Pipeline withstands shakedown

Fairbanks Daily News-Miner ^ | 4 Nov 2002 | DIANA CAMPBELL

[Lokibob]

Parts of the trans-Alaska oil pipeline's support system were shaken loose and tossed to the ground about 150 miles south of Fairbanks as a result in Sunday's 7.9 magnitude earthquake.

No crude leaks were reported and the pipe itself appears undamaged at first assessment, said Mike Heatwole, a spokesman for Alyeska Pipeline Service Co.

"We have a pretty extensive seismic monitoring system," Heatwole said. "When the earthquake registered, the system started a shutdown. We manually took over and shut it down by 2:12 p.m."

Heatwole couldn't say how long the pipeline would be shut down while engineers completed an assessment of the damage. At Mile 588 of the pipeline, eight shoes--flat metal brackets on which the pipeline rests--broke and fell to the ground, he said. Five crossbars of the vertical support system were broken and pieces of the supports were also on the ground.

Department of Energy Secretary Spencer Abraham offered any technical, engineering or physical help necessary to help get the pipeline running again. It supplies 15 percent of the nation's domestically-produced oil daily.

Alyeska called out up to 100 employees to help repair the damage, Heatwole said. Work crews are expected to build wooden structures today to help support the pipeline while repairs are made.

The crews are having some difficulty assessing the damaged pipeline as a rockslide and road cracks have blocked the Richardson Highway, Heatwole said. Department of Transportation crews are working to make the roads passable and by today both work crews and equipment should be on site.

The pipeline did exactly what its was designed to do in an earthquake, said Michele Brown, commissioner of the Department of Environmental Conservation. The pipeline was built to withstand earthquakes of magnitude 7.0 to 8.5 depending on where the pipeline is located along its 800-mile route from Prudhoe Bay to Valdez, Heatwole said.

That means the pipeline has wiggle room as well as critical supports heavily anchored at strategic locations. The section affected by Sunday's earthquake was designed to withstand a magnitude 8.5 quake since it is located on what is known as the Denali fault, the world's longest faultline, he said.

Assessment teams in four helicopter flew during Sunday daylight hours to review the damage, said Rhea DoBosh, Joint Pipeline Office spokeswoman. Alyeska crews were driving along the pipeline to assess damages elsewhere, but no other damage was reported by Sunday evening.

Williams Alaska Petroleum's North Pole refinery crews readjusted jet fuel manufacturing after the pipeline shut down in order to meet heavy demands at both the Fairbanks International Airport and the Ted Stevens International Airports, said Jeff Cook, Williams Alaska spokesman.

The shutdown was serious, said Ed Meggert, head spill responder in the DEC Northern office.

"They don't shut the pipeline down for nothing," he said.

[Lokibob]

They build thing to survive an earthquake, not to survive undamaged.

I remember a 7 richter earthquake in El Cahone, Calif that continued to stand. However, the building had to be destroyed due to damage. The builders said it worked, because it didn't fall down.

[Jabba the Nutt]

No pictures of the pipeline? I'd like to see the damage.

[Lokibob]

No, and I doubt we will see any since all that broke were things designed to break.

 

I'd like to see the pictures of the 5' cracks in the highway between Fairbanks and Anchorage.

 

I got the below statistics from the pipeline web site.

 

Was amazed at the lateral and vertical movements designed into the pipeline.

 

Somewhere else on the pipeline web site it said that the walls of the pipe is 3 3/4" thick.

 

Earthquake Protection

---

Earthquake magnitude pipeline system designed to withstand

8.5 Richter Scale (maximum). Range from 5.5 to 8.5, depending on area.

Faults crossed by pipeline

3   -  Denali
        McGinnis Glacier
        Donnelly Dome

Predicted limits of lateral movement for above ground pipeline, general

2 ft.

Design values for maximum movement at pipeline crossing of major faults 

Denali fault — 20 ft. lateral and 5 ft. vertical displacement

McGinnis Glacier fault — 8 ft. lateral and 6 ft. vertical displacement

Donnelly Dome fault — 3 ft. lateral and 10 ft. vertical displacement

Minor potential fault locations — 2 ft. lateral and 2 ft. vertical

Earthquake Monitoring

Alyeska's Earthquake Monitoring System (EMS) consists of sensing and processing instruments at all pump stations south of Atigun Pass and at the Valdez Terminal. A central processing unit at the Operations Control Center (OCC) is linked to the Pipeline and Terminal operator consoles. The EMS is specifically designed to process strong ground motions, to interpolate or extrapolate estimates of earth quake accelerations between the sensing instruments and to prepare a mile-by-mile report comparing the estimated accelerations along the pipeline with the pipeline seismic design criteria.

DSMAs

The instrumentation at field locations consists of accelerometers mounted on concrete pads which measure strong ground motions in three directions (tri-axial) which are connected to a Digital Strong Motion Accelerograph (DSMA). The DSMA, generally located in the Pump Station control room, processes the signals from the accelerometers in real time and reports alarms and selected data to the central processor at the OCC.

[Lokibob]

Here is the picture of damage to the pipeline.

 

Vertical supports that hold the above-ground portions of the trans-Alaska oil pipeline lay broken under it Sunday about 40 miles south of Delta. Alyeska Pipeline Service Co. spokesman Mike Heatwole said the pipe was intact after the earthquake. ( Photo by The Associated Press)

[Jabba the Nutt]

Hey, Lokibob, thanks for posting the picture. It must be the angle, but the pipeline doesn't look too big.