OSO — Work crews have started digging up the muck and debris left by the Oso mudslide to uncover Highway 530.

After they dig out the road, it can be repaired and rebuilt. State transportation officials say they hope to have the highway open for general traffic by October.

“We’re working 24/7,” said Mark Sawyer, the site manager for the state Department of Transportation.

Cleanup started Tuesday. Crews have to clear debris about 15 to 20 feet deep from roughly 1,500 feet of the highway, he said.

The March 22 landslide dumped about 10 million cubic yards of material — soil, sand, trees, rocks, clay — onto the valley floor and wiped out a neighborhood, killing at least 41 people. Searchers have found the remains of all but two victims.

Based on debris-field analysis, the missing victims’ bodies are likely not on the road and not likely to be recovered by crews clearing the highway, said Kevin Bartoy, the Transportation Department’s chief archaeologist on the project.

Bartoy usually scours state transportation project sites for artifacts with historical or cultural significance.

It is a task that sounds easy, but doing it efficiently requires a trained eye and experience.

“Most people look for things. We don’t, we look for shapes,” Bartoy said.

Now he oversees teams of state archaeologists helping recover personal possessions buried in the slide.

They are looking for human remains, personal items — things such as wallets, wedding rings and wristwatches — and personal belongings such as photo albums, keepsakes and letters.

Much of the digging is being done by several excavators — powerful, yellow construction machines with an engine, driver cab, boom and shovel on top of tractor treads. Beside each are two spotters looking for items to recover. They can stop excavation if they see something.

The primary spotters are state archaeologists, who watch the shovel go into the ground. The secondary spotters are locals hired to scan the excavated material as its poured into big diesel trucks.

The trucks haul the material to a nearby dump site, where more archaeologists watch for recoverable items.

The highway is mostly covered by soil and debris from the hillside, Bartoy said.

Many of the local spotters are familiar with the debris field, having walked, waded and crawled through it looking for victims after the landslide, he said.

Hiring locals also hopefully provides some economic relief to people affected by the slide, he said.

Most recovered items are cleaned and taken to Arlington, where Snohomish County set up an office to return them to survivors or victims’ families.

The Snohomish County Sheriff’s Office is holding any drugs, guns and money that turn up. Deputies are also taking any high-value items “that might walk off,” Bartoy said.

Dan Catchpole: 425-339-3454; dcatchpole@heraldnet.com; Twitter: @dcatchpole.