Sewer district warns of rising treatment needs, $70 million upgrade and chloride limits

Eric, the Mass Metropolitan Sewage District executive director, told Monona’s Public Works Committee the district is planning a major liquid‑processing upgrade to handle increasing strength in its wastewater and to protect treatment reliability.

The district — which Eric said serves 24 customer communities and cited roughly 440,000 people in its current service area — is moving forward with a biological treatment upgrade it estimates at about $70 million to meet projected loadings over the next two decades. "This project is about $70 million," Eric said during the appearance. He added the project will be bid this summer so the district can refine its budget assumptions.

The district is unusual, Eric said, because 100% of its flow is moved by pumping rather than relying solely on gravity. That makes energy costs and system redundancy key operational concerns. "If we don't have [power], everybody's day goes down," he said, framing the importance of the district's heat‑and‑power and biogas projects to offset rising energy bills.

Why it matters: the district said it can handle current volumes but not the increasing strength, or "loadings," of wastewater arriving from industrial and commercial sources; the upgrade is intended to boost the biological treatment processes so plants can meet permit limits without resorting to more expensive chemical or membrane treatments.

Biogas and revenue opportunity Eric described an existing biogas‑to‑power program and a potential pathway to convert and market pipeline‑quality gas. He said selling to a pipeline and buying back energy or partnering directly with the local utility could produce additional revenue — Eric cited a study suggesting $4–6 million in potential annual value from capturing credits. "We save about a million and a half to $2 million a year in power generation" from current biogas use, he said.

Force‑main failures and pipe condition The director reviewed a recent force‑main break near Pump Station 2 in wetlands near the treatment plant and said the district has experienced about five force‑main failures in five years. When crews excavated the failed section, the interior of the ductile iron pipe appeared sound while the exterior was corroded from wetland exposure. "Force mains for us are the single point of failures," Eric said, describing inspection challenges for fully buried, pressurized mains.

The district is pursuing lining and targeted rehabilitation projects where feasible to extend asset life and avoid full excavation and replacement where possible.

DNR chloride permit and limits Eric said the Department of Natural Resources delayed issuing a new wastewater treatment permit and that the draft includes lower chloride limits. He told the committee the district does not treat chlorides and that full removal — for example by reverse osmosis at large scale — would be prohibitively expensive; he referenced a historical figure of $400 million (from 2005) as an illustrative cost for comprehensive chloride removal.

Because chlorides are mainly from road salt and some commercial discharges, Eric emphasized education, local incentives (rebates for water‑softener improvements) and voluntary measures as primary tools to reduce system chloride concentrations. He warned enforcement by municipal governments could be required if voluntary reduction fails, but said the district prefers to work with customer communities on education first.

Public outreach and operational cautions Eric also urged residents and businesses not to flush wipes, paper towels or other non‑degradable items, describing how fibrous products clog pumps and cause emergency call‑outs. He offered plant tours and said the district has outreach materials and rebate programs to help reduce inflow, infiltration and salt use.

Next steps Committee members asked for follow‑up briefings and more detailed budget information as the district refines bids. Eric said staff would return with project details when available and invited committee members to tour the treatment plant.

Sources: Presentation and Q&A with Eric, executive director, Mass Metropolitan Sewage District (appearance beginning at SEG 015).