Thursday, December 04, 2008

Stream restoration work part of hospital construction

Residents and visitors to Fort Belvoir are likely aware of ongoing construction projects throughout the post. The Belvoir Community Hospital construction has become a common sight for many.

Soon, people may also notice a large amount of equipment and activity within the woods and streambed along Surveyor Road on the other side of Belvoir Road from the hospital. The trucks, rock, and equipment in the forest and the construction activity in that streambed are all part of an important stream restoration project.

It may seem like the construction is destroying the woods and the stream there, but, actually, the project is being done to save the stream. The disturbance will only be temporary. After the construction is complete, it will correct a serious erosion problem that was threatening the continued existence of that stream.

In a year or two, the area should revert to its natural wooded state.

The stream restoration project is scheduled through April and involves two streams. In addition to the Surveyor Road stream, the project will also restore another stream in the vicinity of 9th Street and Gunston Road. The Surveyor Road stream will be the more noticeable of the two restorations. Together, the two projects represent a major effort to restore damaged streams on post. 

The two streams are currently deeply incised, which means heavy stormwater flows have cut into the soil within the stream channel, and the stream is not able to handle these continued flows without suffering further damage. Too much stormwater has been passing too quickly through these stream channels, causing soil erosion, collapsed banks and fallen trees. This situation degrades water quality
and stream habitats.

The stream restoration project will correct the existing physical damage to these two streams by stabilizing the stream banks and the streambed, and replanting trees along the banks. This project was designed to work with the hospital’s stormwater management facilities to enable the streams to properly handle the water coming from the new hospital site.

The hospital will have two stormwater management ponds that collect stormwater run-off from the buildings and parking lots. In the ponds, sediment and excessive nutrients are allowed to settle out before the water flows into the streams. The ponds also slow the rate of the water flow to the stream. The water that then flows to the streams will be higher in quality and will drain at a reduced rate so it can be handled properly by the newly restored streams. 

The stream restoration consists of re-shaping the stream channels so they have gentle bends, rocky areas and small pools. Such features, taken together with other design aspects, control the speed of the water flowing through the stream. With the quantity and speed of the water properly controlled, the risk of incision and erosion is reduced. Completing this restoration project benefits water quality and
habitat conditions within these streams all the way down to Dogue Creek and Accotink Bay.

The project will also include work with surrounding vegetation. People may notice some trees and undergrowth being removed as a first step in the project. However, more vegetation will be planted in their place. By planting trees and shrubs along the stream banks, the site will not only be improved aesthetically, but the appropriate plants will help stabilize the soil. The new plants are part of the riparian
zone (area immediately surrounding the stream) and will help filter excessive nutrients and contaminants from the water. 

Stream restoration projects benefit both the community and the environment because they reduce pollutants entering the waterways and restore natural environments. The restored streams will provide revitalized habitat for both aquatic and terrestrial organisms. The construction project may be unattractive in the short term, but will be a great, long-term benefit to Belvoir and the environment it shares.