As populations and tourism increase near our beaches, new development and increased imperviousness generates more stormwater. Houses, hotels and parking lots are commonly the first impervious surfaces that come to mind when considering development. However, with development comes the need for new or improved highway and bridge systems for residents, tourists, and commerce. As is the case in several coastal towns in NC, these highway and bridge projects are of course located near sensitive waters, and without associated stormwater treatment devices, may contribute to the detrimental effects of stormwater runoff on our coastal water resources.
In 2005, NCSU-BAE, NCDOT, and the Town of Kure Beach began collaborating to address the issue of stormwater outfalls. The ocean outfalls carry runoff from US-421 and surrounding roads, parking lots, and rooftops. NCDOT officials requested a low-cost, effective alternative to treat this runoff. The result was the design of the Dune Infiltration System (DIS), thought to be the first of its kind in the region. Borrowing from existing sand infiltration and subsurface stormwater storage practices, this system was designed to divert stormwater from the outfalls into the dunes with a bypass system for more intense storm events. Two of these systems were installed in February 2006 to capture stormwater runoff from the L avenue outfall (4.7 acre watershed) and M avenue outfall (8.5 acre watershed). Following storm event data collection in 2006, the system appeared to be very efficient in reducing stormwater flow and bacterial transport to the ocean areas. A third system is scheduled for construction in January 2009. When the K avenue DIS is complete, runoff from approximately 1800 ft of US 421, along with approximately 18 acres of nearby residential and commercial areas, will be diverted from 5 ocean outfalls with the three systems (L , M and K avenue. Initial results on the first two systems studied indicated that the systems operated efficiently in the short term, and may be a viable option for other ocean outfalls in NC or at other nearby NCDOT projects near sensitive waters. Longer-term support of monitoring and research on these systems to understand the fate and transport of bacteria in the groundwater beneath the dune system is critical before similar systems can be recommended at other coastal locations by NCDOT.
