Traversing Sierra Nevada Mountaintops

ASI arrived in Fresno, California on a late fall day. The team made final preparations while the amenities of civilization were within reach, and they set off on the winding roads of the Sierra Nevada mountains. The first half of the crew arrived early to test and stage the equipment for a lengthy penstock and surge shaft inspection at a hydro facility. ASI prepared to work 24/7 to complete the data collection within the plant’s scheduled outage.

As the crew approached the site, the views became more mesmerizing, although accompanied by the weight of reality and the destruction caused by wildfires.

The crew arrived at the facility accommodations, a dormitory maintained by the client for their employees and contractors. At the end of the road and still a mountain away from the surge shaft that was our access point, the crew needed a new method of transportation to get there. Two helicopters were contracted, one heavy-lifter for the equipment crates, crane, and shelters, and the other a passenger chopper to transport personnel.

The equipment and crew were ready to begin and proceeded to launch the remotely operated vehicle (ROV) by crane. Once the ROV was submerged, it was maneuvered out of the deployment cage and continued to descend to the tunnel below (nearly 600 feet total). With nightfall approaching, the crew hiked back to the helicopter landing site to hand-off to the nightshift before the helicopter was grounded by darkness. ASI’s nightshift arrived at the dorms in the nick of time despite flight delays. They filled up on dinner and took off into the mountains to continue the inspection.

The morning sky incremented in shade from dark to reddish-brown.

Dan Cousineau

The crew pressed onward throughout the night collecting and recording data; however, by the time daylight was expected, it became evident that it wasn’t arriving. Wildfires were raging (roughly 60 miles south) and kicking up thick clouds of smoke that moved in and out of the mountains with the winds.

In the words of crew member and Technical Advisor, Dan Cousineau:

"The morning sky incremented in shade from dark to reddish-brown. It seemed obvious at the time that our airlift out was not going to be coming. Yet, shockingly, shortly after his intended arrival time, the thumping of rotors was heard circling the area, and sure enough, our pilot dropped out of the soup-filled sky. We then find out soon enough, the pilot was lost and couldn’t see the lower landing pad. But then, spotting our big staging area up top, like a halo, had found safety and dropped in the be spared a wilderness landing.

Eventually, with everyone standing about, lost on the atmosphere, five hours was enough for a bit of cleaner air to open up. With this gap in the smoke clouds, the pilot made short work of getting loads down the hill. This final reuniting after 20 hours up on the rock could only be managed with a chilled IPA and some fitness complex sports.

The changing smoke conditions and helicopter limitations meant ASI and the clients re-evaluated and removed further night shifts from the schedule. The dayshift crew continued operations as the weather permitted, and completed the inspection before the end of the scheduled outage window. The team enjoyed their last meal before setting off on the day-long trip back to the East Coast.