[Res. No. 07-06, Zoning Order Art.
8 § A, 7-12-2007]
A. Under the Federal Clean Water Act of 1972 and additions, storm water
management regulations must be implemented for Cass County, in particular
to demonstrate compliance with the National Pollutant Discharge Elimination
System (NPDES) Phase II section of that law. The County is required
to implement a storm water management program for the management of
the impact and potential for pollution of the waters of the County
and the State resulting from rainfall. The Big Creek, Mount Pleasant,
and Raymore townships are specifically designated as requiring permitting
for any new use which leads to disturbance of the existing soil surfaces
or which may contribute polluting materials to existing drainage systems.
B. The Missouri Clean Water Law and the Missouri Code of State Regulations
also require specific permitting in order to regulate activities that
cause land disturbance. A land disturbance permit requires the development
and implementation of a Storm Water Pollution Prevention Plan (SWPPP)
that includes controls to protect against soil erosion and to limit
waste and pollutants on sites, through inspection, monitoring, reporting
and record keeping.
C. In response to these regulatory requirements, the County has established
regulations limiting impacts to the waters of the County from any
land use which damages, alters or removes natural vegetation such
that soil erosion may occur, or which introduces pollutants as defined
by State and Federal standards to a site without limiting the potential
for such pollutants to extend into the public way and waters. Such
uses, include, but are not limited to:
1.
Land clearance operations or construction activities,
2.
Land uses, such as animal density, which diminish the natural
ground cover to the extent that there is a potential for soil erosion,
without creating new protective covering by utilizing best management
practices, (BMPs),
3.
Uses which introduce polluting substances of a type, or by methods,
or to the extent that they have the potential to leave the property
during storm events and reach public lands or waterways, and for which
BMPs are not utilized to limit this potential.
D. Such land uses shall be considered as violations of this Zoning Order,
a misdemeanor. The administration and enforcement response by the
County shall be as described in the Administration Article of the
Zoning Order.
[Res. No. 07-06, Zoning Order Art.
8 § B, 7-12-2007]
A. Effective techniques to aid in storm water management are referred
to as best management practices (BMPs). BMPs seek to maintain or reduce
the amount of storm water runoff generated within a watershed by maintaining
watershed hydrology and natural ground cover. Treatment is then applied
to the runoff where possible to remove the pollutant load. The County
maintains, under separate order, descriptions of BMPs that are recommended
by the Federal Environmental Protection Agency and the Missouri Department
of Natural Resources. BMPs may include structural facilities, non-structural
solutions or biological controls to achieve the following management
practices:
1.
Preserve and promote natural hydrology of a site by maintaining
or reducing the amount of additional storm runoff created by uses
on the site, and by promoting natural hydrological characteristics
of the site and its surfaces. New uses or alterations to surfaces
for existing uses, or failure to maintain surfaces and ground cover
for optimal run off characteristics for existing uses, shall not have
the affect of increasing the volume of storm water leaving the site
from those levels that existed before the change; nor shall the rate
at which run off leaves the site or the direction and location be
altered; nor shall there be any suspended polluting materials in this
storm water.
2.
Install erosion and sediment controls which, when implemented,
prevent or minimize erosion of the surface soils and control the amount
of sediment or pollutants leaving a site. Such controls may be accomplished
by the following:
a.
Stabilizing exposed soils through temporary or permanent plantings,
seeding, grass sod placement, and mulching, using native plants wherever
practical.
b.
Installing perimeter controls to intercept and detain small
amounts of sediment, such as silt fences, straw bale barriers, check
dams, diversions, grass lined channels and using sediment trapping
devices to intercept sediment in run-off water.
c.
Installing structures for protection at inlets to storm water
conveyance piping and providing outlet stabilization structures and
sediment basins at outflow locations.
3.
Provide and protect buffering zones along sensitive water bodies
from new uses, or alterations to surfaces for existing uses which
restrict the approach to shorelines of wetlands, streams and lakes
within the County, in order to protect these areas from disturbance
or encroachment, and to sustain the integrity of their ecosystems
and habitats. Protective measures shall be in the form of:
a.
Water pollution hazard setbacks which separate a potential pollution
hazard from a waterway.
b.
Vegetated buffers and natural areas that divide active land
uses from encroaching on the buffering zones.
c.
Engineered buffers specifically designed to treat storm water
such as depressions, grass filter areas, and forested strips.
4.
Provide and protect water quality through treatment of runoff
from rainfall by incorporating designed elements which infiltrate
and reduce the amount of runoff and pollutants carried by it, or filter
and detain runoff to reduce discharge velocities and remove pollutants.
Such practices include:
a.
Installing detention systems which store excess runoff before
entry into a principal drainage system. Detention areas must be designed
to be easily maintained, and may take the form of wet ponds, wetlands,
and dry basins.
b.
Installing filtration systems at or near the source of runoff
routes which direct the most contaminated first flush of rainfall
through an engineered natural filter such as grass lined channels,
dry swales, sand filters, or bioretention areas.
c.
Installing infiltration basins or trenches which capture a volume
of storm water runoff, retain it, and infiltrate that volume of water
into the ground.
5.
Utilize low impact or cluster design BMP's to maximize controls
as close to sources of potential run off and pollution transfer as
topography and design conditions permit.
6.
Implement good housekeeping practices such that materials used
in production, retail uses and construction, and site wastes resulting
from a use are properly managed and disposed of to reduce the risk
of pollution from such materials. Surplus or refuse materials or solid
waste must be contained within structures or suitable containers such
that they do not have a potential to enter storm water runoff or bodies
of water.
a.
New commercial and industrial uses shall demonstrate BMPs plans
for trash disposal and recycling, proper material handling and spill
prevention and cleanup in order to demonstrate that there will not
be polluting impact from the new use.
b.
Existing commercial and industrial uses which fail to demonstrate
management of trash disposal and recycling, material handling and
spill prevention and cleanup such that there is a continuing polluting
impact from the existing use shall, upon notification by the Zoning
Department of the condition, put into place management plans acceptable
to the County for the control of the polluting impact of their use
within thirty (30) days of notification. Failure to prevent pollutants
from impacting the waters of the County shall be a violation of the
Zoning Order and a misdemeanor.
[Res. No. 07-06, Zoning Order Art.
8 § C, 7-12-2007]
A. The County has adopted an overall urban watershed protection strategy
which includes stream buffer protections based on three (3) zones
of protection along streams, active and seasonal. The effective stream
buffer width zones are the Streamside, Middle Core and Outer Zones.
Each zone performs a different function and has a different width,
vegetative target and management scheme.
B. Two (2) major goals of a stream buffer network are to maintain an
unbroken corridor of riparian forest and to protect the upstream and
downstream passage of natural wildlife in the stream channel.
C. A stream shall be considered as follows: an active channel subject
to a water flow with a duration of at least three (3) continuous twenty-four
(24) hour periods during any seasonal period.
D. Setbacks are based upon contributing area of the watershed involved
as follows:
|
Contributing Drainage Area
|
Streamside Zone
(in feet)
|
Middle Core Zone
(in feet)
|
Outer
(in feet)
|
---|
|
Watershed less than 40 acres
|
25
|
25
|
25
|
|
40 acres to 160 acres
|
25
|
40
|
25
|
|
160 acres to 5,000 acres
|
25
|
50
|
25
|
|
Greater than 5,000 acres
|
25
|
75
|
25
|
E. The Streamside Zone protects the physical and ecological integrity
of the stream ecosystem. The minimum width is to be measured from
each stream bank, and the stream bank is considered to extend to the
limits of ordinary high water, as determined by the County. Land use
is highly restricted, limited to storm water channels, footpaths,
and minimal utility or roadway crossings.
1.
The vegetative target is mature riparian forest that can provide
shade, leaf litter, woody debris, and erosion protection to the stream.
F. The Middle Core Zone extends from the outward boundary of the Streamside
Zone and varies in width depending on stream characteristics, the
extent of the one percent (1%) (one-hundred-year) floodplain as administered
by the County under the requirements of the National Flood Insurance
Program, any adjacent topography, and adjacent protected wetland areas
within the watershed. The minimum width of the Middle Core may be
expanded based on stream size, slope, or the presence of critical
habitats and final determination will be subject to approval by the
County.
1.
The function of the Middle Zone is to protect key stream components
and provide distance between adjacent land uses and the stream. The
vegetative target for this zone is also mature forest, but some clearing
may be allowed for storm water management, access and recreational
uses when permitted by the County, provided such vegetation does not
require the use of additional fertilizer pollutants. A wider range
of activities and uses are allowed within this zone, such as bike
paths and storm water best management practices (BMPs).
2.
Agrarian uses, such as cultivated cropland or pasturage, on
land in an Agricultural District, are permitted to intrude upon the
Middle Core Zone, so long as they do not contribute to a state of
non-compliance with Federal, State and County regulations.
G. The Outer Zone is an additional setback from the outward edge of
the Middle Core Zone to the nearest permanent above or below ground
structure. Uses which do not require structures are generally permitted
within this zone. Gardening, compost piles and other common residential
activities are promoted within the zone.
1.
The vegetative target for the Outer Zone, as it may well include
adjacent residential yard space, is usually natural vegetation, although
the property owner is encouraged to plant shrubs and trees. The use
of fertilizers which contribute to pollution is prohibited in this
zone.
H. Buffer Crossings, such as roads, bridges, underground utilities,
enclosed storm drains or outfall channels shall define a minimum crossing
width for maintenance access and use a crossing angle of ninety degrees
(90°) where possible to minimize buffer clearing crossing angles,
provided such plan is consistent with the stream character and topography.
1.
All such proposed uses which have an impact within the floodplain
shall follow the regulations of the Flood Plain Order of this Zoning
Order.
2.
Crossing frequency will not exceed one (1) road crossing within
each subdivision, and permit no more than one (1) fairway crossing
for every one thousand (1,000) feet of buffer in the case of golf
courses.
3.
Crossing elevations shall have all direct outfall channels,
where effluent is discharged into receiving waters, discharge as required
by the Flood Plain Order, at the invert elevation, or the lowest point
of the stream channel. In case of a conflict, the Flood Plain Order
requirements shall govern.
I. Storm water management practices utilizing BMPs may be incorporated
into the Outer and Middle Core Zones of the stream buffer where they
include a grass/forest filter strip, under limited circumstances.
1.
The buffer by itself may only effectively treat incoming flow
from adjacent impervious areas to a perpendicular distance of approximately
seventy five (75) feet of the contributing adjacent watershed. The
design of additional methods to supplement the buffer plantings, such
as with constructed filters and detention biofilters, must include
a calculated maximum runoff velocity, for both a six-month and a two-year
storm, from each overland flow path, based on the slope, soil and
vegetative cover. If the calculations indicate that velocities will
be erosive under either condition, greater than three (3) feet per
second (fps) for a six-month storm, five (5) fps for a two-year storm),
the allowable area of contributing flow should be reduced.
2.
When the buffer receives flow directly from an impervious area
of an adjacent use, the BMP must include a calculated maximum runoff
velocity, for both a six-month and a two-year storm, from each overland
flow path, based on the slope, and impervious surfacing and such controls
as required to spread run off evenly over the filter strip, and control
and pollution elimination measures.
3.
In order for the stream buffer to be used as a storm water filtering
system, basic maintenance must be assured, such as routine mowing
of the grass filter and annual removal of accumulated sediments at
the edge of the impervious areas and the grass filter. An enforceable
and long term maintenance agreement that requires the adjacent use
to provide this maintenance is required, as defined in the Subdivision
Regulations. An annual inspection shall be performed by the Zoning
Department to assure the maintenance standards are maintained, and
shall include a fee as established by the County Commission.
J. Location of storm water ponds and wetlands may be permitted by the
County within the stream buffer zones under limited conditions. Constructed
ponds and wetlands which may provide for the dry weather flow of a
stream to maintain water levels and prevent nuisance conditions, and
ponds and wetlands which are designed to create a greater diversity
of habitat types and structure may be included as part of a combined
storm water management plan and a stream buffer protection plan for
new uses and the disturbance of surfaces of existing uses. In addition,
storm water ponds and retention wetlands specifically designed to
remove pollutants utilizing BMPs acceptable to the County, as part
of a proposed new use, may be permitted.
K. Buffer regulation which provides for flexibility, in particular for
existing uses that may be proposing alterations which will affect
the land surfaces that are immediately adjacent to the buffer zones,
may be utilized by the County to mitigate negative impacts to the
existing uses associated with the creation of stream buffer strips.
Design methods may include the following, at the discretion of the
County:
1.
Buffer averaging where the buffer is permitted to become narrower
at some points along the stream, as long as the average width meets
the minimum requirement.
2.
Zoning District regulation variances to create compensation
methods, such as additional density of use on the site in some areas
in order to compensate for land lost to the buffer protections when
a Mixed Use Overlay process is being used. Usable land is considered
to be the buffer area remaining after the one-hundred-year floodplain,
wetland and steep slope areas have been subtracted. When more than
five percent (5%) of usable land is consumed, designs which allow
greater flexibility in setbacks, frontage distances, or minimum lot
sizes may also be considered by the County.
3.
Cluster design in a Mixed Use Overlay process may allow for
the recovery of usable land that is taken out of production due to
buffers or storm water management plans. Designs to place uses in
more compact groupings as a means to open up more of the site for
buffer and other uses may be considered by the County.
4.
Low impact design BMPs utilizing pervious paving, disbursed
filters and retention areas.
5.
Conservation easements may be permitted, allowing the landowner
the option of protecting lands within the buffer with a perpetual
conservation easement.
6.
Variances may be permitted by means of the process described
in the Zoning Order in situations where an existing property owner
can demonstrate severe economic hardship or unique circumstances which
make it impossible to meet some or all buffer requirements when making
alterations in the existing use which may impact the buffer zones.