Paulding County › Unified Development Ordinance

Title 3 — Development Regulations, Chapter 340 — Grading and Stormwater Detention.

current as of 2026-04-14verified current · checked 2026-08-24Officialofficial source ↗6 sections · full chapter

§ 340-10

Grading

340-10.01 Approved Plans.

Grading shall be done in accordance with the lines and grades shown on the approved construction plans.

340-10.02 Embankments.

Embankments shall be placed in uniform layers not to exceed a compacted thickness of six inches per layer and shall be compacted to a density of 95% of the maximum laboratory dry weight per cubic foot as determined by AASHTO Method T-99 in all areas where structures, parking lots and drives, streets, and utilities are to be placed. All other embankments are to be compacted to at least 85%.

340-10.03 Slopes.

The maximum slopes for cut or fill shall be 2:1 (two feet of horizontal run for each foot of rise or fall). The depth of cut referred to herein shall be the maximum cut or fill occurring in any one section of cut or fill. The slope of cut or fill shall be uniform throughout for each section of cut or fill except when the development control committee approves benching. When a cut is made in rock that requires blasting, the slope may be steeper if pre-splitting is employed and upon submission of a geotechnical report which substantiates the integrity of the rock in the steeper condition, subject to the review and approval of the development control committee.

340-10.04 Stabilization.

While most soils in the area can be safely stabilized at a 2:1 slope, some soils exhibit a low shearing resistance and a low cohesiveness. These soils typically are micaceous silts and sandy soils with little or no clay. If the 2:1 slope shows evidence of shearing, non-cohesiveness, sliding, or inability to maintain compaction, the slope shall be stabilized at 3:1 or by using such mechanical methods as needed (such as retaining walls or "grow mats" stapled in place) to maintain slope, height and integrity.

§ 340-20

Stormwater Detention Report

340-20.01 Stormwater Management Report Required.

A.Every project shall provide a Stormwater Management Report prepared by a Professional Engineer currently registered in the State of Georgia. The purpose of this report shall be to formulate a plan to manage stormwater runoff so that stormwater runoff hazards are not created and existing runoff-related problems are not exacerbated, either upstream or downstream from or within the boundaries of the property being developed.

B.The Stormwater Management Report shall include a written narrative and identify the locations and quantities of stormwater runoff entering and exiting the site for both pre- and post-developed conditions. Analysis of the off-site properties shall anticipate future development in addition to addressing existing conditions. It shall contain drainage area delineation maps and other exhibits at satisfactory scale and sufficient in quantity and scope to define the boundaries of the site relative to watercourses, drainage divides, drainage structures, and other pertinent features.

C.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 way "immediately" downstream from, the project. This area shall generally extend a flow distance of about one-half mile from the project's boundary line, but shall be longer for projects contributing relatively large amounts of runoff to the study area, and shorter for small runoff contributions. In all cases, the most critical downstream area investigation shall be conducted relative to existing and anticipated land uses on tracts that adjoin the project site.

340-20.02 Stormwater Detention Required.

A.If the stormwater management report indicates that adverse stormwater runoff is expected to result from the development of a property, that project shall be required to provide stormwater detention facilities. These detention facilities shall be designed so that their peak release rates, when combined with those of all detention bypass areas in the same basin, produce peak flow rates and flow velocities at the site's boundary line no greater than those which occurred at the same location for pre-developed conditions.

B.The following criteria shall be evaluated by the engineer preparing the stormwater management report, or the calculations and documents required may be performed and submitted by a registered land surveyor, licensed in the State of Georgia, and in determining whether or not detention should be required for any portion of any site:

1.Existing land uses downstream.

2.Anticipated future land uses downstream.

3.Magnitude of increase in peak flows due to development.

4.Presence of existing drainage problems.

5.Capacity of existing and anticipated drainage systems.

6.Creation of concentrated flows where none had occurred previously.

7.Availability of feasible locations for detention facilities.

8.Existing flows generated off-site that pass through the project site.

9.Anticipated future flows generated off-site that pass through the project site.

10.The nature of the receiving watercourse.

C.Stormwater detention facilities shall be required for any portion of any site for which development activities will result in increased flows, unless the registered professional engineer currently registered in the State of Georgia certifies and provides documentation supporting the conclusion to the Plan Review Committee that the following is true and correct as applicable:

1.The non-detained, post-development runoff requires water quality volume, and will not have an adverse impact upon downstream properties.

2.The effect of detention would be to concentrate flows where sheet flow had occurred under pre-developed conditions, and any impact of increase sheet flows upon downstream properties would be less adverse than that which would result from the concentrated flows from a detention facility even if energy dissipation devices were employed.

3.The runoff will flow directly into a floodplain without crossing off-site properties, and the runoff will constitute less than 10% percent of the total runoff in the watercourse at the point where the watercourse crosses the project site's downstream property line.

4.The undetained flow will pass through downstream properties, in drainage easements obtained by the developer, to an existing detention facility that has been designed to manage the additional upstream property's runoff.

340-20.04 Capital Drainage Improvement Fee.

In the event that the Professional Engineer has concluded that stormwater detention may not be necessary as outlined in Section 340-20.02.B.3 above is anticipated, a pre-design conference with the Plan Review Committee shall be required before the submittal of plans. Fees shall be collected at the rate as defined in the fee schedule approved by the Board of Commissioners per impervious acre of the proposed project to be used for other capital drainage improvements.

§ 340-30

Detention Design Criteria

340-30.01 General.

A.All stormwater detention design calculations shall be certified by a Professional Engineer currently registered in the State of Georgia.

B.All stormwater detention facilities shall be designed to control the peak flow rates associated with storms having 2, 5, 10, 25, 50 and 100-year return frequencies and in accordance with the Georgia Stormwater Management Manual.

C.A variety of methods of achieving stormwater-management goals shall be acceptable in providing detention facilities. The type of facility provided shall be based on the following criteria:

1.The type of development for which the detention facility is being provided.

2.The type of development which the detention facility is intended to protect.

3.Volume of stormwater to be stored.

4.Origin and magnitude of the flows to be managed.

5.Topographic opportunities and limitations.

6.Safety considerations.

7.Maintenance requirements.

8.Aesthetic considerations.

9.Likelihood of facility operation interfering with access to public or private facilities.

10.Proximity of facility to property lines, utilities, buffers, etc.

11.Similar site-specific constraints.

D.Detention facilities may be of any of the following types, and two or more types may be used in combination with one another:

1.Normally-dry basins, whether excavated or created by damming a natural drainage feature, or a combination of both methods.

2.Lakes and ponds, whether excavated or created by damming a natural drainage feature, or a combination of both methods.

3.Other types of facilities shall be approved by the community development department.

E.Reservoir routing methods shall be used for all detention facility design.

F.The detention methodology required for any given project shall conform to standard engineering practices. It shall be the responsibility of the design engineer to use the correct coefficients and applications that will result in compliance with the requirements of this article and the intent of these regulations.

G.Runoff coefficients used for pre- and post-development conditions for the rational method shall be consistent with standard engineering practices. For the SCS method the runoff curve numbers found in the Manual for Erosion and Sediment Control in Georgia shall be used. For any stormwater analysis, the composite "C" (rational method) or CN (SCS Method) used for pre-developed conditions shall not exceed 0.3 or 66, respectively, unless prior approval has been obtained through the community development department.

H.If either the rational method or the SCS method is used for detention design, calculations shall be provided showing how all times of concentration or lag times were computed, both for pre- and post-developed conditions. Likewise, adequate support must be provided for all composite runoff coefficients or curve numbers used.

I.If a computer program is used for detention design, including generating and routing hydrographs, the output from the program shall be summarized in the stormwater management report, and the name and version of the program shall be indicated. Computer output sheets may be attached to the report if desired by the design engineer or if requested by the community development department.

J.The design of every detention facility of any type shall consider the effects both of inflows in excess of those the facility is designed to accommodate and of malfunctioning of the primary outlet system. A safe path for overflow condition flows shall be provided.

340-30.02 Detention Facility Location Criteria.

A.Residential detention facilities shall be located outside the boundaries of a permitted building lot.

B.For purposes of these regulations, a detention facility shall be deemed to consist of the area within the maximum design ponding limits, the dam (if one) including all embankment slopes and wall footings (if applicable), primary and emergency outlet works, any drainage and access easements, and any energy dissipation devices.

C.Detention facilities, to the greatest extent feasible, shall be located so as to minimize the amount of flow generated on-site that by-passes the facility.

D.No portion of any detention facility shall disturb any required buffer, landscape strip, or tree protection area. In the case where a drainage structure or a roadway drainage structure must be constructed in a stream buffer, adequate erosion control measures shall be incorporated in the project plans and specifications as allowed in Section 360-30.03(P).

E.The 100-year ponding limits of a detention facility shall not encroach upon a neighboring lot

F.Detention facilities may encroach upon utility easements or rights-of-way, upon receipt by the Plan Review Committee of written permission from both the property and utility owners.

G.A detention facility may be located within or encroach upon a floodplain in accordance with Chapter 330 of these regulations.

H.The detention facility shall be surrounded by a level 15-foot access road which may be easily traversed by vehicular traffic.

I.When a fence is required, the access road shall be constructed on the detention facility side of the fence.

340-30.03 Residential Detention Facility Access Requirements.

The applicant must ensure access from public right-of-way to stormwater management facilities requiring regular maintenance at the site for the purpose of inspection and repair by securing all the maintenance access easements needed on a permanent basis. Such access shall be sufficient for all necessary equipment for maintenance activities. 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.

340-30.04 Residential Detention Facility Maintenance.

A.The detention storage capacity or function of any detention basin, pond or other impoundment, whether natural or manmade, shall not be removed or diminished without the express approval of the Community Development Department.

B.All residential detention facilities, unless exception is granted by Community Development, shall become the responsibility of the development’s Home Owner’s Association for maintenance upon the county's final acceptance of the development; its approval of said detention facilities; and the expiration of the maintenance bond required in Chapter 430 of this UDO. A maintenance fee as listed on the fee schedule as approved by the Board of Commissioners per residential detention facility shall be paid to Paulding County prior to final plat approval, if written approval has been granted for residential detention facilities to be maintained by the county.

§ 340-40

Detention Facility Construction Standards

340-40.01 Stormwater detention facilities shall be constructed in accordance with plans

reviewed and approved by the community development department, and shall be in place and inspected prior to the initiation of other improvements. If the detention facility is planned to be a lake, temporary detention facilities shall be provided and shall remain in place until such time as the lake has become effective in providing stormwater management and certified by design professional.

340-40.02 Within a detention basin, all stumps are to be cut flush with the ground or removed

and all debris is to be removed below the ten-year ponding elevation. Trees or shrubs may be allowed to remain below the ten-year ponding elevation only upon certification of the survivability of the vegetation.

340-40.03 Detention slopes that are disturbed are to be grassed and the ground cover within

the basin shall be well established with all exposed areas covered prior to the end of the maintenance period. All slopes shall be 3:1 maximum.

340-40.04 The developer shall place a fence around detention facilities when slopes are

approved to be steeper than 3:1. In these cases, the fence shall be a minimum four-foot high fence of durable material with 12-foot wide access gates located at the entrance and the outfall structure.

340-40.05 Gabion walls will require approval from the County Engineer and PCDOT for use

within detention facilities.

340-40.06 A certified record survey of each detention facility shall be prepared by a land

surveyor or registered Professional Engineer currently registered in the State of Georgia. A certified record drawing of the facility shall be prepared based upon this survey. Based on the actual parameters established on the record drawing, an addendum to the stormwater management report shall be prepared that demonstrates that the facility, as constructed, complies with the requirements of these regulations. The amended stormwater management report shall be certified by a Professional Engineer currently registered in the State of Georgia.

§ 340-50

Culverts and Piped Drainage Systems

340-50.01 Drainage improvements required.

Stormwater conveyance facilities, which may include but are not limited to culverts, storm drainage pipes, catch basins, drop inlets, junction boxes, headwalls, gutters, swales, channels, and ditches, shall be provided for the protection of public rights-of-way and private properties adjoining projects sites and/or public rights-of-way.

All stormwater easements shall be cleared of all vegetation (trees, bushes, etc) and structures the full easement width prior to acceptance of the County. It shall be required that a minimum of 10 feet shall be cleared around end treatments and pipes (including the removal of trees, tree stumps, bushes, etc) prior to development acceptance.

340-50.02 Standard Specifications.

Unless otherwise specifically set forth herein or in the Paulding County Standard Details, all of the materials, methods of construction, and workmanship for the work covered in reference to stormwater conveyance facility construction shall conform to the most recent Standard Specifications of the Georgia Department of Transportation (Georgia DOT).

340-50.03 General Design Criteria.

A.All stormwater conveyance facility design calculations shall be certified by a Professional Engineer currently registered in the State of Georgia.

B.Stormwater flows from drainage areas up to 200 acres in size may be calculated using the Rational Method. Flows from drainage areas between ten and 2,000 acres in size may be calculated using the SCS Method or other approved methods. Flows for drainage areas larger than 2,000 acres in size must be calculated using published FEMA data or USGS Regional Regression Analysis.

C.Runoff coefficients used for pre- and post-development conditions for the rational method shall be consistent with standard engineering practices. For the SCS method the runoff Curve Numbers found in the Georgia Stormwater Management Manual; shall be used. For any stormwater analysis, the composite "C" (rational method) or CN (SCS Method) used for pre-developed conditions shall not exceed 0.3 or 66, respectively, unless prior approval has been obtained through the Community Development Department.

340-50.04 Culvert Design Criteria.

A.Culverts (structures designed to convey water from one side of a public right-of-way to the other and carry the runoff from a contributing drainage area) shall be designed to pass the peak flow associated with a 100-year storm with at least one foot of freeboard between the 100-year ponding elevation and the top of the roadway shoulder, without rising the 100-year flood elevation on upstream properties, and in accordance with article 10 of these regulations.

B.All pipes are to be designed for inlet and outlet control conditions. Appropriate charts and tables are to be placed on the plans.

C.The 100-year ponding limits above the culvert shall be shown on the construction plans and on the final plat (if applicable).

D.The minimum allowable culvert diameter shall be 18 inches.

E.Culvert design is to be in accordance with the methods contained in the current edition of the Georgia DOT Drainage Manual For Highways, Chapter 7, and shall include a thorough analysis of both inlet and outlet control structures.

340-50.05 Piped Collection Systems.

A.The design (initial pipe sizing and profile design) of piped collection systems required under Section 340-30.01 herein shall be based upon conveyance of the peak flows associated with a 100-year storm with the hydraulic grade line being at or below the structure throat throughout the system.

B.Based on the analysis of 100-year conditions, the preliminary design shall be revised where necessary to produce a final design for which the likelihood of dwelling flooding, major property damage, or substantial public access and/or utility interruption shall be less than one chance in 100 years.

C.Catch basins and/or drop inlets shall be designed by the developer's engineer or registered surveyor to state highway standards and subject to final approval by the Community Development Department. This table may be used for street water in lieu of calculations per structure:

Table 340.1

Feet	Grades
500 feet	Up to 7%
400 feet	7-10%
250 feet	Over 10%

Gutter spread calculations are required if the above chart is not used.

E.Complete flow, velocity, and hydraulic grade line computations, shall be provided for all portions of a piped collection system. Hydraulic grade lines shall be shown on the storm drainage profiles contained with the development plans for the 100-year storm.

F.Should a bridge or large Culvert/ Arch Span ever be required it must meet all Georgia DOT standards.

G.All structures are to be precast concrete or brick construction in accordance with Georgia DOT standard details and FEMA requirements.

H.On final plats, problem lots will require a residential drainage plan and house location plan prior to obtaining a building permit. Problem lots are to be determined by the Community Development Department. Residential drainage plans shall be drawn at one-inch equals 50 feet minimum with two-foot existing and proposed topography. In addition, for each problem lot, an as-built survey of the dwelling, building or structure shall be provided to the Community Development Department prior to final inspections and the issuance of a Certificate of Occupancy. In the event the as-built survey shows the dwelling does not have proper setbacks, flood standards set forth herein Chapter 330, floor elevations or other discrepancies, the Community Development Department may deny the issuance of the Certificate of Occupancy.

I.Maximum continuous length of pipe shall be 300 feet.

J.Before any traffic over a storm drain is allowed, the developer shall provide an adequate depth and width of compacted backfill to protect the structure from damage or displacement. Any debris or silt that restricts the flow through a pipe shall be removed by the developer as often as necessary to maintain drainage.

All pipe structures shall be cleaned before the work is accepted. Any damage or erosion shall be repaired or corrected before final acceptance by the County.

K.Trench construction for storm drainage pipe shall be in accordance with State Highway Standards 1030D or 1030P.

L.Storm drainage pipe shall be bedded in No. 57 gravel, if firm soil is not available.

M.A certification of the pipe specifications for each pipe shall be required before installation.

N.Storm drainage pipes shall be sloped so as to maintain a minimum velocity of three FPS (feet per second) so that sediment will not collect.

O.State Highway Standard 1030D or 1030P shall be used in determining class (concrete) or gauge of pipe underfill, method of backfilling and pipe installation.

340-50.06 Energy Dissipation; Piped Systems and Culverts.

A.Energy dissipation devices, such as splash pads, rip-rap, stilling basins, etc., shall be provided at the outlet of every culvert and piped collection system.

(Please refer to the Manual for Erosion and Sediment Control in Georgia.)

B.Energy dissipation devices shall be located entirely within the project site, and any encroachment upon a required buffer shall be subject to review and approval. A stream buffer variance may be required.

C.When uniform, graded stone rip-rap in accordance with good engineering practices and the GSMM is used for energy dissipation, ultraviolet resistant filter fabric (200-pound test) shall be used between the stone layers.

340-50.07 Minimum Pipe Specifications.

A.Galvanized corrugated steel pipe and pipe arches shall conform to the requirements of Type I or II pipe per AASHTO M-36 for the specified dimensions and thickness. Corrugated steel pipe shall have a minimum of two ounces per square foot of zinc coating, complying with AASHTO M-218.

1.All corrugated galvanized pipe located within a street right-of-way, drainage easement, or detention facility shall be asphalt coated. All corrugated galvanized pipe that will carry a live stream, within a street right-of-way, drainage easement, or in a detention facility shall be either 1) asphalt coated with a paved invert per AASHTO M-190, Type C, or 2) asphalt coated with a concrete lining. The lining shall be plant applied so as to produce a homogeneous non-segregated lining throughout. The lining shall have a nominal thickness of ¼-inch above the crest of the corrugations.

2.See the standard details for minimum acceptable combinations of gages, diameters, and corrugation configurations for corrugated steel pipe and pipe arches (Georgia DOT 1030D or 1030P).

3.Each end of each pipe section, to be joined by a coupling band, shall have a minimum of two annular corrugations. Coupling bands shall be so constructed as to lap on an equal portion of each of the pipe sections to be connected. The connecting bands shall have a minimum of two annular corrugations and shall fully engage, over the entire pipe periphery, one corrugation on each pipe end. Bands shall be fabricated from the same material as is the pipe, and the gauges shall be as specified in Section 9.2 of AASHTO M-36.

4.Gaskets may be required as determined by the department in the field and shall be either sleeve type or 0-ring type, and shall meet the requirements for gaskets as specified in Section 9.3 of AASHTO M-36.

B.Reinforced concrete pipe shall be required at the entrance of any subdivision containing more than 100 lots. Reinforced concrete pipe shall be in not less than eight-foot joint lengths. All joints shall be bell and spigot type, using an 0-ring gasket conforming to ASTM C-443. Pipe shall be manufactured in accordance with AASHTO M-170 and/or ASIM C-6. Class of pipe and wall thickness shall be in accordance with 1030-D, Georgia DOT specification, Table No. 1.

C.Structural plate drainage structures shall conform to the following specifications:

1.Corrugated steel structural plate pipe, pipe arches, and arches shall consist of galvanized plates, bolts and nuts of the size, shape and thickness as shown on the approved plans. These structures shall conform to the requirements of AASHTO M-167.

2.Corrugated aluminum alloy structural plate pipe, pipe arches and arches shall consist of aluminum plates and galvanized bolts and nuts of the size, shape and thickness as shown on the approved plans. These structures shall conform to the requirements of AASHTO M-219.

340-50.08 Pipe Length.

A.Culverts carrying live streams shall extend to where the crown of the pipe intersects the roadway slope.

B.Pipes that do not carry live streams shall extend at least 50 feet beyond the front building setback lines, and may be required to extend farther where necessary to provide an adequately protected building site on the property. In nonresidential subdivisions, these pipes may temporarily end at the right-of-way line, but shall be extended as part of a subsequent development permit approved for the individual site.

340-50.09 Pipe Installation.

Reinforced concrete pipe, corrugated steel pipe, corrugated aluminum pipe and corrugated aluminized steel pipe shall be bedded and backfilled in the same manner.

A.Bedding. All pipe structures shall be placed on stable earth or No. 57 rock, the characteristics of which would be expected to provide long-term stability. In all live stream pipe installations, in areas of low bearing soils or nonuniform foundations, in areas where rock is encountered at the foundation level, or in other locations where conditions warrant, a minimum of six inches of No. 57 bedding is required.

B.Geotextiles or geogrids may also be required by the department in problem areas.

C.Backfilling. Backfill on all pipe installations shall be constructed using foundation backfill material Type I or Type II, as specified in Section 812.01 and 812.02 respectively, in GA. DOT Standard specifications. These materials shall be placed in layers of not more than six inches loose. Compaction of these materials shall be accomplished by hand tamping or machine tamping.

Required compaction levels are as follows:

1.Backfill within all street rights-of-way shall be compacted to 95 percent maximum density, tested using the AASHT0 Method T-99.

2.Backfill in all other areas shall be compacted to 95 percent maximum density, tested using the AASHT0 Method T-99.

D.Construction loads and minimum covers. If drainage pipe is installed prior to the completion of grading, a minimum of four feet of fill should be provided here needed to adequately protect the drainage structure during the land development phase, unless the structure itself is designed to withstand the anticipated live load during construction.

340-50.10 End Finish.

A.Headwalls or other end treatments are required on all culverts (except under residential driveways) and at the outlet of all piped collection systems.

B.Headwalls are to be precast concrete, stone masonry with reinforced concrete footings, or poured-in-place, reinforced concrete with reinforced concrete footings.

C.End treatments that conform to the slope may be masonry, pre-cast concrete end sections, reinforced poured-in-place slope collars, or grouted rip-rap.

Concrete end sections shall conform to Georgia DOT Specification 1120 and 1125. Concrete headwalls are required on all pipes.

340-50.11 Junction Boxes and Catch Basins.

Junction boxes having access to the pipe shall be constructed to meet the requirements of the Georgia Department of Transportation standards (or most current). All pipe junctions shall have junction boxes. Junction boxes and catch basins shall have metal manhole frames and lids for access.

340-50.12 Other Structures.

Natural bottom arches and box culverts may be used in accordance with the latest Standard Specifications of the Georgia DOT.

Reading grid · rebuilt for display · verify at source (p. 360) ↗

§ 340-60

Surface Drainage

340-60.01 Design Standards.

A.All new proposed channels shall be designed to carry at least the 100-year storm with one foot of freeboard.

B.Transition channels shall be provided at the inlet and outlet ends of all culverts and pipe systems, unless otherwise provided herein.

C.The maximum flow velocity at the project site's downstream property line shall not exceed the pre-developed velocity.

D.In cases of potential erosion due to irregular channel alignment, extreme velocities, or excessive slopes, a paved or rock-lined ditch shall be required, unless otherwise directed by the community development department.

E.The cross-sectional shape of channels shall be as found in the Manual for Erosion and Sediment Control in Georgia. "V" shaped cross-sections are not permitted in grassed channels.

F.If the channel will be affected by backwater from culverts, bridges, other structures or floodplains, backwater elevations shall be shown in profiles of the channel.

340-60.02 Construction Standards.

A.The channel shall be shaped to the dimensions specified on the approved plans and shall be free of overfalls, gullies or other irregularities.

B.Channels in fills shall be lined.

C.Protective cover in grassed channels shall be installed as soon as the earthwork is completed.