City hears feasibility plan to address rising manganese in drinking water

Consultants contracted to study manganese in Gig Harbor’s water system told the City Council at a study session on April 16 that they are beginning a feasibility study to identify a preferred treatment approach and provide representative cost estimates for future budgets. Public Works Director Jeff Langham introduced the team and said the issue is largely aesthetic now but that staff wants to “get ahead of it.”

Luke Tipton, the project manager, said the study will screen and evaluate alternatives — from oxidation/filtration systems to membrane processes — with an emphasis on constructibility, operations and maintenance, operator needs and site space constraints. "You're looking at probably 24 plus months before it's you're gonna see improvements at your tap," Tipton said, noting the project requires data collection, potential pilot testing, engineering design, permitting and construction.

Water treatment specialist Stefan Bradley described current regulatory benchmarks and health guidance. He said the EPA and Washington Department of Health use a secondary standard of 0.05 milligrams per liter (mg/L) for manganese as an aesthetic guideline and noted that some wells in the system are approaching concentrations that make treatment worth considering. "Right now, it's still a secondary standard," Bradley said, adding that higher concentrations can pose concerns for sensitive populations and that industry practitioners watch emerging science.

The team described oxidation/filtration (often using greensand media) as the commonly used and likely practical technology; membranes such as reverse osmosis are technically effective but typically more energy‑intensive and costly for Gig Harbor’s scale. Consultants also warned that treated filters generate backwash waste that would be routed to the city’s wastewater plant; the study will evaluate whether the wastewater facility can accept and process that waste without operational impact.

Staff and consultants said they will collect and analyze historical and new sampling data for each well and for end‑of‑line taps, assess the need for additional sampling, and use a matrix‑based decision tool to weigh cost, performance and community impacts. The team expects to provide budget‑level (class 4) cost estimates by mid‑summer to inform the 2027–28 budget process and return to council with findings in October, with future public workshops planned.

The council asked about whether manganese can be recovered economically; Bradley said recovery is unlikely to be cost‑effective. Members also asked whether other utilities are pursuing similar projects; consultants said multiple Washington utilities are addressing manganese and that the issue is regional. The council directed staff to continue the study and flagged grant or loan options such as Public Works Trust Fund loans as possible funding sources.

The presentation and Q&A were technical and largely informational; no formal action or vote was taken at the session.