California has seen some of the most snowfall it has ever experienced in recent memory over the last few months, prompting the emergency work from Caltrans and Qualcon Contractors to remove hundreds of inches of snow from highways.(Qualcon Contractors photo)
Caltrans highways in the Eastern Sierra Nevada have and are feeling the brunt of the heavy rains and snow falls hitting the area in rapid succession and via intense short periods, which in turn have led to avalanches, mudslides and flooding that have closed roads for extended periods and damaged infrastructure.
While many in California welcome the precipitation to help relieve drought conditions impacting the state, the influx of heavy downpours and snowstorms since last winter have taken its toll in this mountainous region of the state.
Caltrans personnel and crews are responding effectively. This includes Christopher Andriessen, District 9 maintenance public information officer and customer service liaison.
"This winter and this avalanche are unlike anything District 9 has faced in recent memory," said Andriessen. "The severity and duration of these storms were stronger and longer than what's been seen in the past few decades.
"California was impacted by multiple atmospheric rivers this winter," he added. "The first wave of storms arrived at the end of December through the middle of January and the second wave of storms arrived toward the end of February through the middle of March. With February being one of the coldest on record for the state, the snow from the first series of storms didn't have much of a chance to melt before the second wave of atmospheric rivers arrived. Per various resources, this winter has been the snowiest in decades with Mammoth Mountain reporting more than 700 inches of snow this season and June Mountain reporting more than 535 inches. The atmospheric rivers were often accompanied by high winds and rains at lower elevations and we have experienced flooding and mudslides in Mono, Inyo and eastern Kern counties through the winter season."
The extent of damage was such that Caltrans brought in general contractors to pitch in.
"Due to the nature of the avalanches on U.S. 395 and the unknown expectations of how much repair work would be required to reopen the road, it was decided early in the process to issue an emergency contract as the snow removal and possible repairs would require specialized equipment," said Andriessen. "Caltrans maintenance crews would continue to handle snow removal efforts and snow clean-up outside of the avalanche area. Because of the severity of the storms that impacted the region in late February/early March, Caltrans District 9 brought in Caltrans maintenance workers and equipment from other districts to aid in the snow removal process."
Qualcon Contractors Inc. was issued an emergency contract for the snow and debris removal and the required repairs on the avalanche closure. Concpec, a local small business based out of Lee Vining, was contracted to transport the Qualcon heavy equipment vehicles to the avalanche site.
Granite Construction was issued an emergency contract for repairs to State Route 120, State Route 168 W and U.S. 6.
Equipment to Get Job Done
Outside of the equipment used by the contractors, District 9 had a considerable fleet of equipment on-site. This included eight snow blowers, 25 trucks of various sizes with snow plows, eight graders and 37 different equipment operators. In March, the district received 16 additional pieces of equipment — 12 trucks of various sizes with snow plows, three loaders, and one grader with a plow and 31 additional operators from Caltrans Districts 4, 5, 6, 7, 8, 11 and 12.
"Caltrans mechanics were on hand for repairs to all equipment Caltrans used," said Andriessen. "The speed of any repairs would depend on the severity of the issue."
Snow removal operations featured equipment such as a Cat 966M wheel loader and a Cat 336F excavator. For earth operations, a Cat D5K dozer, a Cat 966M wheel loader and Peterbilt trucks were utilized.
Avalanches, which occurred between February 25 to 28, led to the closure of U.S. 395 between Lee Vining and Mono City, covering sections of highway road with snow and debris between 30 to 40 ft. high. This closed roads in some places for up to two weeks. This emergency work had Caltrans bring in Qualcon Contractor Inc. to pitch in. Caltrans maintenance crews also cleared snow from sections of U.S. 395 and State Route 167.
Caltrans performed two avalanche mitigation operations using a helicopter and an explosives team. The first operation occurred on March 7 and the second on March 23.
"In both instances, more than a dozen explosives were dropped from a helicopter on the hillside along U.S. 395 at Mono Lake," said Andriessen. "The purpose of these operations was to trigger avalanches. However, the snowpack proved to be too solid and no avalanches were triggered outside of a few small ones on March 23. Caltrans utilized the Gazex system in tandem with these helicopter operations, and it activated the system again on the morning of March 29."
Gazex is a remote operated avalanche control system that explodes a propane gas/oxygen mixture in areas designated as a risk for avalanches.
"Caltrans has a few of these pipes on the hillsides north of Lee Vining, but not where the avalanches happened this year," said Andriessen. "The area where the avalanches occurred this year had not experienced avalanches in the past. One thing we have seen in recent years is avalanches occurring where they haven't before. Explosives were dropped from the helicopter by a skilled explosives team trained for that type of avalanche mitigation. The hillside was examined by our avalanche crew before the operation to pinpoint the spots that looked most likely to generate an avalanche. In both helicopter mitigation operations, there were two flights to the hillside to drop explosives and the order of each drop location was determined by the explosives crew."
Explosives-wise for the ground operations, a Dyno AP+ 2x16 was employed. The explosions were initiated with a safety fuse with a #8 cap, lit with a pull wire igniter.
The avalanche closure ended at 3:10 pm on April 7and the highway between Lee Vining and State Route 167 fully re-opened in both directions.
"The project was one location and we worked it from both the south and north sides," said Qualcon President Pierre Ithurburu. "We would excavate the snow and debris from both ends and work towards each other in the middle. The challenges were that we kept having storms and shutting the operation down due to unsafe work conditions. We had spotters watching the slopes and snow above us to ensure the crew on the ground was safe. More potential avalanches were the largest risk. We had multiple days where we had to stop work due to the avalanche danger being too high. The road is now open and we just have final cleanup and installation of roadside signs [to install]."
Crews removed trees, rocks, snow, metal rock fence, and guardrail.
"The snow was excavated with an excavator and placed on the downhill slope," said Ithurburu. "The debris was removed and hauled to disposal facilities."
Crews worked 12 to 14 hour days during daylight hours.
"We had as many as 14 people at some points," said Ithurburu. "We ran two five- man crews from each end."
Operators utilized Cat 966 and 950 wheel-loaders and Cat excavators — two 336s and one 320.
Qualcon has been involved in previous emergency operations for Caltrans, and it has drawn up contingency plans to deploy crews and equipment.
"We sent the crew to avalanche training prior to starting work," said Ithurburu. "All the crew members were equipped with avalanche beacons, probes and shovels. We mobilized our crew within a week of getting the call."
District 9 had prepared for the emergency and it received help from other districts as the severity of the weather grew.
"Every year, District 9 begins preparing for winter operations in the fall and maintenance crews approached these storms and their impacts as they have all past storms, working 24-hour shifts clearing snow from the main arteries of Inyo, Mono and eastern Kern counties. We appreciate the hard work and sacrifice our maintenance crews have made this winter, and we know as this record snowfall begins to melt, there will be more work to be done throughout the rest of 2023; work our maintenance crews are more than prepared for." CEG
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