Erosion Control and Stormwater Retention Ordinance
- ORDINANCE REGULATING LAND DISTURBANCE AND EROSION CONTROL IN THE CITY OF MCCOMB CITY, MISSISSIPPI
- ARTICLE IX.: LAND DISTURBANCE AND EROSION CONTROL
- Sec. 7-141. Code Adopted:
- Sec. 7-142. Definitions
- Sec. 7-143. Site Grading Permit.
- Sec. 7-144. Properties exempt from this Ordinance.
- Sec. 7-145. Land Disturbance Plan.
- Sec. 7-146. Construction access routes.
- Sec. 7-147. Cut and fill slopes.
- Sec. 7-148. Stabilization of denuded areas and soil stockpiles.
- Sec. 7-149. Establishment of permanent vegetation.
- Sec. 7-150. Protection of adjacent properties.
- Sec- 7-151. Disturbance In streams and floodways.
- Sec. 7-152. Existing areas with soil erosion problems.
- Sec. 7-153. Performance bonds.
- Sec. 7-154. Appeals.
- Sec. 7-155. Inspections.
- Sec. 7-156. City Correction/Collection Procedures.
- ARTICLE X. STORM WATER DETENTION
- Sec. 7-166. Code adopted.
- Sec. 7-167. General criteria and standards.
- Sec. 7-168. Improvement regulation.
ORDINANCE REGULATING LAND DISTURBANCE AND EROSION CONTROL IN THE CITY OF MCCOMB CITY, MISSISSIPPI
WHEREAS, the Board of Mayor and Selectmen of the City of McComb City, Mississippi wishes to establish rules and regulations for land disturbance and other forms of site excavation which can contribute to the degradation of land surfaces, water quality in streams and lakes and air quality, and
WHEREAS, the Board of Mayor and Selectmen of the City of McComb City, Mississippi, are desirous to protect the health and safety of residents and to protect adjoining or nearby property Including land, streams, hills and vegetation through the oversight of land disturbance activities in the City; and
NOW, THEREFORE, BE IT ORDAINED by the Board of Mayor and Selectmen of the City of McComb City, Mississippi, as follows, to-wit:
SECTION I; That Chapter 7, Building, Construction and Related Activities of he Code of Ordinances of said City, and all amendments thereto, is hereby amend so as to adopt Article ix. Land Disturbance and Erosion Control, Sections 7-141 through 7-156 to provide as follows:
ARTICLE IX. LAND DISTURBANCE AND EROSION CONTROL
Sec. 7-141. Code adopted:
Purpose of this article is to establish rules and regulations for land disturbance and other forms of site excavation which can contribute to the degradation of land surfaces, water quality in streams and lakes and air quality Degradation can be the result of erosion, siltation, earth slides, mud flows, dusty condition, clogged storm sewers, increased water runoff and localized flooding. The resultant damages increase road, storm sewer and other infrastructure maintenance costs, it is the intent of this ordinance to protect the health and safety of residents and to protect adjoining or nearby property in the City including land streams, hills and vegetation through the oversight of land disturbance activities.
Except as otherwise provided for, the following regulations shall apply in all zoning districts of the City of McComb City, Mississippi.
Sec. 7-142. Definitions:
As used in this article the following terms shall have the respective meanings ascribed to them:
Cut: Portion of land surface or area from which earth has been or will be removed by excavation; also, the depth below original ground surface to excavate surface.
Erosion: Any removal or loss of soil by the action of wind and water, includes both the detachment and transportation of soil particles.
Erosion Control Measures: The State's "Planning and Design Manual for Control of Erosion, Sediment and Stormwater" shall be used as a guidance in selecting and developing a plan. One or more of he following measures, or other methods of slowing or stopping the removal of soil by wind, water, slowing or gravity used singularly or in combination as appropriate:
- Diversion: A channel or channel with supporting ridge (berm, dike or wall constructed across a sloping land surface along the contour, or with predetermined grades, to intercept and divert surface runoff before it gains sufficient volume or velocity to create harmful erosion.
- Drains: Surface or subsurface conduits or filter drains to reduce surface runoff or lower a high
- Grade Stabilization Structures: Drop structures made of concrete, corrugated metal pipe or other suitable materials which dissipate the energy of flowing water by dropping it in a relatively short horizontal distance.
- Grassed Waterways: A natural or constructed waterway, usually broad and shallow, covered with erosion resistant grasses used to carry surface
- Land Grading: Re-shaping the ground surface by grading to planned slopes and configurations that will prevent excessive erosion.
- Mulching: The application of plant or other suitable materials on the soil surface to conserve moisture, reduce erosion and aid In establishing
- Sediment Barriers: A temporary barrier installed to intercept sediment laden runoff and to trap and retain sediment.
Excavation: The ace or removing dirt or soil (see Cut).
Fill: Portion of land surface or area to which soil, rock or other approved materials have been or will be added; height above original ground surface after the material has been or will be added.
Grade: The slop or elevation of ground surface prior to and after cutting and filling.
Grading: Any operation or occurrence by which the existing site elevations are changed by cutting, filling borrowing or stockpiling, or where any ground cover, natural or man-made, is removed, or any buildings or other structures are removed or any water course or body of water either natural or man-made is relocated on any site, thereby creating unprotected area. Grading shall be synonymous with land disturbance activity
Grading permit: The permit required before any land disturbing activities may take place as prescribed by this ordinance.
Land Disturbance Plan: The plan required before a grading permit may be issued. It consists of a narrative description and appropriate drawings and maps that spell out the methods techniques and procedures to be followed on a site to control erosion and other potential degradation of adjoining or nearby property, during and after development, including final stabilization of the site. Sediment basins may need to be cleaned out before the developer/contractor is released from the permit requirements.
Owner: The person(s) or entity holding the registered title to property. The city property tax rolls shall be prima facia evidence that the person (s) or entity lists therein are the registered owner.
Permit Holder; The owner of the property or owner's representative in whose name a permit has been applied for and issued by the city.
Sediment; Rocks, sand, gravel, silt or other material deposited by action of wind, water or gravity.
Sedimentation; The settling out of the soil particles which are transported by wind, water or gravity.
Stripping; Any activity which removed or significantly disturbs the vegetative cover including clearing and grubbing operations.
Sec. 7-143. Site Grading Permit.
Permit Required: Except as otherwise exempted In the following section, no Individual, property owner or other legal entity shall engage In any land-disturbing activity which will modify the existing grade and/or may result in Increased soil erosion or sedimentation including, but not limited to, cleaning, stripping, grading, excavation, transporting and filling unless a Site Grading Permit has first been obtained from the Director of Inspections and Zoning or his designee and shall submit a proposed Land Disturbance Plan with the application. The property owner shall be responsible for compliance with all provisions of this Ordinance.
MS DEQ Oversight: In instances where a proposed land disturbance activity will exceed five (5) acres or will occur on any tract as part of an overall commercial or service/institutional site development; plan, or will occur as a part of an environmental restoration project under the supervision of the United States Environmental Protection Agency of the Mississippi Department of Environmental Quality Department of Environment and Conservation or its successors, no site grading permit shall be Issued by the Director of Inspections and Zoning or his designee until the land disturbance plan is reviewed and approved by the Mississippi State Department of Environmental Quality and the City Public Works Director or his designee.
Fees. In order to defray costs associated with the processing of permits, and for Inspections of land disturbance activities, a non-refundable base fee of no less than fifty dollars ($50.00) plus no less than twenty-five dollars ($25.00) for each acre proposed to be disturbed shall be required with the application for a grading permit. This fee shall be periodically adjusted by the City taking into consideration Increased costs Incurred with administration of this program. Notice of any proposed revision to the fee schedule shall be published In accordance with applicable laws.
Sec. 7-144. Properties exempt from this Ordinance.
The following uses and activities shall be exempt from the requirements for a site grading permit:
- Single Family Residence.: The construction of a single family residence or addition to an existing single family residence, provided however, such construction shall be required to comply with the erosion control requirements as outline in Section 7-145., paragraph (c).
- Public Utilities/Roadways. The installation maintenance and repair of any public utility as well as roadway and storm drainage construction and maintenance by governmental agencies and/or their agents, provided however, that such land disturbing activity shall comply fully with the rules and regulations as set forth by the Mississippi Department of Environmental Quality.
- Agricultural Uses. Farming or other accepted agricultural uses as permitted by the zoning ordinance providing no sediment will leave the site and the integrity of the vegetative cover will be maintained.
- Lawns/Gardens/Landscaping. Home gardens, home landscaping or lawn preparations on existing lots or parcels shall be exempted from the provisions stated herein unless the possibility for erosion or alternation of drainage patterns or structures is such to necessitate a grading permit.
Sec. 7-145. Land Disturbance Plan.
The Land Disturbance Plan shall comply with the minimum general and technical requirements set forth in this section. The complexity of the plan shall be commensurate with the severity of site conditions and potential for off-site damages. Additional information may be required if deemed necessary and appropriate to evaluate the feasibility of the plan. The State's "Planning and Design Manual for the Control of Erosion, Sediment and Storm water" shall be used as a guide when developing the plan.
Plan Required. Except as otherwise exempted from the requirements of this Ordinance, a land disturbance plan shall be required prior to the issuance of a grading permit. The Plan shall identify the specific and appropriate erosion control practices and sediment trapping facilities proposed for the site to be disturbed as well as a schedule for Implementation. The Plan shall also identify final stabilized conditions for the site, provisions for removing temporary control measures and stabilization of the site when temporary measures are removed, permanent storm water conveyance structures and maintenance requirements for any permanent measures.
Professional Design. The land disturbance plan shall be developed by a qualified licensed professional engineer when the area of disturbance exceeds five (5) acres and/or a qualified licensed landscape architect for smaller areas when potentially hazardous soil or drainage conditions exists due to types of soils, steep grades, flood plan development or threatened areas such as nearby lakes, streams, large drainage ditches, roads or wetlands.
Erosion Control. Erosion control measures shall be designed and provided in accordance with generally accepted engineering practices and the requirements of this ordinance. Areas that are to be developed or excavated shall apply these guidelines, fitting the appropriated measures to the specific soils and topography so as to minimize soil erosion and surface.
Protection of Natural Vegetation. Natural vegetation shall be retained and protected whenever feasible during construction. If land must be stripped of vegetation during construction, the expose are shall be limited to the smallest practical size and the duration of the exposure to the shortest.
Information required shall consist of:
- Name, address and telephone number of the owner and developer (permit holders of the property to be graded.
- The registration seal and signature of the engineer or architect who designed the Plan.
- A brief property description.
- A plan drawn to a scale no less than one Inch = 100 feet Including pre-development and post development topography and grades no greater than two (2) foot contour Intervals Including twenty (2) feet of all adjacent properties and to the centerline of any adjacent roadways,
- The site location, boundaries, adjacent properties, location of any buildings or structures on the property or any adjacent land within one hundred (100) feet of the area to be disturbed, flood plain areas, ditch line and any existing on and off-site structural or natural features of the land which have a significant impact on drainage or sediment control or may be threatened by the development.
- The location and a description of temporary and permanent erosion control measures and drainage devices to be constructed and structural changes and improvements to the land including clearing and grading limits, dally cleanup and site control practices and other activities to mitigate the adverse Impact of land disturbance. Also, the location needs to be noted of temporary stockpiles of topsoil or other soil material to ensure such stockpiles will not pose a potential problem.
- A time schedule for initiation and completion of the measure and devices and periodic maintenance after completion.
Sec. 7-146. Construction access routes.
A stabilized stone pad shall be place at any point where traffic will be entering and leaving a construction site to work from a public road prior to the Initiation of any grading work.
Stone pads shall contain ASTM-1 stone, six (6) Inches thick and shall be place a minimum width of twelve (12) feet and length of one hundred (100) feet from the public road into the site.
Sec. 7-147. Cut and fill slopes.
Permanent cut and fill slopes shall be designed and; constructed in a manner that will minimize erosion, consideration shall be given to the length and steepness of the slope, the soil type, upslope drainage area, groundwater conditions and other applicable factors. Any slopes Installed at two (2) foot horizontal to one (1) foot vertical or steeper shall be stabilized with rock riprap or other method approved by the City.
Sec. 7-148. Stabilization of denuded areas and soil stockpiles
Permanent erosion control measures shall be applied to denuded areas within fifteen (15) days after final grade is reached on any portion of the site. Soil stabilization shall also be applied within fifteen (15) days to any denuded area which may not be at final grade, but will remain dormant (undisturbed by construction activity) for longer than sixty (60) days. Any temporary soil stockpiles shall be stabilized or protected with sediment trapping measures to prevent erosion. Applicable erosion control measures shall include establishment of vegetation, mulching and the early application of gravel base on areas to be paved. Selected permanent or temporary erosion control measures should be appropriate for the time of year, site conditions and estimated duration of use.
Sec. 7-149. Establishment of permanent vegetation
A permanent vegetative cover shall be established on denuded areas not otherwise permanently stabilized through the construction of approved structures and parking lots/driveways.
Permanent vegetation shall not be considered stabilized until a ground cover is achieved, which is mature enough to control erosion and to survive seasonal conditions for a period of one (1) year from initial planting. Permanent vegetation species and their establishment should be appropriate for the time of year site conditions and land use intended for the area.
Sec. 7-150. Protection of adjacent properties.
- Downhill protection. All properties adjacent and/or downhill from the site of a land disturbance shall be protected from soil erosion and sedimentation. This shall be accomplished by preserving a well-vegetated buffer strip around the lower perimeter of the land disturbance or by installing perimeter controls such as sediment barriers, filters or dikes, or sediment basins, or by a combination of such measures.
- Use of buffer strips. Vegetated buffer strips shall be used alone only where storm water runoff is anticipated to occur through sheet flow and shall be a minimum of 20 feet in width. However, the buffer strip width should be designed according to soil type, slope and other conditions on site. If at any time it is found that a vegetated buffer strip alone is Ineffective in stopping erosion onto adjacent property, additional perimeter controls shall be provided by the owner.
- Sediment control. Sediment basins and traps, perimeter dikes, sediment barriers, dams, diversions and other erosion control measures intended to trap sediment on-site shall be constructed as the first step In grading, and shall be made functional prior to the disturbance of unslope land. Earthen structures such as dams, dikes and diversions shall be seeded and mulched within seven (7) days of installation. Sediment shall be removed from basins and traps or other measures when sediment has reached design capacity and there is a potential for additional sedimentation.
- Storm water runoff. Storm water runoff from disturbed areas five (5) acres of greater shall pass through a sediment basin or other suitable sediment trapping facility All storm drainage Inlets shall be protected during construction with a sediment barrier to prevent clogging and localized flooding if necessary, basins or traps may need sediment removal or repairs.
Sec- 7-151. Disturbance In streams and floodways.
The applicant for proposed land disturbance activities in streams (defined by a blue line on a 7 1/2 minute United States Geological Survey quadrangle) and designated floodways shall be required to provide evidence of obtaining appropriate permits from Federal and State regulatory agencies or a written waiver of such permits prior to the issuance of a site grading permit by the City.
Sec. 7-152. Existing areas with soil erosion problems.
Upon written notification for the City, the owner of any parcel of land which exhibits unstable or eroding soil conditions and impacts downhill properties, public right-of-ways or water courses, whether such conditions exist before or arise after enactment of this ordinance, shall correct the problem with (90) calendar days from receipt -of official notification. Upon written request to the Public Works Director, the period for correction may be extended if seasonal conditions warrant any temporary erosion control measures are installed.
Minimum corrective measure may include stabilizing eroding slopes and revegetating all exposed soil surface. Before commencing corrective measures, the owner shall consult with the Public Works Director or his designee to determine an acceptable method of correction. A permanent plan for erosion control shall be submitted to the Public Works Director or his designee for review and approval prior to initiation of corrective measures.
Sec. 7-153. Performance bonds.
Prior to the issuing of a permit for any land disturbance activity in excess of five (5) acres, and for smaller areas when potentially hazardous soil or drainage conditions exists due to types of soils, steep grades, floodplain development of threatened areas such as nearby lakes, streams, large drainage ditches, roads, or wetlands, the applicant shall be required to provide a performance bond or similar form of security acceptable to the City to complete all land and grade stabilization measures and improvements as shown in the approved plan. The City shall establish the amount and time period of the bond, based on the estimated cost and time for completing the plan. Within thirty (30) days of the completion and final Inspection by the City of all provisions of the approved plan, said bond or security shall be refunded or terminated, provided, however, that a maintenance bond on greater that fifty percent (50) nor less than ten percent (10) of the original bond as determined by the City shall be required for a period of one (1) year to ensure that the permanent vegetation is mature enough to control erosion and to survive seasonal weather conditions.
Sec. 7-154. Appeals.
Whenever an application for permit is rejected, it is claimed that the provisions of this article do not apply or that an equally good or more desirable form of construction can be employed in any specific case, or when it Is claimed that the true intent and meaning of this article or any of the regulations there under have been misconstrued or wrongly Interpreted, the owner of such property of his duly authorized agent may appeal the decision to the Board of Mayor and Selectmen. Notice of appeal shall be in writing and filed within thirty (30) days after the decision is rendered by the City. A filing fee of fifty dollars ($50.00) shall accompany such notice of appeal which shall be refundable if the Board of Mayor and Selectmen upholds the appeal of the applicant. The Board of Mayor and Selectmen shall meet and conduct a hearing on the appeal within sixty (60) days unless the appellant requests or consents to additional time.
Sec. 7-155. Inspections.
- Owner's responsibility. It shall be the responsibility of the site grading permit holder;
- To provide in writing an anticipated phasing plan and schedule of the land disturbance activities from
- initiation to completion. The permit holder shall promptly notify the City in writing if there are any changes to the schedule or delays associated with the phasing plan; and
- To conduct periodic inspections of the installed erosion control measure during construction and of nearby down stream facilities, to determine if such control is effective. Any damage to downhill property caused by erosion, such as clogged storm sewers, inlets or drainage ditches, shall be immediately repaired or cleaned by the permit holder.
- City oversight. An agent of the City may enter upon any site and periodically make inspection of any disturbed or graded area before, during and after construction to ensure compliance with the requirements of this article and the authorized Land Disturbance Plan. If the City determines that significant erosion problems are occurring on the site despite compliance with approved protective practices, the permit holder shall be required to take additional corrective actions to protect the adversely affected area. The specifications of the additional measures shall be part of an amendment to the Land Disturbance Plan.
- Correction of problem by owner. If it is determined that the permit holder has failed to comply with the approved plan, a correction notice shall immediately be served upon the permit holder in writing, setting forth the measure needed to come into compliance and specifying time for such compliance. Where an immediate threat to public health and safety exist, verbal notice given by the Director of Inspection and Zoning or his designee to immediately correct the problem shall be sufficient, but it shall be followed by written notice. Failure to comply within the time specified shall subject the permit holder to a Stop Work Order which shall remain in effect until the work in progress is In compliance with the specifications of the approved plan.
Sec. 7-156. City Correction/Collection Procedures.
- All temporary and permanent erosion control measures I shall be maintained and repaired as needed by the property owner to assure continued performance of their intended function. If it is determined that a property owner has failed to correct an existing unstable or eroding soil condition which impacts downhill properties, public right-of-way or water courses or has failed to maintain temporary and permanent erosion control measures installed after enactment of this ordinance, or has failed to comply with any of the provisions of this ordinance, a corrective notice shall be sent by Certified mall to the property owner, setting forth the measures needed to come into compliance and specifying time for such compliance. When an immediate threat to public health and safety exits, verbal notice given by the Director of Inspections and Zoning or his designee to immediately correct the problem shall be sufficient, but it shall be followed by written notice within seven (7) days.
- Should the property owner fail to remedy the above conditions within the prescribed time, the City shall remedy the condition or cause the same to be done by an appropriate City department or other contractual arrangement. Thereafter, the governing authorities may, at their next regular meeting, by resolution, adjudicate the actual cost Incurred in correcting and remedying the situation. The cost may become a civil debt against the property owner, or, at the option of the governing authority, an assessment against the property.
- In the event the governing authority declares, by resolution, that the cost shall be collected as a civil debt, the governing authority may authorize the institution of a suit on open account against the owner of the property in court to competent jurisdiction in the manner provided by law for such cost, plus court costs, reasonable attorney's fee and interest from the date that the condition was
- In the event the governing authority does not declare that the cost shall be collected as a civil debt, then the assessment above provided shall be a lien against the property and may be enrolled In the ^1office of the Circuit Clerk of the County as other judgments are enrolled, and the Tax Collector of the municipality may, pursuant to resolution of the municipal governing authorities authorizing such action, proceed to sell the land to satisfy the lien as now provided by law for the sale of lands for delinquent municipal taxes.
SECTION II: That all ordinances in conflict or inconsistent with the provision of this ordinance are hereby
SECTION III; That this Ordinance shall take effect and be in full force and effect on and after November 1, 1998
PASSED AND ADOPTED, at the September 22, 1998 regular meeting of the Board of Mayor and Selectmen of said City by the following vote:
Voting Aye: Marvin Godbold, Whitney Rawllngs,
David Myers, Gene Sharkey, Robert Earl Smith
Voting Nay: None
Present and Not Voting: None
Absent and Not Voting: Danny Esch
DATE; September 22,1998
MB XX PP 146/150
On motion by Robert Earl Smith, seconded by Whitney Rawlings, Selectmen, with all members present voting aye, the Board adopted an Ordinance entitled Storm water Detention in the City of McComb City, Mississippi.
ORDINANCE ENTITLED STORMWATER DETENTION IN THE CITY OF MCCOMB CITY, MISSISSIPPI
Whereas, the Board of Mayor and Selectmen of the City of McComb City Mississippi, wishes to diminish threats to public health. and safety caused by the runoff of excessive storm water reduce economic losses to individuals and the community at larger and protect, conserve and promote the orderly development of land and water resources in the City of McComb City; and
WHEREAS, the Board of Mayor and Selectmen of the City of McComb City, Mississippi, are desirous to further regulate, guide and control storm water in the City of McComb City, Mississippi; and
NOW THEREFORE, BE IT ORDAINED by the Board of Mayor and Selectmen of the City of McComb City, Mississippi, as follows, to-wit;
SECTION I: That Chapter 7, Building, Construction and Related Activities of the Code of Ordinances of said City, and all amendments thereto, is hereby amend so as to adopt Article X, Storm water Detention, Sections 7-166 through 7-168 to provide as follows:
ARTICLE X. STORM WATER DETENTION
Sec. 7-166. Code adopted.
The purpose of this ordinance is to diminish threats to, public health and safety caused by the runoff of excessive storm water; reduce economic losses to individuals and the community at large; and protect, conserve and promote the orderly development of land and water resources. The provision of this ordinance further regulates, guide and control:
- The subdivision layout, redevelopment and Improvement of lands located with the City.
- The construction of buildings and drainage of the sites on which structures are located, Including parking and other paved areas.
- The design construction and maintenance of storm water drainage facilities and systems.
Sec. 7-167. General criteria and standards
- Applicability. This shall apply to any residential development of five (5) acres or more or any non-residential development of three acres or more. This ordinance shall also apply to any residential development of less than five (5) acres or any nonresidential development of less than three acres but having 50 or greater impervious surface.
- Limitation on storm water runoff. No development shall be undertaken that Increases the rate of surface runoff to downstream property owners or drainage systems.
- Detention of excess storm water runoff. The increased storm water runoff resulting from the proposed development shall be detained by the provision of retention or detention facilities.
- Storage capacity. Retention or detention facilities shall be designed with sufficient capacity to accommodate all runoff caused by the development in excess of that runoff which would occur from the site if left in its natural, undeveloped condition. This storage shall be sufficient to store all excess flows for the 100-year storm of 24-hour duration.
- Channel stability. The storm water runoff from the proposed development shall not Increase channel instability
- Retention/detention facilities In floodplains. If detention storage is provided within a floodplain of a major stream, no storage volume for the facility may be provided below the high water elevations established for that floodplain. No retention/detention facility should be located in a regulatory.
- Storm water bypass. Drainage system shall have adequate capacity to bypass through the development the existing flow from all upstream areas.
Sec. 7-168. Improvement regulation.
The following information and data prepared and certified by a registered professional engineer in the State of Mississippi shall be furnished with the plans of each proposed residential, commercial and industrial development.
- Contour map. A topographic map with two foot minimum interval contours of the land to be subdivided and such adjoining land whose topography may affect the layout or drainage of the subdivision. On such a map, the following shall be shown:
- The banks and centerline of streams and channels.
- The normal shoreline of lakes, ponds, and retention/detention basins and lines of inflow and
- The location, size and slope of storm water conduits and drainage swales.
- Storm, sanitary and combined sewers and outfalls of
- Delineation of upstream and downstream drainage features and watersheds which might be affected by
- Base flood (100-year) elevations and regulatory floodways which have been identified for the
- Environmental features including the limits of wetlands areas and any designated natural areas.
- Drainage plan. A comprehensive drainage plan designed to safely and completely handle the storm water runoff and to detain increased storm water runoff. This plan shall provide and be accompanied by maps and/or other descriptive material
- The extent and area of each watershed tributary to the drainage channels in the development.
- The storm sewers and other storm drains to be built, the basis of their design, the outfall and outlet locations and elevations, receiving stream or channel and its high water elevation and the functioning of the drains during high water conditions.
- Existing streams and flood plains to be maintained and new channels to be constructed including their locations, cross-sections and profiles.
- Proposed culverts and bridges to be built including their materials, elevations waterway openings and basis of design.
- Existing retention/detention facilities to be; maintained, enlarge or altered and new facilities to be built including their design.
- The estimated location and percentage of impervious surfaces existing and expected to be constructed when the development is complete.
- The slope, type and size of all sewers and other waterways.
- Any proposed environmental enhancement or mitigation features.
- Retention/detention basin to be built including a plot or tabulation of storage volumes with corresponding water surface elevations and of the basin outflow rates for those water surface elevations.
- For all retention/detention basins, design hydrographs of Inflow and outflow for 100-year peak flows from the site under natural and developed conditions.
- The formula for determining the storage for a retention/detention basin is; Volume (acre-feet) equals (=) Runoff of 100-Year Storm on developed drainage area less (-) Runoff from off site that naturally flows through the the drainage area.
- The live detention storage to be provided shall be calculated on the basis of the 100-year frequency rainfall as published by the U.S. Weather Bureau for this area.
- Landscaping plan of retention/detention facility.
- One or more typical cross-sections of all existing and proposed channels or other open drainage facilities, showing the elevation of the existing land and the proposed changes thereto, together with the high water elevations expected from storm water runoffs under the controlled conditions called for by this ordinance, and the relationship of structures, street and other utilities.
- Detention Basins. Detention basins shall be constructed to temporarily detain the storm water runoff in excess of the volumes of runoff occurring on the site before development and will conform to the following standards;
- Storage volumes. The column of storage provided in these basins, together with such storage as may be authorized in other detention facilities, shall be sufficient to control the excess runoff from the 100-year storm of any duration.
- Maximum depth. The maximum planned depth of storm water stored shall not exceed five feet unless natural ground conditions lend themselves to greater depths.
- Approach slopes. The approach slopes of the basin shall conform as closely as possible to natural land contours. Regarding is preferable If necessary to keep the slopes under ten percent (10). Erosion control measures shall be provided as well as devices or measures to insure public safety.
- Outlet control structures. Outlet control structures shall be designed as simply as possible and shall operate automatically. They will be designed to limit discharges Into existing or planned downstream channels or conduits so as not to exceed predetermined safe capacities and not in excess of flows which would have occurred with the land in its natural, undeveloped condition. If necessary, velocity dissipation measures shall be employed to ensure that the discharge does not increase downstream erosion.
- Spillway. Emergency overflow facilities shall be provided unless positive measures are Installed to control the Inflow so as not to exceed the safe capacity of the basin.
- Appearance. Detention facilities shall where possible, use natural topography and natural vegetation. In lieu thereof, these facilities shall have planted trees and vegetation such as shrubs and permanent ground cover on their borders.
- Fencing. Detention facilities shall be enclosed by a six-foot fence where the depth of the water would reach two feet. Each fenced facility shall be effectively and attractively screened with trees and
- Retention basin. Basins designed with permanent pools shall conform to the standards for detention basin as specified in paragraph C unless modified or amended as follows:
- Minimum depths. The minimum normal depth of water before the introduction of excess storm water shall
- Facilities for emptying. 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.
- Pollution abatement. Aeration facilities may be required, dependent on the quality of the influent and detention time.
- Side slopes. The side slopes shall be of non-erosive material with a slope of 3:1 or flatter. The ledge shall be four to six feet wide, three feet below normal water depth and sloping gently toward the shore to prevent people or objects from sliding into deep water. There shall be a free-board of 18 inches above the high water elevation on all retention basins. Alternate designs for side slopes may be considered under special circumstances where good engineering practice Is demonstrated.
- Sediment storage. Adequate area for sediment storage shall be provided in all retention basins.
- Maintenance of Facilities. All improvements, including landscaping, shall be maintained In perpetuity and cannot be developed for any other use which would limit or cause to limit the use of the improvements. The Improvements shall be owned and/or maintained by the property owner. When problems arise due to inadequate maintenance, the City may inspect the improvements and compel the correction of the problem by a written notice.
- Inspection of facilities. The City shall inspect all drainage facilities while under construction. When facilities are not constructed according to approved plans, The City has the explicit authority to compel compliance and have nay situations corrected which are not according to the approved plans.
SECTION II: That all ordinances in conflict or inconsistent with the provisions of this Ordinance are hereby
SECTION III: That this Ordinance shall take effect and be in full force and effect on and after November 1, 1998.PASSED AND ADOPTED, at the September 22, 1998 regular meeting of the Board of Mayor and Selectmen of said City by the following vote:
Voting Aye: Marvin Godbold, Whitney Rawlings,
David Myers, Gene Sharkey
Robert Earl Smith
Voting Nay: None
Present and Not Voting: None
Absent and Not Voting: Danny Esch
APPROVED /s/ J.C. Woods_____
ATTEST:/s/ Sam C. Mims______ Sam C. Mims, City Clerk
I, Sam C. Mims, City Clerk in and for the City of McComb City, Mississippi, do hereby certify that the above is a true and correct copy of a certain Ordinance passed and adopted at the regular meeting of the Board of Mayor and Selectmen of said City.
Witness my hand and Official Seal of the City of McComb This the 22nd day of September, 1998.
Signed: /s/___________________ Sam C. Mims