Crews in Ellicott City set to break ground on massive flood-fighting tunnel this summer, county exec says

Construction on a massive underground tunnel in Ellicott City is set to kick off this summer — a major step forward in a multimillion dollar effort to reduce flooding along the town’s historic Main Street, which was devastated by two deadly deluges in 2016 and 2018.

Howard County Executive Calvin Ball announced the groundbreaking on the extended North Tunnel in a video address Thursday on the “State of Ellicott City.”

According to plan designs, the Extended North Tunnel will carry up to 26,000 gallons of stormwater per second through a mile-long, 18-foot diameter tunnel away from the West End of Ellicott City and toward the Patapsco River.

The tunnel is the most expensive aspect of a project to protect flood-prone Main Street. When first announced in 2019, the tunnel was set to cost $82 million with a groundbreaking set for December 2022. However, costs later ballooned to $130 million, the county announced last year, delaying the groundbreaking.

In the video Thursday, Ball said the project had received $68 million in new funding in the past year.

Calling it a “once-in-a-generation” project, Ball said construction on the project would take about three years.

“Once complete, the Extended North Tunnel will be the single largest public works project that Howard County has ever undertaken,” he said.

Teardown begins on 4 Main Street buildings

An artist’s rendering of the expanded Tiber Park after the clearing of four buildings from Main Street. (Courtesy Howard County)

In addition, county crews began work this month on tearing down four buildings along lower Main Street, under the “Ellicott City Safe and Sound” plan that Ball first announced in 2019. Before Ball took office, an earlier plan would have called for the destruction of 10 buildings to widen the channel that carries water toward the Patapsco River during heavy rains.

Ball’s office said the demolition is generally being done by hand in a process known as “building deconstruction,” so that crews can salvage ironwork, cornices, doors, windows and other “character-defining elements” that will be preserved.

“These places are significant,” Ball said in the video. “They are monuments to our past, spaces in which memories were made. For many of us, they are fixtures of what Ellicott City once was. While the loss of these four buildings is bittersweet, this work will help us ensure that Historic Ellicott City can and will prosper for another 250 years and beyond.”

The county executive said the county is committed to “preserving and renovating the six remaining structures and ultimately returning them to use.” That includes the historic Caplan’s Department Store building, which is set to get a new facade.

Once the four buildings slated for demolition are razed, the space will be turned into a “new, vibrant outdoor space with views of the Tiber River in time for Summer of 2024,” Ball said. “This is a critical first step toward realizing our vision for an expanded Tiber Park and the continued revitalization of Lower Main Street.”

Ellicott City was devastated by two nearly back-to-back flash floods that ripped through the town’s historic downtown in 2016 and 2018. Two people died in the 2016 floods, and one person died in 2018.

Ellicott City was also hit by severe flooding in 2011.

Founded in 1772, the former mill town’s topography has made it perpetually prone to flooding.

WTOP’s Neal Augenstein contributed to this report.

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Jack Moore

Jack Moore joined as a digital writer/editor in July 2016. Previous to his current role, he covered federal government management and technology as the news editor at, part of Government Executive Media Group.

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