Spill Snarls Rush-Hour Traffic on Riverside Freeway : Accident: Drum of cement sealant falls off construction truck, causing a three-car collision and stopping westbound traffic for six hours. Substance also falls into nearby creek.

Thousands of rush-hour commuters came to a standstill for six hours Tuesday when a 500-gallon drum of cement sealant fell off a freeway construction truck, pouring a milky slick across the Riverside Freeway.

Westbound Riverside Freeway traffic was backed up for six miles to Weir Canyon. The spill also closed the northbound transition from Costa Mesa Freeway to the Riverside freeway.

“We treat all these spills seriously until we find out what we have,” said CHP Officer Alvin Yamaguchi. “Luckily, this isn’t toxic, but it’s a lot of inconvenience.”

Just before 2:30 p.m., a construction worker with Ball, Ball and Boshammer was unloading drums of xylene naphtha in the center lane of the freeway, where a new toll lane is being built, Yamaguchi said.

The truck’s load shifted and one of the drums toppled, its top breaking open. Between 350 and 400 gallons of the substance, which gives off toxic fumes if burned, spilled under the divider and onto the westbound lanes of the freeway, near Kraemer Boulevard.

Almost immediately, Yamaguchi said, the 100-by-50-foot slick caused a three-car collision, which resulted in minor damage to the cars but no injuries.

For a time, all westbound lanes of the Riverside Freeway were closed between the Costa Mesa and Orange freeways, with traffic detoured.

Before sandbags could be laid, a small amount of the sealant, which is used to keep concrete from drying too quickly, spilled into nearby Carbon Canyon Creek, causing authorities to notify officials of the state Department of Fish and Game.

While traffic was diverted, Caltrans, along with a hazardous-materials team from Los Angeles County and private contractors in protective gear used high-pressure hoses to collect the sealant near a tanker truck, which vacuumed it. Other workers dug up contaminated soil along the shoulder of the roadway.

While some of the stalled drivers were resigned to their wait, others fumed.

“This is aggravating,” said Hugh Craddock, 49, of Corona, who was missing his son’s Scout meeting. “I’ve lost a day out of my life sitting on freeways. It’s crazy. Think how many man hours are tied up in his mess.”

But Ty Morgan, 36, of Riverside, said, “It’s all right. It’s a different way to spend an evening.

“It could be worse. It could be raining.”