Superintendent reports 1.71 million gpd flow; pilot study shows operational issues

At the Scarborough Sanitary District’s regular monthly meeting, the superintendent presented the June operations report and said the district’s average effluent flow for the month was 1,710,000 gallons per day. The superintendent told trustees the plant’s effluent quality was within permit limits and that the plant averaged about 92% biochemical oxygen demand removal and 93% total suspended solids removal, with concentrations near 15 and 16 milligrams per liter.

“The pilot did not respond well to this change and has had trouble recovering,” the superintendent said, describing a decision to move the pilot’s influent from the grit tank effluent to the primary clarifier effluent, which now includes all side‑stream flows. Staff reported a subsequent plugged return pump on the pilot and high filamentous bacteria growth after the blockage. The superintendent said those problems are helping staff focus on operational issues and that they are investigating whether side‑stream flows have a deleterious impact on plant performance.

Trustees asked for and received a correction to one of the concentration numbers; a trustee clarified that 15 and 16 mg/L were the correct reported values and that 21 mg/L represented a maximum. The superintendent acknowledged the correction and offered to provide further explanation or data if trustees want more detail. Staff noted no other pump station flow issues were observed in the June report.