Posted on February 27, 2017
By Tyler Kula, The Observer
Sarnia Harbour is a little deeper and the city’s airport a little hillier after dredging wrapped up late last month, says the city’s economic development director.
Some 35,000 to 40,000 cubic metres of riverbed sediment was scooped after work started in the early fall, said Peter Hungerford, and trucked to the Sarnia Chris Hadfield Airport where it’s being graded and seeded into a berm this spring.
The move, a nearly $3-million project contracted to Quebec-based Ocean Group, was commissioned in the wake of some fully loaded ships passing Sarnia’s port because they couldn’t navigate the shallows, Hungerford said.
“We’ve lost business over the years by virtue of the fact that we didn’t have seaway draft.”
Sarnia took over ownership of the harbour after the federal government divested it three years ago.
Dredging typically has to happen every eight to 10 years, Hungerford said, noting the latest project brings the depth to 8.4 metres below datum – long-term average water level – which is on par with the St. Lawrence Seaway.
“The intention is to do a measurement of the harbour annually so we can start to make a record of what kind of infill we’re getting,” Hungerford said, noting that should lead to a better understanding of how often dredging is required.
The sediment is “slightly contaminated,” but the concentrations are low enough that there was no reason to landfill it, Hungerford said.
“A local environmental company, Pollutech EnviroQuatics, did extensive testing on the sediment and determined it was suitable for disposal at the airport,” he said.
“There was minimal amounts of contamination in terms of different metals or substances that were found.”
Hungerford emailed a summary of Pollutech’s report. The summary says core samples from the harbour were tested for metals, inorganics, volatile organic compounds, petroleum hydrocarbons, chlorophenols and polycyclic aromatic hydrocarbons, and organochlorine pesticides. The sediment, it says, meets the standards set in the Ontario Environmental Protection Act for coarse textured soils in an industrial/commercial/community property use.
Some extra costs have been incurred for disposal and creating a lined pond for water runoff from the soil at the airport, Hungerford said, but the final bill isn’t in yet.
Runoff water goes into the sewer system to be treated, he said.
“It’s all properly managed.”
The move didn’t significantly impact the number of ships berthing for the winter, he said. Just one had to move on after it arrived four days early – before dredging in its reserved spot was done.
Eight ships are currently tied up for the winter, along with the dredging equipment, Hungerford said.
An extra 0.2 metres was dug at the Sydney Smith dock, he said, since computer modeling shows that area fills in faster.
He’s pleased with the job the contractor did, he said.
“It’s like repaving a road so you can continue to drive on it,” he said about the project.
“In this case, it’s dredging the harbour so ships can continue to use it.”
Source: The Observer
