ANDREWS AFB, Md. –
The Cabin Branch stream barely trickles through the woods next to Patrick Road on the east side of Andrews. Over many years, the effects of rainfall and runoff have eroded the stream's bed and banks.
During rainstorms, water quickly fills the eroded banks of the Cabin Branch stream, which slowly turns into a river of muddy water, said Joseph L. Copeland, 316th Civil Engineer Squadron project manager.
The water is washed downstream and combined with the rest of the Chesapeake Bay Watershed, said Mr. Copeland. The watershed is an area covering Maryland, Virginia, West Virginia, Pennsylvania, New York, Delaware and the District of Columbia.
"The watershed has a murky habitat unsuited for aquatic life and deposits unwanted sediment into the Chesapeake Bay," he said. "Something had to be done to prevent further erosion of the Cabin Branch bed and banks."
Mr. Copeland is supervising the project to stop the erosion of the bed and banks of the Cabin Branch stream and reduce the amount of sediment coming from the base. The project began this summer and is expected to cost $300,000 by completion in the spring. The project includes employees from CH2M Hill International in Herndon, Va., and Cape Environmental Management Inc. in Alexandria, Va., which are under contract with the 316 CES Environmental Flight for the stream restoration.
"The project is a proactive one," said Mr. Copeland. "The 316 CES and the contractors are taking care of the off-base sediment problems before they become a bigger, costlier issue. This initiative will also sustain the natural infrastructure of Andrews, thereby supporting the base mission."
To slow down the water flow causing the eroded bank and beds, cross vanes have been constructed, said Mr. Copeland. Cross vanes are made by carefully arranging large stones in a "V" formation with the point heading upstream. Some of the large stones weigh up to 1,500 pounds.
Mr. Copeland said the cross vanes create a low-velocity flow of water, which reduces erosion on the Cabin Bank stream banks and allows the growth of vegetation, eventually bringing back habitat for more animals and trees.
"Additional trees eventually create overhangs, which lower the temperature of the stream and support an environment conducive for different types of animals," he said.
A water pool has been constructed with rocks and coir logs at the upper end of the stream on base, he said. The purpose of the water pool is to slow the rushing water streaming under Patrick Road after a big rainstorm. Derived from coconuts, coir is developed by using the coarse husk from the outer shell.
"The contractors selected boulders weighing nearly a ton to ensure the exact flow of water they wanted," said Mr. Copeland. "Everything had to fit exactly so the water is slowed down and the stones didn't end up downstream."
The use of innovative materials, such as coir logs, make the stream restoration project here unique, said Mr. Copeland. Coir logs stabilize the stream bank, where the steep vertical walls meet with the horizontal bottom. They allow natural sediment deposit on and around them, building up edges of the bank and allowing plants to root.
"Best of all, coir logs are biodegradable, compared to the plastic netting, which is more commonly used," he said. "Within four to 10 years, the coir logs will completely biodegrade."
To finish the project, the contractors will plant saplings in the coir matting, he said. The coir matting will hold the soil bank in place. The young trees will eventually root and help the trees provide shade and lower temperatures in the stream.
The Cabin Branch will soon become a perfect habitat, which benefits plants and animals, said Mr. Copeland.
Mr. Copeland said he has already seen results from the restoration project.
"One day after we finished with the water pool, there were several frogs as well as frog eggs in the pool," he said. "This is good news for Cabin Branch stream."