STANWOOD — A construction error on Highway 532 could knock two to four years off the road’s useful years, according to an official with the Washington Department of Transportation.

Workers accidentally used the wrong sealant to fill cracks on a four-mile stretch of the road in August. After pouring a new layer of asphalt over the highway, the old cracks worked their way through the new asphalt and reemerged, said Russ East, the department’s assistant regional administrator for Snohomish and King counties.

“Sometimes — and I hate the pun — things slip through the cracks,” East said. “And this is a situation where something wasn’t caught when it should have been.”

Workers have since repaired about 100 feet of cracks by filling them with the proper sealant. Nonetheless, the error could cut into the 15 to 20 years the road is expected to last, East said.

Stanwood resident Robert Rawe said there’s no excuse for the mistake.

“I’m not impressed at all with our Department of Transportation,” said the retired machinist who lives near Highway 532. “It’s absolutely ridiculous. … Somebody with 10 gallons of paint and a paintbrush could go out and do a better job of it than they did.”

East said he’s not sure how the error happened. Rinker Materials of Everett contracted with the Department of Transportation to fill the cracks and pave Highway 532. However, East said it appears that state workers messed up by giving Rinker Materials the wrong sealant. He said there were half a dozen opportunities to catch the mistake before the sealant was applied.

“It’s a little baffling to us as to how it could go through a number of these checks and not be discovered,” he said.

The sealant that should have been used is a crack sealant, which contains small sand and bits of crushed rock and is designed to fill cracks. Instead, workers used a joint sealant, which is a rubberized asphalt that is more flexible and works best to fill thin splinters in the road.

When the cracks re-emerged, the Department of Transportation spent $500 to $1,000 to fill them a second time, East said.

“Ninety-nine percent of the time, our quality control system works,” he said. “In this case, our quality control and quality assurance simply failed.”

The $1.5 million paving project is part of a larger plan to improve safety and conditions on Highway 532 that is expected to take several years.

Reporter Kaitlin Manry: 425-339-3292 or kmanry@heraldnet.com