Underwater warriors clear pipe-blocking mussels
|A diver jumps into the pond on the northeast side of Wilson Hall.
A few times a year underwater warriors converge on Fermilab. They look like octopus slayers from "20,000 Leagues Under the Sea." Armed with vacuums and high-pressure power hoses, divers tackle razor-sharp, clam-sized zebra mussels.
The invasive species clog the intake pipes necessary to circulate water to cool Fermilab's accelerator magnets. Since January, divers have removed more than 8,000 pounds of mussels.
"At any given moment, 5,000 gallons of water a minute pass through the intake pipes," FESS's Bill Shull said. "Without a constant supply of cooling water through the pipes, the accelerators would stop running."
The aquatic squatters hitched a ride on a ship from the Caspian Sea in Eastern Europe and made their way to the Fox River that supplies water to Fermilab.
"The mussels form a thick carpet in the intake pipes and find a nice little place to attach and live out their lives," Shull said.
Trained commercial divers swim through three-foot-in-diameter, 75-foot-long pipes to blast the mussels off the walls with high-pressure water. The stubborn ones require the use of scrappers and wire brushes. A vacuum sucks the dislocated, smelly mussels up to be buried on site.
"The shells degrade and are perfectly compatible with the ground," Shull said. "We just bury them so the smell doesn't offend anyone."
Casey's Pond supplies most of the cooling water on site so divers concentrate their efforts there, but they also clean the pond pump intake structures at the Main Injector and Tevatron ring ponds when needed.
Although cleanings take place all year-long, most zebra mussel dives take place during the summer.
"The pipes are pretty small, especially when we start dragging the hoses in there, so this is definitely not for the faint of heart or the claustrophobic," said diver Pete Perich Jr. "They're sharp little buggers, too."
The job sounds dangerous, but Perich Jr. said the divers make sure to take proper safety precautions. They train regularly during the year and follow Fermilab's Lockout/Tagout standard.
-- Jennifer L. Johnson
A load of zebra mussels in the back of a pickup truck. Divers removed 8,000 pounds of zebra mussels from the Fermilab ponds and pipes since January.