Martin County water board backs limestone contactor plan to curb seasonal 'brown water'

The Martin County Water District voted to advance a calcium‑carbonate (limestone contactor) treatment as its preferred solution to recurring summer “brown water” complaints, board members said after hearing engineers lay out two treatment alternatives and long‑term cost comparisons.

Engineers from Prime E presented data showing the district’s raw source water has low alkalinity during summer months, creating corrosive conditions by the Langelier Saturation Index that can mobilize iron and manganese from pipe scale into customers’ taps. “In the summer months our alkalinity is in the range of 20 to 30 milligrams per liter; we need to increase alkalinity by roughly 70 mg/L to reach the ideal buffering range,” Michael of Prime E said during the presentation.

Prime E described two options: a soda‑ash feed system with lower capital cost (engineers estimated roughly $700,000) but higher annual operating and chemical costs, and a limestone contactor approach with higher capital cost (engineers estimated $3.5–4.0 million) and substantially lower annual operating costs. When evaluated over a 30‑year financing horizon, the board heard the limestone option produced lower annualized program costs despite the larger up‑front investment.

Board members focused on tradeoffs between near‑term affordability and long‑term rate pressure. One member said the soda‑ash option would raise operating costs by about $176,000 a year, a figure the district would likely have to recover through rates. Another member argued the larger capital project would avoid that recurring cost and might be easier to cover through grants.

After discussion the board voted in favor of the limestone contactor alternative (Option 2B) to carry forward into grant applications and the district’s WRS portal entry. The vote was conducted by voice; the transcript does not record individual yea/nay votes.

Next steps: Prime E will update its report and the district will use the selected approach for funding applications and permit planning. Board members asked staff to pursue grant funding aggressively so capital costs can be covered without imposing large ongoing operating costs on ratepayers.

Why it matters: The decision commits the district to a capital‑heavy fix intended to reduce recurring water‑quality complaints and long‑term operating expenses. The board and engineers emphasized the final design will still require permitting and potential adjustments once the master plan and funding awards are secured.