SUA approves replacement sludge-injection equipment as lawmakers consider PFAS ban

The Stoner Utilities Authority voted April 7 to approve purchase of replacement sludge-injection equipment after hearing from James Driscoll, the city’s water utilities director, about a pending state bill that could restrict land application of sewage sludge.

The item won approval by a 5-0 vote. Driscoll told trustees that Senate Bill 3 would “reduce land application” on a phase-down schedule — “25% this year by September 1, 50% in the following year, and a 100% for the third year if it passes” — and that the measure is aimed at perfluoroalkyl substances (PFAS/PFOS) but does not set concentration limits for sludge application.

Driscoll said the utility’s existing injector is nearing 15 years of service and operates in harsh field conditions, so staff recommend buying a new tractor-and-trailer injection unit to bridge the gap. He described the tractor as the major cost component that could be repurposed for field maintenance, easement work and Lake McMurtry grounds upkeep, while the trailer injection component could be sold or used by agricultural operators if land application is later restricted.

Trustees pressed staff on current practices and alternatives. Driscoll said, “We do not surface apply. We subsurface inject. Our units get down about 6 inches. Our spec on this unit was a 6 inch minimum injection depth,” and described the new unit’s plow that lifts soil, injects sludge into the void and returns the soil to reduce surface disturbance. He said alternatives if land application is banned include dewatering and hauling sewage sludge to landfill—which would require building a dewatering facility with design lead times he estimated at roughly three years and typically would use belt presses—and incineration, which he said would require temperatures above what most incinerators achieve to destroy PFAS and therefore is not a cost-effective solution.

Trustee Clark introduced Driscoll’s remarks and said the board is preparing to spend funds for the equipment; the specific dollar figure in the meeting transcript was unclear. A staff speaker noted that because the legislation is proposed, the utility’s current application method remains appropriate until any law takes effect, which is one reason staff recommended proceeding with the purchase.

The authority approved the item and removed it from the consent docket. With the bill still pending in the legislature, Driscoll and trustees said they hope the measure will be delayed pending further scientific guidance; no change to the city’s practice takes effect until state law changes.