New concerns arose about the ability of the tires on the trailer to withstand the load. Rather than risk a flat deep in the tunnel, Harald decided to send out the tires to be filled with a special foam154. This ran $400 a tire, but it made them much better suited to the dicey terrain. Those tires wouldn’t be ready until the weekend, meaning the plug-pulling operation would now have to wait until Monday.
After their exhausting day, DJ was relieved to hear they’d be getting a rest. He detected that even Harald, who had always seemed so preoccupied with the demands of the calendar, appeared to be fine with the delay. That was probably because the day had ended with some rare good news. The elusive MAP Mix 9000155 had not only arrived from Denmark, but it had cleared customs at Logan Airport and been delivered to the island. Two weeks after the training sessions had begun in Tap’s yard, and one week after the divers had begun working on site, Harald’s vaunted breathing system would finally be ready to go.
Riggs stood at the base of the shaft, hunched over, staring at the piece of equipment everyone had been waiting for. It was Friday morning, and Harald had selected him for the important job of helping to install the gas mixer that their breathing system had been built around. As he looked it over, Riggs mumbled, “Hey, this sure don’t look like diving equipment.”
It was, in a word, underwhelming. The stainless-steel unit looked more like an old-model toaster oven than a high-tech gas blender. It was small—just eight inches tall, nine inches wide, and sixteen inches deep156. And it looked unsophisticated—with a gray faceplate featuring just two big dials and a small light sitting between them. The red dial on the left was labeled FLOW, and it went from 0 to 300. The blue dial on the right was MIX, and it went from 0 to 100 percent. The small red light in the middle was labeled ALARM. Across the top, the unit read PBI DANSENSOR, the name of its Danish manufacturer. In smaller letters across the bottom, it read MAP MIX 9000 GAS MIXER, to the right of a warning message in red letters: “!!Danger!! This mixer is mixing OXYGEN. Using oxygen may lead to mortal danger of EXPLOSION. Use only oxygen as specified by the rules of the specific country.”
Even if the mixer seemed unimpressive, Riggs was pleased that Harald had picked him for this installation assignment. The only other diver he had chosen was Mike Mars, the thirty-six-year-old trusted veteran with Norwesco whom Harald had designated to be his crew foreman in the tunnel. Riggs took his selection as a good sign for his long-term goal of establishing a permanent home with Norwesco.
Unlike Mars, Riggs had had very limited experience working with Harald prior to Deer Island. Harald’s role on the Lake Mead job had been largely at the front end, and by the time Riggs joined that project, day-to-day operations were in the hands of someone else. Riggs had interacted with Harald just twice during his year in Nevada, and he’d found the engineer to be quiet and low-key. So he hadn’t been prepared for the imperious and impatient Harald he encountered in Tap’s yard. He especially didn’t care for the imperious part, the suggestion that, as the smart engineer, he had done the hard thinking for everyone else. Riggs’s father had spent his career as an engineer, and even though he never once told his son he wanted him to follow in his footsteps or was anything but respectful of his choices, Riggs could sense that his dad had higher aspirations for him than life as a blue-collar laborer. Still, even if Riggs hadn’t been a star student, he knew he was smart. He didn’t take kindly to anyone implying that divers couldn’t somehow measure up mentally, no matter how many framed degrees that person might have.
But now, working alongside the stout engineer, Riggs saw a more relaxed and collegial Harald, who wore a blue-gray jumpsuit with norwesco printed on the back and his name written in cursive on the front. Maybe, Riggs thought, Harald was finally settling into his role and learning to deal with the pressure. Maybe, like DJ, he’d simply made a bad first impression in New Hampshire.
When Riggs asked how this small machine could handle such a big job, Harald explained that the elegant little proportional gas mixer was fully up to the task. Just three hoses157 had to be hooked up to the MAP Mix 9000: one input from the oxygen, one input from the nitrogen, and one output for the blended gas once the MAP Mix had worked its magic. Opening the regulators atop the liquid oxygen and liquid nitrogen cylinders would send the liquid through a coil inside the tank, vaporizing it so that it would be converted into a gaseous state before traveling to the mixer. As for the two dials on the front of the MAP Mix, Harald turned the flow up to its highest setting, 300 liters per minute. This would make it an “on demand” breathing system, dispensing air to the divers as needed. He turned the mix dial to 22 percent, meaning that would be the desired oxygen content of the blended gas supply—setting it a smidge over the usual 21 percent would provide a small cushion. Once the blended air left the mixer, which rested on the Hummer’s back seat, it would travel by hose to the plywood manifold wedged between the vehicle’s front seats.
The MAP Mix 9000 might have been small, but it certainly wasn’t cheap. Norwesco had paid more than $10,000158 for the pair of mixers, buying two so that both the main pair of Humvees and the backup/standby pair would have identical setups. Even though Topac, the mixer’s Massachusetts distributor, had requested rush delivery for Harald, that hadn’t been possible because the Danish manufacturer didn’t normally stock models that mixed nitrogen and oxygen. Most of its customers159 used the mixers for industrial purposes and typically requested models that blended carbon dioxide with either oxygen or nitrogen. So Harald’s mixers had to be specially assembled. During the long delay, Harald had warned160 the owner/salesman of Topac, Tony Drybanski, that every day lost was costing Norwesco $20,000, presumably given payroll, lodging, and other costs. Finally, after all the waiting, Drybanski had personally dropped off the mixers to Deer Island. Now, with relatively easy work on the part of Riggs, Mars, and Harald, both units were being installed.
Riggs asked Harald what the power supply would be for the mixer. He was surprised when Harald explained that the device was pneumatic, meaning it didn’t require a power source. It was driven solely by pressure. Underneath the mixer’s stainless-steel cover, there were multiple valves and diaphragms, including a large one that looked like a waffle maker resting on its side, with a rubber gasket inside it. As long as the pressure of the gas coming into the mixer—the vaporized oxygen and nitrogen—was greater than the pressure of the gas moving through and out of the unit, the machine would continue to hum along. That was because, on its own, gas flows from high pressure to low pressure, always attempting to achieve equilibrium. The same principle applies to something as basic as a balloon. When you blow one up and pinch the end of it, the air compressed into that stretched balloon is much higher in pressure than the air outside it. If you release your pinch, that high-pressure air will automatically flow out of the balloon, racing toward the low-pressure ambient air.
Like the miracle of the hydraulics in the outfall tunnel itself, where a billion gallons a day of treated water could flow along the 9.5-mile route, up one of the fifty-five risers, and finally out to sea—all without so much as a pump or a motor—so, too, could this mixer work without any electrical power.
156 (Chapter 7, note 24)
eight inches tall, nine inches wide, and sixteen inches deep: “MAP Mix 9000 User’s Manual,” PBI Dansensor A/S, Ringsted, Denmark, 1996. I’ve converted the measurements from the metric.
158 (Chapter 7, note 26)
Norwesco had paid more than $10,000: A-L Compressed Gases of Spokane, invoice, June 30, 1999. Each mixer cost $5,062.50.
159 (Chapter 7, note 27)
Most of its customers: Steen Hansen, interview by author, Ringsted, Denmark, June 2011.
160 (Chapter 7, note 28)
During the long delay, Harald had warned: Trooper Mary McCauley, “Interview of PBI Dansensor Company (TOPAC Gas Mixer) in Reference to Tunnel Death Investigations at Deer Island,” Massachusetts State Police Suffolk County Detective Unit, October 9, 1999, 3.