§ 8.04.00. Standards for stormwater management.

8.04.01.

Generally.

A.

Intent. The intent of section 8.04.00 is to provide standards and criteria to protect, maintain, and enhance the public health, safety, environment, and general welfare by establishing minimum requirements and procedures to control the adverse effects of increased post-development stormwater runoff and nonpoint source pollution associated with new development and redevelopment. Proper management of post-development stormwater runoff will minimize damage to public and private property and infrastructure, safeguard the public health, safety, environment, and general welfare of the public, and protect water and aquatic resources.

B.

Purpose.

1.

Require that new developments and redevelopments maintain the pre-development hydrologic response in their post-development state as nearly as practicable in order to reduce flooding, stream bank erosion, nonpoint source pollution, increases in stream temperature, and maintain the integrity of stream channels and aquatic habitats;

2.

Establish minimum post-development stormwater management standards and design criteria for the regulation and control of stormwater runoff quantity and quality;

3.

Establish design and application criteria for the construction and use of structural stormwater control facilities that can be used to meet the minimum post-development stormwater management standards;

4.

Encourage the use of nonstructural stormwater management and stormwater better site design practices, such as the preservation of green space, conservation areas and floodplain to the maximum extent practicable;

5.

Coordinate site design plans with other standards in the ULDC that address resource protection, erosion control and the connectivity of open space; and

6.

Establish provisions for the long-term responsibility for and maintenance of structural stormwater control facilities and nonstructural stormwater management practices to ensure that they continue to function as designed, are maintained, and pose no threat to public safety.

C.

Applicability. No owner or developer shall perform any land development activities without first meeting the requirements of section 8.03.01 prior to commencing the proposed activity. The standards and requirements of section 8.04.00 shall be applicable to all land development meeting the standards in subsection 8.04.01.C.1. through 5., where a development plan, subdivision plat, or an application for a grading or land disturbance are required, unless specifically exempt pursuant to paragraph D., below.

1.

New development that involves the creation of five thousand (5,000) square feet or more of impervious cover;

2.

New development that involves one (1) acre or more;

3.

Redevelopment that includes the creation, addition, or replacement of five thousand (5,000) square feet or more of impervious cover;

4.

Redevelopment that involves one (1) acre or more; and

5.

Land development activities that are smaller than the minimum applicability criteria set forth in paragraphs C.1. through 4., above if such activities are part of a larger common plan of development, even though multiple, separate, and distinct land development activities may take place at different times on different schedules.

D.

[Exempt activities.] The following activities are exempt from the requirements of section 8.04.00:

1.

An individual single-family residential dwelling unit on a legal lot of record;

2.

Additions or modifications to existing single-family or duplex residential structures; and

3.

Agricultural or silvicultural land management activities within the RA zoning districts.

E.

Stormwater design manual. All stormwater management plans shall utilize the policy, criteria, technical specifications, and standards in the latest edition of the Georgia Stormwater Management Manual (GSMM). The manual may be updated and expanded periodically, based on improvements in science, engineering, monitoring and local maintenance experience. All references to the GSMM mean the latest edition as defined on the GSMM website at
www.georgiastormwater.com. Updates, errata, and revisions will be provided on the website.

8.04.02.

Stormwater management plan requirements.

A.

An application for development activity as defined in subsection 8.04.01.C., above shall be accompanied by a stormwater management plan and an inspection and maintenance agreement regarding ongoing maintenance of the stormwater management facilities.

B.

The stormwater management plan shall detail how post-development stormwater runoff will be controlled or managed and how the proposed project will meet the requirements of section 8.04.00.

C.

The stormwater management plan shall be in accordance with the criteria established in section 8.04.00. The plan shall contain the stamp and signature of a professional engineer licensed in the State of Georgia, who must verify that the design of all stormwater management facilities and practices meet the submittal requirements outlined in the submittal checklist(s) found in the stormwater design manual.

D.

The stormwater management plan shall contain sufficient information to demonstrate that the requirements and criteria in section 8.04.00 are being complied with and that opportunities are being taken to minimize adverse post-development stormwater runoff impacts from the proposed development. The plan shall consist of maps, narrative, and supporting design calculations (hydrologic and hydraulic) for the proposed stormwater management system. The plan shall include all of the information required in the stormwater management site plan checklist found in the GSMM.

E.

The following information is required, at a minimum:

1.

Existing conditions hydrologic analysis for stormwater runoff rates, volumes, and velocities, which shall include:

a.

A topographic map of existing site conditions with the drainage basin boundaries indicated;

b.

Acreage, soil types and land cover of areas for each subbasin affected by the project;

c.

All perennial and intermittent streams and other surface water features;

d.

All existing stormwater conveyances and structural control facilities;

e.

Direction of flow and exits from the site;

f.

Analysis of runoff provided by off-site areas upstream of the project site; and

g.

Methodologies, assumptions, site parameters and supporting design calculations used in analyzing the existing conditions site hydrology.

2.

For redevelopment sites, predevelopment conditions shall be modeled using the established guidelines for the portion of the site undergoing land development activities.

3.

A post-development hydrologic analysis for stormwater runoff rates, volumes, and velocities, which shall include:

a.

A topographic map of developed site conditions with the post-development drainage basin boundaries indicated;

b.

Total area of post-development impervious surfaces and other land cover areas for each subbasin affected by the project;

c.

Calculations for determining the runoff volumes that need to be addressed for each subbasin for the development project to meet post-development stormwater management performance criteria;

d.

Location and boundaries of proposed natural feature protection and conservation areas (see chapter 3);

e.

Documentation and calculations for any applicable site design credits that are being utilized; and

f.

Methodologies, assumptions, site parameters, and supporting design calculations used in analyzing the existing conditions site hydrology.

g.

If the land development activity on a redevelopment site constitutes more than fifty (50) percent of the site area for the entire site, then the performance criteria shall be met for the stormwater runoff from the entire site.

4.

The description, scaled drawings, and design calculations for the proposed post-development stormwater management system, which shall include:

a.

A map and/or drawing of the stormwater management facilities, including the location of nonstructural site design features and the placement of existing and proposed structural stormwater controls, including design water surface elevations, storage volumes available from zero (0) to maximum head, location of inlet and outlets, location of bypass and discharge systems, and all orifice/restrictor sizes;

b.

A narrative describing how the selected structural stormwater controls will be appropriate and effective;

c.

Cross-section and profile drawings and design details for each of the structural stormwater controls in the system, including supporting calculations to show that the facility is designed according to the applicable design criteria;

d.

A hydrologic and hydraulic analysis of the stormwater management system for all applicable design storms (including stage-storage or outlet rating curves, and inflow and outflow hydrographs);

e.

Documentation and supporting calculations to show that the stormwater management system adequately meets the post-development stormwater management performance criteria;

f.

Drawings, design calculations, elevations and hydraulic grade lines for all existing and proposed stormwater conveyance elements including stormwater drains, pipes, culverts, catch basins, channels, swales and areas of overland flow; and

g.

Where applicable, a narrative describing how the stormwater management system corresponds with any watershed protection plans as required in chapter 3 or open space connectivity requirements for conservation subdivisions, as set forth in section 6.02.01.

5.

A downstream peak flow analysis is required, which includes the assumptions, results and supporting calculations to show safe passage of post-development design flows downstream. The analysis of downstream conditions in the report shall address each and every point or area along the project site's boundaries at which runoff will exit the property. The analysis shall focus on the portion of the drainage channel or watercourse immediately downstream from the project. This area shall extend downstream from the project to a point in the drainage basin where the project area is ten (10) percent of the total basin area. In calculating runoff volumes and discharge rates, consideration may need to be given to any planned future upstream land use changes. The analysis shall be in accordance with the stormwater design manual.

6.

An erosion and sedimentation control plan that meets the requirements of section 8.05.00.

7.

The landscaping plan, as required in section 5.00.02 shall describe how vegetation will be placed within and adjacent to stormwater management facilities.

8.

Detailed description of ongoing operations and maintenance procedures for stormwater management facilities and practices to ensure their continued function as designed and constructed or preserved. These plans shall identify the parts or components of a stormwater management facility or practice that need to be regularly or periodically inspected and maintained, and the equipment and skills or training necessary. The plan shall include an inspection and maintenance schedule, maintenance tasks, and responsible parties for maintenance, funding, access, and safety issues. Provisions for the periodic review and evaluation of the effectiveness of the maintenance program and the need for revisions or additional maintenance procedures shall be included in the plan.

9.

A minimum twenty-foot easement shall be provided to ensure access from a public right-of-way to the stormwater management facilities. Such access shall be sufficient for all necessary equipment for maintenance activities. Depending on the depth of pipe, the drainage easement width may be required to be increased. Upon final inspection and approval, a plat or document indicating that such easements exist shall be recorded and shall remain in effect even with the transfer of title of the property.

8.04.03.

Stormwater management inspection and maintenance agreements.

STORMWATER BEST MANAGEMENT PRACTICES
OPERATIONS AND MAINTENANCE AGREEMENT

THIS AGREEMENT, made and entered into this ________ day of ________, 20___, by and between

[Insert Full Name of Owner]

___________ (hereinafter called the "Landowner") as party of the first part, and Henry County, Georgia, a political subdivision of the STATE OF GEORGIA, (hereinafter called the "County") of the second part;

WITNESSETH

WHEREAS, the undersigned is the owner of that certain real property lying and being in the ___ Land Lot/District, ___ identified as [Tax Map/Parcel Identification Number] and being more particularly described by deed as recorded in the land records of Henry County, Georgia, Deed Book ___ Page ___, hereinafter called the "Property".

WHEREAS, the undersigned is proceeding to build on and develop the property; and has submitted the Site Plan/Subdivision Plan known as ___________, (Name of Plan/Development) hereinafter called the "Plan", which is expressly made a part hereof, as approved or to be approved by the County, provides for detention of stormwater within the confines of the property; and

WHEREAS, the County and the undersigned, its successors and assigns, including any homeowners association, (hereinafter the "Landowner") agree that the health, safety, and welfare of the residents of Henry County, Georgia, requires that on-site stormwater management facilities be constructed and maintained on the Property; and

WHEREAS, the County requires that on-site stormwater management facilities as shown on the Plan (the "Facilities") be constructed and adequately maintained by the Landowner.

NOW, THEREFORE, in consideration of the foregoing premises, the mutual covenants contained herein, and the following terms and conditions, the parties hereto agree as follows:

1.

The Facilities shall be constructed by the Landowner, in accordance with the plans and specifications identified in the Plan.

2.

The Landowner shall at all time, adequately maintain the Facilities. Such maintenance obligation shall include the obligation to properly maintain all pipes, channels or other conveyances built to convey stormwater to the Facilities, as well as all structures, improvements, and vegetation provided to control the quantity and quality of the stormwater. Adequate maintenance is herein defined as keeping the Facilities and all components thereof in good working condition so that these Facilities continue to perform their design functions. The Stormwater Structural Control Maintenance Checklists are to be used to establish what good working condition is acceptable to the County.

3.

The Landowner shall inspect the stormwater management facility and submit an inspection report annually. The purpose of the inspection is to assure safe and proper functioning of the Facilities. The inspection shall cover the entire Facilities including embankments, berms, inlet and outlet structures, pond areas, access roads, etc. Deficiencies shall be noted in the inspection report.

4.

The Landowner hereby grants to the County, its authorized agents and employees, a non-exclusive perpetual easement of ingress and egress over, across, under and through the Property for the purpose of inspecting the Facilities. The purpose of such inspections is to follow-up on reported deficiencies and/or to respond to citizen complaints. The County shall provide the Landowner copies of any inspection findings and a directive to commence with the repairs if necessary.

5.

In the event the Landowner fails to maintain the Facilities in good working condition acceptable to the County, the County may enter upon the Property and take such steps as are necessary to correct deficiencies identified in the inspection report and to charge the costs of such repairs to the Landowner. This provision shall not be construed to allow the County to erect any structure of permanent nature on the land of the Landowner outside of the easement for the stormwater management facilities. It is expressly understood and agreed that the County is under no obligation to routinely maintain or repair said facilities, and in no event shall this Agreement be construed to impose any such obligation on the County. The Landowner grants to the County, its authorized agents and employees, a non-exclusive, perpetual easement over, across, under and through the Property for such purposes.

6.

The Landowner shall perform all work necessary to keep the Facilities in good working order. In the event a maintenance schedule for the stormwater management facilities (including sediment removal) is outlined on the approved plans, the Landowner shall comply with such schedule.

7.

In the event the County performs work of any nature on the Facilities in accordance with this Agreement, or expends any funds in performance of said work for labor, use of equipment, supplies, materials, and the like, the Landowner shall reimburse the County upon demand, within thirty (30) days of receipt thereof for all actual costs incurred by the County hereunder.

8.

This Agreement imposes no liability of any kind whatsoever on the County and the Landowner agrees to hold the County harmless from any liability in the event the stormwater management facilities fail to operate properly.

9.

This Agreement shall be recorded among the deed records of Henry County, Georgia, and shall constitute a covenant running with the land, and shall be binding on the Landowner, its administrators, executors, assigns, heirs and any other successors in interests, including any homeowners association.

IN WITNESS THEREOF, the parties hereto acting through their duly authorized agents have caused this Agreement to be signed, sealed and delivered:

(Insert Company/Corporation/Partnership Name) [SEAL]

___________

By: (Type Name and Title)

The foregoing Agreement was acknowledged before me this day of ________, 20___, by

___________
Unofficial Witness

___________
NOTARY PUBLIC

My Commission Expires: ________

COUNTY OF ________, GEORGIA