[Ord. No. 3510 §1, 5-10-2010; Ord. No. 4034 §1, 11-14-2016]
A.
This Article seeks to provide those standards, criteria, procedures
and controls necessary to minimize the harmful physical and economic
effects of erosion and flooding from stormwater within the City. This
is to be accomplished through the requirement of special measures
to mitigate erosion both during and after construction or grading
and the detention and controlled discharge of the differential runoff
from any site whereon any grading, excavation, filling or other disturbance
of the natural vegetation or any construction, erection or alteration
of a building or structure is to be undertaken.
1.
Generally. Except as provided below, these
stormwater and erosion control regulations shall be complied with
whenever any person constructs, erects, alters or enlarges any building
or structure or otherwise develops any property within the City in
such manner as to change the land area covered by the building or
structure and whenever any person clears, grades, excavates, fills
or otherwise changes the contour of any land in the City.
2.
Exceptions. The provisions of this Article
shall not apply to:
a.
Any reconstruction, repair or alteration of any existing building
or structure when no land, trees, shrubs, grass or other vegetation
is to be disturbed, destroyed or removed;
b.
The clearing, grading, excavation, filling, removing topsoil
from or changing the contour of less than two thousand five hundred
(2,500) square feet of land.
c.
Any project which disturbs more than one acre of land and is
therefore required to obtain a land disturbance permit through the
Missouri Department of Natural Resources and the Metropolitan St.
Louis Sewer District shall be exempt from Section 415.105(C) but rather
will be required to meet the requirements of the other regulating
agencies.
d.
In considering the applicability of these exceptions, the effective
acreage for a project, development or subdivision is not limited to
a fractional part of the total concept. Rather, if a project is developed
in phases or small plats, the total acreage of the project, development
or subdivision shall be considered. Furthermore, projects of less
acreage than provided for in this Article shall also provide detention
if, in the judgment of the Director, conditions in the receiving system
are inadequate or harmful effects can be anticipated if detention
is not implemented.
[Ord. No. 3510 §1, 5-10-2010]
A.
Plans
and documents clearly demonstrating that all permits for stormwater
discharges required by the State including, but not limited to, those
set forth in 10 CSR 20-6.200, have been secured and that the proposed
construction and/or development meets all standards and criteria for
stormwater and erosion control as described in this Article shall
be submitted as a part of any application for a site improvement permit
or an application for a building permit.
B.
All
plans and specifications submitted for review and/or approval shall
be prepared by or under the direct supervision of a registered professional
engineer licensed in the State of Missouri and shall meet the minimum
standards and requirements of the City, the Metropolitan St. Louis
Sewer District and other applicable authorities. Each of the plan,
profile and special drawing sheets for a project shall bear a legible
seal of the professional engineer in charge.
All plans shall include a letter of transmittal stating the
name of project, name and address of owner or developer, name, address
and telephone number of engineer and the purpose of submittal.
C.
No
permit for any construction, improvement or development within the
City shall be issued until the Director has verified that the proposed
construction, improvement or development fully complies with these
stormwater and erosion control regulations.
[Ord. No. 3510 §1, 5-10-2010]
A.
Facilities for storm drainage shall be designed and constructed so as to prevent any increase in the rate of storm runoff into the water shed over that which existed prior to development with some portions mitigated as delineated in Section 415.105 of this Code. It is not the intent of these provisions to eliminate specific erosion or flooding which existed prior to development but rather to prevent any increase or expansion of said situations by the construction improvement or development.
[Ord. No. 4034 §2, 11-14-2016]
B.
All
stormwater improvements shall be designed, constructed and installed
in conformance with Metropolitan St. Louis Sewer District (MSD) regulations.
C.
Every
land development or subdivision shall make adequate provisions to
accommodate or dispose of stormwater and prevent damage to off-site
streets and downslope of adjacent properties due to soil erosion or
siltation by means of sodding, erecting silt barriers, detention storage
areas, sewers, catch basins, culverts, terracing, walls and other
facilities or combination of similar methods per the requirements
of this Article. Such facilities are to be maintained by the owners
of the subject property or owners of the subdivision through agreement
by the appropriate trust indenture or deed restriction or by the appropriate
public agency or utility.
D.
All
detention basins shall be located in stormwater control easements
with access easements provided where required. In multi-lot subdivisions,
detention basins shall be located in common ground.
E.
Stormwater
pipes, outlets and channels shall be protected by silt barriers and
kept free of waste and silt at all times prior to final surface stabilization
and street paving.
F.
Slopes
steeper than five (5) feet horizontal to one (1) foot vertical (5:1)
shall be protected by sodding or paving upon completion of grading
or construction.
G.
Any construction, improvement or development shall make adequate provisions to minimize and control both long- and short-term erosion utilizing temporary control measures and long-term erosion control measures as described in Section 415.090. Such measures shall be planned or in place prior to clearing or grading operations.
H.
The
storm system for a proposed subdivision or land development shall
be designed to accommodate potential runoff from its entire upstream
drainage area, whether inside or outside the subdivision or land development.
The Director shall review the proposed system to assure it is sufficient
to accommodate existing upstream stormwater and any anticipated increase
in upstream volume resulting from development permitted by the Zoning
Code and adjacent jurisdictions and the estimated development potential
of the watershed.
I.
The
Director shall study the effect of each subdivision or land development
on the existing downstream drainage facilities both inside and outside
the area of development. Where it is anticipated that the additional
runoff incident to the development of the subdivision will overload
an existing downstream facility, the Planning and Zoning Commission
may withhold approval of the improvement plans and final subdivision
plat or site development plans until sufficient provisions have been
made to eliminate such overload. No subdivision or land development
shall be approved unless adequate drainage will be provided to an
adequate drainage watercourse or catchment and storage facility. Complete
hydrologic computations including, but not limited to, outlet velocities
shall be submitted with subdivision improvement plans or site development
plans, where requested, to support the storm sewer design.
J.
Water
shall not be directed through a pipe, culvert, hose, spout or drain
which discharges within ten (10) feet of an abutting property line.
The following are exceptions to this prohibition:
[Ord. No. 4034 §3, 11-14-2016]
A.
Prior to the issuance of any permit which controls the application
of new structures, site improvements or other systems which impact
stormwater flow patterns or rates, the applicant must provide the
following:
1.
Site plan sealed by a professional engineer (multiple sheets as necessary) developed in accordance with Section 405.260(A)(1)(a) through (i) of the Town and Country Municipal Code.
2.
Calculation of stormwater flow rate differential from the preexisting
site conditions to the proposed post-construction condition. This
shall be for the fifteen-year, twenty-minute design storm calculated
by the Rational Method using PI factors in accordance with the most
recent "Storm Water Design Criteria" of the "Design Requirements for
Storm Drainage Facilities" as issued by the Metropolitan St. Louis
Sewer District.
3.
Provision of a system which mitigates one hundred fifty percent (150%) of the flow rate increase identified in Section 415.105(A)(2) above by storing a volume equal to one hundred fifty percent (150%) of the calculated volume for the fifteen-year, twenty-minute design storm. This shall then be designed with a release mechanism which allows for dissipation over a twelve-hour-to-thirty-six-hour period using small orifice structures or Metropolitan St. Louis Sewer District-approved volume reduction best management practices.
4.
An operation and maintenance manual for the system referenced in Section 415.105(A)(3) shall be provided at the time of the site plan submittal. This manual and the site plan shall clearly note that the maintenance of the system is the responsibility of the property owner and not the City of Town and Country or the Metropolitan St. Louis Sewer District.
5.
Provision of a stormwater pollution prevention plan (SWPPP)
sealed by the engineer of record addressing the temporary site conditions
from the commencement of the project until issuance of permanent occupancy:
[Ord. No. 3510 §1, 5-10-2010]
A.
Generally. Every land development or subdivision shall make
adequate provisions to minimize and control both long- and short-term
erosion in accordance with the requirements of this Article.
B.
Temporary Control Measures.
1.
Temporary erosion and sediment control measures are intended to maintain
siltation on the land development or subdivision especially if construction
is not going to be complete within a single construction season.
2.
Grading shall be phased so that the amount of exposed area at any
one (1) time is minimized. Each application for a site improvement
permit or building permit shall include a grading plan of the site
in sufficient detail to indicate proposed grading phases.
3.
Graded areas shall be stabilized immediately upon grading and maintained
to prevent or minimize erosion until permanent stabilization measures
are in place. Permissible temporary erosion control techniques include
contour furrowing or other surface roughening techniques, fertilizing,
seeding, mulching and/or sodding. On steep slopes (twenty-five percent
(25%) or greater) the application of asphalt emulsion is a desirable
technique.
4.
Slope changes should be designed to keep the slope length and gradient
to a minimum, thus minimizing stormwater velocities over graded areas.
5.
Measures shall be taken to direct stormwater from graded portions
of the site. This may be accomplished utilizing diversion berms, ditches
and/or sediment basins.
6.
Sediment shall be retained on site by filtering runoff and/or by
providing properly designed siltation basins.
7.
Truck and equipment accessways to the site of the operation shall
be located so as to minimize danger to traffic and nuisance to surrounding
properties. Such access shall be kept either wet or oiled or treated
with a chemical dust deterrent or placed to the extent necessary to
prevent any dust nuisance to surrounding properties. All such accessways
shall be posted approximately two hundred (200) feet distant from
such accessways or other traveled areas. Such signs shall read "Caution:
Trucks Entering" and be of an appropriate size, type, coloring, lettering
and format per the Manual on Uniform Traffic Control Devices for Streets
and Highways (MUTCD). Debris, soil and other materials shall be removed
from trucks before they leave the site. Streets and sidewalks shall
be maintained free of soil and debris.
C.
Long-Term Erosion Control. All subdivision and land development
plans shall incorporate into the improvement or site improvement permit
plans measures designed to minimize grading and control erosion. Approval
of any subdivision plat shall be conditional upon verification by
the Director that the plans conform to the following standards:
1.
All excavations, grading or filling shall have a finished grade not
to exceed thirty-three percent (33%) except that embankments less
than three (3) feet in height shall be exempt therefrom if properly
sodded. Steeper grades are allowed if the excavation is through rock
or the excavation or fill is protected by a properly designed revetment
or retaining wall approved by the Director. Such walls shall not normally
exceed a height of six (6) feet.
2.
Grading plans shall provide for sediment basins, silt barriers, diversions,
grass waterways, mulching, seeding and other acceptable erosion control
techniques whenever necessary to avoid damage to adjoining properties,
road ditches and storm sewers.
3.
The finished grade shall provide that surface water from drainage
areas in excess of two (2) acres shall be intercepted by diversion
swales or inlets and lowered to a stable outlet constructed of concrete,
riprap or pipe.
4.
Land adjoining the proposed land development or subdivision shall
be provided with protection from accelerated and increased surface
water, silt disposition and any other consequences of erosion. Where
it is necessary for the protection of such property to enter upon
property outside the control of the applicant for such purpose, appropriate
consent must be obtained by the applicant. The applicant shall, at
his/her own expense, shore up and protect all buildings, walls, fences
or other property likely to be damaged during the progress of the
grading and shall be responsible for all damage to public or private
property resulting from his/her failure to properly protect and carry
out such grading.
5.
Lots shall be laid out so as to provide positive drainage away from
all buildings. Individual lot drainage shall be coordinated with the
general storm drainage pattern for the area. Drainage shall be designed
so as to substantially prevent stormwater drainage from each lot onto
adjacent lots.
6.
Landscaping shall be provided in the form of seeded or sodded grass,
ground cover, low walls, earth berms, trees and shrubbery to enhance
the appearance and the functions of all erosion control facilities.
[Ord. No. 3510 §1, 5-10-2010]
A.
Detention
facilities, when mandatory, are to be built in conjunction with the
storm sewer installation and/or grading. Since these facilities are
intended to control increased runoff, they must be partially or fully
operational soon after the clearing of the vegetation.
B.
Silt
and debris connected both with early construction and with general
erosion from the site and elsewhere in the watershed after construction
shall be removed periodically from the detention area and control
structure in order to maintain close to full storage capacity.
C.
The
responsibility of maintenance of the detention facilities in subdivision
projects shall remain with the developer until such time as applicable
escrows are released. Upon release of escrows the maintenance responsibility
shall be vested in the trustees of the subdivision by virtue of the
trust indenture. The indenture of the trust shall clearly indicate
resident responsibility for maintenance in cases of projects without
common areas.
D.
The
responsibility of maintenance of the detention facilities in single
owner development projects shall remain with the general contractor
until final inspection of the development is performed and approved
and a legal occupancy permit is issued. After legal occupancy of the
project, the maintenance of detention facilities shall be vested with
the owner of the project.
[Ord. No. 3510 §1, 5-10-2010]
Compliance with stormwater and erosion control regulations shall
be subject to all provisions of the Municipal Code relating to enforcement,
violations and penalties. In addition, a corporate surety bond conditioned
upon carrying out all and every part of approved plans for at least
the sum estimated to be the full costs of carrying out such plans
or a cash escrow upon the same conditions and in the same amount shall
be furnished the City whenever such costs exceed five hundred dollars
($500.00). The bond or escrow shall be released upon proper completion
of all of the requirements of such approved plans.
