Designers present 3 MGD Grantsville wastewater plant plan, schedule and $39 million estimate to council

Aqua Engineering presented a design and schedule update for Grantsville's proposed new wastewater-treatment plant at the Feb. 19 council meeting, describing the project as a 3 million‑gallon‑per‑day (MGD) average-capacity plant sized to meet new phosphorus permit limits and allow future expansion.

Eric, the Aqua Engineering project manager, said the design is approaching a 90% submittal and the consultant expects to issue a full 90% package to the city next week, followed by a council workshop in early March. The design timeline anticipates solicitation of bids in June with contractor selection by mid-July and contractor mobilization in August. "That 5 year window means we want to be compliant by essentially January first of 2029," Eric said, noting the state set a compliance window after permit results on phosphorus triggered a timeline.

Eric described the facility footprint and principal elements: a headworks building, grit removal, aeration/biology basins sized for the phosphorus removal process, secondary clarifiers, a solids dewatering system and UV disinfection. He said the design emphasizes expandability: the initial plant is sized for roughly a 3 MGD average with a build footprint that would allow average capacity to grow to around 6 MGD and peak handling higher if the city chooses to add process modules later.

Engineering staff and the consultant discussed procurement steps and equipment lead times. Eric said major equipment preselection has been done and the bid documents will specify make and model for major items as owner-selected, contractor‑furnished equipment; the design team is requiring conservative fabrication schedules and price holds to limit escalation. On costs, the consultant presented a current engineer's estimate of about $39 million including a 20% contingency; Eric said the team will refine that number at the 90% stage.

Council members asked about operational staffing and electrical and gas services; the consultant said the plant could be operated with existing staff plus one additional hire initially and that the electrical room and service are being sized with future expansion capacity in mind. The consultant also said the design left space and stubbed connections should the city later choose tertiary filtration for reuse water.

Why it matters: Grantsville faces a regulatory deadline on phosphorus limits and significant system growth prospects. The proposed plant represents the city's primary capital-response strategy to meet the new permit limit and to provide long-term capacity and maintainability.