City of Lawton responds to notice of violation from Department of Environmental Quality

The City of Lawton has formally responded to a Notice of Violation centered on its wastewater treatment plant.

The written response comes in reaction to an April 18 notice from the Oklahoma Department of Environmental Quality (ODEQ) that the Lawton plant didn’t meet treatment standards on multiple occasions, exceeding permitted levels for ammonia, five-day carbonaceous biochemical oxygen demand, total suspended solids and dissolved oxygen levels in its effluent (treated water released from the plant to an outside water source). ODEQ gave the City of Lawton 30 days to file a response.

The May 13 letter of response explains the problems stem from “unexpected equipment failures” at the plant and states the city is taking steps to resolve those issues, including some work that has been planned or underway for three years to address previous violations cited by ODEQ. The letter of response also asks for an in-person meeting with ODEQ officials to discussion actions already taken and the path forward, as well as to react to Lawton’s request for eight additional months to complete the upgrades included in the $85 million Phase I upgrades. Approval of that extension would take the Phase I completion date of Phase I to August 2025, rather than requiring completion by December 2024.

In their letter, city officials said the most recent failures to meet water treatment standards stem from three issues related to the plant’s ability to remove contaminants in the wastewater it receives: an aeration basin blower failure; the effect of a rescheduled rehabilitation of a trickling filter; and a high biochemical oxygen demand loading by an industrial user.

The aeration basin blower failure came as the plant tried to cope with failure of three obsolete blowers that “are no longer reliably serviced by the manufacturer.” Plant staff said when a blower failed, the aeration basins turned septic, “thus compromising the performance of the activated sludge process. The city already is addressing the issue: the City Council voted Tuesday to amend Phase I to include four new blowers and directed city staff to order the equipment. Until that $1.04 million worth of equipment arrives in mid-2025, temporary blowers will be used.

A scheduled rehabilitation of one of four trickling filters (also part of Phase I work) is part of a process that will take each filer off line for cleaning and repair. While one filter was off line, the remaining three were unable to keep pace to reduce biochemical oxygen demand, a problem that compounded the blower failure in the aeration basin, city officials said.

The plant also is experiencing a high biochemical oxygen demand influent (water coming into the plant) due to problems one major industrial user is having at its pre-treatment plant. That has meant the concentration coming into Lawton’s wastewater plant is four times higher than the permitted concentration typically received. That industrial user has been issued a notice of violation, city officials said.

City officials said they were already taking action to address the non-compliant treatment issues, using temporary solutions while work is being completed under the plant’s three-phase planned upgrades. Lawton is in the middle of Phase I and has begun designs for Phase II, which is estimated at $85 million to $100 million. Phase II is expected to include a new ultraviolet disinfectant facility and a new solids handing facility, as well as other work.