Cold Region Research and Engineering Laboratory (CRREL) personnel recently recovered a wrecked vehicle from a deep frozen lake.

Last winter, a CRREL contract employee was driving a government-owned Jeep Cherokee along the Glenallen Highway in central Alaska when he lost control and plunged 80 feet over a cliff. The vehicle rolled several times, landed in the lake and sank in the frigid water.

The driver's seatbelt saved him from serious harm. He managed to unfasten his seatbelt, swim to the surface, and back to the bank. He climbed up the snow-covered cliff, walked down the highway, and was picked up by a passing motorist. He suffered a small cut on his cheek, ruptured eardrums from water pressure, and hypothermia.

Months later, the Jeep was recovered from 40 feet of water under four feet of ice. CRREL employees and the Arctic/Subarctic Aquatic Pararescue Group (ASAP) managed the recovery.

A diver enters the lake. The ice is 48 inches deep.

Challenge

The Jeep was removed from the lake for environmental reasons. The General Services Administration, who owned the Jeep, planned to contract the recovery to a private contractor, but CRREL felt they could recover it at lesser cost and wanted the challenge. Plans were made and ASAP agreed to lead the extraction team.

Underwater topographic maps showed the lake was up to 90 feet deep with a steep underwater slope. The slope of the shoreline was too steep to use a vehicle on the slope or on the road 80 feet higher.

By springtime the lake was frozen solid. The initial plan called for cutting a small hole through the ice so divers could go down to locate the vehicle. Chainsaws would cut away large sections of ice next to the shore, allowing cables to be attached to the Jeep. Divers using lift bags would raise it off the bottom. As people on the shore hauled the cables, divers would maneuver the vehicle toward the opening.

Change of plans

But reconnaissance showed that the lake ice was thick enough to support heavy vehicles, so CRREL changed plans to extract the vehicle through the ice. ASAP provided diving equipment, rigging, medical equipment, and expertise. Paramedics were on the scene and they developed a detailed dive plan and adhered to it. The volunteers assembled at Lake Long from around Alaska.

When we arrived, we found the ice thickness had been underestimated. Instead of 18 inches, it was 48 inches thick. This was due to high winds which sweep the ice clean of snow, allowing it to freeze thicker than surrounding snow-covered lakes.

Cutting the first section was a tedious process. We cut the first section for the dive with two chainsaws, one with a three-foot bar, the other with a four-foot bar. The first section took four hours of cutting, prying, and smashing ice. As the ice was cut, divers in insulated suits wedged the pieces under the ice sheet.

The ice-cutting went much slower than expected due to the ice thickness. Chainsaws froze up in minutes after getting wet. We set up a heater and the chainsaws were alternated in front of it to thaw every time one froze.

The first diver finally went through the dive hole to locate the wreck. A second diver stood by as an emergency back-up. The depth directly under the opening was 60 feet, sloping to 90 feet. Due to the altitude (2,000 feet above sea level), the divers' bottom time was reduced to 15 minutes.

Within minutes after starting his search, the diver located the Jeep in 40 feet of water. It was lying on its side, hung up on a large boulder. If the vehicle was not handled properly, it could slip off the boulder and slide down the incline, crushing any diver under it.

Once the first diver was topside, a second diver went in to mark the site so a hole could be cut directly over the vehicle. The ice was so clear that it was easy to watch the diver as he moved underwater. He attached a float to the vehicle; those standing on the ice marked the float's location, and began cutting the recovery hole.

Hard work

The divers reported back that attempting to float the vehicle under the ice to the shore was impossible. It would be extremely difficult to route the vehicle through the large boulders on the bottom.

But with the ice thickness at four feet, it would be possible to bring a wrecker onto the lake and pull the Jeep up through a hole in the ice. Eight hours later, a recovery hole measuring 8x7 feet was finished. Seven tons of ice had been cut and moved in two days.

The water was so clear that everyone could see the Jeep on the bottom of the lake once the ice was removed. Two divers suited up using air supplied from the surface, and a two-way intercom. They carried an underwater video camera to record the event.

Both divers descended through the dive hole to the Jeep. They attached a safety line to the vehicle which was secured to trees along shore to keep the vehicle from sliding down the slope and injuring anyone.

After all winter on the bottom of a frozen lake, the Jeep finally breaks surface.

Recovery

There was a wrecker at the site and the divers attached its cable to the Jeep's axle. Once the divers were back topside, it was all up to the wrecker. To improve the wrecker's traction on the ice and keep it from sliding into the hole, we put sand and gravel on the ice. We chained a second vehicle to the wrecker to provide additional traction.

Then the wrecker lifted the Jeep off the bottom of the lake. As it neared the surface, large poles were used to pry it away from the underside of the ice and into the center of the recovery hole.

Once the Jeep broke surface, we allowed the water to drain from it to reduce the weight the wrecker had to lift. Within minutes the Jeep was safely on the ice.

Absorbent pads were placed on the water to soak up oil or fuel that might have been released during the recovery. Warning signs were placed around the hole so that snowmobilers would stay clear. Much of the ice that was removed was replaced back in the hole to aid refreezing.

From The United States Army Corps of Engineers (USACE)
Engineer Update is an unnofficial publication authorized under the provisions of AR 360-81. It is published monthly for the U.S. Army Corps of Engineers. Editorial views and opinions expressed are not necessarily those of the Corps of Engineers or the Department of Defense. Inquiries and comments can be forwarded to editor of Engineer Update by e-mail to Bernard.W.Tate@usace.army.mil.