RALEIGH – Officials are seeking public comments on a proposed change to state water quality guidelines that would allow developers in the entire state to earn stormwater credits if they use permeable pavement on projects rather than asphalt or concrete.
Currently, only development projects in eastern North Carolina are eligible for stormwater treatment credits when permeable pavement is properly designed and installed. The change being proposed by the N.C. Division of Water Quality would make projects that properly use permeable pavement anywhere in North Carolina eligible for the credits.
Permeable pavement is an alternative to concrete and asphalt that allows stormwater to infiltrate through its surface and soak into the ground or be stored and released. When it’s compared to asphalt or concrete, properly used permeable pavement can reduce the volume of stormwater discharged from developed areas by as much as 90 percent. That’s important because stormwater and the sediment it carries represent North Carolina’s No. 1 source of water pollution.
Construction permits issued by the N.C. Division of Water Quality often require developers to put in place measures to offset the impacts that a project will have on streams and wetlands. The change to the state water quality guidelines would give developers in the entire state credit for using permeable pavement as one measure to offset environmental impacts.
The proposed change from the state Division of Water Quality takes into account the different soil types found in the state and gives more credit for properly designed and constructed systems in sandy soils than for those in clay soils. Proper maintenance of the permeable pavement is critical to continued benefits from its installation. Without proper maintenance, sediments can clog the pores that allow infiltration and compromise the pavement’s effectiveness.
The proposed change came about as a result of new research on the effectiveness of permeable pavement in North Carolina soils. Until recently, concerns about permeable pavement’s ability to provide long-term stormwater treatment limited its use as a management device to those areas such as the Sandhills and Coastal Plains, both of which have sandy soils with high infiltration rates. However, research conducted at N.C. State University has shown that permeable pavement can be used successfully to improve stormwater treatment in most soil types as long as the paved areas are properly designed, installed and maintained.
Research has shown that permeable pavement removes more pollutants than many other treatment practices. It also recharges more water into the ground, aquifers and streams. In addition to its environmental benefits, permeable pavement can reduce development costs. That’s because developers who properly design and install permeable pavement may be able to reduce costs associated with stormwater treatment and qualify for higher-density development.
People who would like more information about the N.C. Division of Water Quality’s proposed change, can find that information at www.ncwaterquality.org. Click on the Permeable Pavement Revisions link on the left side of the page under Hot Topics. People who wish to comment on the proposed change have until July 31.
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