Arizona Pipeline Delivers The Goods

By Terry Ertter | September 28, 2010

Pipelines have at least one important thing in common with offensive linemen on a football team. Both generally prefer to be ignored. If they're getting noticed, it usually means something has gone wrong.

Choose 100 people at random in the Phoenix area and ask them what they know about the pipelines that supply the gasoline, diesel and jet fuel to the city. A few will likely recall that a leak in the line between Tucson and Phoenix caused a brief gas shortage and some long lines at the pumps for a couple of weeks in 2004. Some from that group may remember reading that Phoenix gets all its fuel from two lines — one coming in from Los Angeles and the other from El Paso. Most of the random sample probably won't know a thing about pipelines. And, as long as there's plenty of gas at the pump, they won't care.

That's actually quite amazing when you think about how incredibly important the two pipelines are to nearly every Arizona resident. Arizona's economy — much like the economies in of the other Mountain states — has been driven by construction for several years. New residential developments, tall buildings in the big cities and new freeway interchanges get lots of press.

But a $100-million construction project stretching 150 miles and employing more than 320 people has been going strong for months now in Southeast Arizona with a remarkable degree of anonymity. Residents of Benson and Willcox know about it. Their motels and restaurants benefit from the influx of well-paid workers. For most of the state, however, it is out of sight, out of mind.

The wide-open spaces of the Rocky Mountain states make it easy for pipeline companies such as Rockford Corp. of Hillsboro, Ore., to maintain the low profile they prefer. Rockford is the company building the new Arizona pipeline for Kinder-Morgan. The new line is a replacement for a stretch of the existing pipeline, and it ties into another section of new line completed two years ago.

On the east, the project starts at the north end of historic Apache Pass in the mountains southeast of Willcox. It runs alongside the existing petroleum line and a larger natural gas pipeline through the pass before turning west again on the south side of the Dos Cabezas range. After exiting the difficult and rocky mountain pass, the line has a relatively straight and easy run through flat desert and into a stretch of farmland. It even cuts through the south edge of a low area that becomes a shallow lake during the rainy season.

West of the lake, the line runs through the Apache Station electric generating plant. From there, it continues to Benson, where it passes under a rail line and Interstate 10. Benson is one of the few places where the pipeline is actually in a town. From Benson, the current project continues across open land to the eastern edge of Tucson, there tying into the line that runs northwest to Phoenix.

Many challenges

Every section of the project presents a different kind of challenge, according to Rockford's Carsten von Borstel. The challenges in the Apache Pass section are obvious. The terrain is incredibly rocky, with steep ascents and descents giving crews a roller-coaster ride as they travel along the dirt road next to the trench. In several areas, the steep slope prevents some crews from setting up support equipment they would normally use, and they must find ways to do their jobs without it.

Rocks and rust are a pipeline's natural enemies. Rockford crews working in Apache Pass must build a bed for the 16-inch-diameter pipe. The bed consists of sandbag supports (bottom pads) on the trench floor at 10-foot intervals. The pipe must be carefully set onto the supports, and fill material that is free of rocks is then placed into the trench to surround and encase the pipe.

Out on the flats, the trenching is easier. The soft dirt serves as a natural bed for the pipe, so there's no need to build artificial bedding. It's all good ... unless it rains. July and August produced some incredible deluges last summer, according to von Borstel, and the trenches did what trenches will do when it rains. They filled with water.

One particularly violent storm delivered nearly 4 inches of rain in less than an hour. Pipes washed off their staging platforms into the trenches. Rockford trucks were hopelessly mired all over the long run across the valley. It took days to get everything back to where it had been before the storm.

In Benson, the flooding presented some problems as well, but the real difficulties a pipeline faces in a city involve the existing infrastructure that must be avoided. Rail lines, freeways, sewer lines, and water lines must be located and dealt with. Property owners don't want their land torn up, and motorists don't want their streets closed.

When trenching is not an option, tunneling is often the best solution. Rockford uses a couple of different tools to tunnel under rail lines, freeways and even rivers, says von Borstel. One uses an auger bit to cut through the soil and rock. The other is much like a well drill that's been turned on its side. Horizontal drill rigs are set up on each side of the obstacle and begin tunneling until the shafts meet. The operation requires careful planning and precise calculations, since the shafts are drilled with a slight downward slope from each side to get well under the obstacle.

Since the pipes will be inaccessible under the obstacles, Rockford inserts sleeves into the shafts. That allows them to completely withdraw the pipe later if it needs to be repaired or replaced.

On this job, Rockford's crews tunneled under the San Pedro River near Benson. Previous pipelines soared over the river on three imposing structures that look like unfinished bridges.

The process from beginning to end

A cross-country pipeline company such as Rockford employs a broad range of employees with specialized skills. First in on a job are the survey crews who establish the path and slope information. Next, comes an environmental specialty crew to identify plants that will need to be relocated and sensitive animal habitat issues. That crew also must take into account drainage issues that may be created during the process when new berms and trenches intrude into the existing watershed.

Before any excavation can begin, existing underground infrastructure must be located and marked. Carsten von Borstel says it's not unusual to encounter an undocumented or incorrectly mapped pipe or cable in the middle of nowhere. In fact, his crews cut through — and immediately repaired — a PVC pipe just below the surface early in the climb up the north side of Apache Pass. It fed water to a ranch in the valley below.

When the preliminaries are complete, the trenching and drilling crews move in and do their work. Any special bedding, rock removal or other trench preparation must be completed before pipe is placed alongside the trench. For safety purposes, nobody should ever be in a trench that has staged pipe next to it.

With the trench ready, pipe sections are delivered and staged alongside the trench. The pipe sections are manufactured with caps to keep moisture away from the uncoated steel on the inside of the pipe. Welding crews cut the caps off shortly before it's time to join the sections. The joints must be brought together perfectly and welded precisely to form a tight seal and a smooth inside transition.

The cutting and welding necessarily leave a bit of uncoated steel exposed. That exposed steel has to be coated with a strong epoxy-like substance, but first each joint must be X-rayed to verify complete integrity. When the X-ray specialist pronounces the seal flawless, the coating crew can come in and add the protection that will keep water from contacting the bare steel. Depending on the situation, that work may be done before or after the pipe is set in the trench.

When the time comes to cover the pipe, Rockford uses specialized pipeline padders. The padders take the material that was removed when the trench was excavated, and they separate the fine dirt and sand from the rocks. The fines go in first to pad the pipe and make sure it's well supported and completely covered before rocks or other large material get pushed in to fill the top of the trench.

The job isn't complete until the section of pipe has been hydro-tested. Test pressure is 2,150 psi. That's nearly three times the pressure the finished line will need to endure during operation.

The final step brings in landscaping crews to restore the surface to the same condition as before the project began.

How the pipeline works

A modern pipeline uses some interesting technology to get a gallon of gasoline from El Paso to Phoenix. At any given time, there will likely be gasoline, diesel and jet fuel all traveling through one pipe at the same time. Devices called pigs keep the various fuels from mingling. A pig is basically a plug with O-rings to maintain a tight seal. At the launch point, two pigs are inserted and the intervening space is filled with the liquid to be transported. Pressure is applied from the launch point to send the pigs and their cargo on their way.

Kinder-Morgan also uses smart pigs to find and report dents and rust within a pipe in order to catch situations in their early stages before they become real problems.

The goal

So, two years from now, if the average Tucson or Phoenix driver is asked what he or she knows about Arizona pipelines, what answer would Kinder-Morgan and Rockford want to hear? "I don't know. Do we have pipelines in Arizona?" will probably sound like music to their ears.



Trenching: Double M Construction Inc., Okema, Okla.

Directional drilling: Mears Co. (Mears/HDD LLC), Rosebush, Mich.

Weld X-rays on pipe joints: Shaw Pipeline Services, Tulsa, Okla.