HARMON DEN — North Carolina Department of Transportation announced Thursday morning it had cleaned up enough of Interstate 40 near the Tennessee border to allow some traffic to return to the road.

One lane in each direction is now open.

A slide of rocks, dirt and trees on Feb. 22 closed a 20-mile section of Interstate 40 in Haywood County. Dozens of workers have worked around the clock this week to remove debris and set up an alternate route, according to DOT engineer Nathan Tanner, who is overseeing the project.

Though the highway is now passable, it will likely be more than a month before traffic is flowing normally again. Standing at the base of the slide, Tanner said that the DOT hopes to have I-40 fully open on April 4. Bad weather, however, might push that back.

Three to four days of consistent rain can destabilize the hillside, thereby halting the job, Tanner said.

► What we know about the I-40 rockslide and its detour

The slide of about 30,000 cubic yards of material occurred at mile marker 7.5, near the Harmon Den exit.

"We had a small slide with rocks falling from a pretty high elevation, and when they were hitting the road, they were bouncing into the eastbound lanes," said Ted Adams, construction engineer for NC Department of Transportation's District 14, on Saturday afternoon.

Since then, workers have removed as much as 5,000 cubic yards of loose material from the mountainside, Tanner said.

When the slide started, nine cars were damaged, many getting flat tires from running over rocks in the road, Adams said. One car was hit on the side by a falling rock when as the vehicle stopped so it wouldn't hit debris in the road. No people were hurt.

More:NCDOT works to open I-40 'as soon as possible' after rockslide blocks all lanes in Haywood

More:Video: Rocks still sliding onto I-40

More:What we know about the I-40 rockslide closure: Details, timeline and detours

The slide generated miles of backup for hours on Interstate 40, and N.C. State Highway Patrol helped clear the backup by turning cars around. This stretch of road carries an average of 26,000 cars daily.

The closure set up a major detour, sending vehicles up Interstates 81 and 26 to get between eastern Tennessee and WNC.

This marks the first landslide along I-40 in Western North Carolina since 2010, Tanner said. Though emergency slide repair is a part of Tanner's job, which typically revolves around new DOT contract work, he said it's been a larger part of his duties in the last several months.

Tanner was also tasked with overseeing landslide repair in Henderson County when, in late June, a slide closed N.C. 9 for months. That slide was not quite the size of the one he's currently working on.

The total project cost for the I-40 slide repair is estimated to be about $2.1 million, Tanner said.