Mono council hears report on sewer-plant membrane cleaning, awaits validation tests

The Mono City Council heard an update on Jan. 27 about repairs and cleaning at the municipal wastewater treatment plant, where staff and a vendor from Viola carried out membrane cleaning and filter maintenance.

Unidentified Speaker (S1), speaking after an all-day inspection, said one set of filters is currently submerged and being cleaned and that the council should know by the next day or by Thursday whether the work reduced back pressure and restored normal flow. ‘‘If that number goes from minus 11% and it goes back down to where it's supposed to be — to minus 3 or minus 4 — then it means it's actually letting the fluid pass through the holes in the membranes,’’ Unidentified Speaker (S2) said.

Staff described the cleaning process as alternately emptying one tank into another, adding chemical, refilling and allowing a 24-hour soak. The vendor recommended starting with monthly cleanings and, once performance stabilizes, moving to a six-month interval. Unidentified Speaker (S2) said properly cleaning the membranes could extend their useful life and reduce pump wear.

Council members also discussed placing a service contract on an upcoming meeting agenda. A staff estimate included a high-line item of $9,080 posted to the agenda packet; speakers said the actual bill is likely to be lower and suggested the final cost could be under $5,000 depending on days of vendor work and discounts.

No formal motion or vote was recorded during the work session. City staff said they will run validation tests and report results to the council at the next meeting or earlier if tests complete sooner.