New technologies in dredging and the potential to use dredge spoils as fertilizer will be the focus of an upcoming presentation sponsored by Tisbury Waterways Inc. (TWI) and the Martha’s Vineyard Commission (MVC). The program begins at 5 pm, Thursday, October 3, at the Katharine Cornell Theatre in Vineyard Haven.
Major developments in dredging methods offer the ability to accelerate the process and also reduce the impact of sludge deposited on the banks of ponds and ocean shorelines, TWI board member Harriet Barrow told The Times in a phone conversation.
“This could be a wonderful discovery for everyone Island-wide,” Ms. Barrow said. “This particular presentation should appeal to a lot of people on a lot of levels — town officials, environmentalists, farmers — anyone who is interested in protecting and revitalizing our ponds.”
One of the methods utilizes a belt press, a machine that squeezes water out of the sludge as it is dredged, leaving only solid “cakes.” As a result, the system eliminates the need for a large area near the dredging operation to accommodate thousands of cubic yards of wet sediment, Ms. Barrow explained.
Another new method uses geotubes, which are coated inside with polymers that bind sludge particles. Sludge is pumped into the tubes, which trap the organic carbons. Clean water then seeps out through a mesh filter back into the water body.
The dredge spoils from projects that use the belt press and geotubes may be used as fertilizer, provided the results of water and sludge testing reveal no pollutants. Ms. Barrow said TWI hopes one of the new methods may be used when Tashmoo Pond is dredged.