Seaside says Memorial Day sewer‑plant odor event has ended; operational fixes and upgrades underway

City public‑works staff and the sewer supervisor briefed the council June 8 after public complaints about a strong odor around the wastewater treatment plant and estuary area. The city described the event as an odor incident—not an overflow or permit violation—and said sampling showed treated discharge did not have elevated fecal coliforms compared with upstream water.

Sewer supervisor Walter told the council the episode lasted about 10 days, shorter than a similar Memorial Day incident last year that took roughly four weeks to stabilize. Staff identified the cause as a seasonal transition in flows: spring rain and groundwater dilute winter flows and Memorial Day’s rapid influx of visitors produces a concentrated wastewater pulse. The stress was compounded by reduced capacity in one of the plant’s aeration basins while a major aeration upgrade project is underway.

Operational responses included running aeration equipment at higher capacity where possible; moving more solids directly to the dryer to remove material faster (a higher‑cost step); and targeted clarifier and aeration repairs. Staff reported that the affected basin had returned to similar color and operation as the other basin by the end of the week and that the plant remained in regulatory compliance throughout the episode. Fecal coliform sampling at Quatatap (upstream in the estuary) showed non‑detects for the city’s discharge samples and no evidence of untreated sewage entering the river.

Longer‑term work: staff said the aeration‑system replacement is a custom, multistep engineering project (parts, contracting and installation) that is expected to continue through the summer with a target to complete the major items by the end of July. Council also discussed the 12th Avenue/Holiday lift station (a known localized odor source) and plans to rebuild or recondition that station to reduce persistent neighborhood odors.

Council direction and next steps: staff will continue monitoring the plant, complete the aeration upgrades and present timing and scope for the 12th Avenue lift station project at a future meeting. Mayor and council members asked staff for follow‑up reports on project timing and to include an update in relevant annual reports as work proceeds.