Pipe Ramming Key to Gas Main Installation
Gonzales Boring & Tunnelling Inc. Pushes Through in Washington

After 20 years in the industry specializing in auger boring, microtunneling, TBM tunneling and pipe ramming, Jim Gonzales and his company, Gonzales Boring and Tunneling Inc. (GBT), crossed over into trenchless industry stardom after installing more than 1,600 ft of 36- and 42-in. diameter casings in Auburn, Wash., for Williams Gas Pipeline-West.

Williams' Evergreen Expansion project consisted of more than 10 miles of 36-in., high-pressure gas line, including one HDD river crossing and 10 road bores. The project was part of a "looping" effort to increase capacity to the West Coast.As such, all construction was parallel to and in the immediate vicinity of operating 26- and 30-in. lines.

Williams/Northwest Pipeline Corp. hired Bozeman, Mont.-based Barnard Construction Co. Inc. to assist with the design and permitting of the project. Barnard Construction in turn hired GBT to install more than 1,600 ft of 36- and 42-in. diameter casing on the project.

GBT is no stranger to difficult crossings, Gonzales says, but this was a real accomplishment.

"We've rammed casings as large as 86 in. in diameter," he says. "But this 42-in. ram may be one of the top 10 longest rams done in the United States to date."

Two Generations of Casing Installation

More than three decades ago, Gonzales' father installed a 36-in. casing that now lies about 40 ft away from the new 42-in. casing that GBT installed last year.

At the time, it was common practice to open-cut creeks and wetland areas, and Gonzales used hand tunneling to install the casing. It took him more than two months to complete 200 ft. GBT, on the other hand, didn't have the luxury of two months or open-cutting the creek. The casing had to be installed so that gas would be flowing by Oct. 1, 2003 - no exceptions.

While a 42-in. ram is not an astonishing feat in and of itself, ramming a 42- in. casing 349 ft is another story. But, as it turned out, the ramming dimensions were the least of GBT's worries.

Gonzales' crew was faced with extremely heavy cobble - about 90 percent of the terrain was 12-in. and smaller cobblestone. Then, there was a water table just 20 ft above the casing to consider and the fact that running sand frequently mixed with the cobblestone. There were also 4- to 5-ft boulders to displace. And, to further complicate matters, the 42-in. casing installation was taking place beneath Maple Valley Highway SR 169, railroad grade and the protected wetland area of Maxwell Creek, an endangered salmon species tributary.

A blowout under Maxwell Creek not only posed a threat to the endangered salmon but could have also delayed the crossing, which was already facing a tight and

GBT completed an impressive ram of 42" casing at 349' in severe cobble conditions.

Jim Gonzales, owner of Gonzales Boring and Tunnelling Inc. in front of the 24” HammerHead Mole pipe ramming tool.

A shot of some of the boulders within the bore.

One of GBT’s crew installing a pipe ramming collet using the new collet lifter.

inflexible deadline. The water table was another serious concern. Barnard Construction installed eight wells that had to pump at all times to maintain the water level at the floor of the 25-ft deep launch pit. A CDF wall was also installed at the face of the launch pit to prevent soil from entering the pit during the start of the crossing. To overcome these extraordinary conditions and protect the sensitive wetlands, Gonzales first considered microtunneling. But he decided because of the massive boulders, a microtunneling bore would not be as efficient as a pipe ram. "The pipe ramming method allowed the face of the casing to be supported, while allowing large boulders - up to 38 in. in diameter - and cobble to enter into the inside of the casing without losing the face," says GBT foreman Bob Johnson.

Deploying the 24-In. HammerHead Tool

GBT bored the first 20 ft of the 42-in. crossing using a 60-in. Michael Burns 600-ton boring machine.Unfortunately, 15 ft into the bore, GBT encountered a 5-ft boulder. The following week was spent not only removing the first boulder, but also clearing a second one behind it. Upon removing most of the second boulder and making sure the 42-in.casing was still on line and grade, GBT turned to ramming.

"The 24-in. HammerHead made the job a walk in the park,"Gonzales says. "It just marched right through the remaining boulder."

Gonzales says GBT couldn't have finished this significant project without the HammerHead 24-in. pipe ramming system.

The GBT crew used the HammerHead system over a span of nine days to finish the project, averaging 40 ft per day - including welding and cleaning the 42-in. casing. A Hammerhead representative was onsite to complete the project with ongoing support from the Vermeer Oregon dealership.

HammerHead officials say the project also made HammerHead history. "This is definitely the longest 42-in.- diameter pipe ram ever done with a Hammerhead 24-in. tool," says Jeff Wage, vice president of sales and marketing for HammerHead.

GBT continued pipe ramming at a rate of about 30 ft per 10-hour shift for the first 180 ft of the crossing. Each weld took about three to four hours, including X-raying. The ramming rate slowed to 20 ft per shift at the 260-ft mark, and then to 13-ft per shift at the 338-ft mark. On the last day, it took about 10 hours to ram the final 11 ft.

GBT used a 60-in. boring machine not only to clean out the casing at 100,180, 240, 270 and 320 ft into the crossing, but also to support the 24-in. tool and, on occasion, provide hydraulic assistance. Hydraulic assistance stopped at the 300-ft mark, which meant that the last 49 ft were, remarkably, completed without hydraulic assistance.

The power of the 24-in. HammerHead was amazing, says night-shift foreman Mark Buck. "While we were cleaning the auger of the 42-in. casing at the 270-ft mark, we hooked the 600-ton boring machine up to the casing and attempted to push it through with everything the 60-in. machine could muster, which was about 600 tons, but the casing didn't budge," Buck says. "Then the 24-in. HammerHead hammer was put back to work and the casing pushed ahead almost effortlessly."

During the installation of the casing, bentonite was pumped around the outside diameter of the 42-in. casing. The bentonite was used to help lubricate the casing and stop water from flowing around the outside. Unfortunately, somewhere between 240 and 250 ft into the crossing, the lube line was lost.Incredibly,the crossing was still completed without it.

"This crossing was tough as hell," Gonzales says."Even so, thanks to the HammerHead system, at no time did we ever fear we wouldn't be able to complete it.

"The HammerHead tool worked better than we ever imagined it could, and the factory and dealer support was second to none.We are very pleased, and very proud to have accomplished this feat with HammerHead's help."

April Goodwin, Technical Writer
Des Moines, Iowa

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