[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:
1. 
Roof or foundation drains that discharge within two (2) feet of the building foundation; or
2. 
Discharge into an open natural creek or swale on the same property; or
3. 
Discharge that is parallel to the abutting property line and at least five (5) feet from said line.
[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:
a. 
Temporary erosion control measures.
b. 
Temporary water volume control measures.
c. 
Operation and maintenance guidelines.
[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.