Human error, including a lack of preventive maintenance, caused a massive sewage spill at a South County wastewater treatment plant in December 2010, according to state Regional Water Control Board prosecutors.
They maintain that the South San Luis Obispo County Sanitation District should pay a proposed $1.3 million penalty.
But attorneys for the sanitation district argue the treatment facility should not have to pay the penalty because the spill was unintentional and caused by a series of uncontrollable events that district staff could not have foreseen.
Two briefs filed over the past week show stark differences in what was believed to have caused the spill, in which thousands of gallons of sewage overflowed in the plant and from manholes in a neighborhood near the Oceano County Airport.
The two sides will meet at a Sept. 7 hearing to argue whether the district should be fined more than $1.3 million for the spill. The hearing follows months of negotiations between state water board and district staff, who failed to agree on the volume of the spill, the fine and other issues.
State prosecutors said the spill was the largest public health exposure to raw sewage in private homes since the state board started collecting the information in January 2007. They said raw sewage backed up in 11 Oceano homes in toilets or bathtubs, and residents reported becoming sick with the flu for days following the spill.
The wastewater treatment facility, constructed in 1965, serves about 38,000 residents in Arroyo Grande, Grover Beach and Oceano. It is overseen by a three-member board; John Wallace of San Luis Obispo-based Wallace Group has served as the district’s administrator since 1986.
Rain, then a short
Heavy rain preceded the Dec. 19, 2010, spill, when floodwater flowed into the wastewater treatment plant and caused an electrical short that shut down four influent pumps about 10:30 a.m.
A discharge valve was also left closed and could not be opened fully, hampering efforts to move wastewater through the plant.
The district argues that three events — the storm, the electrical failure and the inadvertently closed valve — were unintentional and beyond the district’s control.
But state water board prosecutors allege the spill was caused by human effort — specifically that the district could have prevented it if a project to install waterproof electrical wiring had been completed when originally proposed in 2004.
State officials also contend that the discharge valve was closed not by accident, but because of incorrect operating procedures.
The sanitation district contracted with San Luis Obispo-based Thoma Electric Inc. to study the treatment plant circuit breakers. In a declaration, company owner Bill Thoma states that the wiring work would not have solved the problem that led to the sewage spill.
“For the prosecution team to jump to the conclusion that replacing of the wiring and conductors would have ‘solved’ the problem and avoided the December 19, 2010, electrical issues is not logical or valid in my professional opinion and is certainly not negligence,” he said, according to the declaration.
The briefs filed by the sanitation district and the state water board differ on a number of other issues: the amount of the spill, whether the proposed fine is consistent with penalties assessed in sewage spills elsewhere in the state and whether the sanitation district properly reported sewage that spilled from pipes it does not own.
The district’s brief also argues that paying the fine would deplete the district’s fund balances and that efforts to pass some of the cost to district customers through a rate increase are not always successful.
“Bringing severe economic hardship on this small community that has no other options for wastewater treatment will not improve, and may adversely impact, water quality,” the district’s brief states.
The district argues that its track record — district officials say the plant has not had a spill in 25 years — should also be taken into account.
The Sept. 7 civil hearing will start at 8:30 a.m. at the Central Coast Regional Water Quality Control Board office, 895 Aerovista Place, Suite 101, in San Luis Obispo.