An Alaskan city remains trapped behind a wall of snow after avalanches cut off its only highway late last week.

The Alaska Department of Transportation said several snow slides hit the area near Valdez Friday, closing the roadway to the city of 4,100 people.

Avalanches Cut Off City

Ssnow and ice cover the closed Richardson Highway, near Valdez, Alaska. One of a number of avalanches covered the roadway in the Keystone Canyon, closing the only road access to Valdez, the city at the end of the trans-Alaska pipeline. Alaska authorities said snow 40 feet deep and 1,000 to 1,500 feet long covered the highway. (AP/Alaska DOT&PF)

Another slide dammed the Lowe River in Keystone Canyon, causing water to flood the Richardson Highway.

Even on Wednesday, conditions were still too unstable for crews to clear the at least 40-feet deep dumping of snow from the only road into the city at the end of the trans-Alaska pipeline. Keystone Canyon, a 300-foot wide mountain opening, begins 12 miles from the Valdez.

Check out this aerial footage showing the blocked road:

Drainage has slowed from a lake formed by one of the slides and the water is too deep for heavy equipment to pass, the transportation department said.

According to Valdez’s clerk, residents of the city are taking the inconvenience of hundreds of tons of snow in stride.

Avalanches Cut Off City

A lone highway sign stands above the closed Richardson Highway, near Valdez, Alaska, on Saturday, Jan. 25, 2014. (AP/Alaska DOT&PF)

Transportation officials on Wednesday planned to verify the stability of the snowpack on mountainsides and use explosives fired from a 105 mm howitzer and dropped from a helicopter in 50-pound bags to trigger controlled avalanches.

“Safety is our first priority,” Blankenship said.

The trans-Alaska pipeline is buried in the area and was not affected by the avalanche.

The water Tuesday was draining at a rate of 5 inches per hour through an abandoned rail tunnel, said Transportation Department spokeswoman Hannah Blankenship. By Wednesday, the lake had receded to a length of 1,500 feet, but drainage had slowed.

“The water is now draining at a rate of 3 inches per hour,” Blankenship said.

The water remained too deep for heavy equipment to reach the avalanche from the upstream side. Crews have not removed snow from the downstream side because officials fear collapsing the snow dam and triggering a dangerous surge of water.

The water likely is flowing more slowly because it’s no longer moving through the train tunnel, Blankenship said. Transportation officials continue to monitor the lake level as water saturates the snow.

Avalanches Cut Off City

Road crews begin the job of clearing the closed Richardson Highway, near Valdez, Alaska. (AP/Alaska DOT&PF)

“The snow is still wet and very heavy and it’s not safe for us to move with heavy equipment,” she said.

The second major avalanche blocked the highway through Thompson Pass.

Snow gates remain down, preventing travel from Miles 12 to 42 on the highway, Blankenship said.

The Associated Press contributed to this report.