Study could help water systems react to oil spills

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FORT PIERRE, S.D. (AP) — New research from South Dakota State University will help rural water systems better respond to oil spills.

The study demonstrated that the oil running through the Keystone pipeline probably would not corrode water lines in the event of a spill, though the oil did weaken the joint gaskets, where contamination would most likely occur.

The goal of the research was to develop a design standard for casings where water lines cross oil pipelines. Rural water planners say it gives them a better idea of how much time they would have to respond after a spill.

“The event of a crude oil spill is pretty unlikely, but in case it happens, we want to make sure there is a barrier between the spilled material and the water pipeline,” said Delvin DeBoer, professor of environmental engineering at SDSU and director of the Regional Water System Research Consortium. DeBoer presented his findings recently at the South Dakota groundwater quality conference in Fort Pierre.

The research was sponsored by the South Dakota Department of Environment and Natural Resources and the pipeline safety division of the U.S. Department of Transportation.

During the permitting process for Keystone, rural water systems raised concerns about crude leaks contaminating their water supplies. The oil pipeline, which came online in 2010, crosses hundreds of rural lines in eastern South Dakota. It also runs through eastern North Dakota.

Others have raised similar concerns about Keystone XL, a larger line that would cross western and south-central South Dakota — if it ever gets built. The Obama Administration denied Keystone XL a construction permit earlier this year. TransCanada, the company behind the Keystone system, has said it will reapply.

Pipeline opponents claim that diluted bitumen derived from tar sands is more corrosive than conventional blends and so poses a higher spill risk. An industry study disputes this, but there is little independent research on the subject.

The Pipeline Safety Act, passed in January, requires federal pipeline safety officials to complete such a study by mid-2013.

There have been a dozen mostly small spills at pump stations that keep the crude flowing through Keystone. But one of them, triggered when a valve broke at the Ludden pump station in North Dakota, spilled about 20,000 gallons of oil, prompting the government to briefly shut down the line while the company replaced the valves at all the stations.

For this study, DeBoer and a graduate student, Dan Julson, filled short lengths of plastic pipe with water, capped the ends and submerged them in buckets of sand heavily saturated with oil.

They also soaked rubber gaskets in oil and tested them for weight gain and tensile strength. Water was used as a control.

The pipes did well in compression and strength tests, but the oil weakened the rubber gaskets, raising the risk of oil permeating the pipe wall. It took several weeks for hydrocarbons to leach into the water through the pipe joints.

For this and other reasons, the researchers determined that jointless, fusion-bonded PVC pipe offers the best protection against contamination.

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