Giant 'Lady Bird' Machine Digging Huge Tunnels Under Washington, DC

Geo Beats
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To reduce DC waste by 98 percent, the 20-year D.C. Clean River Project has a 1,323-ton, 442-foot tubular machine digging a 23-foot-diameter concrete water tunnel to begin efforts.

A third of D.C.’s nearly 200-year-old sewer system has both stormwater and sewage going through the same pipes. To reduce waste by 98 percent, the 20-year D.C. Clean River Project has a 1,323-ton, 442-foot tubular machine digging a 23-foot-diameter concrete water tunnel to begin efforts.

The tunnel boring machine was named “Lady Bird” after former first Lady Johnson, an environmental activist.

"Imagine in a storm, this thing filled like a river. Torrent of flow coming down here and then pumped to the surface all the way to the top here where it'll go through a treatment process plant that we are building right on top of where we are standing."

Longer than a football field and heavier than 7.5 Boeing 747s, Lady Bird was lowered, piece by piece, 100 feet underground where it was assembled to begin the 4.5-mile route under the Potomac River.

6 days per week, Lady Bird digs up to 100 feet per day in 6-foot sections. As her cutterhead spins, a soapy liquid mixes with dirt to make a pasty muck. The muck is then sucked up, boxed, lifted back to ground level, and transported to a dumping ground.

With each section, her mechanical arm installs a ring of the concrete tunnel wall by moving pieces weighing up to 7 tons into place. Workers then secure the ring and prepare for the next one.

When this tunnel’s completed, Lady Bird will be joined by other machines to complete several more tunnels.

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