The Milwaukee Journal Sentinel reports the spill caused traffic delays Sunday afternoon for about three hours on Interstate 94 eastbound. The department says a "liquid non-hazardous substance" spilled across all lanes. It was not clear what type of vehicle the waste came from.
The Wisconsin State Patrol in Waukesha says the spill hadn't been cleaned up by Sunday night. It says so many cars unknowingly drove through the 30-foot spill that fire and highway officials couldn't clean it up.
Officials decided to leave the spill in the road and clean it overnight because it had started to harden.