There’s a new girl in town…well, at least among the ranks of Tweeting tunnel boring machines (TBMs).
Over the next month and a half, the 250-ft long,150-ton TBM will nibble her way through 3,028 feet of limestone to make way for the Lemay Redundant Force Main, the first major construction project in the St. Louis Metropolitan Sewer District’s 23-year, $4.7 billion combined sewer overflow (CSO) program, Project Clear.
The new force main will allow the District’s Lemay Wastewater Treatment Plant to accept a higher volume of wastewater, and permit the first inspections of the system’s original force main since it was constructed 50 years ago.
According to the District, Chelsea’s previous gigs have been in the Caribbean and Latin America, the most recent one being an 8,202-ft power tunnel in Costa Rica. Upon her arrival in the Gateway City, she was renamed for the granddaughter of a principal at tunneling contractor SAK Construction, based in O’Fallon, Mo.
Chelsea’s current assignment is relatively brief compared with the marathon efforts of her “sisters” Bertha in Seattle; Lady Bird in Washington, D.C.; and Big Alma and Mom Chung in San Francisco. (Cleveland’s Mackenzie, who completed her dig last year, still Tweets occasionally despite being disassembled.)
But with more tunnels to be constructed under Project Clear over the next two decades, some up to 9 miles long and 230 feet deep, Chelsea may well become as much of a fixture around St. Louis as the Gateway Arch and the baseball Cardinals. (One would think her 11.25 ft diameter cutting head would be of interest to the offensive line coaches of the NFL’s Rams as well.)