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State puts Modesto on notice over waste-water discharge

Hole found and sewer trunk fix underway

City of Modesto Utilities Director Larry Parlin said the city believes it has found the hole in a main sewer trunk that was letting water from the swollen Tuolumne River into the sewer system and causing it to reach its storage capacity. Crews are
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City of Modesto Utilities Director Larry Parlin said the city believes it has found the hole in a main sewer trunk that was letting water from the swollen Tuolumne River into the sewer system and causing it to reach its storage capacity. Crews are

A state agency has issued a notice of violation to Modesto for discharging roughly 755 million gallons of partially treated waste water in to the San Joaquin River in March because the city’s sewer system had been overwhelmed by storms and rising river water.

The Central Valley Regional Water Quality Control Board’s April 13 notice of violation asks Modesto to provide the board with documents, including sewer system inspection and maintenance records for the past two years and paperwork on the steps the city has taken and will take to fix the problem that lead to the discharge.

The notice says Modesto could face fines of as much as $10,000 per day for each day waste water was discharged and $10 for each gallon discharged. But Andrew Altevogt — a water board assistant executive officer — said it is too soon to consider fines because his agency has not yet received and reviewed the city’s records, which are due May 9 and June 1.

Altevogt said about 50 waste-water treatment plants within his water board’s jurisdiction have violated their discharge permits because of heavy rain and flooding from the rainy season. Notices of violations have been sent to other cities and treatment plant operators.

“This is all related to the rain,” he said. “This is not a normal year. The purpose of the letter (notice of violation) is to gather as much information as we can. We believe in most cases this was not the result of negligence but of circumstances that added up.”

Modesto’s circumstances are that in February sewer flows into its Sutter Avenue waste-water treatment plant on the Tuolumne River doubled. Several days later, the city discovered the culprit: a huge hole in a major sewer line along the Tuolumne. The line was submerged by the swollen river.

The city patched the hole and is in the process of making a permanent repair, but Modesto still had more waste water than it could store. The water first is treated at the Sutter plant and then sent by pipeline to the city’s Jennings Road treatment plant along the San Joaquin River, where the water receives additional treatment.

The city treats some of the water to a high-enough standard that it can be safely and legally released in to the San Joaquin. The rest is stored at the Jennings plant and is used to irrigate nearby farmland planted with animal feed during the growing season.

But the Jennings plant had reached its capacity, and Modesto released the partially treated waste water in to the San Joaquin from March 2 to March 31 in violation of its discharge permit. Utilities Director Larry Parlin has said the water had 85 percent to 90 percent of its pollutants removed. But it was not disinfected so it had bacteria in it.

Parlin said Monday that water quality tests the city conducted upriver and downriver of the Jennings facility show the waste water did not make a significant difference in the water’s quality because of the river’s high flows and the other contaminants in the river from the flooding and storms.

Parlin agreed it was to soon to say whether Modesto will be fined, but he said the city could face what are called mandatory minimum penalties of $3,000 for each day waste water was discharged, or roughly $90,000. “Even though this (the sewer line failure) was an act of God,” he said, “we did not meet our permit requirements.”

He said he believes Modesto’s sewer system will be fine if the rivers rise again because of melting Sierra snow. He is more concerned when the rivers recede this summer because the Tuolumne’s riverbanks are so saturated they could shift. That could damage the sewer line and what is called the cannery segregation line, which is used in the summer by food processors.

“That’s what we are losing sleep over now,” Parlin said. But he added Modesto has a plan to stabilize the riverbank if necessary.

The permanent solution is a project that will replace the sewer line with a new one that is not in the flood plain. The project includes a way to divert the cannery segregation line flow if needed. The project is in the design stage and could be completed in 2023.

Kevin Valine: 209-578-2316

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