Algae growth in Lake Stevens, the reason why the city built the world's largest water aerator 10 years ago, hasn't become bad enough this year for the system to be activated.
However, if it becomes a problem, the system will be ready to handle it, Mayor Lynn Walty said.
The aeration system, which was refurbished last year, has experienced some problems that are prompting the city to make some fixes. Temperatures inside a new building that houses aeration-cooling equipment have been getting uncomfortably high, so the city is installing fans, Walty said.
The system was installed in 1994 to pump air 3,000 feet out into the lake and curtail algae growth by restoring oxygen to deep water. It worked, but problems related to the construction of the aeration system caused the city to file lawsuits, which were eventually settled.
Last summer, 358 feet of onshore cast-iron pipe sealed with gaskets was replaced with stainless-steel and polyethylene pipes. The gaskets had frequently failed because of high temperatures in the pipes.
Also installed last summer was a cooler in a new building along Lundeen Parkway, intended to cut air temperatures in the pipes that carry compressed air to the lake, Walty said. The cooler resembles a large automotive radiator, he explained.
The cooler has lowered the temperature of the compressed air, Walty said, but now the heat inside the building becomes intolerable when the system is operating. Temperatures have reached 300 to 400 degrees, he said.
Opening the doors has improved airflow and lowered temperatures, but that's not an ideal fix.
"It's been a challenge," Walty said. "We can't leave the building open all the time."
The new fix, which is expected to be in place about the end of the month, will be to install two electric fans, about 4 feet in diameter and costing around $6,000 each, to improve airflow over the radiator.
That's expected to lower temperatures inside the equipment building and that of the air being pumped into the tubing, Walty said.
The new cooling system is expected to be in place by the time algae usually starts blooming in late summer and early fall, he said. Water-quality testing so far this year hasn't shown it's necessary to run the system. When testing does indicate it's time to activate the system, it will be ready, Walty said.
"When it's working, it's doing fine," he said.
Peyton Whitely: 206-464-2259 or firstname.lastname@example.org