How to Do Phase II:How to Do Phase II:Post-Construction Site Runoff ControlsPost-Construction Site Runoff Controls

NC STATE UNIVERSITY

NC STATENC STATE UNIVERSITY UNIVERSITY

1. What does the permit say you have to do and what kind of help is available?

2. What BMPs can you use?

3. Discussion time

4. A new stormwater program on the horizon

Post-Construction Runoff Controls: Post-Construction Runoff Controls: Agenda for PresentationAgenda for Presentation

NC STATENC STATE UNIVERSITY UNIVERSITY

These BMPs are required:

a. Establish a post-construction stormwater management program.

b. Establish a program that includes BMPs appropriate for the MS4.

c. Establish a program to control sources of fecal coliform to the maximum extent practicable.

d. Establish nutrient sensitive waters (NSW) protection measures (for programs draining to NSW waters).

What does the permit say you have to do?What does the permit say you have to do?

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• Develop, adopt by ordinance, implement, and enforce a stormwater program runoff for new development and redevelopment.

• The ordinance must be reviewed and approved by DWQ.

a) Establish a Post-Construction StormwaterManagement Program

The UNC School of Government and the Environmental Finance Center has developed a model stormwater ordinance.

The ordinance includes a section on Illicit Discharges.

http://h2o.enr.state.nc.us/su/phase_2_mod_ord.htm

Developing a Stormwater Ordinance

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• Can combine structural and non-structural BMPs.

• Adequate long-term operation and maintenance of structural BMPs.

• Annual inspection reports of permitted structural BMPs performed by a qualified professional.

(b) Establish strategies which include BMPsappropriate for the MS4

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• Water Supply Watershed areas (WS-I - WS-IV)

• HQW and ORW watersheds

• Neuse River Basin stormwater program areas

• Tar-Pamlico River stormwater program areas

• Randleman Lake Water Supply Watershed

These areas already comply with Phase II:These areas already comply with Phase II:

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LOW DENSITY:

(A) No more than two DUs per acre or 24% built-upon area.

(B) Use vegetated conveyances to the maximum extent practicable.

HIGH DENSITY:

(A) Structural BMPs must control and treat the difference between pre- and post-development conditions for the 1-year 24-hour storm.

(B) Structural BMPs must be designed to achieve 85% average annual removal of total suspended solids.

(C) Stormwater management measures must comply with the requirements listed in 15A NCAC 2H .1008(c).

All other areas must meet or exceed this:All other areas must meet or exceed this:

DWQ has developed a draft Stormwater BMP Manual.

357 pages!

http://h2o.enr.state.nc.us/su/bmp_updates.htm

Establishing BMP Design Standards

Stormwater wetlandsBioretentionWet detention basinDry extended detention basinGrass swaleFilter stripInfiltration systemsManufactured BMPsBufferPermeable pavementRooftop runoff management Sand filter

Stormwater BMP Manual

DefinitionDescription and purposeAdvantagesDisadvantagesLocation/general characteristicsDesign CostPerformance enhancersConstruction guidelinesMonitoringMaintenance References and additional resources

Stormwater BMP Manual

• Comments on the manual are due by September 30th.

• It will take 3-6 months after September to prepare a final version.

http://h2o.enr.state.nc.us/su/bmp_updates.htm

Stormwater BMP Manual

NC STATENC STATE UNIVERSITY UNIVERSITY

Control the sources of fecal coliform to the maximum extent practicable. Develop and implement an oversight program to ensure proper operation and maintenance of septic systems. Municipalities must coordinate this program with the county health department.

(c) Establish a program to control the sources of fecal coliform to the maximum extentpracticable

This model ordinance provides language that will allow a jurisdiction to enforce maintenance obligations for septic systems.

As a start, the jurisdiction should consider how tointegrate the existing health department permit data for onsite systems into an inventory of onsite systemsin the Phase II jurisdiction.

http://h2o.enr.state.nc.us/su/phase_2_mod_ord.htm

Septic System Maintenance

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Develop, adopt, and implement an ordinance to ensure that the BMPs for reducing nutrientloading are selected. In areas where the EMC has approved an NSW Stormwater Management Program, the provisions of that program fulfill the nutrient loading reduction requirement. Develop and include a nutrient application (fertilizer and organic nutrients) management program.

(d) Establish nutrient sensitive waters (NSW)protection measures (for programs withdevelopment or redevelopment drainingto NSW waters)

Jurisdictions in the Neuse and Tar-Pamlico basins can follow their existing NSW Stormwater programs.

Other Phase II jurisdictions with NSW waters can use the Neuse and Tar-Pamlico programs as examples.

http://h2o.enr.state.nc.us/su/Neuse_NSW_Management_Strategy.htm

http://h2o.enr.state.nc.us/nps/tarpam.htm#Stormwater%20Rule

Establishing NSW Protection Measures

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Keep all built-upon areas at least 30 feet landward of perennial and intermittent surface waters (USGS and Soil Survey maps).

Have deed restrictions and protective covenants to ensure that future development activities maintain the development (or redevelopment) consistent with the approved plans.

Both low and high density developments Both low and high density developments must:must:

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Phase II local governments may develop comprehensive watershed protection plans to meet part, or all, of the requirements for post-construction stormwater.

Watershed Protection PlansWatershed Protection Plans

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Some examples:• Bioretention areas• Stormwater wetlands• Sand filters• Wet ponds• Buffers• Water reuse• Green roofs

What BMPs can you use?What BMPs can you use?

NCSU campus

Golf course in Kinston

Bioretention areas are landscaping features adapted to provide on-site treatment of storm water runoff. Surface runoff is directed into shallow, landscaped depressions.

Bioretention areas are usually designed to use many of the pollutant removal mechanisms that operate in forested ecosystems.

NC Aquarium in Dare County

Strip mall in Charlotte, NC

Stormwater wetlands are similar to wet ponds but also incorporate wetland plants into the design. As stormwater runoff flows through the wetland, pollutants are removed through settling and biological uptake.

Constructed wetland in Avery County, NC

Stormwater wetlands are fundamentally different from natural wetland systems. Stormwater wetlands are designed specifically to treat stormwater runoff, and have less biodiversity than natural wetlands.

Sand filters are good options in ultra-urban areas because they consume little space. Underground and perimeter sand filters in particular are well suited to the ultra-urban setting because they consume so surface space.

Sand filters are an excellent option to treat runoff from storm water hot spots because stormwater has no interaction with groundwater.

(Hot spots include areas where vehicles are fueled, serviced, washed or stored and places where hazardous materials are generated or stored.)

Ponds remove stormwater pollutants through settling and biological uptake.

Buffers are areas along a shoreline or stream where development is restricted or prohibited. Buffers cleanse stormwater and provide a physical barrier to protect waterways.

Water reuse involves capturing stormwater from a roof before it is discharged into a storm drain. This reduces peak flow and also reduces the need to purchase treated water.

Green roofs are simply a layer of vegetation grown on a layer of soil and drainage material on a rooftop. Rainwater is stored in the layers of drainage material for a short time before it is discharged.

NC STATENC STATE UNIVERSITY UNIVERSITY

DWQ recently initiated the USMP, which would be a

voluntary new program.

The USMP would allow a local government to implement a single set of post-construction requirements throughout its entire jurisdiction. 

The USMP would be more straightforward, easier to implement, and more protective of the natural environment. 

Universal Stormwater Management Universal Stormwater Management Program (USMP)Program (USMP)

NC STATENC STATE UNIVERSITY UNIVERSITY

The USMP would combine the following The USMP would combine the following programs:programs:NPDES Phase 2

WS-II

WS-II Critical Area

WS-III

WS-III Critical Area

WS-IV

WS-IV Critical Area

HQW – freshwater

ORW – freshwater

Coastal counties

HQW - saltwater

ORW - saltwater

Shellfishing (SA)

Neuse & Tar-Pamlico NSW

401 Certifications

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Durham CountyDurham CountyBefore & After the USMPBefore & After the USMP

NC STATENC STATE UNIVERSITY UNIVERSITY

Montgomery CountyMontgomery CountyBefore & After the USMPBefore & After the USMP