Showing posts tagged as "intake screens"
World’s Toughest Job?
People always tell us it’s their dream to work at the Aquarium. It is great, but not all the jobs are as romantic as you might imagine. How would you feel about scrubbing the barnacles and jellies off our intake screens?
What is That Goo?
Did you know that the Aquarium pumps about 2,000 gallons per minute of raw seawater into our exhibits? The intakes, which are marked by buoys just offshore, require regular cleaning—but they rarely look like this! A perfect storm of barnacle growth and jellies caused the stout stainless steel screens to clog and collapse over Labor Day weekend, and we had to quickly pull them up for cleaning.
“The growth was almost unbelievable,” says Facilities Systems Manager Eric Quamen. “In two months we accumulated a half inch of organisms.” Most of the time, jellies can pass through the porous screens. “But if barnacles grow, the jellies become entangled and plug part of the screens,” says Eric. “Then the incoming water picks up velocity, sucking in more jellies, and so on. They stick like Velcro. Then finally the whole thing collapses like a beer can from the pressure.”
The systems are carefully monitored, and there are backups, so no exhibit animals were ever in danger. But it did require a quick response, including arranging a special dive team and a crane on a holiday weekend—at considerable expense.
“We clean the screens four times per year, but this summer was particularly bad,” says Eric. “They’re normally a lot cleaner.”
The six-foot screens will be pressure-blasted and sent to a local fabricator to be bent back into shape, and re-used. They have a hard life, but generally last about five years.
Why the unusual growth? “Things are different every year,” says Eric. “It depends on nutrient conditions in the bay, and this year it just happened to be perfect for barnacles and jellies!”
(Thanks to Randy Wilder for the great photos.)