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Why is it taking months to clean up contaminated soil from a semi-trailer truck crash on Interstate 5 (I-5) in Lacey?

The state has been shutting down the left lane of southbound Interstate 5 in Lacey for the better part of the last six weeks. The Sunday to Thursday overnight closures moved into the right lane this week. The closures start at 7 p.m. and last through 10 a.m. It has caused daily backups to get into Olympia.

A listener recently asked me why it is taking so long to clean up from this crash.

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Before we get to that, let’s go over the crash and what the state is dealing with. It was a double-fuel tanker that rolled over on March 13.

“That crash spilled 2,850 gallons of diesel fuel, which spilled on both sides of the roadway, so we’ve had crews out there since the last week of April cleaning up the contaminated soil along the roadway,” the ‘s April Leigh said.

Compounding the cleanup is that workers don’t know how far the diesel made it into the soil, so they just have to keep digging.

“Digging up the contaminated soil and then replacing that soil with fresh fill, so it’s an arduous process,” Leigh said. “They’re digging about 15 feet deep and in 20 feet increments along the roadway in order to clean up that contaminated soil.”

It’s a situation where they don’t know how far that diesel spread until they dig. They just finished in the median and are now working on the right shoulder.

“They’re testing that soil as they go to determine whether or not more dig out is needed,” Leigh said. “In some areas, they’ve had to dig a little more, and in some areas, they’ve had to dig a little less, but this is definitely not an exact science.”

Workers have removed 2,400 tons of contaminated soil so far. That’s about 171 dump truckloads.

What awaits them on the right side of the freeway isn’t known, but Leigh said she doesn’t expect it to take as long as the work in the median. Until this job is finished, there is a temporary 45-mile-an-hour speed limit through the area.

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“Remember to slow down in work zones,” Leigh said. “Our crews are out there. It’s at night. Slow down, pay attention to posted speed limits, and we’ll get out of there as soon as we can.”

Workers initially removed two-and-a-half tons of contaminated material right after the crash. This is the hard work that follows. The soil that is removed is taken to a landfill.

Check out more of Chris’ Chokepoints.