Council hears near-$30 million estimate for new Minnetrista water plant; asks staff for options and Feb. 3 follow-up

At a Jan. 22 Minnetrista City Council work session, city engineers told the council the current 60% design for a new water treatment plant has come in far higher than earlier estimates and that the total program cost could approach $30 million when drilled wells, looping pipe and decommissioning are included.

The presentation by Eric Holder, the consulting engineer for the project, laid out the project site, an updated compact plant footprint and the plant’s intended capacity. “Our team started design last year with the goal of a 2,100-gallon-per-minute plant,” Holder said, and the design includes a large clearwell to give operational flexibility. Holder told the council the firm’s refined estimate for the treatment facility alone is about $26 million to $27 million; adding the wells already contracted (about $1.8 million), piping/looping, decommissioning and other project items pushes the program toward $30 million.

The nut graf: the council focused on whether the design could be scaled or changed to reduce near-term cost without unduly shortening the time before the city must build additional elevated storage. The engineering team proposed three principal approaches: (1) continue with the current design but pare nonessential elements and value-engineering (small savings); (2) switch to steel gravity filters (moderate savings but still requires future storage sooner); or (3) pursue a compact pressure-filter design and pilot-test the new wells to verify treatment performance (largest potential savings, but with technical risk). Holder said a pressure-filter option could reduce project cost by roughly $5–7 million if the pilot demonstrates it will treat the local groundwater effectively.

Supporting details: Holder described the project’s process spaces (filtration, chemical storage, electrical/mechanical, operator lab), a proposed clearwell on the order of 600,000–750,000 gallons, and an ability to pump up to about 2,800 gpm in short bursts to defer an elevated storage tower. He said an elevated one-million-gallon tower typically costs in the $6 million–$8 million range. Holder recommended piloting a pressure-filter approach by running a small trailer-mounted pilot on the newly drilled wells for a few weeks once the wells are equipped; the pilot would test iron/manganese and organic-treatment challenges and help determine whether a compact pressure-filter plant is feasible.

City staff and council members raised finance and timing concerns. Mayor Lisa Leland and Council President Claudia Lacey asked for scenarios that show the effect on household water bills and debt service under different funding assumptions (with or without state/federal bonding support). Public works staff noted the city already pays roughly $1.1 million a year in current water debt service and that adding this project without external grants or bonding could substantially raise rates for the roughly 2,400 metered accounts. Councilmember Brian Delworth and staff discussed possible pilot timing, the degree of design work that could be paused, and whether the city could afford to delay the project while pursuing grants and piloting.

Outcome and next steps: The council directed staff to return to the Feb. 3 work session with narrowed cost comparisons (current design vs. gravity vs. pressure filter), estimated household bill impacts under alternative funding scenarios, and recommendations about piloting. Staff said they will pause parts of the detailed filter/clearwell design while the pilot and funding options are explored. No formal action (vote) was taken on the plant design at the work session.

Ending: City staff said they will refine numbers and outreach materials so the council and residents can assess tradeoffs between near-term cost savings and longer-term system reliability. The council scheduled further review at its Feb. 3 meeting and said members want clearer dollar-and-rate scenarios before committing to a final design.