Sheriff's Community Labor Force Plays Role in County's Low Impact Development Practices
June 6, 2012
The Fairfax County Sheriff's Office is ramping up its efforts to be part of the county's environmental consciousness. The Sheriff's Community Labor Force, made up of well-supervised low-risk inmates, is restoring and maintaining stormwater management structures in partnership with the county's Maintenance and Stormwater Management Division.
What makes this effort unique is that the stormwater structures are not the typical curbs and gutters, concrete ditches and underground pipes that usually handle the runoff from rain and snowmelt. Instead, the Community Labor Force is taking care of low impact development (LID) practices that manage stormwater runoff as close to its source as possible.
Stormwater is the rainfall and snowmelt that keeps gardens green, streams and rivers flowing, and wells from running dry. But when there is too much of a good thing, causing the stormwater to run off the surface rather than to infiltrate it, then erosion, pollution and flooding can occur.
Infiltration of stormwater depends mostly on the type of land cover. Stormwater falling on trees, plants and mulch is slowed, filtered and absorbed as it makes its way into the ground or to the nearest stream. In contrast, impervious (nonporous) surfaces such as roof tops, roads, sidewalks and parking lots send stormwater rushing to the nearest ditch or storm drain, which then delivers the runoff to a nearby stream. When the runoff reaches the stream, the fast flowing and large volume scours away the stream banks, thereby widening and deepening the channel. The dislodged sediment from the banks smothers small aquatic life and also is deposited in downstream ponds, lakes and rivers.
Along the way, stormwater runoff picks up pollutants, such as heavy metals, gas, oil, sediment and nutrients. An excess of nutrients creates oxygen-depleted "dead zones" in local waterways, including the Potomac River and the Chesapeake Bay.
Rain gardens, green roofs, vegetative swales and tree box filters are some of the most widely-known low impact development practices. Not only do these structures lessen the volume and slow down the flow of stormwater into nearby streams and rivers, they also cut down on the pollutants that otherwise would be picked up by the runoff and deposited into the water bodies.
Rain garden before CLF cleanup
Rain garden after CLF cleanup
Dry pond after CLF cleanup
- A rain garden can be a shallow landscaped basin (often what is installed by homeowners) or a larger excavated area backfilled with gravel and a special soil mix before it is topped with a layer of mulch and planted (usually the stormwater facilities the Community Labor Force helps to maintain). A rain garden pools stormwater runoff on its surface, allowing it to slowly infiltrate the soil. The rain garden is planted with native plants that tolerate periodic flooding. Native plants need less maintenance, absorb some of the stormwater and pollutants, and provide habitat and food for native birds and other critters.
- A green roof is a roof that is partially or completely covered with low maintenance, succulent vegetation that is planted over a waterproof membrane. Green roofs absorb stormwater and also reduce the surface temperature of the roof, thereby reducing the energy costs inside the building.
- A vegetative swale is a channel lined with plants that slow the flow of water and absorb pollutants. It replaces the more traditional concrete channel or curbs and gutters.
- A tree box filter collects runoff in a container under a tree; it is filled with energy dissipating stone, a three-inch layer of mulch and a sand/gravel mixture. The treated stormwater flows out of the box filter into a drain system or the surrounding soil.
Rain gardens, like any landscaping feature, need maintenance—weeding, trash removal and attention to the plants. Before tackling the county’s stormwater management structures, Sheriff’s deputies in the Community Labor Force met with Fairfax County ecologist Chris Mueller for on-the-job training in a rain garden. Mueller explained the do's and don'ts of rain garden maintenance. He identified native plants and each of the plant groupings. Before too long, the deputies were instructing and directing their inmate labor crews in and around the rain garden. Because each rain garden is unique, Mueller continues to meet with the Community Labor Force at various locations for area specific training, particularly to identify which plants stay and which ones go. He also provides guidance on mowing and trimming, mulching levels, and drain cleaning specific to each rain garden.
Currently, the Community Labor Force is maintaining 21 rain gardens, 16 tree filters, one vegetative swale and one green roof. Each gets serviced about once per month.
The Community Labor Force recently added 1,200 stormwater management dry ponds to its maintenance duties. Each pond gets serviced about twice per year. While the term "dry pond" sounds like an oxymoron, it refers to a basin or depression that detains, or slows, the flow of water for short periods of time and is dry between rain storms. Dry ponds may go completely unnoticed in the landscape. Whether wet or dry, stormwater management ponds serve an important purpose. They control the volume of runoff by releasing it over time. Every county pond has a pipe outlet, generally sized to hold and release the stormwater over a 48-72 hour period in a heavy storm and less time in light precipitation. If an increase in runoff is not controlled in this manner, it may cause downstream flooding and stream bed and bank erosion.
If you see the Sheriff's Office Community Labor Force in your neighborhood, say "hey" to the sheriff’s deputy and the labor crew. They are working to make Fairfax County a greener place to live, work and visit.
For more information about the Sheriff’s Office Community Labor Force, send an email or call 703-246-3210 (TTY 711 for hearing impaired).
For more information about stormwater management structures, including rain gardens and green roofs, contact the Northern Virginia Soil and Water Conservation District or the Fairfax County Department of Public Works and Environmental Services.