The effort to clear snow to the summit of Independence Pass was in the final stretch Monday after a helicopter crew dropped bombs into avalanche chutes that posed a threat to equipment operators.

A helicopter hired by the Colorado Department of Transportation dropped 36 bombs on the east side of the summit and five charges in the Roaring Fork West and Roaring Fork East slide areas about two miles from the summit on the Aspen side.

From a safe site a short distance east of the Independence ghost town, highway maintenance supervisor Don Poole and two members of his crew, Adam Wano and Jeff Lewis, watched the helicopter hover over the Continental Divide and drop the 33-pound charges. After a lengthy delay, the explosions sounded like rifle blasts, reverberating off the high peaks. Other times, the sound was muffled, depending on the direction of the chute that was targeted.

When a CDOT avalanche expert examined the control work from the air and deemed it a success, the ground crew fired up a snowblower the size of an SUV and started eating into the 5-foot-high wall of snow that covers the final two miles of the road. By late Monday, the crew was close to the Upper Lost Man Loop parking area — where Highway 82 forms a big horseshoe before heading up the steep, long grade to the summit.

“It is the toughest two miles from this point, for sure,” Poole said.

“It’ll probably take us as long to clear that out as it did the whole rest of the danged road,” said Jeff Lewis, a highway maintenance worker who is driving some of the equipment to clear the pass.

The crew started working the last week of April, preferring to get started early in the day, when temperatures are lower. Wet, heavy snow clogs the snowblower.

While the winter was mild, the snowpack caught up in April. It’s left behind a 5-foot blanket that covers the roadway and surrounding terrain, making it tricky for an equipment operator to know exactly where the road is located.

“It’s like a brick wall,” Lewis said of the remaining snowbank. “Once you start breaking it up, it melts like crazy.”

CDOT records indicate that the west approach to Independence Pass has about 90 percent of its average snowpack. The east side of the pass is about 100 percent of average, Poole said, but the Aspen side gets a higher amount of snow than the Twin Lakes side because of the mountain dynamics.

Poole expressed confidence that the crew will have the road cleared to the summit by the scheduled opening May 23.

“If we do get it (cleared) before then, we’ll be opening it up,” he said.

Cyclists in Saturday’s Ride for the Pass have clear sailing from the closure gate to Independence, where the official, timed course ends. Many riders continue up the road after the event. They shouldn’t expect to make it to the summit. Poole said the crew would be roughly halfway up the steep, long grade by Saturday.

The avalanche-control work didn’t bring down much snow on the Aspen side of the pass Monday, but CDOT won’t take any risks with its employees. It errs on the side of caution. The recent warm weather has increased the chances of “wet” avalanches, Poole said.

Each member of the maintenance crew has an avalanche beacon, a probe and a shovel. They take mandatory snow-safety training.

Lewis said there is more peace of mind for him as an equipment operator after the avalanche-control work is performed. Still, he said, the crew keeps an eye on the slopes for any developing danger. A spotter works with the equipment operators on the final stretch.

The crew is using one heavy-duty loader with chains wrapped around the 6-foot-diameter tires to push the oversized snowblower along. It chews an 8-foot-wide swath through the snow with rotors and spits it out in a large arc to the side of the road. The snowblower clears the left half of the road. A second loader trails behind to scoop the snow off the right lane.

The crew expects to cover less than a quarter mile per day while clearing snow. The snowblower creeps along despite its size and power. There is more to opening the highway than clearing the snowbanks. The crew must clear rocks that continually pepper the road at this time of year. Guardrails beat up by the snow must be repaired, potholes will be patched, and erosion on the shoulder will be filled.

While waiting for the avalanche-control work, the maintenance-crew members said working in the solitude of the pass is a treat compared with their usual duties. The only sounds were water rushing beneath the snow and birds in the forest. The staff is responsible for maintenance of Highway 82 from mile marker 14 near Carbondale to the summit of Independence Pass and Highway 133 to the south side of McClure Pass. Lewis said the other Highway 82 crew was sweeping the road through Snowmass Canyon. That’s in contrast to the work on the pass, where traffic isn’t an issue right now.

A different crew is working to open the road from the Twin Lakes side.

“It’s kind of a competition to see who gets to the top (first),” Poole said. Radio communication is tough between the east and west sides, so it’s a guessing game on how the opposing crew is doing.

scondon@aspentimes.com