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How to Do Phase II: Post-Construction Site Runoff Controls. NC STATE UNIVERSITY. Post-Construction Runoff Controls: Agenda for Presentation. 1. What does the permit say you have to do and what kind of help is available? 2. What BMPs can you use? Discussion time
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Post-Construction Site Runoff Controls
NC STATE UNIVERSITY
Post-Construction Runoff Controls: Agenda for Presentation
The UNC School of Government and the Environmental Finance Center has developed a model stormwater ordinance.
The ordinance includes a section on Illicit Discharges.
appropriate for the MS4
(A) No more than two DUs per acre or 24% built-upon area.
(B) Use vegetated conveyances to the maximum extent practicable.
(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).
DWQ has developed a draft Stormwater BMP Manual.
Wet detention basin
Dry extended detention basin
Rooftop runoff management
Description and purpose
References and additional resources
(c) Establish a program to control the sources of fecal coliform to the maximum extent
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.
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 to
integrate the existing health department permit data for onsite systems into an inventory of onsite systems
in the Phase II jurisdiction.
protection measures (for programs with
development or redevelopment draining
to NSW waters)
Develop, adopt, and implement an ordinance to ensure that the BMPs for reducing nutrient
loading 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.
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.
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.
Phase II local governments may develop comprehensive watershed protection plans to meet part, or all, of the requirements for post-construction stormwater.
Bioretention areas are landscaping features adapted to provide on-site treatment of storm water runoff. Surface runoff is directed into shallow, landscaped depressions.
Golf course in Kinston
Bioretention areas are usually designed to use many of the pollutant removal mechanisms that operate in forested ecosystems.
Strip mall in Charlotte, NC
NC Aquarium in Dare County
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.
Before & After the USMP
Before & After the USMP