The South San Luis Obispo County Sanitation District has upped the ante in its battle with the State Water Resources Control Board over a $1.1 million fine the district received for a sewer spill in 2010.

The sanitation district sought relief in San Luis Obispo County Superior Court on Nov. 24, when it filed for a writ of mandate from the court directing the State Water Resources Control Board to vacate the fine. The penalty was issued for a spill that got a nine on a scale of one to 10 measuring the potential harm for discharge, according to court documents.

The original incident, which happened in December 2010, lasted a total of 11 hours.

On Dec. 17, the sanitation district held a meeting to debate the possibility of following through with the litigation. As of press time, the agency declined to comment on the status of the pending litigation. The State Water Resources Control Board could not be reached for comment as of press time.

The district oversees the Oceano Community Service District, Arroyo Grande and Grover Beach, and its three-member board has one representative from each community. At the board’s Dec. 3 meeting, Arroyo Grande Mayor Jim Hill requested that the South San Luis Obispo Sanitation District initiated a forensic audit of the district to investigate the fine.

According to court documents, the district alleges that its influent pump station automatically shut down after floodwater entered an electrical conduit, short-circuiting the motor. This also shorted a power “shunt switch,” the agency alleges, which tripped a main circuit breaker switch supplying power to all four pumps inside the station.

The result was untreated sewage flowing into the treatment plant and then surging upstream. Staff struggled to open an emergency standby pump discharge valve due to an electrical failure, the district claims in the court filing.

The untreated sewage released from the treatment plant mixed with stormwater and travelled into the ocean, resulting in the regional water board issuing the fine on the grounds that it was a violation of U.S. Clean Water Act.

However, in the Nov. 24 court filing, the district claims that the state board’s order issuing of the $1.1 million fine held findings and conclusions that were “inappropriate and improper because they are inconsistent with the evidence presented in the case, inconsistent with the law, and otherwise inappropriate for various reasons” such as its alleged violation of the Porter-Cologne Water Quality Control Act.

A technical report issued by State Water Resources Control Board and Central Coast Regional Water Quality Board following an investigation of the event found that utility boxes near the wastewater treatment plant that housed the electrical system were not adequately protected from potential flooding. It was the migration of floodwater through unsealed conduits that shorted the shunt switch and pump motors, the report said.