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Davis, California

Tuesday, June 11, 2024

UC Davis, Woodland fined for wastewater treatment violations

UC Davis and Woodland received fines earlier this month from the California Regional Water Control Board (CRWCB) for wastewater treatment violations.

The university paid a $9,000 fine for exceeding the amount of coliform allowed in sewage.

Coliform bacteria are indicators for the sanitary quality of water. They are naturally found in aquatic environments, soil and vegetation, as well as fecal matter of warm-blooded mammals. In large amounts, coliform bacteria can cause illnesses, such as diarrhea.

Between Aug. 11 to 19, the total coliform measured at the treatment facility was double the amount allowed.

“We don’t believe it’s our system’s fault,” said Mark Fan, supervisor and senior engineer for the university treatment facility.

In the past, treated wastewater samples were tested from one of two water channels within the facility. Two years ago, the facility began to take samples from the reservoir past these channels to test the levels for both channels.

“The numbers were fine until August,” Fan said. “Suddenly, out of nowhere, we got a high number [of total coliform].”

According to Fan, the problem is inherent in ultraviolet (UV) disinfection.

“UV disinfection alters DNA sequence [of bacteria],” Fan said. “It doesn’t kill completely, and it can cause a re-growth problem.”

After the wastewater is treated with UV, bacteria that survive can reproduce. Bacterial re-growth is a widely known problem for UV disinfection systems, which are used by many wastewater treatment facilities, including the Water Pollution Control Facility (WPCF) in Woodland.

Wastewater from the campus reservoir flows to Putah Creek and the Arboretum Waterway.

The CRWCB, which issues the permit for the treatment facility, recognized that the problem lies in the UV disinfection technology, Fan said. The facility is allowed to test treated wastewater from the two channels once again.

The facility has not been found in violation since they changed the testing location.

As for the total coliform level in the reservoir, the facility is currently not taking measures to address the problem.

“More research needs to be done on the UV disinfection system,” Fan said.

Total coliform violations also occurred at the WPCF in Woodland. The facility reported four of these violations from August 2008 to March 2009. However, it was not fined for these violations

“The treatment system is designed to remove coliform organisms,” said Mark Severeid, lab supervisor at the Woodland treatment facility. “It doesn’t always work 100 percent. Sometimes there are glitches in the process.”

The facility also reported three violations for having more selenium than is permitted under their National Pollution Discharge Elimination System (NPDES) permit. The facility was fined $3,000.

Selenium is a naturally occurring element in groundwater. It is a nonmetal that, in large doses, can be toxic to plants and animals. Woodland and Davis use groundwater wells as a source for drinking water.

The NPDES permit allows for an effluent limit of 3.2 parts per billion (ppb) of selenium in wastewater.

From June to September last year, the facility violated the selenium limit three times.

“Only one [of these violations] was a serious violation,” Severeid said.

In the first of the violations, which occurred in June, there was 6.3 ppb of selenium found in the treated water, twice the limit allowed. The other two violations were within 0.2 to 0.4 ppb of the limit.

“We don’t have any control of the amount [of selenium] in the water,” Severeid said. “There’s no way to remove it. We’re at the mercy of what goes on in nature.”

SARAHNI PECSON can be reached at city@theaggie.org


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