And the agency found that the commission did not conduct annual testing of the respirators that its employees at the plant are supposed to wear.

The penalty amounts were not big. The state issued close to $20,000 in fines against the SFPUC. But state officials deemed two of the violations serious.

The SFPUC is appealing all of them.

"The safety order was not violated, the classification is incorrect, the abatement requirements are unreasonable, (and) the proposed penalty is unreasonable," SFPUC spokesman Will Reisman wrote in an email.

Representatives for the two agencies plan to meet on March 4 to see if a settlement can be reached in the case.

Still, the Cal/OSHA citations prompted the SFPUC to make a series of safety improvements at the plant, according to Reisman.

The agency has developed new training material for the safety devices worn to detect gases inside wastewater plants. It has made a series of repairs to an exhaust system inside its gravity belt thickener, a facility in the sewage plant that filters out water.

The Oceanside plant serves San Francisco's Richmond and Sunset neighborhoods as well as the Lake Merced urban watershed. On average, 16 million gallons of wastewater travel through the plant per day during dry weather. City officials said that on rainy days it deals with an average of 65 million gallons a day of wastewater.

The plant is one of three wastewater facilities run by the commission: The other two are the Southeast Treatment Plant, which treats 80 percent of the city's flow, and the North Point Wet Weather Facility, which operates when the Southeast plant approaches capacity.

In the last five years, four workers employed at the plants were injured in incidents that resulted in emergency room visits, according to Reisman. Three of those incidents took place at the Southeast facility and one took place at North Point.

The injury at the North Point facility led to a Cal/OSHA fine.

More than two dozen engineers operate the Oceanside plant. Electricians, maintenance, laboratory technicians and control room staff are also employed there.