Cleaner DC-Area Rivers – The “Lady Bird” TBM. (More on Resiliency.)

A giant mechanical earthworm named “Lady Bird” has been carving a cavernous storage conduit beneath the Potomac from Blue Plains wastewater treatment plant in southwest Washington, DC (just south of Bolling Field) toward Nationals Park, creating the first of several tunnels that will greatly reduce sewage overflows into the area’s rivers.

Technically, the “Lady Bird” is a TBM (Tunnel Boring Machine).

It moves 6 ft. at a time, or for 18 minutes, then stops so that techs can construct the newest section of the tunnel’s inner liner by attaching 6 precast concrete liners, plus a keystone, to the previous section. Tunnel dimensions are sufficient for a Metro subway train. Total tunnel length–13 mi.

The overall project, when complete by 2025, should reduce combined sewer overflows (CSOs) into the Anacostia and Potomac rivers and Rock Creek by 40% during heavy rainfall, i.e., extreme weather. I think of this project as a piece of the Resiliency puzzle. What to do when the grid’s down and there’s major flooding, among human/civic challenges. Initial foray into the subject was blogged here.

Just last week the “Lady Bird” completed the 4.5 mi. stretch of tunnel between Blue Plains and a stopping point not far from Nationals Park.  Took about 24 months. In one of its best weeks, “Lady Bird” dug 631 LF. Total 1.2M tons of material excavated and removed–nearly 72K truckloads worth. While “Lady Bird” will be sold back to its manufacturer in Germany for retrofitting and another deployment elsewhere, 2 other TBMs, including the “Nannie,” are still at work digging tunnels for DC Water. These machines cost about $30M/ea.

“DC Water’s TBM was named ‘Lady Bird’ after Claudia Alta ‘Lady Bird’ Johnson, First Lady and wife of President Lyndon B. Johnson,” as per its website. “When her husband became president in 1964 she made it her mission to preserve and protect the environment. She encouraged her husband to declare the Potomac River ‘a national disgrace,’ [which he did in 1965…drawing] attention to the declining health of America’s waterways and [acting as] a catalyst for the eventual Clean Water Act of 1972.” The “Nannie” namesake is Nannie Helen Burroughs who was a DC African-American educator, civil rights activist and religious leader who died in 1961 at age 78.

There’s a lot of information in this image. For those of you who prefer to climb aboard, as it were, a YouTube video of “Lady Bird” ops can be seen in the link immediately below.

The project engineer who leads the tunnel effort for DC Water, Carlton Ray, says: “There will still be other sources of pollution, such as runoff of fertilizers and pesticides from lawns.” When the tunnels are finished, he adds: “…we’re going to have rivers that meet water quality standards.”