Wetlands for Stormwater Management

July 1, 2009

Wetlands, newly constructed or restored, are playing an important role in sustainable design strategies to manage stormwater. They are integral parts of projects in both urban and open or undeveloped areas around the country. Sometimes wetlands are created to manage stormwater only onsite, but increasingly they are an option where a watershed or portion of one is involved.

F. X. Browne Inc., in Lansdale, PA, is a civil engineering firm that replaced a detention basin with a constructed wetland adjoining the parking lot in front of the firm’s headquarters. The constructed wetland measures about 0.3 acre.

The main reason for the change, company president Frank Browne says, “was to practice what we preach. We encourage clients to install constructed wetlands and natural basins to provide water-quality and habitat benefits. We wanted to have a constructed wetland that cleaned the stormwater runoff from our parking lot and created a natural habitat for wildlife.”

The project has gained recognition. “Our wetland is currently listed as a demonstration project on the Montgomery County Conservation District’s Web site,” notes Browne. “It’s also part of their regular “˜Stormwater BMP Tour.’ Sometimes a busload of people comes by to look at our wetland, and sometimes developers and planners come by to see how it looks.”

Photo: F. X. Browne Inc.
This constructed wetland replaced a detention basin.

Browne says the wetland, which was completed in 2004, “has worked great since it was constructed. We have not modified it at all. The first year, lots of invasive plants–weeds–dominated the wetland. My staff and their spouses spent a Saturday morning removing a huge amount of weeds. The weeds have a shallow root system and grow quicker than the native plants we planted. Removing the weeds allowed the native plants to grow and eventually dominate the wetland. In the second year, we only had to do some minor weeding. Since then, the native plants have done well.”

The wetland at F. X. Browne is about one foot deep and of the free water surface type. It was designed to allow stormwater from two inlets to meander through, slowing the flow of the water and maximizing detention time.

Browne says that bureaucratic hurdles to the wetland’s installation were nonexistent. “We were able to convince the township engineer that we could modify the existing basin without going through a major application or remodeling of the stormwater runoff through the wetland. The only thing we had to do was assure the engineer that the storage volume would be the same as the basin.”

The constructed wetland was funded through a $5,000 grant from the Partnership for the Delaware Estuary. The company contributed $3,000 of in-kind services for the design and permitting of the project.

Overlooked by homes in a suburban location, the constructed wetland is an attractive addition to the neighborhood. Its colorful plants attract birds, butterflies, and bees and provide both water and a refuge for frogs and other wildlife.

F. X. Browne also designed one of the first pocket wetlands in New Jersey, as a demonstration project, at Bayne Park/Christ the King Church in Harding Township. The church, as part of expanding its facilities for a new activity center, was required by the township government to upgrade its stormwater management facilities so that they included water-quality treatment. The wetland not only let the church meet the stormwater permit requirements but also added natural beauty to the urban site.

Another New Jersey project by F. X. Browne retrofitted an existing dry detention basin into a pond-wetland system to provide stormwater quantity and quality benefits. St. James Church and School in Great Swamp also needed a means to treat stormwater, particularly runoff from smaller storms.

Protecting Lake Shipshewana
Lake Shipshewana in northeastern Indiana was plagued by algal blooms, aquatic vegetation, and excessive accumulations of sediments from adjacent urban and agricultural areas. The Shipshewana Lake Improvement Association asked F. X. Browne to design two constructed wetlands for the treatment of urban stormwater and agricultural runoff.

Both constructed wetlands were designed with large sediment settling forebays to take in high runoff volume during storm events. These large forebays remove the high concentrations of sediments from incoming water, detail large amounts of runoff during major storms, and provide an even flow of water to the created downstream emergent wetland area.

Wetland vegetation in this emergent wetland area also provides additional treatment by removing finer particles of sediment that have passed through the forebays. The native plants also remove dissolved nutrients such as nitrogen and phosphorus.

Photo: JFNew
Wetlands are part of this 210-acre business park.
Photo: JFNew
Coffee Creek Center has wetland areas and a green roof.

The constructed wetland known as Sara Davis Ditch was created as an inline system that treated the entire ditch flow during dry-weather and wet-weather conditions. The watershed upstream of this wetland drains from land primarily used for agriculture. This wetland was designed to treat runoff from up to the 25-year storm.

The second constructed wetland, at the Shipshewana Elementary School, was designed to treat urban stormwater runoff from impervious areas at the school and an adjacent factory. This wetland is an offline system that treats stormwater runoff and discharges treated runoff into a branch of the Sara Davis Ditch.

The retrofit design deepened the basin to add a forebay for sediment removal and equalization. The low-flow channel was removed from the basin. Its remaining area was recontoured to create a meandering path from inlet to outlet. Different native plants were chosen for specific areas, based on water depth. The benefit of flood storage continues to be available with the constructed wetland. F. X. Browne’s water-quality specialists monitored runoff to determine pollutant removal efficacy of the retrofitted basin.

Thinking ahead to be sure that the wetland systems would function well over time, F. X. Browne added access road into the sediment forebays of both wetlands. Doing so allowed for much easier removal of accumulated sediments.

To avoid washout by larger storms, the sediment forebay of the created wetland system for agricultural runoff at the Sara Davis Ditch site has an emergency overflow channel. This channel allows excessive runoff to by pass the more sensitive emergent wetland portion of the system.

Big Haynes Creek
The Big Haynes Creek Wetland and Stormwater Pond project in Snellville, GA, sits on a tract of land that measures about 9 acres. Forebay, wetland system, and an outfall structure take up about 3.78 acres. The project is a joint venture between the Gwinnett County Department of Water Resources (45%) and the EPA (55%).

Pete Wright, director of water resources for Gwinnett County, GA, says that the main reason for the project was to “protect downstream water supply in Rockdale County.”

It also improves aquatic habitat and fits into the goals of Gwinnett County’s watershed protection plan. Wright says the EPA was “interested in ecosystem benefit, biological, and habitat.”

Although located in a Federal Emergency Management Agency (FEMA) 100-year floodplain, “the area probably floods during a 10-year event,” explains Wright. He adds that the project is “primarily designed to treat the first flush of runoff, from the first 1.2 inches of rainfall. It’s an offline facility, so a diversion structure is required to split the flow.”

Now a portion of the stormwater runoff is diverted from a tributary of Big Haynes Creek, detained, and improved through a series of water-quality treatment ponds and constructed wetlands. Wright says wetlands may have been present at this location years ago, but construction of a sanitary sewage treatment plant eliminated them and also diverted a stream.

Photo: JFNew
The Warren Golf Course before restoration
Photo: JFNew
Prairie and level spreaders at Coffee Creek

Planning for the project began in 2001. Construction started in fall 2007 and was completed in May 2008. Planning and engineering cost about $250,000. The construction cost was about $460,000.

The project was designed to treat nutrients, chemicals, oils, suspended solids, and bacteria. Four years of sampling and monitoring for water quality will begin in 2009.

The project also includes a walking path surrounding the facility, which attracts area residents for recreation. “Local residents think it’s great,” says Wright. “They have indicated a willingness to get involved in monitoring and maintenance.”

The opportunities for nature study and bird watching also draw visitors. “The Boy Scouts have built and installed bird and bat houses and have done a cleanup of the adjacent stream,” notes Wright.

He says the most difficult part of the project was “designing and constructing a functional [and] aesthetically pleasing facility.” Given the involvement of local residents, it sounds as though the design and construction teams succeeded.

Incorporating Wetlands in a Golf Course
A constructed wetland is part of an unusual golf course project done by JFNew. The Warren Golf Course is the University of Notre Dame’s golf course in Notre Dame, IN. The project was completed in December 2003 at a cost of $83,836. Its triple purpose was restoration, stream channelization, and stormwater management.

Juday Creek is one of Indiana’s few coldwater trout streams. Relocating approximately 2,800 feet of the creek to more secluded wooded areas created a better habitat for brown trout by shading the water to lower its summer temperatures. In-stream improvements included “lunker structures,” sediment traps, gravel spawning beds, log deflectors, and stream boulders.

After moving the natural stream to the wooded area, JFNew designed and constructed an artificial stream to border a fairway through the course. The recirculating, rubber-lined channel used the original, degraded path of Juday Creek and transformed it into an amenity to the golf course.

Scott Fetters, JFNew senior ecological resource specialist and project manager for the Warren Golf Course project, says the installation of the channel was the most difficult part of the project. “The channel was designed to mimic the natural bends and curves of a stream, and it was important that we kept the aesthetic appeal in mind as well,” he explains.

The biggest surprise, he says, was discovering that stormwater needed to be routed away from the project. “The project directly impacted an adjacent natural coldwater trout stream. Due to the sensitive nature of trout, a stormwater capturing system had to be installed that would redirect and cool stormwater flows.”

The constructed wetland filters oil and other pollutants in the stormwater runoff from an adjacent four-lane road. Measuring approximately 0.5 acre, it is planted with native wetland vegetation. Fetters described it as “essentially a constructed wastewater/stormwater wetland with the purpose of treating stormwater before discharging back into Juday Creek. It is 6 to 12 inches deep when holding water and [ranges from] saturated to seasonally flooded.”

Photo: JFNew
Notre Dame’s golf course after stream restoration
Photo: JFNew
Improvements at Warren Golf Course include in-stream boulders.
Photo: JFNew
Notre Dame’s Juday Creek is one of Indiana’s few coldwater trout streams.

Another improvement for managing stormwater on the site was the interception of a stormwater drain and its subsequent rerouting into a constructed wetland to reduce nonpoint-source pollution.

Initial biological monitoring of the stream by the University of Notre Dame has shown outstanding results for fish and invertebrates. The Consulting Engineers of Indiana presented JFNew and the University of Notre Dame a design award for excellence in water resources projects.

Fetters says that golf club members and other who see the course “feel that the channels are now an amenity rather than an eyesore.” Another favorable result of the project: “The university continues to use the Warren Golf Course as a positive case study for students studying wildlife ecology and restoration.”

Intech Park
Another JFNew project that includes created wetlands for stormwater management is Intech Park, a 210-acre new business development park near I-465, on the west side of Indianapolis, IN. This project was completed for $464,270 in 2003, but JFNew still does ongoing monitoring and maintenance, including prescribed burns.

Intech Park has an extensive wetlands area, with approximately 12 acres of preserved and newly created grounds. The Indiana Department of Environmental Management recognized this largest office park in the state for its “sensitivity to the environment, stewardship, and balancing nature with human needs.”

The city of Indianapolis was awarded the 2003 America in Bloom (AIB) national beautification award, beating out Boston, MA, and Rochester, NY, in the category of cities with population more than 500,000. One of the sites the AIB judges visited was Intech Park.

With its own extensive nursery of native plants, JFNew was able to suggest and supply the native species for the wetland and prairie areas on the site. The original landscaping plan was changed to use almost all native plants.

The project is an outstanding example of “parkology,” which is the marriage between technology and nature. The way in which advanced infrastructure design is combined with low-impact development (LID) and stormwater practices made the project truly “innovative and well ahead of the local curve on projects,” says Drew Bender, JFNew’s Indianapolis regional manager. “The original concept seemed like such a stretch at the time,” he recalls.

Stormwater runoff from the parking lots flows through bioswales for primary treatment. From there, it enters detention ponds and then a constructed wetland. This treatment train approach delivers what it promises: stormwater is improved above minimal required standards. That was the basis for creating the stormwater management system here.

Intech Park uses shelves of native wetland plants around the stormwater detention system. Although this practice is rarely proposed because the survival of native plants is difficult with wildly fluctuating water levels in stormwater ponds, the developer agreed to the increased maintenance costs because the results are so striking.

Asked what the most difficult parts of the project were, Bender says, “Land development projects, by their very nature, are about managing the conflicts between the necessary uses of the site. In the case of Intech Park, it was about competing land use interests of stormwater storage, stormwater treatment, natural resource protection, and green space for lifestyle uses such as walking trails.”

Intech Park resolved these inherent conflicts. “We found a balance by blending these areas into the central core area of the development: parking on the exterior edges, buildings overlooking a central green space that contains walkways and bridges connecting the campus,” explains Bender.

“Within the central green space are the stormwater storage and treatment as well as the creation of wetland areas to serve as necessary natural resource mitigation. The area is managed to maximize the site efficiency and the public use of the space,” he adds.

Interest in Intech Park remains high. “We are asked about the project, to give a talk about Intech or to participate in site tours, on a monthly basis,” notes Bender. “Local birders love the place, the users of the business park are always fascinated with work on the natural areas–especially during prescribed burning of the prairie areas–and the local development community has looked to Intech for ideas. The reaction has been almost universally positive.”

Bender characterizes Intech Park as “still one of the best demonstration projects for innovative stormwater approaches and a layering of multiple land uses. The encouraging thing is that most projects today start with a discussion of approaches like those Intech took many years ago.”

Coffee Creek Center
JFNew also used constructed wetlands for stormwater management at the Coffee Creek Center, a mixed residential and business community in Chesterton, in northwest Indiana. Completed in 2001 at a cost of $2,115,000, the development contains 640 acres. The company continues to serve as land steward, performing ongoing monitoring and maintenance.

It is also involved with the adjoining Coffee Creek Watershed Preserve. The two areas “are integral to one another,” says Steve Barker, JFNew ecological resource specialist and executive director of the Coffee Creek Preserve.

The developers insisted that the project be based on the most innovative concepts of LID and sustainability. JFNew’s Native Plant Nursery provided more than 100,000 custom-grown plants native to the prairies and wetlands of northwest Indiana.

“The response to Coffee Creek Center has been very positive, as it connects neighborhoods and people,” says Barker. “It is a frequent location for school field trips and environmental case studies.”

Coffee Creek was awarded the 2001 Merit Award of Design from the Illinois Chapter of the American Society of Landscape Architects (ILASLA). The project won the 2002 Urban Land Institute World’s “Greatest” Planned Community award.

Because Coffee Creek “was a complicated project involving multiple stakeholders, gaining support and marketing the overall concept required a lot of meetings,” says Barker. He adds, “I think a lot of restoration projects flounder because they’re really never given the PR needed to get the positive momentum behind them. In the case of Coffee Creek, we included PR from the conceptual phase forward and allowed the community time to buy into the project.

“Another reason for Coffee Creek’s success is that JFNew, along with many partners, worked to integrate sustainable concepts that complemented the project site–not competed with it,” explains Barker.

“The Coffee Creek Center project is the first in the country to prove the concepts of civil engineering without traditional expensive and destructive stormwater draining systems, while providing a wide range of shared community open space,” he says.

Coffee Creek uses a series of level spreaders for water filtration. “This innovative solution slows the rate of stormwater runoff and allows for a series of capture and filtration,” explains Barker.

The 9,000 linear feet of level spreaders capture the stormwater through an underground system of pipes. As the water level rises, excess runoff is collected in an underground pipe. When the pipe fills, the water seeps through a grate and flows over the ground, down through the restored prairie, and eventually into the wetland areas.

The wetlands area at Coffee Creek is about 40 acres. The average range of water depth is saturated to 12 inches. Native plants treat runoff and keep road salt and other contaminants out of Coffee Creek.

The pavilion restroom within the Coffee Creek Watershed Preserve “utilizes a subsurface-flow constructed wetland planted with native species selected for their effluent treatment and evapotranspiration capabilities,” explains Barker. “The treated wastewater is piped to an absorption area, or biofield, planted with deep-rooted native grasses and flowers.”

Barker says that JFNew is working to get funding to evaluate the performance of the level spreaders. “The 9,000 linear feet where the level spreaders were installed are working great, but there are other areas where the developer installed these spreaders–particularly in low-lying areas–where sediment and settlement issues are occurring, which really reduces their functionality. We are also looking at partnering with Valparaiso University to help collect and analyze such results.”

Future plans include updating the watershed management plan for the Coffee Creek watershed. Barker says that doing so might open the doors for additional Section 319 Grant funding for nonpoint-source pollution.

With the built-in advantage of increased wildlife habitat and the appeal of natural beauty for visitors and onsite employees, wetlands should increase in popularity as another LID strategy for managing stormwater. That they manage stormwater very well only adds to the increased likelihood of their inclusion in future projects.

One of those future projects is the South Los Angeles Wetlands Park, planned for 2010. A 9-acre urban site, once a maintenance yard for the Metropolitan Transit Authority, will be transformed, at a cost of $19 million, into a park with a small lake, marshes with native plants, a winding waterway, and footpaths. Stormwater runoff and its pollution will be reduced by constructed wetlands, and residents will gain an area of natural beauty.
About the Author

Margaret Buranen

Margaret Buranen writes on the environment and business.