From the day we first left Billings (May 17th), I've been hearing about this HUGE job that we had coming up somewhere in Wyoming. My team lead wasn't sure when or exactly where the job was, but we knew it was coming.
That time came on June 7th just outside a small town called Hanna, Wyoming. The nearest brand name motels to Hanna are in the town of Rawlins, 40 miles away. After driving from Pinedale to Rawlins on the 6th, we drove to Hanna on the morning of the 7th and quickly realized that the scope of the job was larger than anyone had anticipated.
The tank is a 20 MILLION gallon reservoir that the town of Hanna uses as a reserve water supply to fill their treatment tanks. The tank is approximately 300 feet wide by 500 feet long (bigger than a football field), 20 feet deep with walls that angle down at about 45 degrees from the edges to the bottom. The tank used to be cleaned very three years, but the rep from the water department told us that it hadn't been cleaned since 2002 or so. The job had been bid at 18-20 days and we were budgeted 15 days to clean the tank.
Due to the tremendous amount of work, my team lead obtained authorization to stretch the rules a bit and put two divers in the water, leaving him as the sole tender and dive operator. We commenced dive operations on the 7th and dove two divers for six hours per day.
Our first day in the water was horrible. I was the first diver in the water and discovered 6" of plant growth down the wall of the reservoir. Once the plant material was touched with our hydradyne (the underwater vacuum), it kicked up turbidity (underwater dust) that was so thick that visibility went to zero. Cleaning the walls was extremely difficult - the hydradyne left a small layer of sandy dust after cleaning off the plant material, which proved to be very slippery. I found myself slipping down to the bottom of the reservoir despite my best efforts... and ascending and decending repeatedly in the water column is tough on the ears and very exhausting. To further complicate things, the tank had an entire ecosystem complete with foot long salamanders, leeches, and all kinds of critters that lived inside the stuff we were vacuuming up.
My coworker and I agreed that if all of our cleaning jobs were like this one that we would both have quit after the first day in Hanna.
Fortunately, Day 2 was a little better for me. I got into a rythm and was able to make some progress. After three days of working two divers at six hours per day, we had cleaned about 75% of the first quadrant of the reservoir.
On Day 5, the utility determined that it was taking too long to clean the tank with divers and that they were going to drain the tank to perform cleaning and repair operations with it empty.
That news was welcomed. The process really was taking too long, so we packed up on Saturday the 11th and spent Sunday the 12th recharging in Rawlins.
Here are my pictures from the tank in Hanna, as well as a few from Rawlins:
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