The $131 million job is dwarfed by a more controversial $3 billion project now stalled in a standoff between Mayor Shirley Franklin and City Council. That plan would address two bigger problems -- combined-sewer overflows and the city's decrepit wastewater pipes -- and would triple sewer rates.
Critics of Franklin's plan are keeping a close eye on the Nancy Creek tunnel. Even a mild setback could strengthen opposition to the larger project, which would include two bigger tunnels.
The Nancy Creek project faces its own challenges. If it's not completed on time, the feds may hit Atlanta with millions in fines. And building a tunnel ain't easy. Something major almost always goes wrong. The rock can be too hard or too soft. Pumps can malfunction. Boring machines can break down.
The project got physical a year-and-a-half ago, when contractors dug three huge shafts along the length of the planned tunnel. They assembled massive "tunnel boring machines" at the bottom of westernmost and middle of two of the shafts. And, like giant mechanical earthworms, those TBMs are methodically grinding northeast through the granite beneath the city.
Contractor Jordon Jones & Goulding is supposed to complete the tunnel by Oct. 26, 2005, giving Project Manager Michael Robison just a two-month buffer before the court-ordered deadline.
We took a couple of trips down the shaft. And we decided that, whatever you think of the project, the underground lair of the tunnel builders is pretty damn cool.
|Tunnel crews arrive to work in the caged bucket, which is attached to a crane that drops the bucket 200 feet straight down. Joe Moreno, left, preps for liftoff.|
|Project Manager Michael Robison steps out of the bucket onto the tunnel floor. His next stop is the TBM or tunnel-boring machine, which can be reached either by a diesel-powered rail car or, if the car's not available, by a long, wet walk.|
|It took crews 12 months and 40,000 pounds of dynamite to blast the opening shaft and the first 360 feet of the tunnel. Jason Rogers' job is to load and unload the caged bucket that serves as a sort of free-swinging elevator into the real Underground Atlanta.|
|The rail car isn't around. Our mile-long walk to the TBM takes us through the portion of the tunnel bored so far.|
|Robison stops to check out swirls in the rock. We're somewhere below northwest Atlanta, 200 feet or so below Buckhead, but 300 million years back in time. The bedrock -- a mixture composed mainly of granite -- was formed by the repeated clash of continents that created the Appalachian Mountains. Geologists believe the swirly rock once was 12 miles deep. But as the Appalachians eroded away, the bedrock floated upward. Now, a relatively shallow prick on the surface -- this tunnel -- exposes the 300-million-year-old rock.|
|Almost to the tunnel-boring machine, Robison checks on Rob Hatch, right, and David Splendiani, center, who are repairing a part of the rail line.|
|We arrive at the rear end of the TBM, which is 320 feet long and weighs 77 tons. It's a $5-million-dollar, rock-chewing monster, which leaves an 18-foot, 4-inch wide passage behind it. Its teeth, way up at the front end, are 39 solid steel wheels that crush the rock into pieces no bigger than your palm.|
|Robison and a worker confer while the machine head, 20-feet away, bores away.|
| TBM operator Paul Gonzales monitors the machine's
progress from inside its control center. Just outside the window behind
him, hydraulic plates push against the sides of the tunnel, wedging the
machine in place. Other hydraulic arms push the boring face forward, crushing
through the rock.
Maintenance is crucial. Every 30 feet, the TBM must be stopped so crews can measure the steel wheels. If any are worn down by an inch, then the crew has to replace the wheel. Each wheel weighs 400 pounds
|Crushed rock is scooped up and put on a conveyor belt that carries the debris to the surface. As the machine inches forward, crews lengthen the belt and must extend a ventilation system, electric lines and water lines. They need the water to spray down freshly bored rock.|
|Mayor Shirley Franklin visited the Nancy Creek tunnel in October for a photo op, just two weeks before she asked City Council to approve her $3 billion plan to repair and upgrade Atlanta's crumbling sewer system. Though the two issues aren't directly related, she held up Nancy Creek as an on-track project that really will prevent sewer overflows -- and stave off federal fines. That wasn't enough to convince a majority of City Council to back the sewer rate increase that she requested for the much larger project.|
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