SAVANNAH, Ga. -- While many Savannah residents clogged roads returning home following Hurricane Matthew last week, a small group worked to ensure a major artery into the city -- the Savannah River -- remained clear.

Employees from the U.S. Army Corps of Engineers Savannah District's Operations Division, in partnership with the Georgia Ports Authority, the National Oceanic and Atmospheric Administration, the Savannah Pilots Association and the Coast Guard, worked at a feverish pace to survey the river, remove debris, and relocate buoys and navigation aids displaced by the hurricane.

And though it took just three days to restore the flow of container ship traffic, each organization overcame its share of challenges.

Gaining access to the survey vessels was the first speed bump, according to Jason O'Kane, chief of navigation for Savannah District's operations division.

In preparation for the storm, the district relocated two of its survey vessels and an emergency fuel truck to higher ground; however, the storm's intense winds knocked down several trees, making the road to that area impassible.

On Oct. 9, O'Kane and his team reached out to a Georgia Ports Authority contractor, who ferried them to their survey vessels via the Savannah River. And while the Georgia Ports Authority contractor surveyed the berths at the Garden City Terminal, the operations division methodically checked the channel between the terminal and City Hall.

O'Kane said the teams used a side scan sonar, which provides a snapshot of the river's depth and helps identify obstructions that could impede navigation for cargo ships.

Further downstream, NOAA surveyed the river from the northern end of Cockspur Island to City Hall, while the Savannah Pilots Association covered the section from Tybee Island to the north end of Cockspur Island.

The following day, Oct. 10, O'Kane and his team used chainsaws to clear trees from the road and access the rest of their equipment.

Within the next 24 hours, the four organizations responsible for surveying the river reported "all clear" to the Coast Guard, which was tackling other Matthew-related matters.

In addition to rendering the Coast Guard's Cockspur Island pier unserviceable, Matthew's storm surge displaced several buoys and navigation aids in the Savannah River and its approaches.

Although cargo ships use GPS to determine their position at sea, they rely heavily on these buoys and navigation aids (in addition to harbor pilots) to transit safely into and out of port.

The Coast Guard used four boats to efficiently restore the buoys and navigation aids, and by the morning of Oct. 12, just three days after Matthew left town, the harbor was open with some restrictions to traffic.