City staff outlines plan to replace Arvada Water Treatment Plant; estimates $330 million, phased bonds

City of Arvada utilities staff presented a plan at a study session to replace the Arvada Water Treatment Plant, describing the facility as out of date, operationally constrained and at risk of failing within about five years unless replaced.

Mary Stahl, utilities engineering manager, said the city’s 2020 treatment master plan and follow-up work, including a 2024 pilot plant, led staff to conclude the Arvada plant’s “capacity should simply be replaced.” She told councilmembers the city needs two treatment plants to meet peak summer demand and resilience needs and that the Ralston Water Treatment Plant alone cannot carry the system if Arvada fails.

The presentation laid out technical findings, a budget estimate and a financing path. Staff gave a Class IV project estimate of roughly $330 million for replacement of Arvada treatment capacity and related distribution and intake work and noted that preliminary site-specific rebuild costs at the existing Arvada location could be higher (staff cited an illustrative $346 million figure for a constrained rebuild). Chris (finance staff) said the city plans a phased revenue-bond approach: an initial issuance of up to about $90 million to fund design and near-term work and later bond issuances of roughly $150 million in 2027 and $150 million in 2029 to fund construction, with an estimated project completion in the first quarter of 2030.

Why staff says replacement is needed

Staff said the system met drinking-water safety requirements overall but recorded four regulatory violations in 2024 tied to how the Arvada plant is designed. Bethany Kolb, utility engineer, summarized operational limits: Arvada is a seasonal plant permitted at 16 million gallons per day (MGD) but rarely produces that amount continuously; Ralston is permitted at 36 MGD and is the year‑round workhorse. The city’s summer maximum-day demand last…