The purpose of this article is to diminish threats to public health and safety caused by the runoff of excessive stormwater; reduce economic losses to individuals and the community at large and protect, conserve and promote the orderly development of land and water resources. The provisions of this article further regulate, guide and control:

(a)

The subdivision layout, redevelopment and improvement of lands located within the City of Long Beach.

(b)

The construction of buildings and drainage of the sites on which structures are located, including parking and other paved areas.

(c)

The design, construction and maintenance of stormwater drainage facilities and, systems.

(a)

This ordinance shall be applicable within the City of Long Beach's jurisdictional area and shall apply to any residential development of five acres or more or any non-residential development of three acres or more. This article shall also apply to any residential development of less than five acres or any non-residential development of less than three acres but having 50% or greater impervious surface.

(b)

No development shall be undertaken that increases the rate of surface runoff to downstream property owners or drainage systems.

(c)

The increased stormwater runoff resulting from the proposed development shall be detained by the provision of retention or detention facilities, sometimes referred to as "Stormwater Retarding Structures or Facilities."

(d)

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.

(e)

The stormwater runoff from the proposed development shall not increase channel instability downstream.

(f)

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 the floodplain.

(g)

Drainage systems shall have adequate capacity to bypass, through the development, the natural flow from all upstream areas.

(h)

It shall be unlawful to dump trash, debris, landscape waste and other deleterious materials in any and all drainageways in the City.

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.

(a)

A topographic map with two-foot (2') minimum interval contours, meeting National Map Accuracy Standards, 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:

(1)

The banks and centerline of streams and channels;

(2)

The normal shoreline of lakes, ponds and retention/detention basins, and lines of inflow and outflow;

(3)

The location, sizes and slope of stormwater conduits and drainage swales;

(4)

Storm, sanitary and combined sewers and outfalls of record;

(5)

Delineation of upstream and downstream drainage features and watersheds which might be affected by the development;

(6)

Base flood (100-year) elevation (BFE) and floodways for the property, established pursuant to Long Beach's Flood Ordinance; and

(7)

Environmental features including the limits of wetlands areas and any designated natural areas.

(b)

A comprehensive drainage plan shall be designed to safely and completely handle the stormwater runoff and to detain increased stormwater runoff. This plan shall provide and be accompanied by maps and/or other descriptive material showing the following:

(1)

The extent and area of each watershed tributary to the drainage channels in the development;

(2)

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;

(3)

Existing streams and floodplains to be maintained and new channels to be constructed including their locations, cross-sections and profiles;

(4)

Proposed culverts and bridges to be built including their materials, elevations. waterway openings and basis of design;

(5)

Existing retention/detention facilities to be maintained; enlarged or altered and new facilities to be built including their design;

(6)

The estimated location and percentage of impervious surfaces existing and expected to be constructed when the development is completed;

(7)

The slope, type and size of all sewers and other waterways;

(8)

Any proposed environmental enhancement or mitigation features;

(9)

Retention/detention basins 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;

(10)

For all retention/detention basins, design hydrographs of inflow and outflow for the 100-year peak flows from the site under natural and developed conditions;

(11)

The formula for determining the storage for a retention/detention basin is:[sic]

(12)

The live detention storage to be provided shall be calculated on the basis on the 100-year frequency rainfall as published by the U.S. Weather Bureau for this area;

(13)

Landscaping plan for retention/detention facility and located to reduce visibility from residential structures and public ROW; and

(14)

One of 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 stormwater runoffs under the controlled conditions called for by this article, and the relationship of structures, street and other utilities.

(c)

Detention basins shall be constructed to temporarily detain the stormwater runoff in excess of the volumes of runoff occurring on the site before development and will conform to the following standards:

(1)

The volume 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.

(2)

The maximum planned depth of stormwater stored shall not exceed five feet unless natural ground conditions lend themselves to greater depths.

(3)

The approach slopes of the basin shall conform as closely as possible to natural land contours. Re-grading is preferable if necessary to keep the slopes under ten percent. Erosion control measures shall be provided as well as devices or measures to insure public safety.

(4)

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.

(5)

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.

(6)

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.

(7)

A six-foot fence shall enclose detention structures where the depth of the water would reach two feet. Each fenced structure shall be effectively and attractively screened with trees and plant material.

(d)

Basins designed with permanent pools shall conform to the standards for detention basins, as specified in paragraph [(c)] unless modified or amended as follows:

(1)

The minimum normal depth of water before the introduction of excess stormwater shall be four feet.

(2)

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.

(3)

Aeration facilities may be required, dependent on the quality of the influent and detention time.

(4)

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.

(5)

Adequate area for sediment storage shall be provided in all retention basins.

(e)

The developer shall be responsible for the maintenance of all improvements until such time as 80 percent of the lots have been improved with buildings and occupancy permits issued. However, the developer shall not transfer these improvements for the purpose of maintenance until he has complied with the above and until he has received final approval, final inspection, and a Certificate of Compliance from the City Engineer and the Public Works Director.

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's Association of the development and each property owner shall own a proportionate share of the improvements and shall bear his proportionate responsibility for the continued maintenance in accordance with the above.

Each property owner shall, within the contents of his deed, be liable for the combined maintenance of the improvements. A special note to this effect shall appear on any final plat of subdivision or any plat of condominium and their declarations.

The Property Owner's Association shall be formed by the Developer in perpetuity for the maintenance of the improvements. Membership shall be mandatory by all property owners. Articles of agreement of the Property Owner's Association must be approved by the Board of Aldermen of the City of Long Beach before recording.

In subdivisions consisting of five single-family residential lots or fewer, the provisions of Property Owner's Association may be waived, provided that other parts of this section have been met.

The City of Long Beach will maintain all facilities that are located in dedicated public rights-of-way and/or dedicated easily accessible drainage easements.

When problems arise due to inadequate maintenance, the City Engineer or public Works Director or their Agents of the City of Long Beach may inspect the improvements and compel the correction of the problem by written notice. Whenever facilities fail, the Property Owner's Association may contract with the City of Long Beach for the correction of the problem provided the City is adequately reimbursed.

(f)

Whenever drainage facilities are planned to service several projects or a specific area deemed necessary by the City of Long Beach; the drainage facilities may be dedicated to the City. When these projects are of a regional nature, the City of Long Beach will maintain these facilities. In these cases, access easements shall be provided to the City.

(g)

The City Engineer shall inspect all drainage facilities while under construction. When facilities are not constructed according to approved plans, the City of Long Beach has the explicit authority to compel compliance and have any situations corrected which are not according to the approved plans. All drainage facilities located on private property, whether dedicated to the City or not, shall be accessible at all times for inspection by the City Engineer of other responsible public official.

(h)

The requirements for on-site retention/detention facilities may be waived by the City of Long Beach if it is determined that a development project is too small, or if engineering, aesthetic or economic factors make a combined or regional facility more practical for construction by the City. In this case, the City of Long Beach shall require a fee and/or dedication of land from the developer, which the City shall use to construct the regional facility. This fee and/or dedication of land shall be based on the proportionate share for the development in its completely developed state of the present costs of constructing the regional facility.

(a)

The Mayor and Board of Aldermen shall have the power to authorize variances from the provisions or requirements of this article.