Consultants recommend phased $42M bio‑solids dewatering project; council seeks federal help

Bolton & Mink engineers told the Brainerd City Council on Feb. 17 that the city’s wastewater treatment facility needs multi‑stage upgrades to meet future nutrient limits and bio‑solids storage requirements.

Morgan Salem, principal wastewater engineer with Bolton & Mink, summarized a facility plan that projects community flows and loadings through 2050 and evaluates alternatives for both the liquid (nitrogen/phosphorus removal) and solids (bio‑solids) streams. The consultant said current sequencing‑batch‑reactor (SBR) processes are operational today but are limited for future, more stringent nutrient limits and that the plant is approaching the Minnesota Pollution Control Agency’s 180‑day on‑site bio‑solids storage benchmark in some years.

Bolton & Mink’s recommended, limit‑driven roadmap is phased: Phase I would build a dewatering bio‑solids facility (screw press or centrifuge), add tank/storage and make pre‑treatment and electrical improvements, and prepare the site for future drying options—an estimated $42 million capital cost. Phase II—conversion from SBR to activated‑sludge biological nutrient removal (BNR) to meet likely future nitrogen and phosphorus permit limits—would be undertaken only if and when permit limits drive the change; consultants estimated that conversion could raise total program capital to the $58–88 million range. The consultant estimated the existing baseline O&M is roughly $5.2 million per year; Phase I would raise annual O&M by an estimated amount (order‑of‑magnitude) and Phase II would add further operating costs, largely for chemicals, energy and staffing.

Salem said dewatering reduces truck trips for bio‑solids transport dramatically: under today’s land‑application disposal the plant expects roughly 1,300 tanker trips and about 33,000 annual miles; dewatering to a 20% ‘cake’ product would cut that to roughly 150 trips (~3,700 miles), and a future heat‑drying phase (90–95% solids) could reduce disposal trips to a few dozen per year.

Council members asked about equipment useful life, rate impacts for customers, odor and air‑scrubbing for dryers and how grant and SRF funding would factor into the plan. Staff stressed equipment life cycles (15–20 years for process equipment; concrete tanks longer), and cautioned that rates rarely fall permanently because of continuous asset‑replacement cycles. Funding options discussed included the Clean Water SRF (low‑interest loans), point‑source implementation grants (PSIG) for nutrient limits, affordability grants, state bonding and congressional appropriations.

Following the presentation, the council voted to authorize staff to submit a community project funding request to Congressman Stopper for $10 million toward Phase I pre‑treatment and bio‑solids dewatering and ancillary improvements; Bolton & Mink offered to prepare the congressional application as part of their contract. The motion to authorize the $10 million request passed by voice vote.

What happens next: The Brainerd Public Utilities Commission will hold a public hearing and consider adoption of the facility plan; if adopted the city will pursue SRF/PSIG and other funding and begin preliminary engineering for Phase I with the intent to start construction in late 2027 or early 2028.