Digging St Clair

Toronto, from the east part of the harbour, bright fall day

Thought I’d share a recent email I sent my young boys at home, wondering what I do “at sea”, on a dredger.

This crew signed on in Toronto, almost two weeks ago. We then proceeded across lake Ontario to Port Weller, through the seaway locks, all eight of them, to “climb” the Niagara Falls. We crossed Lake Erie, east to west,  which was surprisingly rough this time, I felt like we were in the Atlantic.

From Lake Erie we went up the Detroit River, past Detroit on the American side, and Windsor on the Canadian side. From there, we enter into Lake St Clair, which is a small lake between Lake Huron and Lake Erie, then into the St Clair river. Just has you enter the river from the lake, we are working there, dredging the seaway – the Canadian side, as the middle of the river is the Canada / USA border, and we are not allowed to work the US side. Dredging this area allows the big ships to navigate from the Atlantic ocean, up the St Lawrence river, through the locks and lakes of the Seaway and almost make it to Manitoba, deep into central Canada, or down to Chicago, it’s quite a trip really.

Lake St Clair, between Lake Huron and Lake Erie
A brisk October morning on the St Clair River

Over time, the current of the river brings down sand and sediment, that settles on the bottom, making the bottom of the river come up – becoming shallow – which would mean the big ships could get stuck there. Like cleaning our room and such, we go and vacuum this dirt out to maintain a safe channel, to keep the seaway operating and the ships moving.

We are allowed to drag only one hour fifteen minutes at a time, because the government does not want too much turbidity – “dirty” water – to hurt the fish. In that time we usually suck up about 600-700 tons of sand from the bottom of the river.

We have a dredging plan, made up from data provide by our small survey boat. The survey is done using sonar to take a “picture” of the bottom of the river. Then we use this picture, and our measuring instruments on board to navigate the ship, and precisely lower the dredge head to vacuum the parts of the bottom we want.

The very old Interlake Shipping Lee A Tregurtha, a classic “laker” – self unloading bulker
Pipe ashore connection, with floating pipe

Once our time dredging is up, we travel up the river, past all the cottages and fancy homes on the waterfront, to discharge the “dredge spoils” near the town of Algonac. Usually we dump our spoils by opening the ship (hopper) but on this project, we are pumping ashore, into a contained area on an isolated island. Essentially, we are making new real estate by building up the ground, that is now marshy.

Making real estate ashore

Once we arrive at the discharge area, the Captain maneuvers the ship up to our floating discharge hose, we grab it with a winch, haul it up to our connection at the bow of the ship, then lock it in with hydraulic cylinders. We then pump out the sand from the hopper using the piping and doors at the bottom of the hopper. We use lots of water to discharge ashore as it helps carry the sand with it. We also use big water cannons, and water jets inside the hopper to get all the sand ashore.

Right now it takes us about 6-7 hours per round trip – 1.25 hours to load, 1.5 to discharge, 1.5 travel each way, and we do this 24 hrs a day, for two weeks straight. We are going to stop next week for one day, to refuel, take on grub (food) and water, and carry out maintenance. Then well be right back at it, probably for another two or three weeks. Its all about routine; because there is lots happening, I am on my feet lots, checking and checking, tweaking things here and there, helping with the connection and disconnection and such, so we are very busy, but the time passes well.

 

Using water to get the sand moving

 

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