Extended North Tunnel project in Ellicott City begins with groundbreaking

Construction has begun on the next phase of Ellicott City’s Safe and Sound flood mitigation plan, an 18-foot tunnel that will divert 26,000 gallons of water per second from the West End to the Patapsco River.

The $141.5 million Extended North Tunnel is considered not only the focal point of the plan, but it is the largest public project in Howard County’s history. The tunnel is a water conveyance project designed to carry floodwaters from the West End of Ellicott City through an 18-foot diameter, underground tunnel to the Patapsco River. The county says the project will reduce the risk of flash flooding by intercepting water from the western portions of town and diverting it underground and away from Main Street.

The three-year construction project is expected to be completed in the fall of 2027.

“Today, we mark another giant leap in preserving Ellicott City,” Howard County Executive Calvin Ball said at a ceremonial ground breaking Monday. “The ground on which we stand will soon become the path to the Ellicott City Extended North Tunnel.

“This tunnel will channel water from vulnerable lower elevations and carry it safely to the Patapsco River,” he said. “When complete this tunnel will have the capacity to move 26,000 gallons of stormwater per second.”

The Safe and Sound plan, unveiled in September 2018, is the county’s response to heavy rains in 2011, 2016 and 2018, that caused major flooding in Ellicott City’s historic district, killing three people and leaving behind massive destruction.

The plan also includes the construction of five stormwater retention projects.

“Just three weeks ago many of our partners here also gathered to celebrate the construction of the H-4 Pond, our largest stormwater retention pond to date,” Ball said. “We are taking the essential steps today to ensure a vibrant tomorrow for this incredible town. Today, we are writing a new chapter for Ellicott City’s future, in which it will become the national model for flood mitigation and climate resilience.”

When completed in fall 2025, the $3.96 million H-4 Pond will have the capacity to hold 5.5 million gallons of stormwater, which otherwise could flow directly into the Tiber-Hudson River and down to Main Street in historic Ellicott City.

Excavation of the Extended North Tunnel will include carving through solid granite. The work will be executed primarily using Rocky, a 300-foot tunnel boring machine. The name Rocky was chosen in an online voting campaign participated in by some 800 residents.

Ball described the county has having a “reputation for punching above its weight.” In the vein of its fighting spirit, and the very literal geological feat ahead, Rocky seemed like the perfect name, he said.

The name Rocky hails from the 1976 American sports drama movie about a club fighter written by and starring Sylvester Stallone.

Ball hosted a naming campaign earlier this year. Residents were asked to choose from the following six names: Ellicott Drills, Ellicott Excavator, Granite, Granite Grinder, Hudson and Rocky.

The tunnel construction will be overseen by a joint venture between Omaha, Nebraska-based Kiewit Corp. and Evansville, Indiana-based Traylor Bros. Inc., experts in tunnel excavation, a Howard County news release states.

“Our Kiewit-Traylor team is proud to partner with Howard County to bring our breadth of resources and tunneling expertise to construct the North Tunnel and realize the vision of the Safe and Sound program for the Ellicott City community and future generations,” Matt Swinton, Kiewit’s senior vice president and district manager stated in the release.

Rocky is currently being outfitted at the manufacture’s facility in Ohio.

“Between now and when Rocky will arrive in late 2025, crews will be preparing the site,” Ball said. “It will include excavating a mining shaft, which will be approximately a 150-feet deep. We will also be extending power to and down the mining shaft to power Rocky and related support equipment.”