industrial, or institutional subdivisions, multiple lots or multiple land tracts shall be constructed within a public right-of-way or land dedicated to the City of Farmington for stormwater management use and shall be connected to a public road or other approved location from which operation and maintenance is legally available. Minimum rights-of-way and maintenance easements shall be provided by instrument or plat dedication for all waterways used to convey or detain runoff. The minimum widths of rights-of-way and easements shall be in accordance with "Chapter 420, Table I" at the end of this Chapter.
B.
Easements
must include the "top of the bank width" and the maintenance access
width.
C.
The
maintenance access width begins at the top of the bank or slope of
the facility.
D.
Additional
maintenance access width may be required by the Administrative Officer
in special circumstances where more width on one (1) or both sides
is necessary for maintenance purposes.
[Ord. No. 11-2I 86 §§1 — 2, 7-30-2012]
A.
General. The Administrative Officer and other officials
of the City charged with the enforcement of this Chapter are hereby
granted inspection rights and right-of-entry privileges in order to
ensure compliance with the requirements of this Chapter.
B.
Inspections During Construction. The owner or authorized
agent shall employ a registered design professional to inspect all
stormwater improvements during construction. The Administrative Officer
or other City Officials may conduct inspections from time to time
as necessary to ensure compliance with the provisions of this Chapter.
The owner or authorized agent shall coordinate with the City a minimum
of twenty-four (24) hours in advance of beginning work on the public
infrastructure components to facilitate inspection times and shall
provide any field survey as required to verify that the elevations
of improvements are in accordance with the plans.
C.
After Construction. The following procedures shall apply
after construction activity is completed.
1.
Upon completion of any stormwater improvements, the owner or authorized
agent shall also submit a certification letter signed by the registered
design professional of the project to the Administrative Officer which
states that the improvements have been completed in accordance with
the following:
2.
The inspection and completion of construction of public and private
stormwater improvements shall comply with all applicable provisions
of this Title and the Plumbing Code of the City.
3.
After final stabilization of the site is achieved, the owner or authorized
agent shall submit a written request for notice of termination, for
the Administrative Officer to terminate the permit. The notice shall
contain the following information.
4.
Notwithstanding the requirements of this Subsection, the Administrative
Officer shall terminate the permit after determining that final stabilization
has been achieved.
[Ord. No. 11-2I 86 §§1 — 2, 7-30-2012]
A.
General. The owner or authorized agent shall utilize methods,
approaches and techniques in the design and construction of stormwater
management improvements that will allow for the improvements to be
properly maintained.
B.
Responsibility. The responsibility for maintenance of stormwater
management facilities shall be as follows.
1.
The owner or authorized agent shall be responsible for all stormwater
management improvements not officially accepted by the City.
2.
The owner or authorized agent shall be responsible for all stormwater
management improvements on any lot that is not a part of a common
promotional plan.
3.
The owner or authorized agent shall be responsible for the stormwater
management improvements on property that is part of a common promotional
plan until the improvements are either accepted by the City or the
improvements are accepted by a board, association or other permanent
maintenance organization.
C.
Maintenance Arrangements. Any maintenance arrangements shall
conform to the following.
1.
No detention basin shall be considered accepted by the City unless
specifically expressed, written approval and acceptance is made by
the City Council.
2.
The maintenance of stormwater management improvements by a board,
association or other permanent maintenance organization shall be arranged
through appropriate legal means such as agreements, indentures or
covenants. Any such documents shall be submitted to the Administrative
Officer for review and approval.
3.
The owner or authorized agent shall dedicate all necessary easements
to the City for all stormwater management improvements to be accepted
by the City in accordance with the requirements of this Chapter and
the Subdivision Code.
D.
Minimum Standards. Stormwater management improvements shall
be maintained in a clean, safe, sanitary condition complying with
all applicable provisions of this Chapter and the Property Maintenance
Code of the City and shall not cause a public nuisance as defined
by the Municipal Code.
E.
Periodic Inspections. The Administrative Officer may inspect
existing stormwater management improvements from time to time in order
to ensure compliance with the provisions of this Section.
[Ord. No. 11-2I 86 §§1 — 2, 7-30-2012]
A.
Approved Projects. The Administrative Officer or his/her
designated representative shall carry out periodic inspections of
the project site to ensure the applicant's compliance with this Chapter.
If it is determined that the project is not being carried out in accordance
with the approved stormwater management plan, the Administrative Officer
is authorized to:
1.
Written notice. Issue written notice to the applicant
or owner, specifying the nature and location of the alleged non-compliance,
with a description of the remedial actions necessary to bring the
project into compliance within a reasonable specified time.
2.
Stop work order. Issue a stop work order directing
the applicant or owner to cease and desist all or any portion of the
work which violates the provisions of this Chapter, if the remedial
work identified in the "written notice" is not completed within the
specified time.
3.
Revocation of approval. Should the applicant or owner not bring the project into compliance with the written notice and stop work order, he/she shall then be subject to immediate revocation of his/her stormwater management plan approval and to the penalties described in Section 420.200.
4.
Appeals. The Board of Adjustment shall serve as
the means of appeal or variance in accordance with the zoning regulation
of the City.
B.
Unapproved Project. With respect to any development activity
determined by the Administrative Officer or his/her designated representative
to be subject to this Chapter or Title and being carried out without
approval, the Administrative Officer is authorized to:
1.
Written notice. Issue written notice to the owner
specifying the nature and location of the alleged non-compliance,
with a description of the remedial actions necessary to bring the
project into compliance within a reasonable specified time.
2.
Stop work order. Issue a stop work order directing
the owner to cease and desist all or any portion of the work which
violates the provisions of this Chapter, if the remedial work identified
in the "written notice" is not completed within the specified time.
3.
Non-compliance with stop work order. Should the owner not bring the project into compliance with the written notice and stop work order, he/she shall then be subject to the penalties described in Section 420.200.
4.
Appeals. The Board of Adjustment shall serve as
the means of appeal or variance in accordance with the zoning regulation
of the City.
[Ord. No. 11-2I 86 §§1 — 2, 7-30-2012]
A.
General. Violation of the provisions of this Chapter or
failure to comply with any of its requirements, including conditions
and safeguards established in connection with variances or special
use permits, shall constitute an ordinance violation. Any person who
violates this Chapter or fails to comply with any of its requirements
shall upon conviction thereof be fined not more than five hundred
dollars ($500.00) or imprisoned for not more than three (3) months,
or both, and in addition, shall pay all costs and expenses involved
in the case. Each day such violation continues shall be considered
a separate ordinance violation.
B.
Corrective Actions. Nothing herein contained shall prevent
the City from taking such other lawful action as is necessary to prevent
or remedy any violation. All such costs connected therewith shall
accrue to the person responsible.
[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]
A.
Before
starting any work regulated by this Chapter, an applicant shall comply
with the requirements set forth in all other applicable ordinances
including, but not limited to:
1.
The submission and approval of preliminary and final subdivision
plats, boundary adjustments, rezoning, improvement plans, site plans,
and plot plans for construction.
2.
Building, grading, development, and zoning permits, along with those
set forth in this Chapter and as may be required by State Statutes
and the regulations of any department of the State.
B.
A discharge
permit from the State of Missouri shall be obtained individually or
under the applicable general permit for any activity regulated under
the Department of Natural Resources Clean Water Commission (10 CSR
20) Stormwater.
C.
A permit
or other appropriate approval shall be obtained from the Missouri
Department of Transportation to discharge stormwater onto State rights-of-way.
[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.
