Rocky Branch Restoration
Wake County, NC
NC State University, NC Sea Grant and the NC Stream Restoration Institute have launched a three-phase stream restoration and greenway plan to renovate Rocky Branch. Rocky Branch is an urban creek that runs more than a mile through the heart of the university campus. The restoration strives to stabilize the creek; improve water quality, aquatic and wildlife habitat; and integrate the creek into the campus environment. In addition to fixing the creek, 6000 feet of greenway path will be constructed, connecting to Pullen Park and the City of Raleigh Greenway System. Phase I, from Gorman Street to Dan Allen Drive, was completed in spring of 2002. Phase II, from Morrill Drive to Pullen Road, is slated to begin construction in summer of 2004. DOT has committed both stream and riparian buffer mitigation funds along with a Federal Transportation Enhancement Grant to the project. The project has a substantial funding commitment from the NC Department of Transportation (DOT), N.C. Clean Water Management Trust Fund, the U.S. Environmental Protection Agency, the Federal Emergency Management Agency and NC State University.
A Tumultuous Past
Rocky Branch has been impacted by more than 100 years of campus development
Floodplains were filled in and large sections of the creek were channelized
and culverted. NC State constitutes a large portion of the creek's two-square-mile
watershed, which includes roads, parking lots, buildings and other impervious
surfaces. Stormwater runoff from impervious surfaces caused the stream
to erode and cut a deep channel apart from its traditional floodplain.
Trees were undermined and streambanks collapsed as the erosion undermined
them. Rock and concrete were used to armor the streambanks to protect
utilities, providing no benefit to aquatic habitat.
The stream has been polluted with urban waste, and its eroding streambanks deposited large volumes of sediment downstream into Walnut Creek and the Neuse River. Algal blooms occur periodically in the creek. In 1978, the Division of Water Quality classified Rocky Branch as the state's most polluted urban stream based on the lack of aquatic fauna.
The Road to Recovery
Using natural channel design techniques, the restoration plan allows the
stream to meander through a newly created floodplain. The new vegetation
provides habitat, cover and food for wildlife. Natural materials (rootwads,
logs and willow branches) are used to stabilize the streambanks. A greenway
path along the restored creek provides a transportation alternative and
brings people close to the creek. Future phases will create a network
of public green space by building a pedestrian underpass for Pullen Road
that connects to Pullen Park and the Raleigh Greenway System. Interpretative
signs will be installed along the greenway to explain the restoration
concepts.
The restoration design must consider numerous lateral restrictions, including underground utilities, overhead power lines, parking lots, and tennis courts. Phase I relocated 1100 feet of sewer line, removed 7100-square-feet of parking lot and replaced two culverts. In addition sixteen stormwater outfalls were equipped with energy dissipaters designed to reduce the erosiveness of storm flows entering the stream. Given its urban location, Rocky Branch challenged NC State to coordinate invasive construction operations while maintaining campus life, walkways and normal operations. The contingency plans included a temporary steel structural support to maintain steam, water and fiber optic services, as well as temporary roads to support student move-in during August.
The landscape adjacent to the greenway path was designed to create scenic views of the creek and to provide a more graceful transition between the natural and urban environment. Plantings include native trees, shrubs and grasses that will increase the width of the forested buffer zone and in many cases create a wildlife corridor. Once established, a tree canopy will provide shade over the creek. Clusters of understory vegetation have been connected throughout the corridor to provide food and cover.
In addition to restoring the creek, enhancing the riparian buffer and installing the greenway path, stormwater controls were installed in the watershed to filter and treat stormwater runoff before it enters the creek. A stormwater pond and three bioretention areas were installed with the first phase of the project. The stormwater pond has a12-foot wide aquatic wetland bench. The bioretention areas, also known as rain gardens, were designed to filter and detain stormwater runoff from campus roads and parking lots. Curb cuts divert water from Sullivan Drive through two rain gardens adjacent to the greenway path.
Phases II and III of the project
will include the upgrade of two stream culverts to allow safe passage
for pedestrians and wildlife beneath major thoroughfares. The culverts
will also increase floodplain area, thus improving stream stability. The
culverts will not only protect pedestrians, but also embrace the opportunity
to bring people closer to the stream and improve wildlife connectivity.
Phase III currently proposes to "day-light" a minimum of 250-feet
of stream. The stream will be removed from culvert pipes and recreated
to have a streambed and a small floodplain. This unearthing of the channel
will further increase both visibility and access to the stream.
- $1.123 million Clean Water Management Trust Fund grant for stream restoration, the installation of stormwater filtration systems to treat runoff that drains into the creek, and to monitor the creek’s stability.
- $55,700 Environmental Protection Agency 319 grant from the NC Department of Environment and Natural Resources to repair the upstream portion of Rocky Branch Creek, add an educational campus greenway, and survey the stream's invertebrate inhabitants
- $500,000 commitment by the university to help restore the stream and construct the greenway
- $120,000 allocation from FEMA for Hurricane Fran damage to the stream
- $1,688,500 federal transportation enhancement (TEA 21) grant from NC Department of Transportation for greenway path construction and landscaping and the expansion of two roadway crossings.
An additional $1.1 million is needed to complete the stream
restoration component of the project.
- Facilities Planning and Design
- Facilities Operations
- The School of Design
- Marine Earth and Atmospheric Sciences department
- Zoology department
- NCSU Water Quality Group
- NC Cooperative Extension.
