Arcata reports 82% completion on wastewater plant Phase 1; UV system online and chlorine removed

Arcata City staff told the City Council Wednesday that Phase 1 of the city's wastewater treatment facility upgrade is substantially complete and moving into final construction and commissioning phases.

Laura Kalichak, senior project manager, told council members the project was "82 percent complete" as of March, with a new ultraviolet-light disinfection system online and controls and process commissioning underway. Kalichak said a key safety milestone has been reached: the plant no longer stores or uses chlorine gas on site.

Work completed over the last two years includes upgrades at the Hauser pump station to increase flow to enhancement marshes, wiring and controls for new aerators and 16 aerators deployed in Oxpond, installation of a new electrical building and switchgear battery backup, and placement of a new emergency 500 kW generator with emissions controls.

Kalichak described foundation work for a new headworks building: crews installed 29 deep foundation piers (described in the presentation as approximately 90 feet deep and 3 feet in diameter), tested the piles for structural integrity and began preparing the foundation for concrete pours. New primary screws and modifications to the existing primary clarifier were underway, and a sludge-pump-control system was brought online last fall.

"We started the project in January 2023," Kalichak said, "and to date in March we're 82 percent complete on the project. So we're really making progress now." She said PG&E service connection work was underway and the utility connection was expected within about 40 to 45 days; headworks work will continue over the next nine months and staff expects to proceed to final instrumentation, process adjustments and paving before project closeout, planned between January and June of next year.

City staff said the existing project budget remains unchanged from the council-approved baseline, but council members were told that upcoming consent items would move funds internally from administrative and soft-cost categories into construction contingency and construction-management time to keep consultant firms on the project through March and to cover extended construction oversight.

Council members asked timing questions about the generator and emergency pond pump station; staff said the generator went online mid-March (approximate) and that the backup pumps and generator will operate whenever PG&E power is unavailable, such as during extended outages or seismic events. Staff also described supply-chain challenges that required temporary workarounds for electrical busways and transformers and said permanent transformers were expected in July.

Kalichak and staff invited council and public visits to review progress and said they will return with formal requests for additional soft-cost reallocations and construction contingency adjustments in coming meetings.

No formal decisions were taken at Wednesday's meeting; council received the update and asked follow-up questions.