At nine-thirty, with all the preliminaries done164, the Humvees began their slow journey east, stopping at every mine phone so a diver could check in with Harald as he sat in his topside trailer. Forty-five minutes later, after reaching ring 6000, they stopped to fire up the oxygen-injection system that would feed the Humvee’s diesel engine. Even though the oxygen level in the tunnel was dropping steadily, the divers decided to push it a bit more on the ambient air, before turning to their breathing supply. In addition to being more comfortable and natural, the ambient air allowed them to carry on conversations without having their voices distorted by their facemasks and the sound of hissing air.
On the drive out, Billy talked a lot with Tim. Although they’d known each other for only a couple of weeks now, the two found they got along well. They were both fun-loving guys who were good at what they did but low-key about it. They were both famous for their facial hair, Billy with his mustache and Tim with his beard, which he had reluctantly trimmed to a goatee for this job. And they each had a great woman at home who was growing increasingly worried about this assignment. The day before, around the same time that Michelle was sharing her fears with Billy, Judy was doing the same with Tim. “I don’t want you to go in the tunnel if you don’t think it’s safe,” Judy told her husband on the phone. Even the usually upbeat Tim had been worn down by the frustrations and setbacks the divers had encountered during the first week. When Judy said, “Tell me again about the tunnel,” he conceded, “It’s cold, it’s wet, and I’ll be glad when this job is over.” Now Tim and Billy were both looking forward to a productive, drama-free day so they’d have some calming news to report during their next call home.
When the divers arrived at the venturi at 11:15 a.m., they followed the protocol for activating the mixed-gas breathing system. Once the mixer and regulators and manifolds were all properly aligned, the divers put on their facemasks and started breathing the blend of the vaporized gas from the liquid oxygen and liquid nitrogen. Before long, the pair of Hummers began their trip into the diffuser tunnel.
Even after they had donned their facemasks, the divers would continue to make periodic stops to test the air. Harald had instructed them to use their Drager Multiwarn handheld gas monitors to measure the ambient air in the tunnel, not just for its oxygen content but also for the presence of dangerous gases, such as methane, hydrogen sulfide, and carbon monoxide. Although no worrisome levels of those gases had turned up during the factfinding mission a year earlier, back then the divers had ventured only partway into the tunnel. Now as they prepared to make their way to the very end, they needed to know everything they were up against.
Six weeks earlier during their Drager training sessions, the divers had been schooled in how to use these Multiwarn analyzers to test ambient air. But just before the start of this Monday mission, they had been surprised when Harald told them they should use these same Multiwarn devices to measure the oxygen content of their own breathing supply—after that air had exited the MAP Mix 9000165.
Because no one had made it out to the final stretch of the tunnel since the sandhogs had ripped out the ventilation, the environment there was shrouded in mystery, cordoned off like a crime scene. Still, the divers had good reason to believe that the air toward the far end of the tunnel had only gone from bad to worse, as rusting metals likely consumed much of the remaining oxygen. And thanks to all the water that had leaked in through cracks in the bedrock around it, the tunnel was now home to a host of microorganisms that thrive in damp oxygen-starved air.
These microbes are usually harmless. In fact, Deer Island’s state-of-the-art sewage treatment plant had been cleverly designed to harness the power of microorganisms. Inside the 3 million-gallon egg-shaped digester tanks166 that defined the new island landscape, battalions of the single-cell bugs feasted like Romans at an orgy, except their menu consisted of thickened sludge from human waste. Playing the role of a giant collective stomach, those microbes broke down the sludge into water, carbon dioxide, and methane. That resulted in a vastly reduced amount of sludge, which could then be converted into fertilizer pellets. By far the biggest by-product of this digestion process—about 70 percent—was methane gas, which was sent across the island to boilers, where it was ingeniously converted into electricity to help power the plant167.
In a controlled setting like the sophisticated sewer plant, methane wasn’t a threat. But because the gas happens to be highly flammable, in a confined space like a coal mine or a dead-end tunnel, a simple spark could turn a pocket of methane into a calamitous explosion. That’s why they had to be so vigilant in testing the ambient air.
Around two o’clock, the divers arrived at riser number 12168. They spliced a mine phone into the wire running along the side of the tunnel and put a phone console inside the Humvee so there would be a direct line to Harald. They detached the towed Humvee wagon from the trailer and parked it a few feet away, facing back toward the shaft, so it would be in position for the return drive at the end of the shift. Billy and Tim climbed into the Humvee wagon, with Tim taking the driver’s seat and Billy clambering around all the equipment packed inside the vehicle to get to his place in the back seat, right beside the MAP Mix 9000. Billy and Tim would remain in the Hummer to monitor the mixed-gas breathing system that all five divers would continue to rely on. Outside the Humvee, the oxygen level in the ambient air had already fallen to 8 percent. The three guys on the excursion crew would have to trek all the way to the end of the tunnel, where it choked down to five feet in diameter, alternately dragging and pushing the flat-bottomed boat that groaned with all their gear. DJ was supposed to have been part of the excursion crew, but Tap had benched him for being late, and Riggs was given a break from tunnel duty for the day. So Monday’s excursion crew consisted of Hoss, Mike Mars, and Tracy Markham. Once the trio made it to their final destination, one diver would begin crawling into the thirty-inch off-take pipe leading to riser number 1.
After they removed each plug, the divers would be required to videotape their work so that Kiewit and the MWRA had verification of its removal. But even before the excursion crew left the Humvees, they tested the video camera and found it wasn’t working. So much for the hope that Monday would be free of complications. The day was shaping up to be one in which even the easy stuff proved hard.
At ten minutes to five, the excursion crew began its schlep east. Hoss, Markham, and Mars were connected to the main breathing system via a twelve-hundred-foot umbilical—which was actually four separate three-hundred-foot hoses strung together. This umbilical stretched from the plywood manifold on the Humvee wagon to another plywood manifold in the boat. Attached to the manifold in the boat, each excursion diver also had his own umbilical that gave him an additional three hundred feet of running room. This was critical, since the boat could only comfortably go about as far as riser number 4. That was because the final stretch of the tunnel was a series of three reinforced concrete pipes, each one narrower than the one before, with diameters shrinking from seven feet to six feet to five169.
164 (Chapter 8, note 3)
At nine-thirty, with all the preliminaries done: Kaiser, shift report, July 19, 1999.
165 (Chapter 8, note 4)
after that air had exited the MAP Mix 9000: Hoss, DJ, and Riggs, interviews by author, 2009-12; Hoss’s accident notes from July 23, 1999: “On Monday, I asked Harold if the gas mixer was meant for breathing and why it didn’t have an analyzer built into it. He said, ‘I guess this model doesn’t have one’ ” (p. 11).
166 (Chapter 8, note 5)
Inside the 3 million-gallon egg-shaped digester tanks: MWRA,
167 (Chapter 8, note 6)
electricity to help power the plant: MWRA, “The Deer Island Sewage Treatment Plant,” September 2, 2009, www.mwra.state.ma.us/03sewer/html/sewditp.htm.
168 (Chapter 8, note 7)
divers arrived at riser number 12: Grob topside log, July 19, 1999.
169 (Chapter 8, note 8)
shrinking from seven feet to six feet to five: Tom Corry, deposition, 75.