Dredging Mississippi River to 50 feet clears Corps approval hurdle
James Dalton, director of civil works for the corps, concluded that the 5-foot increase in the river's depth will result in average annual benefits of $127.5 million to the nation's economy, compared to average annual costs of $17.7 million.
Dredging the channel 5 feet deeper will allow modern "New Panamax" vessels, built larger to use the widened Panama Canal, and "Post Panamax" vessels that may be too large for the canal, to reach as far north as Baton Rouge, as long as their superstructure fits below the Crescent City Connection bridge in New Orleans.
It also will reduce the present costly practice of loading some ships with less cargo weight than their size allows, or unloading cargo from ships before they enter the river's mouth. Officials also hope that the deeper dredging will increase the intervals between required maintenance dredging.
"This is truly a great moment for Louisiana and the thousands of men and women whose livelihood depends upon the Mississippi River," said Louisiana Gov. John Bel Edwards in a news release. "One in five jobs in Louisiana is tied to our ports and this project will help to make our world-renowned port system even more competitive, while creating opportunities for manufacturers, growers and producers who rely on our ports up and down the entire Mississippi River."
The final proposal, which still must be approved by the White House Office of Management and Budget and Congress, represents a major expansion from the tentative plan submitted to public review in December 2016. Congress must also include funding for the project in its fiscal year 2019 budget, and money for the increased cost of annual dredging - estimated at $17.7 million - in future annual budgets.
About 80 miles of river through and below Baton Rouge have been included in the deepening project, adding to both the cost of dredging and of relocating major pipelines and utilities buried beneath the present river bottom.
In his approval memo, chief engineer James Dalton said the project will now cost $237.7 million, compared to a 2016 estimate of $88.9 million. The memo was sent to R. D. James, assistant secretary of the Army for public works on Aug. 3.
According to a corps spokesman, the state's share of that cost could be as much as $119.6 million, which includes $39.4 million, or 25 percent, of the actual deepening project construction costs.
The other $80.2 million attributed to the state is the cost of relocating pipelines and other utilities that run through the river. Both the corps and state estimate least half of the relocation cost will be picked up by the utility owners, and not the state, thanks to relocation requirements that were included in permits allowing them to use the river bed.
The state expects to use a variety of sources of money to pay for its share of the project, including the state's annual capital outlay budget, or other federal grants, said Rodney Mallett, a spokesman for the state Department of Transportation and Development, which is acting as the non-federal sponsor for the project.
An earlier version of the dredging project, without the Baton Rouge extension, would have cost the state about $22.2 million.
The project will deepen the main shipping channel an extra five feet where needed along 256 miles of the river as it passes through four of the nation's top 15 ports measured by tonnage: the Plaquemines Port, Harbor and Terminal District; Port of New Orleans; Port of South Louisiana; and Port of Greater Baton Rouge. Those ports handle more than 500 million tons of cargo a year, including 60 percent of the nation's grain and are connected to 14,500 miles of inland navigable waterways.
The southernmost part of the project is between river mile 13.4 above Head of Passes near Venice and mile 22 below Head of Passes, at the river's mouth. The portion of the river below Head of Passes is Southwest Pass.
The navigation channel in that area would be officially deepened from the present 48 feet below its lowest low-water level -- during lowest tidal levels -- to 50 feet, but in reality it would be 54 feet in the beginning. That's because the dredging also would include 2 feet of "advanced maintenance" and 2 feet of allowed "overdepth", both aimed at increasing the time between required maintenance dredging.
Material dredged in the lower river would be used to build about 2.2 square miles of new wetlands in the federal Delta National Wildlife Refuge and the state Pass A Loutre Wildlife Management Area. Material dredged from the southernmost 2 1/2 miles of Southwest Pass will be placed in an existing ocean dredge material disposal site.
Upriver, the project will require dredging of a dozen "river crossings," the straight reaches of the river between river bends, with the sediment deposited in deeper water areas just downstream, where it will flow downriver.
"More commerce on the Mississippi means more jobs for Louisiana workers and more economic opportunity in our state," said U.S. Sen. Bill Cassidy, R-La.