- May 2016 - The city held a ribbon cutting for
the Alexandria portion of the Four Mile Run Project, officially opening the wetlands, parking lot and trail. The pink flags will remain in the wetlands for one year in order to deter geese as plants establish.
- June 2016 - The city contracted an engineering firm to design a bridge that will connect the wetlands to the softball field.
- September 2016 - Arlington County begins a Four Mile Run Stream Bank Restoration Project. Click here for more information: https://projects.arlingtonva.us/projects/four-mile-run-stream-restoration/
Four Mile Run Overview
Four Mile Run is a nine-mile long stream located in a highly urbanized area in Northern Virginia. Its 19.6 square mile watershed covers portions of Arlington and Fairfax Counties and the Cities of Alexandria and Falls Church. The lower portion of Four Mile Run, from I-395 at the upstream end to National Airport at the mouth, is contained in a hardened flood control channel and marks a rough boundary between Arlington County and the City of Alexandria. Along this stretch of Four Mile Run are neighborhoods, commercial districts, and some industrial facilities, including the Arlington County Water Pollution Control Plant. Because of the highly urbanized nature of the Four Mile Run watershed, the neighborhoods and businesses adjacent to this portion of the run were subjected to repeated flooding, beginning in the 1940s. In response to this flooding, the municipalities forged a partnership with the US Army Corps of Engineers (USACE) to build a flood-control channel in the lower portion of Four Mile Run. Construction of that channel took place during the 1970s and early 1980s. Since its completion over twenty years ago, the channel has safely conveyed the high storm flows through the two jurisdictions and prevented flooding.
Four Mile Run Restoration Project
The restoration project is a joint venture to restore 2.3 miles of a highly degraded stream within the hardened flood control channel - or levee corridor - of Four Mile Run. Through a partnership of efforts and funds, residents and staff from Alexandria, Arlington, the Northern Virginia Regional Comission (NVRC), the US Environmental Protection Agency, the US Army Corps of Engineers and Congressman Jim Moran's office have been working collaboratively to successfully implement the framework set forth by the Four Mile Run Restoration Master Plan (2006).
The Four Mile Run Design Guidelines, as approved by Arlington County and the Alexandria Planning Commission in September 2009, were created to govern the aesthetic and physical components of the stream corridor. The Design Guidelines include recommendations that will guide trails and paths, stream crossing, bridges, lighting, building orientation and setbacks, benches, the proposed Nature Center, and vegetation; among other physical components.
- Staff report
- Available for download as separate chapters on NVRC's website
- Full document (this is a very large file)
A citizen-led Joint Task Force (JTF), with representatives appointed by the chief administrative officers of each jurisdiction, examines project alternatives, gathers public input, and provides recommendations to the project’s Agency Coordination Group (ACG). Members of the ACG represent the various local, regional, and federal government agencies involved in the planning and implementation of the restoration effort. A list of JTF members and an archive of meeting summaries are available on the project website.
NVRC is facilitating the
administration of the Four Mile Run Restoration Project and additional
information related to the project can be found on their website.
Tidal Restoration Demonstration Project
The Tidal Restoration Demonstration Project works to restore the banks of the shoreline and wetlands in the channelized portion of Four Mile Run, from Mt. Vernon Avenue to Route 1.
A major objective of the Master Plan is to reestablish the vegetation that once lined the stream and existed in the lowland wetlands areas but has since disappeared or been colonized by invasive species. The Four Mile Run Wetlands Restoration, completed in December 2015, plays a prominent role in regional efforts to protect the Potomac River basin and the endangered Chesapeake Bay by restoring the natural cycles and diversity of habitat to support a variety of life in and along these waterways. The Restoration project restored the historic 2-acre tidal wetland where the water levels fluctuate with the daily tidal cycle along Four Mile Run. Wetlands were once common along all the tidal tributaries and protected shorelines of the Potomac River, but many tidal wetlands have been lost to urban and suburban shoreline development. The upland trail serves as a buffer between the tidal wetland and the existing forested wetland. Wetlands are important to both wildlife and humans and provide a connection between aquatic and terrestrial habitats that is important to fish and aquatic organisms as well as many birds and terrestrial animals. Tidal wetlands are important nurseries and foraging areas for fish, waterfowl and other birds, reptiles and mammals. Wetlands also benefit humans by improving water quality and storing floodwaters.
Tidal wetlands can be divided into different plant zones based on fluctuating water depths. This created wetland includes a low marsh zone and a high marsh zone and is surrounded by an upland meadow.
The low marsh zone is typically flooded for more than ½ of the day by water up to several feet deep. This extensive inundation limits the diversity of plants that can grow in this zone. Common low marsh plants, such as the yellow pond-lily (Nuphar advena) and the arrow arum (Peltandra virginica), provide cover for juvenile and adult fish and other aquatic species. The ten-foot tall, emergent grass, wild rice (Zizania aquatica), was an important food crop for Native Americans and remains an important food source for water fowl. The prolonged and deep inundation by tidal waters allows the low marsh vegetation to take up nutrients and trap sediments from the flood waters.
The high marsh is flooded less than ½ the day by water that is typically less than one-foot deep. The vegetation community is composed of many species that form a dense cover. Grasses, sedges and rushes, such as rice cut grass (Leersia oryzoides), soft rush (Juncus effusus), woolgrass (Scirpus cyperinus) and three-square (Schoenoplectus pungens) are common in the high marsh, as are forbs such as rose mallow (Hibiscus laevis), broadleaf arrowhead (Sagittaria latifolia), and swamp milkweed (Asclepias incarnata). The diverse plant community provides habitat to many insects, amphibians, birds and other animals. The high marsh is not inundated for long periods, but the dense vegetation is efficient at capturing sediments and pollutants from floodwaters.
The upland meadow is a perennial herb community that is not regularly flooded. It provides terrestrial habitat utilized by many of the same species that live in the wetland; frogs forage in the meadow and turtles nest here. A mix of grass species and flowering herbs, such as black-eyed Susan (Rudbeckia hirta) and goldenrods (Solidago spp.), provide foraging and nesting habitat for many song birds and provide nectar and act as larval hosts for native pollinators while providing cover habitat for other wildlife. The meadow vegetation also provides soil stabilization and erosion control.
The City also renovated the parking lot at Mount Vernon Avenue. The parking lot renovation included twenty marked parking spaces on permeable pavers, a turnaround for drop-off and pick up, a rain garden and additional trees.
Four Mile Run Bridge Demolition
Construction on the westernmost bridge between Route 1 and Potomac Avenue is complete. The removal and subsequent dedication of land is part of the The Four Mile Run Restoration Master Plan, endorsed by the Four Mile Run Joint Task Force and ultimately adopted by both the Alexandria City Council and the Arlington County Board in 2006. The removal of the bridge is part of a large, ecological plan that provides regional benefits as intended by the Commonwealth’s Chesapeake Bay requirements, the City’s Water Quality Supplement to the City of Alexandria Master Plan, as well as the City’s Eco-City Alexandria initiative, and the approved Eco-City Environmental Charter and Action Plan. Improving the existing streams and adjacent buffer areas increases the natural light levels within the Run, improving the stream’s natural ability for pollutant removal.
Pedestrian/Cyclist Bridge Competition
The City of Alexandria, Arlington County, in partnership with the Northern Virginia Regional Commission, announced the signing of a contract for the design of the Four Mile Run Pedestrian-Cyclist Bridge based on the March 2010 Bridge Design Competition and Call for Qualifications. This step began the formal design and technical engineering process for this bridge envisioned in the
Four Mile Run Restoration Master Plan.
Since the design competition, Arlington, Alexandria, NVRC and the Virginia Department of Transportation worked to develop the Scope of Services for the design and engineering. Understanding the constraints of the project, timeframe, budget and scope, the 2nd ranked team entered into an agreement for design services. The jurisdictions began the design process with Buro Happold and member of the second ranked team of Olin/Buro Happold/Explorations Architecture/ L’Observatoire International. A presentation of their work and the competition renderings of their concept can be viewed on the NVRC website.