[Ord. No. 1250, 10-15-2002]
A.
The goal of the regulation is to effectively minimize erosion and
discharge of sediment by application of relatively simple and cost
effective Best Management Practices. This goal can be attained by
meeting the following objectives:
1.
Minimize the area disturbed by construction at any given time.
2.
Stabilize disturbed areas as soon as possible by re-establishing
sod, other forms of landscaping, and completing proposed structures,
pavements and storm drainage systems.
3.
Provide for containment of sediment until areas are stabilized.
4.
Provide permanent erosion controls.
[Ord. No. 1250, 10-15-2002]
A.
The following items must be considered in preparing a sediment and
erosion control plan:
1.
Temporary vs. Permanent Controls. The greatest potential for
soil erosion occurs during construction. Temporary controls are those
that are provided for the purpose of controlling erosion and containing
sediment until construction is complete. Temporary controls include
straw or hay bale dikes, silt fences, erosion control blankets, etc.,
which are not needed after the area is stabilized. Permanent controls
consist of riprap, concrete trickle channels, detention basins, etc.,
which will remain in place through the life of the development. It
is possible for the same facility to serve both a temporary and permanent
purpose. The difference between temporary and permanent erosion control
should be clearly recognized in preparing a sediment and erosion control
plan.
2.
Sheet Flow vs. Concentrated Flow. In areas where runoff occurs
primarily as sheet flow, containment of sediment is relatively simple.
In these areas straw or hay bales, silt fences and vegetative filter
areas can be very effective. Where concentrations of flow occur, containment
of sediment becomes more difficult as the rate and volume of flow
increase. In these areas, more sophisticated controls such as sedimentation
basins must be provided.
3.
Slope. Control of erosion becomes progressively more difficult
as the slope of the ground increases. Areas with steeply sloping topography,
and cut and fill slopes must be given special consideration.
4.
Soils And Geologic Setting. Area soils and the geologic setting
must be considered in preparing the plan and any special considerations
deemed necessary for a particular site provided.
5.
Environmentally Sensitive Areas. Where construction occurs within
the vicinity of permanent streams, springs, sinkholes, lakes, or wetlands,
special attention must be given to preventing discharge of sediment.
[Ord. No. 1250, 10-15-2002]
A.
Permit Requirements. Grading permits are required for all construction
sites with the following exceptions:
1.
Grading for single-family or duplex residences constructed in
subdivisions where approved sediment and erosion controls have been
constructed.
2.
Construction sites that have received an individual storm water
discharge permit or water quality certification from the Missouri
Department of Natural Resources in accordance with the Clean Water
Act.
3.
Emergency construction required to repair or replace roads,
utilities, or other items affecting the general safety and well being
of the public. For emergency construction sites which would otherwise
be required to obtain a permit, and for which remedial construction
will take more than fourteen (14) calendar days, application for the
permit must be made within three (3) calendar days from the start
of construction.
4.
The following activities, provided that they are not located
within twenty-five (25) feet of a spring, sinkhole, wetland, or watercourse:
a.
Gardening or landscaping normally associated with single-family
residences which cover less than one-half (1/2) acre.
b.
Grading and repair of existing roads or driveways.
c.
Cleaning and routine maintenance of roadside ditches or utilities.
d.
Utility construction where the actual trench width is two (2)
feet or less.
5.
Sites that were graded prior to the effective date of this regulation,
provided that they do not provide an imminent threat to the general
health, safety, and welfare of the public in the opinion of the City.
B.
Permit Procedure. The following items must be received by the City
prior to issuance of a Grading Permit.
1.
Grading, sediment and erosion control plans shall be submitted
to the City along with the plans for the proposed improvements, in
conformance with the requirements of the City of Branson West Regulations.
2.
The City will issue Grading Permits after approval of the plans
for the improvements, in conformity with the requirements of the City
of Branson West Subdivision Regulations.
C.
Plan Requirements. Plans must be prepared by and bear the seal of
an engineer registered to practice in the state of Missouri. Plans
will not be required in the following cases:
1.
Grading associated solely with a single-family residence and
which is not exempt from the permit requirement.
2.
Grading or filling of less than one (1) acre if located outside
of allowable building areas and not located within twenty-five (25)
feet of a spring, sinkhole, wetland, or watercourse. In these instances
a Grading Permit can be issued provided that an inspection of the
site by a representative of the City does not reveal any conditions
that would warrant preparation of a detailed plan in the opinion of
the City Engineer.
[Ord. No. 1250, 10-15-2002]
A.
NPDES Storm Water Permit. Construction sites where the area to be
disturbed is five (5) acres or more must apply for a storm water discharge
permit from the Missouri Department of Natural Resources.
B.
"404" And "401" Permit. Pursuant to the Clean Water Act, grading
activities in streams or wetlands may require an Army Corps of Engineers
404 permit and/or a Missouri Department of Natural Resources 401 certification.
[Ord. No. 1250, 10-15-2002]
A.
Grading.
1.
Maximum Grades. Cut or fill slopes shall not exceed 3:1. 4:1
slopes are preferred where possible.
2.
Maximum Height. Cut or fill slopes shall not exceed fifteen
(15) feet in vertical height unless a horizontal bench area at least
five (5) feet in width is provided for each fifteen (15) feet in vertical
height.
3.
Minimum Slope. Slope in grassed areas shall not be less than
one percent (1%).
4.
Construction Specifications. Construction specifications stating
requirements for stripping, materials, sub-grade compaction, placement
of fills, moisture and density control, preparation and maintenance
of sub-grade must be included or referenced on the plans or accompanying
specifications submitted. Construction activities must also comply
with the City's standard construction specifications, and the plans
referenced accordingly.
5.
Spoil Areas.
a.
Broken concrete, asphalt and other spoil materials may not be
buried in fills within proposed building or pavement areas.
b.
Outside of proposed building and pavement areas, broken concrete
or stone may be buried in fills, provided it is covered by a minimum
of two (2) feet of earth.
c.
Burying of other materials in fills that are not suitable for
the specific construction activity is prohibited.
B.
Sediment Containment.
1.
Existing Vegetative Filter Area. These areas may be used where:
a.
Unconcentrated sheet flow occurs.
b.
An area of existing vegetation a minimum of twenty-five (25)
feet in width can be maintained between the area to be graded and
a property line, watercourse, sinkhole, spring, wetland or classified
lake.
c.
Existing ground slope is no greater than 5:1 (twenty-percent
(20%)).
d.
The existing vegetative growth is of sufficient density and
in sufficiently good condition to provide for filtration of sediment.
2.
Hay/Straw Bale Dike, Or Silt Fence. As a temporary measure,
containment areas constructed of hay or straw bales, or silt fence
may be provided in areas where:
a.
Unconcentrated sheet flow occurs.
b.
An area of existing vegetation a minimum of twenty-five (25)
feet in width can be maintained between the area to be graded and
a property line, watercourse, sinkhole, spring, wetland or classified
lake.
c.
Existing ground slope is no greater than 5:1 (twenty percent
(20%)).
d.
Concentrated flow from an area no greater than one (1) acre
occurs and a minimum volume of one thousand (1,000) cubic feet per
acre is contained behind the dike.
3.
Temporary Containment Berms.
a.
Temporary containment berms may be provided where concentrated
flow from areas greater than one (1) acre and less than five (5) acres
occurs. Temporary containment berms must contain a volume of one thousand
(1,000) cubic feet per acre of drainage area.
b.
Temporary containment berms shall have a riprap outlet with
a sediment filter, or a perforated pipe outlet.
c.
Temporary containment berms and accumulated sediment may be
completely removed after the tributary area is stabilized, and must
be removed prior to final acceptance.
4.
Sedimentation Basin. Sedimentation basins shall be provided
for all areas where concentrated flow occurs from an area of five
(5) or more acres. Sediment basins shall be designed to detain the
runoff from one (1) inch of rainfall, for a period of at least twenty-four
(24) hours using the methods contained in Part 6 of this Article.
The basins shall be provided with an outflow structure consisting
of:
a.
A flow restriction device which provides for the required detention
time.
b.
An outfall pipe sized to carry the maximum estimated outflow
rate.
c.
Protective structures at the pipe outlet to prevent crushing
or damage of the end of the pipe, and to prevent blockage of the pipe
with debris.
d.
An overflow spillway capable of discharging the peak flow rate
for the four percent (4%) annual probability (25-year) storm while
maintaining a minimum freeboard of one (1) foot.
e.
Erosion protection at the pipe and spillway outlet.
C.
Erosion Protection.
1.
Seeding And Mulching.
a.
Seeding, fertilizer and mulching requirements shall comply with
the City's standard construction specifications Section 02936.
b.
Whenever grading operations are suspended for more than thirty
(30) calendar days between permanent or seeding periods, all disturbed
areas must be reseeded with temporary cover.
c.
Maintain seeded areas for one (1) year following permanent seeding.
2.
Cut And Fill Slopes.
a.
Cut and fill slopes shall be protected from erosion by construction
of straw or hay bale dikes, silt fences, diversion berms, or swales
along the top of the slope. Diversions shall be maintained until permanent
growth is firmly established on the slopes.
b.
Where drainage must be carried down the slopes, pipe drains,
concrete flumes, riprap chutes, or other impervious areas must be
provided. Suitable erosion control measures such as riprap stilling
basins, must be provided at the bottom of the slope.
3.
Channels And Swales. Permanent channels and swales shall be
provided with a stabilized invert consisting of one (1) of the following
materials:
a.
Sod.
(1)
Where the average velocity of flow is five (5)
feet per second or less and there is no base flow, the channel shall
be lined with sod.
(2)
For channels with a bottom width less than fifteen
(15) feet, sod shall extend up the side slope to a minimum height
of six (6) inches above the toe.
(3)
Channels with a bottom width of fifteen (15) feet
or greater, shall be lined with sod in the low flow area.
(4)
The remainder of the channel slopes shall be seeded
and mulched as previously specified.
b.
Erosion Control Blanket. Commercial erosion control blankets
may be used in lieu of sod provided that samples are submitted and
approved by the City. The guaranteed maintenance period shall be one
(1) year.
c.
Non-Erosive Lining.
(1)
In grass channels where base flow occurs, a non-erosive
low-flow channel of riprap must be provided. Low flow channels shall
have a minimum capacity of five (5) cubic feet per second. Other suitable
non-erosive materials may be approved by the City.
(2)
For channels which have an average velocity of
five (5) feet per second or greater a non-erosive lining of riprap
concrete or other approved material must be provided.
4.
Storm Sewer And Culvert Outlets.
a.
Erosion protection shall be provided at storm sewer and culvert
outlets. Minimum erosion protection shall consist of a concrete toe
wall and non-erosive lining.
b.
Flared end sections and headwalls are not required, but may
be provided at the discretion of the designer to meet grading or aesthetic
requirements. Where headwalls or flared end sections are specified,
toewalls must be provided at the downstream end. The required length
of non-erosive lining will not be decreased where flared end sections
or headwalls are provided unless calculations and data to support
the decrease in length are submitted and approved.
c.
Non-erosive lining shall consist of riprap, unless otherwise
specified and approved. Field stone, gabions, or riprap shall extend
to the point at which average channel velocity for the peak flow rate
from the minor (five-year) storm has decreased to five (5) feet per
second maximum.
5.
Curb Openings. Where drainage flows from paved areas to grass
areas through curb openings, erosion protection shall be provided.
6.
Ditch Checks And Drop Structures. In grass channels, grades
and velocities may be controlled by use of ditch checks and drop structures.
Riprap ditch checks may be required in natural channels where average
velocity for the peak flow rate from the 5-year storm exceeds five
(5) feet per second for post-development conditions.
7.
Spillways. Erosion protection must be provided at spillways
and outlet structures for detention ponds. Protection shall extend
to the point where flow has stabilized and average velocity in the
outlet channel is five (5) feet per second or less.
D.
Temporary Construction Entrance.
1.
A minimum of one (1) temporary construction entrance is required
at each site. Additional temporary entrances may be provided if approved.
The location of each construction entrance shall be shown on the plan.
2.
Only construction entrances designated on the sediment and erosion
control plan may be used. Barricades shall be maintained if necessary
to prevent access at other points until construction is complete.
3.
Construction entrances shall be constructed of crushed limestone
meeting the following specifications:
a.
Construction entrances shall be a minimum of twenty-five (25)
feet wide and fifty (50) feet long.
b.
Minimum thickness of crushed limestone surface shall be six
(6) inches. Additional two-inch lifts of crushed limestone shall be
added at the discretion of the City if the surface of the initial
drive deteriorates or becomes too muddy to be effective.
c.
In locations where an existing drive or street extends at least
fifty (50) feet into the site, the existing drive may be designated
as the construction entrance, and construction of a new gravel entrance
is not required unless job conditions warrant.
E.
Cleaning Streets. Streets both interior and adjacent to the site
shall be completely cleaned of sediment at the end of construction.
F.
Damage To Streets. Any damage conducted to streets as a result of
development shall be repaired by the developer to the satisfaction
of the City.
G.
Dust Control. The contractor will be required to use water trucks
to water haul roads and construction areas to minimize dust leaving
the site when conditions warrant.
H.
Sequencing And Scheduling. Costs of sediment and erosion control
can be minimized if proper consideration is given to sequencing and
scheduling construction. Any special sequencing and scheduling considerations
should be noted in the grading plan.
