Snakeden Branch Stream Stabilization Project
Snakeden Branch in Reston benefited from a restoration plan designed and implemented by the Northern Virginia Soil and Water Conservation District and the Virginia Department of Forestry. The banks of a 200-foot stretch of stream were severely eroded, exposing the roots of many large trees. The restoration project was slated to begin in Spring 2003, but greater than normal rainfall delayed the start of it until August 12. This project marked the start of the implementation phase of the Reston Association's watershed management plan. Follow the progress of the Snakeden Branch project through this series of photos.
Above you can see the serious erosion and the garbage that was caught in the exposed roots of shrubs and trees. A water pump diverts the stream flow to another channel during construction. A track hoe is used to re-grade the banks to a gentler slope.
The rock cross vane shown above extends upstream from both sides of the bank. It concentrates the flow in the middle of the stream, thus narrowing the flow path. As a result, it removes stress from the banks and prevents erosion. The rock cross vane also increases the flow depth downstream from the structure, which improves fish habitat. Below, biodegradable matting, secured with wood stakes, holds the soil in place on the streambank until the roots of native grass and other riparian plants grow sufficiently to stabilize the bank.
Above, an NVSWCD team member guides the track hoe operator in strategically placing large stone under the bank to protect the exposed roots of the tree. The 18-inch diameter tulip poplar is valuable for stream habitat and ensuring bank stability. A two-tier row of biologs will line a long stretch on the opposite side of the channel. Biologs are tightly bound cylinders of coconut (coir) fiber held together by coir fiber netting. Generally, they come in lengths of 10-20 feet and diameters of 10-12 inches. They are installed at the toe of a bank. The material is tough, flexible, and absorbent. Once installed, the biolog becomes saturated with water, and vegetation can be planted directly in it. By the time the log degrades in seven or eight years, a root network of plants will have been established through and behind it.
After three days of construction, the project is about halfway done. Supervisor Cathy Hudgins (Hunter Mill District) stops to talk with Reston Association President Susan Jones about the many partners on the project. Joining Hudgins for the gold shovel ceremony are representatives from the Northern Virginia Soil and Water Conservation District, Virginia Department of Forestry, and the Reston Association. Also partnering on the project is the County Department of Public Works and Environmental Services.
Early on the fifth day of construction, the last stretch of bank is graded. Plenty of grass already is visible on the bank that had been seeded the week before. With only a few hours left to finish the project, the crew is attacked by a swarm of bees whose nest has been disturbed. (No pictures are available!) Nevertheless, work continued.