Learning On The Big Long Job

By Donal Philby

Mactec Constructors are battling the advance of a slow, but unstoppable, avalanche of work on what may be the largest polyurea coatings job ever.

Around 8,000 square feet a day, a contractual minimum of almost 40,000 square feet a week. Week after week. An estimated 3.23 million square feet in total.

It’s a job 4 ½ miles big and 2 ½ years long. And they’re learning every day.

Stretching from Alameda on the east side of lower San Francisco Bay to its namesake city in the west, the San Mateo Bridge is doubling in width. The original three lanes no longer suffice to carry the traffic.

Almost everything is steel reinforced concrete manufactured by Pomeroy Corporation, a specialist in large-scale concrete pre-cast structures.

Pilings plunge 30-feet deep into the shallow waters of the bay. Bent (end) caps span a pair of pilings. Trusses rest on the bent caps, and a layer of deck plates tops the whole structure. That’s four different pre-cast pieces ranging in weight from one thousand pounds to 11 tons.

The sheer scale of the Pomeroy concrete fabrication yard boggles the imagination. Here, tiny-looking men in towering TraveLifts lower huge welded rebar sculptures into giant metal molds. Other tiny men pour truckload after truckload into the molds. The pieces are cured for 30 days, then carried by other giant TraveLifts and settled onto Mactec’s concrete supports, ready for coating.

On its own, with bare concrete subjected to corrosive salt water, CalTrans estimates 100-year lifespan for the new bridge addition. With the right plural-component materials, applied by professional in the right way, CalTrans expects another 20 years of service life. But it sometimes there are as many right ways and right materials as there are applicators, material suppliers, engineers and, of course, sidewall superintendents.

That this was to be the first attempt to apply polyurea coating to a pre-cast, partially submerged superstructure just added to the unknowns. Anyway you look at it, a job this size was going to be a learning experience — for everyone.

The logistics of moving multi-ton concrete fabrications necessitated that Mactec Constructors stage the coatings application in the Pomeroy yard in Petaluma, a city about 45 miles northeast of San Francisco, and an hour-plus drive from the bridge.

The wind swirls hot and cold past the meandering Petaluma River that runs into San Pablo Bay, a large, shallow body of water that adjoins San Francisco Bay. The yard is not far, in fact, from the famed Napa Valley wineries.

The yard is situated on the Petaluma River and includes piers for barge access. Once a week tug boats tow waiting barges south to the bridge site loaded with coated parts ready for assembly.

One of Mactec’s first mobilization challenges involved designing and building the system to handle the high volume and massive size and weight of the pre-cast pieces. While TraveLifts needed vertical access to drop the pieces into place, the need for environmental control mandated a containment system.

Part of the creative magic of any coating application is designing a system to overcome seemingly impossible conflicts. This was certainly no exception.

For the giant pilings, bent caps, and trusses, (moved by TraveLifts) two buildings 25x40 and 40x60 feet were fitted with rollers and mounted on railroad tracks. Forklifts push the moveable buildings, exposing the coatings area to enable transport of the huge pieces. Then the lifts remove and replace the pre-cast pieces, and the buildings are pushed back over to start the process anew on fresh surfaces.

Since the smaller deck plates could be moved by forklift, a stationary building 60x200 square feet was erected to provide shelter and containment for the coatings.

All these temporary buildings are fabric-covered metal-framed structures sturdy enough for the big winter storms that blow in from the Gulf of Alaska.

Even before the contract was let in October 1999, it became evident to Mactec Constructors (then known as Harding Lawson Associates) that proper material selection would require extensive research, and testing.

“What we did not know at the time was how far into the noose we had stuck our heads,” remembered Frank Limas, Mactec site superintendent.

The day before bidding closed, CalTrans issued a specification change. The consequences of that change is now making its way through the legal system, but Mactec quickly identified what Limas described as the “nightmare issues of the job: bug holes and pinholes in the concrete and out-gassing of the concrete.”

The problem was “finding a single material thin enough to eliminate the pinholes while thick enough to hang in the bug holes on vertically applied surfaces,” said Limas.They were well into the job before they did.

CalTrans specifications restricted all coatings materials to those of a single manufacturer. Mactec found materials that would meet various requirements for each layer of coating, including efficient application, but not from a single manufacturer. To meet the single supplier requirement, Mactec was forced to increase application costs.

During the initial start period, Mactec Constructors experimented with the materials from 10 manufacturers “trying to find a system that met all of CalTrans’ specifications and Mactec’s financial boundaries. What we found was that only four manufacturers had or would ultimately develop materials that met the basic job specifications,” said Limas.

Eventually Mactec settled on Elastomer Specialties, Inc., of Broken Arrow, Oklahoma, in part because of their willingness to develop — at their own expense — a compatible primer to meet CalTrans’ specs.

Part of the problem was trying to hit a moving target. As testing and then production moved from summer, through fall and into winter, Elastomer and Mactec had to work out material formulas and application techniques tailored specifically to the seasonal conditions, driven primarily by temperature and dew point.

In the meantime, they were contractually obligated to keep up the production schedule, prepping, priming, and coating a minimum of 36,956 square feet a week.

Some of the early efforts to find a successful formula have failed after installation at the bridge site. Fortunately, Certified Coatings has the contract to provide on-site coating of the fabrications at the bridge. They are able to prep and re-coat these problem areas under supervision of Mactec’s QA supervisor, Ron Piloneo.

Another hitch in the job’s get-along was finding crew. Not only is there a shortage of people with extensive experience, Mactec, struggled to find even good, trainable laborers. The available pool of experienced laborers had been diminished by the white-hot pace of construction in California.

Finding people who can keep their wits about themselves in a potentially dangerous environment is difficult. “One apprentice was learning to use a sandblaster. When I asked him a question, he turned toward me, swinging the nozzle as he turned,” said Limas, who managed to dodge the high-pressured stream of sand. Mactec has tried temp agencies, ads in newspapers, even driving up to street corners where people hang out looking for day jobs, and finally, asking about friends of people already on the payroll.

“We’ve hired on 200 people to get the 64 we now have working. Most only last a couple of days,” says Mactec foreman Dale Whittam.

According to several of the management team, keeping the spray equipment running is a never-ending skirmish. Which is not to fault Glas-Craft, Inc. of Indianapolis, Indiana, the supplier. “Never before has spray equipment had to withstand this volume of work,” said Limas. “Right now we stock back-up for the back-ups,” indicating that cleaning and regular maintenance is vital to keeping up with production schedules.

Murphy Mahaffey, Product Manager for Glas-Craft, said there are nine machines of various sizes on the job, and they have yet to fail to yield the weekly requirement of nearly 40,000 square feet.

Mactec is working closely with Gals-Craft to develop better, longer lasting, higher productivity equipment. Such advances should benefit the industry in general.

That’s no small matter when production schedules are so tight. In fact, only the starting time for each shift is set. Each shift works as long as it takes to get done what the next shift needs. Generally, using two shifts over 24 hours, the entire coating process is completed. So shifts will commonly work between six and 12 hours.

Given the volume of the job and also the warranty that the applicator and the material supplier must stand behind, Elastomer Specialties has a full-time representative/inspector on site. For both the rep and the applicator, this can be a delicate balance of mutual respect and territorial protection. With the size of this job, the stakes are enormous, but of course the need to solve and resolve problems is in everyone’s best interest.

John Stannard, who represents Elastomer Specialties, Inc. on site, said, “The material we’re using is the latest, top-of-the-line. I’m on the phone constantly with the home office staff to adapt to the changing needs of the project.”

At the beginning of the project, CalTrans fielded a team to oversee production. As the coating process has been refined and proven, there is now only one.

CalTrans Addis Ambaye is a civil engineer who said he understands the coatings, but was often frustrated with all the variables when trying to hunt down the problems, such as blisters. “Despite all the struggles,” said Ambaye, “This is an excellent crew and the end results are excellent, too.”

Mactec’s quality assurance specialist, Ron Piloneo, conducts systematic adhesion testing every day, verifying each application cycle, then logs those test results into a computer-tracking program.

“This helps us see the effect of changes in the materials or the application process or the weather or other conditions,” said Piloneo.

One problem condition is visible from an overlook of the Mactec facility. Plumes of dust rise behind almost every vehicle — pickups, dump trucks, travel lifts, fork lifts, covered with a concrete-gray film. And that fine powder affects adhesion of the material.

Spray foreman Dave Harris said he works closely with Pomeroy, scheduling water trucks to keep the dust under control.

The conditions are anything but plush for the crew. Feet can crunch through the thickening layer of grit-like blasting aggregate, overspray, and trim. During sandblasting, the shrill, high-pitched screams of the air-driven guns pierce even protected ears like an ice pick. And inside the tent, the dust swirls as light from the overhead mercury vapor lamps make the air glow a yellow brown, thicker than a London fog, and ghostly figures in white suits appear and disappear, trailing snaking black hoses.

It’s a big, long job, and all these guys work hard. They learn quickly, too. Now half way through, the stresses are diminishing, yet the slow-moving avalanche of pre-cast concrete rolls on.

According to Elastomer, Mactec has emerged as the premier polyurea applicator for large-scale coating projects demanding high volume production.

Which is just fine with Frank Limas, who is “looking forward to new and challenging jobs,” and anticipates a bright future in the superstructure coating arena.

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