Posted on November 1, 2016
By Peregrine Frissell, greenwich time
The long-awaited dredging of the Mianus River began last week, scooping the first buckets of silt out of the channel in 31 years.
The project was set to begin earlier but was delayed because of gusty weather .
“The dredge equipment did get in on Friday the 21st really late at night,” said Mark Jackson, president of Coastline Consulting. “But they started on the 23rd.”
The dredging equipment consists of a barge with a crane to scoops sediment, mostly fine-grain clay and silt, and place it on scows. Tug boats tow the scows about eight miles out to the Western Long Island Sound Disposal Site.
The silt at the northern end of the project near the Post Road bridge is the most contaminated, because of runoff from the highway and the nearby town garage, said Harbormaster Ian Macmillan.
“There’s a hill on either side, and those hills contribute a lot of water during a rainy day,” Macmillan said. “They wash a lot of petrochemicals and other offending elements into the river right in that area. It’s got no place else to go.”
About 6,000 cubic yards eventually will be removed from that portion of the channel, Macmillan said. After dumping, it will be covered with cleaner silt collected from further down the channel as the project moves on.
About 50,000 cubic yards of silt is expected to be removed from the channel of the river in Cos Cob Harbor by Christmas, said Jack Karalius, project manager with the U.S. Army Corps of Engineers.
“The entire dredge window, due to environmental constraints and restrictions, runs from Oct. 1 to Jan. 31, so hopefully he’ll be out of there by the end of December,” Karalius said earlier this month.
The completion time for the project will depend on weather and equipment, Karalius said.
“Most dredging is done in the middle of winter because that is the least amount of biological activity,” Karalius said.
Karalius said poor weather, particularly wind, makes it difficult for the scow to haul dredged material out to the dump site.
The Corps had been working to get the owners of a large pile of lobster pots stowed near the channel to move them so it wouldn’t affect the project, said Frank Mazza, a harbor Management Commissioner in town.
The pots aren’t actually in the channel, but on the side in an area referred to as sideslope channel, Karalius said.
“We sent them a letter basically telling them they had to move,” Karalius said. “We’re cautiously optimistic they will be moved out.”
Karalius said it could take about a month for the dredging work to reach that point in the channel, but cautioned that was a rough estimate.
The busy channel, traveled by recreational and commercial boats, was last dredged in 1985, when 53,000 cubic yards of sediment were removed.
In recent years, boaters have complained that so much silt has built up, the channel is barely passable in sections at low tide, and boats frequently scrape mud and debris on the bottom.
The project will restore the channel to its authorized dimensions of 6 feet deep and 100 feet wide, running from Cos Cob Harbor up the Mianus River to about 400 feet downstream of East Putnam Avenue. From that point to the road, the channel would be 75 feet wide.
Jackson’s team, which was contracted by the Corps to work on the project along with Massachusetts-based Patriot Marine, have started at the northernmost end of the channel and will work its way down.
Source: greenwich time
