By Bob Allen, For The Baltimore Sun
12:09 PM EDT, August 5, 2013
The Howard County Department of Public Works will tap a grant from the Chesapeake Bay Trust Fund to repair and restore a stream in Ellicott City that officials say has been badly degraded by erosion.
Richard Powell, a project manager with the department's stormwater division, said the project involves a roughly 300-foot stretch of the stream running along and under Tuscany Road near Lombardi Drive before emptying into the Little Patuxent River.
The project is scheduled to begin around Aug. 12. Powell said construction will not affect traffic, but a portion of the sidewalk will be closed. It should be completed in May. The cost is about $280,000.
Powell said the erosion is so severe it uncovered a buried sewer line.
"This is our biggest concern," Powell said. "The pipe itself is not broken, but where it was previously buried, it's now exposed. So it will be recovered in the process."
Powell said damage to the stream was caused by increased stormwater runoff as woodlands, marshes and meadowlands that absorb rain have been replaced with impervious surfaces such as roadways, rooftops and parking lots.
"Often the result is that you get vertical stream banks; when the stream starts meandering from side to side, it tends to cut the banks out," Powell said. As a result of erosion, vegetation along the bank is washed away, which destabilizes the banks even more.
Fixing the damage, Powell said, involves reshaping the banks, planting vegetation to hold it in place and making adjustments in the streambed.
"We take the vertical banks and lay them back to a more stable slope and plant a variety of plants on them," he said. "Generally, we will plant something that will not just create a vegetative cover but will also provide more of a naturalized vegetative area around the stream."
Repairs include lining the stream bed with rock and grade controls to control erosion and installing "step pools," which Powell described as "a long, extended waterfall" that steps down gradually to ease the rate of water flow.
Powell said the project will incorporate new techniques that are far more effective and efficient than those used previously.
"These are practices that really slow down the runoff and get the water percolating through the soil again," he said.
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