Commission hears alarm after RBC failure that raised TSS and E. coli readings

The Charlton Water and Sewer Commission received an operations update on Jan. 7 after the town’s rotating biological contactor (RBC) number 1 experienced a chain failure that staff say disrupted treatment and raised total suspended solids (TSS) and E. coli readings.

Dennis, who delivered the monthly operating report, said the plant began "washing out" within a day or two after RBC 1 failed. "As soon as that RBC went down, within a day or 2, we started washing out the plant," he said, describing spikes in effluent TSS and downstream concerns for compliance. Staff reported the RBC chain had been repaired and that they were monitoring whether the fix stops the washout; they also obtained quotes for replacement parts and UV bulbs.

Commissioners pressed staff on the age and condition of the RBCs and the feasibility of taking some units off line for efficiency; staff said earlier engineering suggestions to reduce running RBCs would not be safe now given the plant’s sensitivity and current loading. Vendor life expectancy was cited at roughly 25 years for these units, and commissioners asked for further cost and part‑availability information.

No formal policy decision or capital appropriation was made at the meeting; staff said they would return with vendor quotes and a timeline for needed repairs.