GRANDVIEW - It's a mystery as to how a bubble suddenly appeared in the city of Grandview's aeration lagoon, a part of its wastewater treatment system.
No matter the cause, the city is looking at a potential bill of nearly $500,000 to fix the issue of a bubble in the liner to the lagoon, according to preliminary figures provided to Wastewater Treatment Plant Manager Dave Lorenz.
The news was delivered to the Grandview City Council last night at its regular meeting.
Lorenz said personnel at the wastewater treatment plant noticed a baseball mound sized bubble in the middle of the lagoon late last week.
City Administrator and Public Works Director Cus Arteaga said, "It's an unexpected maintenance issue...we're not in an emergency or a violation (with ecology permits)."
Lorenz said he wanted to get ahead of the problem and inform council members immediately of the issue because Ted Pooler, an engineer with Huibretgse, Louman Associates had never seen such a situation, nor had the Department of Ecology and other experts with whom Lorenz has spoken.
Lorenz said he made a few phone calls and a company in Tacoma has had experience repairing liners.
The wastewater treatment process was not interrupted, but personnel placed it in manual mode during the past weekend, he said.
On Monday, the system was switched off of manual mode, the water that travels into the aeration lagoon was diverted to another lagoon and personnel began draining the water from the aeration lagoon.
Lorenz said the city rented a pump for the process and the city of Sunnyside through an interlocal agreement provided a boom truck for the removal of the aerator motors and motor stands.
"The process took about two hours," he said of the expediency of removing the aerators.
Lorenz said the bubble moved from the center of the lagoon to the shore as water was drained.
"We're not real comfortable with what we're seeing," he said.
The Tacoma company, Northwest Liners, has informed Lorenz that the worst-case scenario is that the liner will need to be replaced. Lorenz said the liner was installed in 2000 and the city had not anticipated repairs or replacement in such a short time period.
It was his belief the liner should last approximately 30 years, and he is hoping it can be repaired.
Lorenz said the repair or replacement of the liner could be months away without jeopardizing operations at the wastewater treatment plant. Right now personnel are working to completely drain the lagoon to determine the exact problem and what steps must be taken.
"From what we have seen, it's believed a seam underwater was compromised," he told the council, stating gases build up via respiration when wastewater is being treated.
"We have spent about $1,500 so far," Lorenz told the Grandview City Council members, noting Northwest Liners will charge the city $2,000 daily when analyzing the issue.
The tentative repair cost, said Lorenz, "...is pretty hefty.
"This was a Sunday morning surprise."