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N.C. Department of Environment and Natural Resources

NC Department of Environment and Natural Resources
Energy Mineral and Land Resources - Universal SW Program

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 Universal Stormwater Management Program (USMP)

This voluntary program enables local governments to adopt and administer a model stormwater program within their jurisdictions that is simpler to understand and administer while also providing an enhanced level of protection from stormwater runoff from development. Under the USMP, a local government can meet the mandates for a wide variety of different stormwater programs with just a single set of requirements.

The Universal Stormwater Management Program is unique for a number of reasons.

First, it is intended to replace a number of existing stormwater control programs, all of which have differing and, sometimes, confusing requirements, with a single, simplified set of stormwater control measures. For more information about how the USMP will simplify stormwater control requirements check out the 'Examples' tab above for before and after maps.

Secondly, the USMP will be more protective of North Carolina’s natural environment than the existing stormwater programs it will replace. So, not only will the USMP be simpler to understand and to implement, but it will also better protect North Carolina’s lakes, rivers, streams, sounds, estuaries, and coast for future generations.

Finally, the USMP is truly unique because it is optional. North Carolina’s local governments (cities and counties) that currently administer stormwater control programs within their jurisdiction will have the option of retaining their existing programs or implementing the USMP. Because the USMP is optional it will only be successful if it is able to gain support at the local level. The optional nature of this program represents a significant departure from DWQ’s normal method for implementing new environmental quality programs and provides the local communities with a greater voice in determining the environmental future of their local area. 

Why Do We Need the USMP?
DWQ realizes that there are many conflicting, overlapping stormwater programs that have been implemented throughout the State and that this has caused a tremendous amount of confusion regarding what set of post-construction requirements apply in a specific area.  In order to attempt to rectify this situation the Division has developed the USMP, which will allow a local government to implement a single set of post–construction requirements throughout its entire jurisdiction.  These requirements will be more straight forward, less confusing, easier to implement, and more protective of the natural environment.  In short, the USMP will be less confusing for local governments to implement and more effective in protecting North Carolina’s natural environment.
Guiding Principles: The following principles were used to guide the development of the Universal Stormwater Management Plan within DWQ:

  • Develop a simplified set of requirements to replace the myriad of existing, confusing stormwater programs that are now in place.
  • Develop a program that will be more protective of North Carolina’s water quality, aquatic ecosystems, and sensitive aquatic species.
  • Develop a program that will attempt to address the serious flooding issues that are currently plaguing home and business owners statewide.
  • Develop a program that is scientifically defensible.
  • Develop a program that will provide a framework for continued growth, but in an environmentally sensitive manner.
  • Develop a program that will emphasize stormwater control, not the limiting of impervious surfaces.
  • Develop a program that can be readily used by a local government to facilitate the implementation of low impact development (LID) techniques.
  • Develop a program that will adopt a decentralized approach and that will promote involvement at the local level.
  • Develop a program that will be user friendly and suitable for implementation statewide.

USMP Advantages To:
The Natural Environment: The USMP will provide greater protection to North Carolina’s rivers, streams, lakes, estuaries, sounds, and coastline than the State’s existing stormwater programs.  This will help to preserve and protect NC’s scenic waterways, recreational swimming and boating opportunities, commercial and recreational fishing, shellfishing resources, and the State’s world famous coast and sounds for future generations.  In addition, the USMP will provide a significantly enhanced level of protection to the threatened and endangered and other sensitive aquatic species that inhabit the State’s water bodies.  In short, the USMP will better protect all of North Carolina’s fresh and salt waters, from Murphy to Nags Head, while at the same time providing local governments with a management plan that is easier and simpler to administer and implement.
Local Governments: The USMP will provide local (city and county) governments the option of adopting one stormwater program and one set of post-construction requirements to replace all of their existing, overlapping programs.  This will reduce the administrative burden on these local governments and provide them with a stormwater program that is not only more straight-forward and simpler to administer and implement, but is also more protective of the natural environment.  For graphic examples of how the USMP would simplify stormwater issues in two counties within North Carolina, click on the 'Examples' tab above.
Developers and Builders: The USMP will replace the myriad of confusing, conflicting post-construction stormwater requirements that builders and developers currently must sort through with a single set of straight-forward, easily understood requirements that would apply statewide.  Remember the USMP will not establish new stormwater control requirements where none currently exist, it only replaces existing programs.  In addition, the USMP will remove most high density development limits.  The emphasis in the universal program is on controlling stormwater run-off, not trying to cap, or limit, impervious surfaces.  This will alleviate the oft-heard criticism that DWQ’s stormwater programs are “de facto” zoning.  Perhaps, most importantly, the USMP will achieve all this while providing greater protection to the natural environment at the same time.

USMP Components

The Universal Stormwater Management Plan requirements will consist of two major components: a design standard for stormwater control and a setback requirement.  These are the two minimal components that are needed for any effective stormwater control strategy.

Design Standard for Stormwater Control:

This is the element of the USMP that will mandate some form of control and treatment of stormwater run-off.  This requirement will differ slightly depending upon whether the covered activity is located in one of the 20 Coastal Counties.

Design Standard for Non-Coastal Counties:  

If the covered activity is located in one of the 80 non-Coastal Counties all residential development disturbing one acre or more and all commercial development disturbing ½ acre or more will require the control and treatment of the stormwater run-off generated by a 1” (one inch) rain event.  At a minimum, these stormwater control and treatment measures must be capable of removing 85% of the Total Suspended Solids (TSS) and must have a volume drawdown of at least 48 hours, but not more than 120 hours. *In addition, the storage volume of the stormwater control device must be discharged at a rate equal or less than the pre-development discharge rate for the 1-year, 24-hour storm. *Furthermore, new development within the critical areas of water supply watersheds is limited to an impervious surface density of no more than 36 percent.

Design Standard for Coastal Counties:  

Development activities located in one of the 20 Coastal Counties that disturb more than 10,000 square feet will require the control and treatment of the stormwater run-off generated by a 1.5” (one and one half inch) rain event.  As required for the non-Coastal Counties, these stormwater control and treatment measures must be capable of removing 85% of the Total Suspended Solids (TSS) and must have a volume drawdown of at least 48 hours, but not more than 120 hours. *In addition, the storage volume of the stormwater control device must be discharged at a rate equal or less than the pre-development discharge rate for the 1-year, 24-hour storm. *Furthermore, new development within 575 feet of shell fishing waters is limited to an impervious surface density of no more than 36 percent.

Map of Design Standard Requirement:

 Map of Design Standard

 

Setback Requirement

All effective stormwater control strategies must include some form of mandatory “setback” for impervious surfaces from the closest receiving waters.  Accordingly, the USMP will include two setback requirements: one for the Coastal Counties and one for the non-Coastal Counties.  

Setback for Non-Coastal Counties:

For those areas covered under the USMP in the 80 non-Coastal Counties no new impervious surfaces will be allowed within the 100 year floodplain (as delineated by the NC Division of Emergency Management), except for roads, paths and water dependent structures.  For those perennial and intermittent streams in the non-Coastal Counties that do not have a NC DEM delineated floodplain, no new impervious surfaces (except for roads and water dependent structures) shall be allowed within 30 feet.

What is the 100 Year Floodplain? The 100 year floodplain is also termed the 1% annual chance floodplain.  This area is delineated as the Special Flood Hazard Area on the Flood Insurance Rate Maps (FIRM) maintained by the NC Floodplain Mapping Program in the Division of Emergency Management.  FIRM maps exist for all of North Carolina and can be viewed online.  For further information on the 100 year flood plain, or to view the delineated floodplain for a specific area visit www.ncfloodmaps.com.

Why use the 100 Year Floodplain?  The 100 Year Floodplain was chosen as the setback for the non-Coastal Counties for a variety of compelling reasons.  The National Flood Insurance Program (NFIP) already mandates a number of restrictions on development in the floodplain and these restrictions have already been adopted by 98 counties and 367 municipalities in NC.  Additionally, a large infrastructure already exists within DEM to maintain and update the floodplain maps on a regular basis.  Perhaps one of the most important reasons is that restricting new impervious surfaces within the 100 year floodplain might help to alleviate the significant flooding issues that are occurring statewide with greater and greater frequency.  Furthermore, restricting development in the floodplain protects water quality, protects lives and property, and would also address a number of other significant economic and insurance issues.  In short, restricting development in the 100 year Floodplain appears to be sound public policy.     

Setback for Coastal Counties:  

For those areas where local governments adopt the USMP in the 20 Coastal Counties there will be a mandatory 30 foot setback for impervious surfaces from all surface waters of the State, except for roads, paths and water dependent structures.

Why not use the 100 Year Floodplain for the Coastal Counties?  The coastal floodplain is expansive and often covers a mile or more in many areas in the Coastal Counties.  This makes it impractical and unreasonable for use as a setback.   

Map of Setback Requirement:

 Map of Setback Requirements

 

Examples of Before & After Implementing the USMP

Durham County could be considered a “poster county” for the adoption of the Universal Stormwater Management Program. With the advent of the Phase 2 program, 100% of Durham County is presently covered by some form of stormwater control plan. Unfortunately, as depicted in the map, there are 8 different programs in place within the county. Every one of the colors on the map represents a different set of requirements (density requirements and setbacks) that must be implemented in that area. By studying the map below, it is easy to understand how this current situation creates great difficulties and confusion for local government officials, builders, developers, and private citizens. Under the USMP, Durham County would have just one program and a single set of requirements for the entire county. Furthermore, the USMP would be more protective of Durham’s natural environment than all these existing programs.  
(click the images below for a larger version)
Before:                                                                 After:
Durham before USMP                                 

In the case below, Montgomery County does not have 100% coverage of stormwater control programs, but it does have 6 different programs within its boundaries, all with differing requirements. As with Durham County, if the USMP were implemented throughout all of Montgomery County there would be only one set of stormwater requirements, as depicted in the “after USMP” slide. Note that those areas in the county that were not covered by a stormwater program “before” the USMP implementation, remain without coverage “after” USMP adoption. Adoption of the Universal Program will not establish stormwater controls where none currently exist. Furthermore, not only would the USMP simplify stormwater requirements in the county, but it would also be more protective of Montgomery County’s natural environment.
(click the images below for a larger version)
Before:                                                                 After:
                                    

Rule & Model Ordinance

USMP Rule (15A NCAC 2H .1020)

USMP Model Ordinance   (PDF)
USMP Model Ordinance Checklist   (PDF) 

 

USMP Requirements Summary


  Non-Coastal Coastal
Design Standards 1" rain 1.5" rain
Setback Requirements 100-yr floodplain 30'
Threshold for Coverage  1 acre (residential) / 0.5 acre (commercial)  10,000 sf
Impervious Surface Limits 36% (critical areas of WS waters)  36% (w/in 575' of SA waters)             

 

If you have questions or are interested in implementing the USMP in your area, please contact the Stormwater Permitting Unit.

Bill Diuguid
Stormwater Staff Planner
(919) 807-6369
bill.diuguid@ncdenr.gov
Mike Randall
Stormwater Staff Engineer
(919) 807-6374
mike.randall@ncdenr.gov

 

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