Council hears wastewater update: industrial treatment plant proceeding; municipal ponds clogged by chlorine and solids

Megan Panofsky, the program and construction manager working with the city, told the Gonzales City Council on Oct. 6 that the industrial wastewater projects are under construction but that the municipal treatment plant is struggling with percolation problems caused in part by industrial chlorine discharges.

Key points: Panofsky said Phase 1A (industrial wastewater conveyance pipeline) was completed and accepted in July under budget; Phase 1B (industrial wastewater treatment facility) was awarded in May 2025 and mobilized in July. The city obtained an SRF loan amendment and increased the project loan total to about $34.9 million to accommodate higher-than‑budgeted bid results.

Temporary measures and schedule: The contractor has completed roughly 95% of grading; excavation for deep infiltration wet wells is the next work item. Panofsky said the contractor's disposal/infiltration basins at the industrial site are being used temporarily to accept flows from the municipal plant; the team must clear the basins for the contractor's use by February and aims for facility completion around March 2027.

Municipal plant stressors: City staff and Panofsky explained that chlorine spikes from industrial users have repeatedly killed the biological treatment "bugs" in the municipal plant, producing sludge and algae that have reduced percolation rates in the basins. Council members and staff said Basin D and other percolation ponds have accumulated fines and organic material; one basin filled and has not been percolating normally for about four months.

Planned responses: Staff described a series of responses: (1) temporary use of the new industrial basins to buy time; (2) consideration of dechlorination at the municipal plant headworks and bioaugmentation to rebuild the microbial community; (3) planned rehabilitation of basins A and C involving removal of several feet of fine material in places and replacement with clean sand; and (4) a pending pretreatment ordinance that would give the city enforcement authority and fines for harmful discharges. Patrick Dobyns (public works) said the city currently records free chlorine at sampling stations and will pursue stricter pretreatment requirements for industrial users.

Council reaction: Council members pressed about responsibility and cost. Staff said industrial users already pay sewer fees and that the proposed pretreatment ordinance will add enforcement tools. No formal council action was required at the meeting; staff said they will return with cost estimates and an ordinance for council consideration.

Ending: The council received the update and directed staff to continue negotiations with industrial users and to return with draft pretreatment ordinance language and estimates for basin rehabilitation.