Urban Stream Restoration in the Nick of Time
With time running out to use precious funding from the U.S. EPA, the Delaware Department of Natural Resources and Environmental Control turned to Biohabitats to prepare final restoration designs for this highly degraded, ephemeral stream. Located in Middletown, Delaware, smack dab in between the cities of Dover and Wilmington, the urban stream is severely incised and downcut, and is within a watershed that appears on the State’s list of Impaired Waters. Previous, failed efforts to stabilize the stream with rip rap and concrete caused further degradation. After assessing more than 800 linear feet of stream, our team went immediately to work on the design, which will raise the streambed and reconnect it with the floodplain to help improve channel stability and water quality. The design also includes a side channel wetland for capturing and treating the first flush of stormwater. Since the stream runs through a city park and near a public school, it will likely provide recreational and educational opportunities for the community as well.
Opening the Door to an Outdoor Classroom
Over the last year Biohabitats and its affiliated companies have been privileged to work with an outstanding educational institution committed to integrating natural capitol and ecosystem benefits fully into campus life. Episcopal High School in Alexandria, Virginia, a residential secondary school located within the Washington, DC beltway, recognized that they possessed a unique asset in the form of a 35 acre woodland parcel, “Laird Acres.” Blessed by benign neglect for decades, this woodland pursued a very different landscape trajectory than the rest of the surrounding pasture and agricultural cropland. Eighty years, while a mere blink to a forest, witnessed the complete obliteration of a cultural landscape that had existed for generations and its replacement with intense urbanization. Like an island in a rapidly eroding streambed, Laird Acres became more unique, and valuable, with each successive development wave. The threat of an eventual storm surge washing over Laird and replacing conifers with condos led the school to undertake the development of a comprehensive woodland management plan. More than just a vegetation assessment and tree management prescription, this document needed to identify a common vision for the woodland and develop a sustainable, regenerative approach to incorporating this green infrastructure into the campus. Recognizing that people will only protect what they value, Episcopal High School has embarked on a mission of bringing people back to the woods for “recreational, educational, and inspirational” purposes.
The School turned to Biohabitats to develop the plan through a combination of field assessment and vision sessions. Documenting the forest composition, successional processes, and ecological values associated with Laird created the foundation for a sound management structure. Community and stakeholder values and goals form the framework. Brought together, these two elements allowed the school to identify a series of initiatives designed to assure the continued existence of Laird as a woodland system. Our team recently completed several projects identified in the management plan. Woodland edges are being planted to soften the transition from manicured turf into forest and to buffer the tree-toppling effects of western winds. Invasive plants are being treated within an ecological restoration context, an approach where selective intervention moves well beyond “weed spraying.” Perhaps most dramatic of all, renovations are complete on an updated trail system designed to engage people with the woods. Using an organic substrate of wood chips that both protects the forest floor and the soles of runners feet, the trail system penetrates deep into the forest and allows the visitor to truly experience the diversity of life present in this refuge. Routed to avoid tree loss and disruption, this loop system has a central entrance beckoning to both students and faculty. It identifies Laird Acres as a destination in itself, an infrastructure element as valuable as the science building, library or gym. We applaud the commitment of Episcopal High School to reconnecting this natural landscape with the rest of the campus. True regenerative design strives to create this sense of place and bridge the false dichotomy between the “natural” and “artificial” landscape by working with and celebrating the biological needs of the rest of the planet’s biota. Opening the door to the woods is a large step in the right direction.
Reconstructing Natural History at Mount Vernon
While we always enjoy seeing our ecological restoration designs go to construction, we are particularly goose bumpy about this one. After all, it’s not every day we get to restore a stream that runs through property once owned by our nation’s first President. An outfall occurring from a culvert under the George Washington Parkway had caused damage to a section of a tributary of Little Hunting Creek (a tributary of the Potomac River). Incised more than five feet, the stream was extremely unstable and had become a sediment source. Our goal in this project for the Fairfax County, Virginia Department of Public Works and Environmental Services, was to stabilize the channel while minimizing intervention. This popular, historic site is now owned and maintained by the Mount Vernon Ladies’ Association, the oldest historic preservation organization in the U.S., and the National Park Service.
With the site’s unique archaeological heritage, it was imperative that the design minimize disturbance. The project also presented design challenges typical of low-order Mid-Atlantic stream restoration projects. First, the channel downcut through existing Coastal Plain deposits and enlarged via bank erosion. Second, since the channel originates from a stormwater outfall, sediment supply to the channel was limited to that originating from bed and bank erosion. Third, though the active channel is small, the steep channel gradient resulted in high shear stresses during flood events. Given these archaeological and geomorphic contexts, the restoration approach included maintaining existing channel alignment while raising the channel back to the elevation of its former banks. A step-pool and cascade morphology was used to improve channel stability and function while mimicking the natural features of a small, steep channel. Structure rocks and bed material were sized to withstand predicted shear stresses given “threshold” sediment transport conditions. Special care was taken along large trees to raise the bed elevation to match existing root masses. Riparian plantings include native trees, shrubs, and herbaceous species to promote root cohesion, enhance habitat, and provide organic input to the stream system. Construction will be complete at the end of this month.
Lake Restoration Along Historic American Parkway
The 807-acre Bronx River Parkway Reservation is Westchester County, New York’s oldest park. Initially created as an adjunct to the famous Bronx River Parkway in 1925, the park runs through the heart of southern Westchester County, and includes a series of on-river lakes. One such lake, Crestwood Lake, has been filling in with sediment at a rapid rate, due to upstream development and the transport of legacy sediment. In an effort to reduce the frequency of dredging while also enhancing the Lake’s ecological functions and preserving its cultural and historical significance, the Westchester County Department of Planning turned to Biohabitats. Our team is currently developing conceptual restoration options, including those that look at the feasibility of providing the added benefit of flood control.
More Opportunities for Restoration in Northern Virginia
After participating in a study of the Cub Run and Bull Run watersheds in Fairfax County, Virginia, our team was called upon by the County’s Department of Public Works and Stormwater Management to conduct an assessment and prioritization of restoration opportunities within the watersheds. Major expansion of Dulles International Airport, with proposed increases of hundreds of acres of imperious area and piping of miles of existing stream channels, portions of which drain into the Cub Run and Horsepen Creek watersheds, increased the need for focus on the channels conveying surface runoff in our project area. Due to a legacy of hydrologic alteration from urban and suburban development (e.g., channel erosion from increased storm flows, channel downcutting, lowering of local groundwater, isolation of the adjacent floodplains, reduction of seasonal stream base flow, etc.), many of streams in the Cub Run, Bull Run and Horsepen Creeks watersheds in Fairfax County, Virginia are deeply incised. Biohabitats developed a restoration concept that involves raising the inverts of the channel to achieve hydrologic reconnection to the historic floodplains, restoring the floodplain functions (e.g., floodflow attenuation, water quality benefits, etc.), restoring the wetland hydrology of the forested wetland floodplain habitat, and controlling invasive vegetation. Using GIS analysis and field reconnaissance, we identified and ranked areas appropriate for this type of restoration approach, and developed initial concepts for those areas. We’re also helping the County to engage the Army Corps of Engineers and Virginia Department of Environmental Quality to further develop and begin to implement the priority restoration projects. We are also working with the County to create a mitigation banking instrument to enable these sites to be used for future mitigation projects.
If you plan to head to Denver for Rally 2007: The National Land Conservation Conference, keep an eye out for Biohabitats Southern Rocky Mountain Bioregion leader, Claudia Browne.
Join Biohabitats president Keith Bowers at the 2007 ASLA Annual Conference – Designing with Nature: The Art of Balance
Kevin Heatley will speak on invasive species at the Association of Zoological Horticulture’s Annual Meeting
Biohabitats senior ecologist Joe Berg will present “A New Paradigm: The Benefits of Integrated Stream and Wetland Stormwater Outfall Practices” at the 10th Wetlands and Watersheds Workshop in Ocean City, MD.
Biohabitats Great Lakes Bioregion leader Ivette Bolender and president Keith Bowers will head to Duluth, Minnesota to present “The Hog Island and Newton Creek Ecological Restoration Master Plan: A Template for Restoration in a Lake Superior Area of Concern” at the Making A Great Lake Superior Conference. A week later, Keith and Ivette will be in Chicago to attend Greenbuild. This year’s conference will explore “Accelerating Green Communities.”
If you plan to attend the Mid-Atlantic Stream Restoration Conference be sure to stop by the Biohabitats booth and say hello to senior ecologist Joe Berg and environmental scientists Mike Thompson and Suzanne Hoehne.
After spending eight years as a water resources engineer in the public works department of a major civil engineering firm, Doug Streaker felt the pull toward more ecologically focused work and joined Biohabitats. A welcome addition to our team, Doug brings extensive experience in stream restoration assessment and design, watershed studies and innovative stormwater management design. He boasts a lengthy skill set, which includes proficiency in numerous GIS, CADD and hydrologic and hydraulic modeling software packages. When he’s not at work, this Lancaster, Pennsylvania native can probably be found outside hiking, paddling, playing ultimate Frisbee, photographing nature, or strumming on his guitar, banjo or bass. Doug holds his B.S. in biological systems engineering from Virginia Tech. Equally impressive, he earned the official title of “Corn Eating Champion” when he once polished off 15 ears in 30 minutes. Shucks, that’s a lot of corn.