Utility cited over sewage plant leak

Pinal community ponds filled with partially treated water

Arizona environmental regulators have cited Johnson Utilities with four violations of state law as a result of last month’s sewage leak into a neighborhood’s ponds in Pinal County.

Residents of San Tan Heights said they were horrified to wake up on May 13 to the stench and sight of what seemed to them like raw sewage in the community pond at the entrance of the neighborhood.

After an initial investigation two days later, the Arizona Department of Environmental Quality found that there was “no evidence of raw sewage” in the ponds, which Johnson employees had been pumping for two days. The state said the ponds had sediment and “some solids,” but no foul odor.

State inspectors did not take water samples but said, “Our inspectors are trained to know what to look for as telltale signs of raw sewage,” said ADEQ’s water-quality compliance manager, Mindy Cross.

On Thursday, ADEQnotified Johnson of four alleged violations at its San Tan sewage-treatment

plant:

» Exceeding standards for maximum and average turbidity levels, a measure of the cloudiness of treated water and an indication of the thoroughness of treatment. » Unauthorized discharge of treated wastewater. » Failing to establish or follow a plan to keep a key part of the treatment plant running after a power outage.

ADEQ’s inspection report reconfirms what happened. Over the weekend of May 11, the treatment plant lost power. Turbidity levels rose above 20 times the standard, before 705,000 gallons of partially treated sewage was released into the ponds.

The plant did keep running when generators kicked in, but an operator on the weekend skeleton crew failed to manually restart the aerators. Those are needed to pump oxygen into the tanks where microbes digest sewage solids, so the treatment was incomplete.

The state did not issue fines. Thursday’s action is the first step in a process, not unlike a criminal investigation, in which ADEQ issued allegations. Johnson has 90 days to answer those charges, and then the state will decide how, or whether, to proceed.

The utility is taking steps to prevent a recurrence, plant manager Greg Brown said.

“We’ve changed controls to turn on the aerators automatically after a power outage,” he said, adding that he plans to install automatic alarms to notify offsite employees when power is cut.

Cross credited the company with responding quickly and responsibly by pumping the man-made lake and removing the possibility of health risks. By the time ADEQ inspectors arrived, three-quarters of a pond had been pumped and crews began disinfecting the rest with chlorine. Inspectors didn’t test the water because they regulate the treatment plant, not the pond, Cross said.

Neighbors remain unconvinced and insist they smelled and saw feces. With the ponds mostly drained, they began noticing more flies this week and feared mosquitoes will be next.

Pinal County Environmental Health Division officials have been at the site every day since the spill and are satisfied with the cleanup effort, county spokeswoman Heather Murphy said. Johnson crews have been adding treated water, skimming off the scum, and repeating the process.