Dredging Saint John Port Authority turns to Canadian Rivers Institute to understand movement of sediment
Scientists at the Canadian Rivers Institute believe they can steer the Saint John Port Authority clear of a financial hole.
Jordan Musetta-Lambert, a masters student in environmental management, downloads information from a nephelometer along the bank of the St. John River in Maugerville. A nephelometer measures the amount of sediment in the water.
Digging mud from the harbour threatens to financially mire the port authority, accounting for about 40 per cent of the cost of operating New Brunswick's major ocean port this year.
The cost of annual maintenance dredging depends on how much material the St. John River brings down, how much the Bay of Fundy tides bring the other way, and what prices dredging contractors bid.
Last year the port authority spent $1.7 million to remove about 120,000 cubic metres of material from shipping channels, berths and turning basins. This year the cost threatens to reach beyond $4 million to remove almost 300,000 cubic metres. Dredging cost an average of $2.7 million per year from 2005 to 2007.
A standard dump truck carries about 15 cubic metres. The dredging contractor takes this material by scow to the ocean dumping place designated by Environment Canada. The port authority monitors this pile.
The Saint John Port Authority's revenues from operations came to about $12 million last year. Dredging could account for 40 per cent of the cost of operating the port this year, compared to 10 per cent in 1996, Capt. Alwyn Soppit, president of the port authority, said in a recent interview.
With money on this scale invested in a mud pile, the port authority has to stretch what it has left for its many other expenses.
So the port authority went to the Canadian Rivers Institute, based at the University of New Brunswick's Fredericton and Saint John campuses, for help.
"It is a group that tries to bridge academia and groups that are interested in water research," said Simon Courtenay, one of 15 "fellows" of the Canadian Rivers Institute. Courtenay, a research scientist for the Department of Fisheries and Oceans, also holds a position as a research professor in UNB's Biology department in Fredericton.
The St. John River provides approximately 60 per cent of the fresh water draining into the Gulf of Maine, according to the port authority. It carries a huge volume of silt, especially in spring, from the headwaters and through the Reversing Falls gorge where it meets the Bay of Fundy tides rising and falling twice daily.
On this research project, Courtenay and Kelly R. Munkittrick, the Institute's associate director based in Saint John, will study the effects of dredging on fish and other organisms in the harbour.
"This is a big project," Courtenay said, involving five scientists along with eight graduate students and four undergraduate research assistants. André Saint-Hilaire will lead the project.
The six components include a "hydrodynamic model" of the river, the harbour and the bay, and how sediment moves. Another component deals with circulation within the estuary. The third component is analyzing seasonal loads of silt. The fourth is the distribution of sediment and how it moves around the harbour, also its physical and chemical composition. Fifth is the effect of dredging on fish. Sixth is modelling erosion and deposition.
"They came to the Rivers Institute," Courtenay said, referring to the Saint John Port authority. "We're very excited about this project because it is a collaboration where the private sector came to us."
The Rivers Institute will learn more about the harbour, where the river and the bay meet. The project will cost about $800,000, with the Institute and the port authority each providing half.
Work started this year by installing instruments called nephelometers, "fancy instruments for measuring the amount of suspended solids in the water," at Maugerville and Oak Point.
This data might allow the port to correlate "hydrological events" such as a heavy spring freshet with the volume of silt coming down the river.
The data might also link sediment to human activity.
This knowledge should help harbour pilots bring ships to their berths more safely. It should allow port managers to predict movement of sediment, budget for it better, and place it where it will remain stable. It might provide information on placing wharves, breakwaters and channels to minimize dredging, and protect environmentally sensitive zones.
Developing a successful model of its home river, the St. John, would put the Institute in good shape to undertake similar projects elsewhere. "In a way, this is the acid test because this is a difficult river to work," Courtenay said.
