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The Dredge Report | Week of January 31, 2021

Sand Shifter – Stage Harbor, Chatham

Another week of putting the many pieces of the Stage Harbor ‘jig saw’ puzzle together continues!

What’s left until we can actually start dredging?

  • Moving the Booster Station from the parking lot in Hardings Beach east about 2,000 feet down the beach.
  • Finish assembling the 10 three hundred foot sections of new pipe that had to be purchased (due to the approximately 12,000 feet of pipe required for this project).
  • Fueling the dredge and push boat.
  • Moving the pipe into position from the Stage Harbor channel to the Booster Station onto the discharge area on Cockles Beach.

And then of course there was last weekends weather that required the dredge crew to secure all of the equipment on Friday ceasing operations until Monday. The forecasted cold temperatures will certainly not be much help either as saltwater temperatures are nearing 35 degrees.

Stage Harbor

Project layout showing the location of the Sand Shifter, Booster Station and Discharge Pipe location

The Stage Harbor channel is a very challenging area for dredge operations, especially during this time of the year. While uncommon for the winter months, any wind out of the South, Southwest or Southeast brings with it seas, and there is very little protection when the winds are coming from the West, Northwest, or North. Unfortunately, when we get wind out of the Northeast, or a Nor’easter, it’s usually quite nasty in this area as the wind will come right over the land and out of the Stage Harbor channel.

Pretty much any wind over 20 knots will make conditions boarder line for dredging. And then there is the surface current….on a typical ebb tide (outgoing), the current speed can get up to 3 kts., with higher speeds when there is a new and or full moon. It is very challenging to operate the dredge and cutter head (that is actually working on the bottom) when the currents are running hard.

A few questions were raised about some of the details of this project.

12,000 feet of pipe seems very long, why do you need such long lenghts?

12,000 feet equals 2.272 miles!  This is indeed a pretty long distance to pump a mixture of sand and water from the Sand Shifter to the Booster Station and onto the discharge location which as noted above is to the west of Stage Harbor and just to the west of Cockle Cove.

Why do we need a Booster Station?

In order to move the mixture of sand & water through the 12,000 feet of pipe, a ‘boost’ is required at some point of the pipe run. Without it, the mixture would slow down to the point where it would barely be moving through the pipe. Note, the Sand Shifter is able to pump without a ‘Booster’ up to 6,000 feet. Having the ‘Booster Station’ located at approximately 3,000 feet from the Sand Shifter will give us the best efficiency allowing the dredge pumps not to work at maximum output for the duration of the project.

Cod Fish II – Sesuit Harbor, Dennis

A nice picture of the Cod Fish II and pushboat J.W. Doane alongside the dock riding out Sunday’s snowstorm.

Cod Fish II

Photo Credit: Michelle Donovan