Regulators have found contaminated groundwater at the site of the June 3 fiery oil train derailment in Mosier.
There’s no current threat to drinking water or beach users, according to Oregon Department of Environmental Quality (DEQ), but concerns have surfaced for wildlife health in the Rock Creek wetland near the Columbia River.
“It really isn’t a significant issue of harming human health; however, there is a wetland (nearby) and we’re mainly concerned for animals (living there),” said Bob Schwarz, DEQ project manager.
DEQ staff found high levels of benzene and other volatile organic compounds in one of four test wells crews installed north of the Union Pacific train tracks in Mosier shortly after the train wreck.
Schwarz described the contaminant levels discovered at the east-most site as roughly 10 times higher than the safe amount for animal populations — 1,800 parts of benzene per billion, compared to the ecological risk level of 130 parts.
The wetland ecosystem includes various amphibians and insects, he said.
DEQ has ruled the local drinking water safe because Mosier’s municipal water supply is located about a mile away from the spill area, uphill.
Beach access at Mosier — a popular watersports access spot — has been deemed safe. Booms laid out on the river following the derailment (to catch a small sheen of oil) have since been removed.
Mosier’s wastewater system is also back in action. While heavy green sewage tanks and pump trucks were a common sight during early June, the town no longer trucks sewage to Hood River for treatment.
In the derailment, 16 cars of a 96-car Union Pacific train bearing Bakken crude oil left the tracks in what U.P. ruled an accident due to faulty rail bolts. At least three cars caught fire. Crews extinguished the blaze by early morning the next day.
About 47,000 gallons of oil escaped from four rail cars.
During the wreck, one of the railcars tore off the lid of a sanitary sewer manhole, allowing roughly 13,000 gallons of oil to flow into the nearby Mosier wastewater treatment plant. That system was shut down as crews worked to pump out oil and clean the piping network.
As a temporary fix, workers trucked sewage from Mosier to Hood River for treatment at the municipal plant on Riverside Drive. By June 16, the plant was restored, and shortly after Mosier’s system was fully functional.
A small sheen of oil leaked into the Columbia River through the wastewater system at some point following the wreck, DEQ reported.
Crews cast out absorbing booms into the river to contain the sheen. The exact amount is “unknown but low in volume,” according to a DEQ fact sheet, but it quickly dissipated.
Surface water samples in the river didn’t show any significant contamination from the spill, Schwarz said. He expects the booms will be replaced in September, before autumn rains, in case new rain flushes any oil from the ground into the river.
Agencies reported that the rest of the oil was burned off or absorbed into the soil. Excavation workers disposed of about 29,600 tons of earth that had been contaminated with petroleum.
Oil remaining in the derailed cars was transferred by truck to The Dalles, then hauled by rail to Tacoma, Wash., its original destination. The emptied railcars were taken by truck to Portland for salvage.
Following the derailment, DEQ oversaw the installation of six wells near the train tracks — two extraction wells and four monitoring wells. At the fourth monitoring site, staff found high petroleum levels and other compounds.
Now, DEQ is working with the railroad’s consultant to design an underground system that will treat the contamination, Schwarz said.
The “biosparge” system will include vertical pipes where air will be injected into the ground water. That oxygen will spur growth of naturally occurring microbes that will break down the oil.
“We are still waiting for groundwater flow direction information from CH2M, the consultant for Union Pacific Railroad,” Schwarz said in a July 6 memo.
Local conservation group Columbia Riverkeeper raised concerns about U.P.’s role in the high pollutant levels and called for a third party to steer the cleanup.
“It’s very concerning that we have such high levels of toxic pollutants so close to the river,” Riverkeeper staff attorney Lauren Goldberg said.
She asserted that the public needs to hold state officials accountable so that “U.P. is not at the wheel of this cleanup.”
Schwarz expects a small drill rig and a half dozen or so workers will be on scene in Mosier to implement the treatment system.
For more information, go to www.deq.state.or.us/lq/ecsi/ecsi.htm
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