Crofton Colony erosion is evident
But source of the vexing problem is disputed — and the debate over mitigation continues
It has been 30 minutes since the rain stopped, but brown water is still rushing through a stream behind Laura Jarvis Van Dornick’s house in Crofton Colony.
When the water recedes, the roots of trees are exposed along the banks, indicating that sediment has been knocked away, polluting the Little Patuxentwatershed.
The erosion is evident; its source is debated.
Van Dornick is one of the youngest people living in Crofton Colony, she jokes, a 53-year-old widow living in a 55-and-older retirement community. When it rains, she puts on her red boots and sets out to record the path and speed of the stormwater.
One video shows the fast-moving water entering the stream from a big pipe that connects to other homes in Crofton Colony as well as a stormwater inlet on the other side of Underwood Road, at The Ridings at North Branch, a development built in recent years.
Van Dornick says the inlet at the new development is the primary source of the high-velocitywater during storms.
But Anne Arundel County Department of Inspections and Permits spokeswoman Tracie Reynolds said the development is in compliance with sediment and erosion control measures.
But Reynolds said the county is asking Toll Brothers’ engineer to verify that the stormwater control measures were built according to the approved plan.
In a statement, Toll Brothers denied the allegation that its propertywas the cause of erosion downstream.
“Anne Arundel County officials have been looking into this situation, including performing multiple on-site inspections, and to our knowledge there is no evidence to support this claim.”
The 42-lot development uses thousands of feet of bio-swales and grass swales to control its stormwater.
Chris Ellis, a Plant Science & Landscape Architecture professor at the University of
Maryland, said that type of “green infrastructure” is meant to hold water on the site, allowing it to soak in. Plantings in the swale use up nutrients, and heavy metals are also pulled out of the water, improving its quality.
The video of Van Dornick walking through the water in the swales shows the systemworking as it should, by holding lots ofwater back, Ellis said.
The swales look like ditches, and have more than a foot of special soil underneath which is between 25% and 40% void space, Ellis said. The idea is that when it rains water can be stored beneath the ground in that medium while it dissipates.
But when it rains day after day, the system can become saturated with water, affecting its ability to slowand store the rain hitting the development.
The swales flowinto four outfalls, places where the new infrastructure connects with old. Three of those outfalls lead to the stream behind homes in Crofton Colony.
Van Dornick is worried that if the speed of water behind the home during storm events isn’t addressed, erosion will continue and their fears of flooding will never subside.