Baker City staff present plan to switch water disinfection from chlorine gas to on‑site hypochlorite
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Summary
City Engineer Brandon Mahon outlined a plan to replace chlorine‑gas dosing with on‑site sodium hypochlorite generation, citing safety and supply reliability; preliminary cost estimates point to roughly $1 million in construction and a multi‑year payback under 2019 assumptions.
City Engineer Brandon Mahon told the Baker City Council on Oct. 28 that the city is evaluating a conversion at the water treatment plant from chlorine gas to on‑site generation of sodium hypochlorite (a low‑strength bleach produced by electrolysis of a salt brine).
Mahon said gas chlorination is a proven method but presents safety and supply risks, noting interruptions in regional chlorine production after the COVID pandemic. On‑site generation produces a weaker (about 0.8%) sodium hypochlorite solution on site; Mahon said it is safer to handle and reduces dependence on off‑site chlorine cylinder deliveries.
Mahon cited a 2019 technical memo that estimated capital costs at about $830,000 (2019 dollars). For Baker City’s capital plan, he said design is planned this fiscal year and current planning projects roughly $1,000,000 in construction costs spread over two construction seasons; he emphasized that final scope and pricing will depend on preliminary design and equipment‑selection steps.
Councilors asked about residuals, corrosion, replacement‑cell lifespans and electricity use. Mahon said electrolytic cells typically last about 10–15 years while tanks and other infrastructure can last 20–30 years; suppliers report additional electrical load but Mahon said he had not seen projects that required utility service upgrades. Mahon said the likely breakeven period from the 2019 memo was roughly 12–15 years, subject to current chemical and capital costs.
No formal vote was taken; Mahon and staff said next steps are preliminary engineering, equipment selection, supplier outreach and final cost estimates before returning with a recommendation to the council.