Spill cause located

A small oil spill in the Swanson River oil field is believed to have been caused by internal corrosion of the pipeline carrying the produced water that spilled Tuesday morning, according to the Alaska Department of Environmental Conservation.

The spill was discovered Tuesday morning after a Unocal employee discovered a leak in the pipeline during a routine check. A response team and a "super sucker" vacuum truck from Unocal were dispatched to the scene immediately. The site of the spill is near the Swanson River in the Kenai National Wildlife Refuge.

Investigation at the site on Tuesday revealed that a 0.105-inch diameter hole at the bottom of a 4-inch section of pipeline had leaked a mixture of water, oil and gas into the ground. Unocal engineers were investigating Wednesday to determine the amount of contamination at the site.

According to the DEC, Unocal engineers believe the amount of produced water spilled to be roughly 398 gallons. Unocal reported that the produced water is a mixture of water and crude oil containing 92 percent water and 8 percent oil and gas mixture.

This means that the equivalent of less than one barrel of oil was spilled.

Unocal is removing contaminated soil from the area and plans to replace the damaged section of pipe once the cleanup operation is finished.

Although the leak occurred roughly one-quarter mile from the Swanson River, it is not believed to present a threat to the waterway, according to the DEC.