Baltimore may get flood protection walls at tunnel entrances

(TNS) – The Army Corps of Engineers is proposing building flood walls to protect the entrances to Baltimore's Fort McHenry and Harbor Tunnels amid increasing flood threats caused by climate change.

The project, with an estimated cost of $77 million, was proposed following a three-year study of storm risk in Baltimore, particularly for key infrastructure along the Patapsco River.

When everything is completed, motorists can expect to see new walls rising 2.5 to 6.5 feet above ground on the south entrances to both tunnels, Cynthia Mitchell, a spokeswoman for the Army Corps' Baltimore District, said in an email.

The existing walls at the tunnel entrances are not designed to withstand flooding, and engineers will determine whether they need to be replaced during the design phase of the project, Mitchell said.

The two tunnels together would receive about 2,800 meters of flood protection walls protecting both the tunnels' entrances and ventilation buildings, an Army Corps news release said. The walls would include closure structures ranging from 20 to 50 feet long. When not needed, the closure structures could be left open, Mitchell said.

The height was chosen based on a “middle” estimate of sea level rise, according to the study – somewhere between the most and least extreme predictions for average Patapsco River water levels in the coming decades. This is intended to reduce the risk of flooding from an intense 100-year storm event, according to Monday's press release.

According to a 2015 Army Corps study called the North Atlantic Coast Comprehensive Study, average sea level in Baltimore is projected to rise by 3.65 meters, 6.55 meters, or 16.55 meters (under the low, medium, and high scenarios, respectively) by the year 2100.

Higher water levels could increase the risk of flooding from storms in the Baltimore area. According to the Army Corps, steady population growth and continued development in the coastal region also increase the risks of injury, death and property damage.

The Fort McHenry Tunnel on Interstate 95, which connects Locust Point in southern Baltimore with the industrial area of ​​Canton on the city's east side, is used by about 45 million vehicles annually, and the Harbor Tunnel on I-895, which connects southern Baltimore communities such as Brooklyn with the city in southeast Baltimore, is used by about 27 million vehicles annually, according to Joe Bieberich, project manager of the Army Corps' storm risk study for Baltimore.

“It is very important to ensure that these vital transportation routes remain open during a coastal storm and that access to jobs, commercial transportation routes and emergency services is maintained,” Bieberich said in Monday's press release.

The area studied by the Army Corps for coastal flood risk included the city's entire Patapsco River shoreline, including the Inner Harbor, Federal Hill, Fells Point, Canton and a strip of South Baltimore. The Army Corps also examined Martin State Airport in Baltimore County as part of the study.

The tunnel projects were selected based on cost-effectiveness and need, but are considered only a “first attempt”, Mitchell said, and future protection measures could be proposed later.

The collapse of the Francis Scott Key Bridge this year due to a boat collision in March that killed six construction workers, officials say, dramatically highlights the importance of protecting infrastructure.

“The people of Baltimore know all too well the impact of losing vital transportation infrastructure. This project would improve the resilience of the tunnels, which are critical routes for transporting goods and services in the state of Maryland and along the East Coast,” said Lt. Gen. Scott A. Spellmon, commanding general of the Army Corps, in a press release Monday.

The Army Corps has recommended to Congress that it fund 65 percent of the project's cost, with the remaining 35 percent to be paid by the Maryland Transportation Authority, which owns and operates both tunnels. Spellmon signed the recommendation on August 5 during a ceremony at Army Corps headquarters in Washington, DC.

The projected costs could rise if contaminants are found in soil near the tunnels, said the study, which was jointly funded by the Army Corps and the Department of Transportation. Construction also requires right-of-way agreements with landowners, which “could be difficult and time-consuming to obtain, particularly on railroad land,” the study said.

If everything goes according to plan, construction could begin in 2027, according to the press release. Planning work is expected to begin this year.

According to the study, the new flood barrier would cost the transportation authority about $60,000 annually for the Fort McHenry Tunnel and about $130,000 for the Harbor Tunnel.

John Sales, a spokesman for the transportation agency, said in a statement that the agency “greatly appreciates” the Army Corps report and called it “a first step in evaluating any potential project.”

“Because the design phase is not scheduled until later this year, MDTA has not yet made a more precise estimate of the total project cost, impacts on rights-of-way, or project schedule. MDTA also has yet to evaluate whether federal grants are available to support MDTA's efforts,” Sales wrote.

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