Stopping Brown Bay Waters
In a recent fishing trip with residents of the Charlotte Hall Veterans Home, we could not help but notice how brown the water appeared even after several miles of boating into Herring Bay. One of the veterans asked why. I explained to him that what he was seeing was mostly clay in suspension.
Where is it coming from?
Clay comes from agricultural fields and home gardeners with exposed soils as well as from construction sites.
“How can it come from construction sites,” he wanted to know, “as they are required to surround such sites with silt fences?”
Silt fences remove only floating organic waste, sand and silt. They do not remove clay from water flowing through them or nutrients soluble in the water.
Only two methods effectively remove nutrients and clay from waters penetrating silt fences. The water must be treated in a waste water treatment facility with tertiary water treatment or be passed through compost.
Research has clearly demonstrated that water filtered through silt fences can be purified by passing the water through a berm of active compost. Because of the negative and positive charges in compost, clay particles are trapped along with nutrients. Growing winter rye in those berms of compost also helps in absorbing nutrients trapped in the compost.
This information — common knowledge to us researchers — has been presented at many public meetings and published in trade magazines. One company manufactures Filtrex Sox, a mesh tube 12 to 18 inches in diameter and filled with compost. The tube has an apron that forces water to flow through it.
This information has been presented to highway departments and at contractor meetings without much success. Rebuttals have been “we use bales of straw or mounds of wood-chips” to filter surface water. These methods do not solve the problem of trapping muddy water because neither has positive and negative changes attracting particles and nutrients.
It’s an old familiar story: Research tells us what must be done, but great resistance rises against new and improved methods. Change comes slowly unless it is made mandatory.
Enough said.
Ask Dr. Gouin your questions at [email protected]. Please include your name and address.