Nevada City Wastewater Treatment Plant faces continued violations amid upgrades |

Nevada City Wastewater Treatment Plant faces continued violations amid upgrades

After facing 132 violations in the last five years, officials now believe the Nevada City Wastewater Treatment Plant is on the path to regulatory compliance.

In March, the plant made a deal with the state water board to make $177,973 worth of upgrades instead of facing $147,000 in fines from more than 50 violations between May 2018 and May 2019.

The mandated upgrades — which included installing automatic cleaning mechanisms to minimize algae buildup; repairing leaking pipes; improving its equalization system to deal with periods of high flow; and hiring a consultant to review plant operations — are about 80% complete, according to Nevada City Engineer Bryan McAlister.

“We saw almost immediate results and haven’t had any significant violation in about a year,” McAlister said, adding about $120,000 has been spent on the plant this year.

However, since the deal was made, the plant has had six serious violations and three chronic violations stemming from effluent emissions above its permitted standards, and an additional violation for not meeting reporting requirements.

All of the effluent violations were for exceeding the limitations for dichlorobromomethane (DCBM) and total coliform, the same substances that led to the original fines.

While total coliform is not harmful to humans, it is commonly used to determine the possibility of other pathogens in drinking water and the adequacy of water treatment. DCBM is a by-product of chlorinated water that is “reasonably anticipated to be a human carcinogen,” according to the National Cancer Institute.

The plant has faced similar violations in the past, agreeing to a compliance agreement in June 2018 instead of paying a $54,000 fine resulting from 18 violations between January 2016 and March 2018.

For that compliance agreement the plant repaired its sand filtration system and improved pump and plumbing repairs for about $68,000.


McAlister said the continued violations are partly a product of the plant’s operations, which uses chlorine instead of ultraviolet light like some surrounding treatment plants. It’s still a challenge for the plant to calibrate the appropriate mixture of chemicals and optimize the timing of cell residence, which helps break down waste.

“There are some violations that are pretty tough for us to avoid,” he said. “The DCBM are created when we use chlorine, then if we don’t use enough chlorine, then we get total coliform hits. So it’s a real fine balance.”

In its latest two monitoring reports, the Central Valley Regional Water Quality Control Board found violations at the Nevada City plant that required mandatory minimum penalties, with fines to be assessed at a later date.

According to McAlister, the board has agree to hold off on penalties for DCBMs while it determines whether it would be appropriate to increase the maximum allowable limit in water discharged into Deer Creek.

“They realized some of the dilution rations into the creek are inaccurate in our current permit,” he said. “I think that’ll make a really big difference for us.”

The city also updated its sewer ordinance in order to reduce the effects of commercial and industrial discharge into the system from restaurants, breweries, laundry facilities and other dischargers. McAlister said some fluctuations of sewage intake from industrial dischargers were also a factor that led to violations.

The plant must complete all required upgrades by March 31.

To contact Staff Writer John Orona, email or call 530-477-4229.

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