In 2001 RiverLink received a cost share grant funds from North Carolina Department of Environment and Natural Resources Department of Water Quality/319 Non Point Source Pollution Section to implement urban stormwater best management practices (BMP’s), to treat nonpoint source runoff from urban areas within the Swannanoa watershed. Non-point source pollution, such as oil from parking lots, fertilizers, pesticides, and sediments is a major threat to the health of our waterways, but by using these BMPs local residents can greatly reduce the amount of pollution that reaches our streams. The goal of these projects is to provide examples and educate residents, developers, and local governments about preventing non point source pollutants from entering our streams and rivers.
Five projects have been installed in frequented public spaces within the watershed to demonstrate a variety of measures that can be replicated. These include rain gardens/bio-filters, stormwater wetlands, vegetated swales, stream bank stabilization, rain barrels, conservation easements, and riparian plantings. Below are examples of the best management practices that are now a model for treating water quality in the Swannanoa River Watershed. In 2010, the EPA acknowledged the success of this project, as the cumulative impact improved the water quality in the Swannanoa River significantly. (Click Here for Downloadable PDF)
Stop 1. Evergreen Community Charter School
50 Bell Rd, Asheville, Please check-in at school office
The Evergreen Community Charter School project is designed to direct roof runoff from the main facility into a rain garden that can serve dual purposes. The rain garden will provide treatment of roof runoff which contains nutrients such as nitrogen, as well as enhance the educational opportunities for the science base curriculum (i.e. butterfly garden). The parking lot was sloped to capture and treat stormwater containing gas and oil contaminants in a vegetated swale into a rain garden.
Both systems are designed to capture the first inch of rainfall, which contains the vast majority of pollutants. Overflow from both of these systems, in addition to runoff from roadways will be directed to another vegetated swale to reduce the water’s velocity and treated again in a stormwater wetland. These BMPs provided tools to enhance the school curriculum, from kindergarten through 8th grade, by providing areas for environmental investigations, biological habitat, and a whole campus approach to low impact development for scientific studies.
Stop 2. Charlie Bullman Athletic Facility, Haw Creek
Bell Rd, Asheville
Sections of Haw Creek were previously straightened to accommodate development, eliminating much of the natural meanders and pool-riffle structure that occurs naturally adding oxygen to the stream. The first phase of this project reconfigured the flow pattern of a section of Haw Creek, creating a more meandering pattern to allow more pools and riffles. This not only provides for a more stable stream but also increases biodiversity of habitat for associated aquatic species. Following reconstruction, native riparian plants were planted to help stabilize the stream bank.
The second phase of this project addressed sediment runoff from the athletic fields. Sediment is the primary polluter in the French Broad River Watershed. This project reduced the need for approximately 6-8 dump truck loads of clay to maintain the ball fields. This project eliminated much of the sediment that was reaching Haw Creek by using vegetated swales and bio- retention cells to filter the sediment before it reached the stream.
This site is open to the public and an excellent educational demonstration for students from Haw Creek Elementary and Evergreen Community Charter School, within walking distance. This project provides educational signage and access points for stream related learning experiences.
The Jones property is bisected by Haw Creek and one of its tributaries. Prior to installing this project, stormwater runoff from Haw Creek Road flowed through their property unabated into Haw Creek. A stormwater wetland was installed to stop runoff flowing directly into the stream. The wetland was designed to allow water to slowly pass through the system, filtering it before discharging to Haw Creek. We planted the wetland with native wetland plants, which provide a means to breakdown pollution, and by slowing the water’s velocity, it allows for water to percolate into the soil, reducing nonpoint source pollution entering the stream.
Streambank erosion is a problem for many areas of Haw Creek where vegetation is sparse. The second phase of this project removed invasive plant species from the riparian buffer areas and then replant with native trees, shrubs and groundcovers. This stabilizes the stream bank reducing sediment loading and providing shade to help maintain cool water temperatures.
Stop 4. Azalea Park, Swannanoa River
A stream restoration
Azalea Road, Asheville
Azalea Park and the John B. Lewis Soccer Complex is a 155 acre city owned property in East Asheville on Azalea Road. It is one of the most utilized parks within the city. With eight soccer fields and a master plan that includes baseball fields, it’s important to recognize there is another side to Azalea Park that attracts fishermen, birders, runners and bikers.
The main stem of the Swannanoa River dissects the park for over a mile. Unfortunately, over time, the river has been abused. It was moved over time to make way for agriculture in the valley, its riparian buffer has been severely diminished in size, and upstream development have taken its toll by adding to the amount of stormwater runoff received. These changes over time have resulted in severe bank erosion increasing the amount of sediment input to the stream, while lack of sufficient riparian buffers has caused stream temperatures to warm in these hatchery supported trout waters. Both of these significantly impacted the ability of trout to reproduce in the Swannanoa River. RiverLink received funding from the North Carolina Clean Water Management Trust Fund to help stabilize banks and improve riparian habitat throughout Azalea Park.
RiverLink, City of Asheville, Wolf Creek Engineering, and North State Environmental through a grant from the Clean Water Management Trust Fund have restored approximately ½ mile of the river through the park. The goal of the restoration project was to improve water quality and enhance both terrestrial and aquatic habitats. Much of the instream work focused on redirection of stream flows from eroding banks and to create, a series of pools and riffles in appropriate sequences. This decreases the amount of sediment entering the stream and increases the amount of oxygen in the water. This along with the root wads and logs greatly enhances aquatic habitat. A conservation easement along both sides of the Swannanoa helps to preserve new buffer plantings and protect them until maturity. A 7.8 acre wetland is also located at Azalea Park, an old oxbow of the Swannanoa cutoff many years ago. This is an excellent sight for birders looking for migratory fowl as well as waders. This area is also protected with a conservation easement preserving it for future generations.
Currently the City of Asheville has received funding from the Army Corp of Engineers for the Lake Craig Project. This project will rehabilitate the dam under the vehicular bridge in Azalea Park and restore additional sections of the Swannanoa River through the park. The rehabilitation of the dam will re-establish the natural flow of the river and provide flood mitigation in the event of extreme flooding, like the 2004 flood. Only during extreme flooding the river would be damned, allowing flood waters to be retained, which would flood the soccer fields and other portions of the park. This would reduce downstream flooding in Biltmore Village and Asheville.
Stop 5. Black Mountain Well Lot behind Arts Center
225 W State St, Black Mountain
Two bio-retention cells (rain gardens) were installed to treat roof runoff from adjacent buildings (Black Mountain Center for the Arts and the Swannanoa Valley History Museum). This runoff is collected and filtered by percolating through the soil in the two landscaped bio-retention cells. The parking lot was graded and resurfaced to allow for stormwater runoff to flow to and be treated in a vegetated swale that functions to slow the runoff velocity. This removes sediment and pollutants from the associated parking lot (i.e., grease, oil, gas, and heavy metals like zinc, cadmium, etc.).
Stop 6. RiverWalk Park, Black Mountain, Behind Bi-Lo Grocery
205 NC Highway 9, Black Mountain
This project was designed to treat stormwater runoff from half of the Bi-Lo roof and parking area. A bio-retention (rain garden) was installed to capture and treat runoff from approximately 1.5 acres of impervious surface. This runoff contains oils, grease, gasoline and sediment. The bio-retention cell was sized to capture the first inch of rainfall and allow sediment and nutrients to settle and filter through soil for approximately 24-48 hours. This slowly releases stormwater and capture pollutants. Sediment is deposited within the bio-retention cell and pollutants are bonded to soil particles.
An additional bio-retention area and a stormwater wetland were constructed onsite to treat stormwater runoff from the adjacent railroad. Appropriate native wetland plants were used on all projects to provide for nutrient uptake and aid in the decomposition of pollutants. All of these projects were designed to both educate and demonstrate new stormwater treatment technologies for students, developers and decision makers.
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