A look at a new construction technology, microtunneling, and how one company has taken the lead in its use.
A look at a new construction technology, microtunneling, and how one company has taken the lead in its use.
After C. Michael Garver bought a robot-tunneling machine, he was so far ahead of the pack, he had to drum up his own competition
When C. Michael Garver rolled into Houston in 1965, he was the classic first chapter. With a degree in mechanical engineering in his pocket and his possessions loaded in a trailer, he was ready to take off after anything that looked legal and big. At the time, the city was growing frantically, with buildings going up all over town. Garver knew that all the action above the surface had to have its reciprocal below, in water and sewer projects. Not everyone appreciates the scale of the infrastructure industry -- out of sight, out of mind -- but Garver did. (U.S. municipalities spend more than $5 billion a year on capital improvements for sewerage and wastewater treatment alone.) And Garver wanted a piece of the action. In 1972, after a few years of selling draglines (Texan for "cranes"), he and two partners started a contracting company, BRH Inc., intending to specialize in underground construction. Nine years later Garver took control of the enterprise, recasting it in his own image as BRH-Garver Inc.
The specialty had been laid claim to for decades, and Garver, like any newcomer in an established sector, had to carve his own path. That meant keeping an eye open for jobs that were novel or complicated, since a newcomer was unlikely to outbid companies on work they had done a dozen times before. It was from that perspective that he contemplated a Houston public-works job, posted in the fall of 1986, endorsing the use of a piece of machinery called a laser-guided microtunneler, a device neither Garver nor any other contractor in Houston had ever worked with. The job was worth nearly $10 million -- potentially the biggest piece of business yet in the short history of Garver's company. He remembers phoning a micro-tunneler vendor and asking what the learning curve was for the equipment. "You know how it is when you talk to sales," he says now. " 'Just slip tab A into slot B.' " Sales sent over a video, which Garver watched. Reassured, he made a low bid for the job, got it, and ordered one of the first microtunnelers to be sold in the United States.* * *
Microtunnelers, also known as robot moles, were developed by the Japanese in the early 1970s as a means to lay pipe without first digging long trenches. The idea was to dig shafts at, say, successive street intersections, lower sections of pipe down into the shafts, and then push (or jack) the sections, laid end to end, until the first section hit the next shaft, while leaving the ground surface undisturbed. As the sections were being jacked from behind, the tunneler would grind along in front using a steerable digging or cutting mechanism, like a toothed wheel, to remove the "muck" and pass it back through the machine, through the pipe, and out into the shaft, where it would be lifted to the surface. The technology turned out to have many advantages: it reduced surface disruption, could accelerate production, and allowed contractors to dive right under the tangle of pipes that clutter the near surface of any city, avoiding service interruptions. By the early 1980s microtunneling was being used in several industrialized countries.
But not in the United States. Americans like to think of themselves as receptive to new technologies, but that enthusiasm is not much in evidence when it comes to machines for constructing roads, sewers, water mains, treatment plants, and other public facilities. The reasons behind the foot-dragging aren't clear (observers have suggested reflexively risk-averse bureaucracies, the worship of the low bid, contractor cartels, regulators, and lawyers), but the phenomenon is real enough. Until well into the '80s, the city engineers of Houston actually forbade the use of a backhoe for work on sewer lines, insisting that trenches be dug with an ancient device that worked by scraping digging buckets hung between chains up against the working face of a site. Those ladder-type trenching machines were clumsy, broke down constantly, and required huge crews to run. But they had been used forever, and the city was confident that they would not create a public-relations disaster. Some- times a contractor would do a job with a backhoe and then stick a trencher down in the cut while the city engineer made his tour. But most used the prescribed tools in the prescribed way, as their fathers had before them.
As the late '70s gave way to the early '80s, Houston city engineers realized that most of the sewer work done over the last 20 years needed to be replaced. For starters, the system included far too many pumps. Pumps are the weak points in any sewer system: the machines have to work 24 hours a day under difficult operating conditions and are constantly breaking down, backing up, or overflowing. The right way to build a sewer between points A and B is to let gravity do as much of the work as possible. That means allowing the pipes running between the pumps to fall as deep as possible. Cutting trenches 25-plus-feet deep in soft, water-saturated soil like Houston's is not only expensive but tricky: such "gumbo clays" are prone to cave-ins. The city had tried to build a cheaper sewer system, with short, shallow connections linked by hundreds of pumping stations, but the overflows were becoming a public nuisance. It was time to start over.
Garver's job would cover one area of renewal. It called for laying a new line through River Oaks, a politically well-connected neighborhood. Excavation on the scale required would have meant shutting up a lot of rich people in their homes for weeks. Tony Crisci, who was the civil construction manager on the job, says that acres of expensive, exotic, and presumably cherished plantings would also have been at risk. The public-works department had looked at the job in the '70s, winced, and shoved it to the bottom of its to-do pile. By the mid-'80s pressure from the Environmental Protection Agency had moved it to the top. By coincidence, an engineer consulting for the city, Calvin Morgan, had family in the British contracting culture and knew that in Europe the job would be microtunneled without a thought. Morgan began advocating the technology; the combination of his enthusiasm and the political constraints of the project opened the door. When the bid went out, microtunneling was written into the specifications, in place of the trenching-machine requirement.* * *
His first day on the job, Garver lowered his new machine into a shaft, aimed it, and started digging. The tunneler ran off into the dirt and stalled, wedged tight. Garver dug a new shaft down from the surface to reach it. When he hit metal, he loosened the machine and pointed it once more. Again it jammed. His vendor's technical consultants were baffled. The machine had worked fine in Japan. The vendor offered to return his money and take the machine back. It was an honorable gesture, but Garver was in no position to accept it. Returning the machine would have left him sitting around watching a $10,000-a-day late-penalty clause eat up his new business.
Garver had a hunch that the water-saturated silts, sands, and clays of Houston must be imposing different forces on the operating cycle of the machine than the rocky, heterogeneous sands of Japan did. So he used a cutting torch to reshape the face of the mole. He eventually got the machine going, but clearly there had been some major miscommunication with the vendor regarding tab A and slot B. "River Oaks was a real baptism by fire," he says.
Microtunnelers take a mix of systems (hydraulic, electrical, electronic, mechanical, optic, even video) down into an environment that is dirty, wet, unpredictable, inaccessible, largely unobservable -- and characterized by extreme pressures. If anything goes wrong with any of the subsystems, the whole cycle stops and doesn't restart until the failure is fixed. One wrong touch on the steering knobs (the machines are guided remotely from a control console on the surface) and the tunneler can start "porpoising": oscillating back and forth across an axis instead of running straight down it. Too little pressure on the jack and the machine will stick -- and the longer it stays stuck, the more tightly the surrounding ground will settle around it. Too much pressure from the jack and the pipes will crack, in a way that may not be obvious until later. The exact value separating too much pressure from too little varies with the soil type, and the soil is unobservable until the tailings start coming out of the shaft.
Those and other constraints mean that microtunneling jobs must be planned in much greater detail than cut-and-cover trenching jobs. Hundreds of connections need to be monitored and maintained. One slipup can lead to trouble: if a cable breaks when the machine is underground, for instance, as much as a week's production -- and tens of thousands of dollars -- can be lost. A large parts inventory has to be kept on-site for preventive maintenance, and a versatile equipment-repair shop must be established in the home office. The workforce needs to be trained to high skill levels and evaluated constantly to make sure it shows an obsessive attention to detail. How fast an employee can be trained is a critical factor in planning work assignments. "A worker who doesn't like to learn isn't going to be very happy doing this work," says Garver.
Amazingly, the River Oaks project was completed on time, though just barely, and Garver even made a profit. From the perspective of many of the local contractors, however, that was not good news. The Houston rebuild, which was coming in at more than a billion dollars, could have kept the whole community of cut-and-cover contractors in steak for years; now Garver was threatening to grab most of it with his Buck Rogers technology. Contractors lobbied the city council, arguing that it was unfair to the taxpayer for city engineers to specify tools. They should just define the job, the contractors insisted, and let the lowest bidder win. Several jobs were, in fact, announced that way, but Garver kept winning the contracts, because while trenching gets more expensive with depth, the cost of microtunneling stays pretty much the same. Today BRH-Garver does roughly $35 million worth of business a year, about half of which comes from microtunneling projects across the country.
River Oaks made believers out of Houston Public Works, but the rest of the country stayed unconverted. The skepticism could have turned into a long-term problem for Garver, who knew the Houston work would end in a few years. So he searched for ways to expand his market. "We decided to let our light out of the basket," says Clifford Tubbs, Garver's vice-president in charge of estimating and project management.
Going against all the instincts of contractor culture, Garver began inviting competition into the business, knowing it was the only way to build market. In 1990 in cooperation with a microtunneling trade magazine, he sponsored the first U.S. conference on the technology. He set up a microtunneling field demonstration (and barbecue) on his company grounds and ran in busloads of engineers, contractors, and clients from the conference to see working demonstrations. In 1992 he helped organize the Gulf Coast Trenchless Association, a promotional group that supports lectures, technology demonstrations, and conferences in underground construction. "He's the leader," says Professor Tom Iseley, of the Purdue University School of Engineering and Technology, in Indianapolis. "There's been nobody else with that kind of vision."
The vision has spawned opportunities. The number of feet dug with micro-tunneling has begun to edge up: 300,000 feet in 1994 compared with 90,000 in 1989. Tim Coss, who does microtunneling research at the Colorado School of Mines, in Golden, Colo., estimates that there are about 40 machines in the country now, which is impressive, given that there were only a half dozen or so here five years ago. (The impressiveness fades somewhat when the number is compared with the thousands of machines currently being used in Japan.) Today Garver can't lose for losing. For a recent job he bid on in Amarillo, Tex., eight microtunnelers bid against him. That he lost is just another measure of his success.* * *
Fred Hapgood (firstname.lastname@example.org) is a freelance writer based in Boston.