A septic tanker truck overturned on the road near the Willis Street/SR-516 ramp around 3:30, leaking its... contents onto the roadway.
"Oil, fuel and mmmm, some other yucky stuff spilled," Trooper Chris Webb tweeted.
The State Patrol said the truck collided with three other vehicles but there were only minor injuries. The backup was at least four miles at the peak of the incident.
WSDOT took to Twitter to warn drivers of their impending challenge:
Planning on driving SB 167? Might wanna pack a nose plug & left arm sunscreen. MT @wsdot_traffic Backup on SB SR 167 at SR 516 is 2 miles.— Washington State DOT (@wsdot) April 30, 2014
There is no word yet what caused the crash.
Here's another look at the overturned septic tank SB 167 at SR 516. Yes, it spilled. Yes, it's gross. pic.twitter.com/B274zq4cPG— WSDOT Traffic (@wsdot_traffic) April 30, 2014