BOISE – It could take three weeks or longer to clean up a liquid asphalt spill in the Payette River and along state Highway 55, a spokesman for the Idaho Transportation Department said Tuesday.
Roughly 1,500 gallons of the chip-sealing product spilled Monday evening after a tanker overturned and ruptured along a steep stretch of road about 14 miles south of Cascade, spokesman Mike Maller said.
Officials with the federal Environmental Protection Agency – which took control of the cleanup effort Tuesday afternoon – estimated that roughly 1,400 gallons of the asphalt oil hit the bank or ended up in the river, with about 100 gallons ending up on the road.
The EPA was testing the substance for toxicity, spokesman Anthony Barber said.
“It’s about two-thirds asphalt oil and one-third water with less than 1 percent of other materials – emulsifying agents to cause the water and asphalt to mix together,” Barber said. “Because we don’t know exactly what compounds are in there, we’ve taken a sample and are analyzing that.”
The river is the source of drinking water for Horseshoe Bend.
“It is not clear yet what damage might be done,” Barber said, adding no dead fish or birds have been sighted.
No one was injured in the accident, and the Idaho State Police were investigating the cause.
Cleanup is difficult because the spill happened along a narrow, sharply curved stretch of the highway with very little shoulder, Maller said. The highway has been reduced to one lane in the area, and the Transportation Department advised travelers to take state Highway 95 when possible.
Still, the cleanup effort may be easier than a traditional oil spill because at least some of the liquid asphalt solidified when it hit the cold river water, Maller said. Authorities believe most of the solid matter simply fell to the bottom of the river.
EPA investigators will check the river for any evidence of spreading oil and will monitor the air quality for any dangerous gases released from the liquid asphalt, Barber said.
The tanker was carrying the asphalt from Idaho Asphalt Supply’s Nampa plant to McCall, said Jeremy Jaramillo, the plant manager.
He said the tanker truck was owned by a trucking company, not Idaho Asphalt.
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