Wednesday, July 10, 2002
On Wednesday, July 31 Reston Association will hold a public hearing to discuss a $3.1 million, 10-year watershed master plan, developed by Reston Association staff along with GKY and Associates, a local environmental consultant company.
Using several different approaches, from installing rain barrels instead of standard rain gutters to completely rebuilding stream banks, the plan is designed to increase water quality and reduce erosion throughout Reston. The first phase of the plan, according to Reston Association watershed manager Diana Saccone, includes public outreach work and three conceptual design projects, in three different areas of Reston.
For the public outreach portion of the plan, Reston Association is asking homeowners to build drainage systems which help stormwater seep into the ground. Many French drain systems, which funnel water directly onto a dirt or asphalt surface, create large amounts of runoff water in Reston’s streams. As more water runs into the streams it picks up oil, chemicals and sediment, reducing stream quality. Too much stream water also contributes to erosion. As more water enters a stream, the stream moves faster and cuts into the stream banks. This destroys trees, trails, and even exposes underground pipelines in some places.
By diverting downspouts into water barrels, instead of onto the bare ground, homeowners can reduce the amount of runoff water they create.
"A lot of people connect hoses to the water barrels, so there is a slow drip," Saccone said.
Right now water barrels are not allowed under Reston Association’s covenants, but staff are working with the Design Review Board to get that changed. Another method to reduce runoff, which is currently allowed, is to bury gravel and rocks in the patch of earth where a rainspout deposits water. This makes it easier for water to be penetrate the earth’s surface, and to be absorbed.
Other low impact development techniques, recommended by the watershed plan, include the use of planter boxes, rooftop gardens, porous pavement systems and soil aeration.
AND WHILE SUCH low impact development techniques are designed to be used around individual homes, the plan also includes projects at stream sites. The plan proposes three pilot projects, beginning this year, to help guide the rest of the plan. The three projects will cost $205,000, and Reston Association will study them to determine which methods work best to stifle water runoff.
One project is at a stream area between Wheelwright Court and Gunsmith Square. An influx of sediment has shrunk and clogged the small stream, which is connected to Snakeden Branch Stream, the most degraded stream in Reston. The watershed plan recommends timber check dams, to limit the amount of water flowing into the Wheelwright-Gunsmith stream.
Another project focuses on Snakeden’s main branch, located between the Reston Community Center at Hunters Woods and Winterthur Lane. Several methods are proposed for this stream section, depending on the amount of erosion. These methods range from stabilizing logs and stakes (in areas where banks are 2.5 feet tall or shorter) to major grading and rock walls in areas where banks are higher than 4.5 feet.
"In nature streams meander, they change course," Saccone said. "In an urban area streams are restricted on how much they can move. In a natural area streams are not likely to down cut, but in urban areas streams down cut until they reach equilibrium. They will continue until, maybe, the banks are 15 feet tall."
A third project is located where Snakeden empties into Lake Anne. After dredging the lake this year Reston Association took 10,000 square yards of sediment out of the lake. 75 percent of the sediment came from the western cove, where Snakeden connects to the lake.
"It was so shallow you could walk across it," Saccone said.
To slow water flow and reduce sediment deposits into Lake Anne, the plan proposes planting vegetation and building check dams along the stream. Reston Association spent a over $300,000 to dredge Lake Anne, when in the past they have spent around $750,000 to dredge all eight of Reston Association’s lakes.
"The price has been increasing exponentially," Saccone said. "Not just to pull out the sediment, but to dispose of it as well."
A LARGE CONTRIBUTOR to the water runoff problem in Reston, according to Saccone, is the series of concrete culverts and drainage structures built in the 1970s.
"Originally the idea was to get rain water off of parking lots quickly," Saccone said. "But they’ve done the job too well. With that much water volume at those speeds, the streams can’t handle it."
Since they are county structures, though, Reston Association is not permitted to remove the culverts. The homeowners association can only build around the culverts, mitigating their effects with dams and other structures. Fairfax County is beginning to update its own watershed plan, and Saccone hopes the county will agree that some of the culverts need to be removed. Fred Rose, chief of the stormwater management branch with Fairfax County, said the culverts themselves are not the problem but that impervious areas, such as parking lots and roadways, keep water from soaking into ground. He did say, though, that the new county watershed master plan, which is scheduled to be finished in five to seven years, will place more emphasis on water quality issues.
"The county had a master plan in the 1970s, but it was mostly concerned with flooding," Rose said. "Now we’re trying to incorporate the latest technology to address water quality issues, like sediment and erosion, and not just flooding issues."
Rose said the county will be using Reston as a "guinea pig," watching Reston Association’s results as the county drafts its own watershed plan. The county will also be offering Reston Association guidance in its plan. When the county plan is finished, different areas of the county will be able to choose their own level of watershed maintenance.
"The county doesn’t have funds laying around to distribute," Rose said. "But we want to lay it out like, if you want stream quality to be 100 percent, it will cost this much. For 90 percent it is this much and so on."
He said different communities across the country have established environmental fees. If the county decides to use such fees, county residents will be able to charge themselves, community by community, for watershed services.
Although erosion and sediment issues may not seem to have a direct impact on most Reston residents, both Rose and Saccone said there are long-term effects.
"Reston has a reputation of having all these trails and open space," Rose said. "But if it becomes an eyesore then the community loses its value, its attraction."