The Franklin Park and Chesterbrook (FP&C) neighborhoods were built in the 1950s in McLean, VA. At the time, there were few if any stormwater management regulations. Over the years, house, yard, and street flooding became a nuisance and then grew into a much larger problem as development around the neighborhoods increased stormwater runoff flowing through the area.
Stormwater improvement projects (SIPs) using green stormwater infrastructure (GSI) to create green streets, such as those installed in FP&C in 2016, were an experiment in how to upgrade the infrastructure that conveys stormwater, reduce localized flooding, and improve stormwater flow and water quality in a traditional mid-century neighborhood with infill of new, larger homes and encroaching development.
“The possibility of using the green street concept for this project was enticing,” says Matt Meyers, chief, Watershed Projects Implementation Branch, Stormwater Planning Division, Department of Public Works and Environmental Services for Fairfax County, VA.
GSI is an approach to water management that protects, restores, or simulates the natural water cycle. It is economical and enhances community safety and quality of life. Effective stormwater management at the top of the watershed can reduce the need for costly restoration efforts of degraded water resources further downstream. GSI reduces and treats stormwater at its source while delivering other environmental, social, and economic benefits.
Decisions about this project date back to 2012 when the Fairfax County watershed management plans pointed out a fixable problem in the neighborhoods. Frequently, engineers and project managers follow the watershed management plans in choosing projects when funding becomes available. These specific neighborhoods were identified as potential locations for implementing SIPs to help address drainage problems, reduce stormwater runoff, and improve water quality in the nearby unnamed tributary to Little Pimmit Run, a local stream that flows to the Potomac River and on to the Chesapeake Bay. Years before the development of the FP&C neighborhoods, McLean had been a region of expansive fields, farms, natural springs, streams, and wetlands. The green street plan was to mimic and restore some of that natural hydrology.
The locale in which the project was to be installed has some unique features, including the ongoing revitalization of nearby Tysons Corner into a thriving urban “city” unto itself; the well-known vicinity of McLean where the Central Intelligence Agency is situated; and Salona, the former home of Light-Horse Harry Lee, the Revolutionary War hero.
This project would be the first of its kind for Fairfax County. A drainage area of about 34 acres was selected to implement a pilot project using green street infrastructure within the right of way. Instead of planning a traditional curb and gutter drainage system, a green street approach was implemented using state-of-the-art green infrastructure and low impact development practices to reduce stormwater runoff while creating aesthetically attractive streetscapes. The Franklin Park and Chesterbrook project lays the foundation for implementing other SIPs throughout the county. These in-neighborhood installations provide multiple program benefits to address local drainage problems, protect nearby streams, support regulatory requirements, and repair aging infrastructure.
As Meyers says, they are improving neighborhoods and protecting streams and water quality “one SIP at a time.”
The project in these well-established neighborhoods:
- upgraded more than 3,000 linear feet of green infrastructure stormwater improvements in the right-of-way sections of the roadways;
- included the construction of amended swales, infiltration trenches, underground stormwater storage chambers, permeable pavers, and driveway culverts;
- rebuilt one street (Patton Terrace) to include a crown to direct flow into the swales running along the street;
- in partnership with the Virginia Department of Transportation, resurfaced all roads throughout the project limits;
- relocated electric, gas, water, cable, and sanitary lines;
- planted native trees and shrubs to replace vegetation lost as a result of construction activity;
- reduced water pollution by 162 pounds of nitrogen per year, 22 pounds of total phosphorus per year, and 8,098 pounds of sediment per year.
“The project is about 18 months old at this time [February 2018] and, based on observations in the spring and summer of 2017, is meeting the overall project goals of improving stormwater conveyance in the community and water quality in the stream that receives runoff from the neighborhood,” says Meyers.
“Using state-of-the-art green stormwater infrastructure techniques in the FP&C neighborhoods provides the foundation for implementing other similar neighborhood improvement projects throughout the county,” he adds. Based on the success of this GSI project, the county will continue to explore opportunities to implement these practices at other sites with similar needs. More information is available at www.bit.ly/2GmQbq4.