Aboard The Sand Shifter: Clearing Aunt Lydia’s Cove To Support Fishing Fleet

CHATHAM – The sound of the powerful Caterpillar engineer is inescapable. It reverberates across Aunt Lydia’s Cove, buffered by the mainland shore and Tern Island, a low rumble that gets louder as the 25-foot skiff nears the source at the northern edge of the mooring basin.

 The Sand Shifter, one of two dredges owned and operated by Barnstable County, slowly drifts from east to west, pivoting on huge spuds and held fast between two anchors at the edges of the cove. Under the water, a large cutter head spins, sucking up sand and water and pumping it through more than 2,000 feet of pipeline to the other side of Tern Island.

 “All it does is swing,” Kenneth Cirillo, director of the Barnstable County Dredge Department, says in explaining how the dredge operates. “It makes a big arc as it moves forward. It’s a very slow, incredibly accurate, methodical process.”

 Every few years the county dredge arrives in the late winter or early spring to clear shoals from the Aunt Lydia’s Cove mooring basin, the anchorage for much of the town’s commercial fishing fleet. Most aren’t actively fishing at this time of year, or are doing so elsewhere, leaving a window for the dredge to deepen the basin.

 “There’s a lot of water moving through here,” Cirillo says. “It’s a dynamic spot.” In a sense, that’s a good thing, because the sand that needs to be removed to maintain a seven-foot depth at low water is mostly clean and loose, having blown or swept into the cove from the harbor and outer beach. That makes it perfect for pumping onto the east-northeast side of Tern Island, helping to both bolster the island’s resilience and create habitat for nesting shorebirds.

 “It’s beautiful sand,” Cirillo says.

 The project aims to remove about 25,000 cubic yards of sand from the basin. The county charges local towns $26.50 per cubic yard, putting the total estimated cost of the project at $662,500, according to Natural Resources Director Greg Berman. Half will come from a state dredging grant, half from the town’s annual dredging appropriation, he wrote in an email.

 The total cost won’t be determined until the work is complete and a survey is done to gauge the exact amount of sand removed. Cirillo says numerous surveys are done during the process; one at the beginning to establish a baseline as well as several during the operation to ensure the dredge doesn’t miss any spots. The county has a survey boat with equipment to determine depth; the plotted data is sent to a hydrographer offsite who crunches the numbers.

 Inside the cabin of the $2 million dredge, Chris Armstrong guides the cutter head along the bottom, keeping a careful eye on several screens displaying data showing the depth as well as the speed of the cutter head, pressure, hydraulic status and other information. Armstrong, a former commercial fisherman, is the dredge’s leverman, a term that harkens back to earlier days when the cutter head was physically operated by levers. Today he uses joysticks and everything is computerized, including realtime tide readings from a wireless tide station at the fish pier.

 “It’s changed a lot since I started,” Armstrong says, noting that the high-tech equipment dramatically improves the dredge’s accuracy.

 “It takes a lot of the guesswork out of it,” adds Cirillo. 

 On a good day, the Sand Shifter can make about 100 feet of progress; one day last week “just right” conditions allowed the dredge to clear 150 feet in the basin, which was “off the charts,” Armstrong said. The county’s other dredge, the Cod Fish II, is smaller and averages about 75 feet a day.

 All of that sand is pumped through 2,050 feet of 14-inch diameter pipe onto Tern Island, which is owned by Mass Audubon. It emerges in a slurry of sand and seawater. The water washes away leaving behind the clean sand. A flock of seagulls loaf around the pipe outlet, hoping to find something to eat amid the water and sand.

 “Who says there’s no such thing as a free lunch?” Cirillo jokes.

 The hard plastic pipe, the same type used in local sewer projects, is moved a few times a day using a skid steer in order to maintain an even distribution of sand, says dredge supervisor Jason Bevis. He has to be careful to situate the pipe so as not to disturb marsh and shellfish beds that ring the island.

Running the heavy machine along the beach can be treacherous; at one point the sand collapsed beneath it as he was moving the pipe. He was able to slowly and safely back out.

 “This whole island is full of traps,” Bevis says. “Around here, you go slow, because if you go charging into something fast, you get into trouble.”

 It’s been a challenging winter for the dredge crews. They were frozen into Sesuit Harbor in Dennis for two weeks, and whenever the temperature dips below 20 degrees overnight, the machinery has to be broken down and winterized, Cirillo explains. With moderating temperatures, this is the perfect time to dredge. There is little boat traffic and yearly restrictions, such as closures of certain areas to protect horseshoe crabs, have yet to kick in. Cirillo says the dredge season begins after Labor Day and runs to about Memorial Day. In the summer, the dredges are maintained and the crew, who work six days a week during the dredging season, get some time off.

 This winter has also been busy with a backlog of dredging projects, Cirillo says. The Cod Fish II is just finishing up work in Dennis and will head toward the Cape’s southern shore for more projects. The Sand Shifter should complete its work in Aunt Lydia’s Cove in a week or so, and Cirillo expects to then move to Mill Creek to complete work begun last fall. It will then move along the south coast, doing projects in Harwich and Falmouth.

 The county began its dredge program in 1996 with the Cod Fish I, adding the Sand Shifter to its dredging fleet in 2017. The original Cod Fish was retired in 2019 when a new dredge, the Cod Fish II, was purchased. Since the start of the program, more than 2.5 million cubic yards of sand has been dredged, with most of the material used to rebuild beaches, according to the program’s website. Chatham is one of the county’s regular customers, with the dredges spending time here just about every year.

 Once the Sand Shifter completes its work in Aunt Lydia’s Cove, mooring blocks and tackle — removed by the harbormaster before the operation began and gathered along the mainland shore — will be replaced, and fishing boats will slowly return to a newly deepened basin.