Two sewage spills caused by the Sept. 8 power outage totaled nearly 3.5 million gallons, roughly 75 percent more than what San Diego city officials told regulators and the public in the aftermath.
The figures could become financially significant for San Diego because pollution fines typically are based on the amount of sewage spilled. Penalties in this case may run into the millions of dollars, though it’s not clear that will happen given the unusual circumstances.
Ann Sasaki, assistant director for wastewater at the city’s Public Utilities Department, said Tuesday that the previous combined total of about 2 million gallons was based on field observations. She said the numbers were updated after employees reviewed records of flow metering devices to create a more accurate estimate.
The newest figures were released in a report for the city’s natural resources committee, which plans to address related issues at 2 p.m. Wednesday at City Hall.
The report said utilities officials are studying options for backup power that could minimize the chances of repeat problems but it noted that the city successfully treated more than 97 percent of the sewage during the regional power failure.
“The Department’s emergency preparedness and response plans are consistent with industry standards and structured to cover expected emergency situations,” said the report. “The unprecedented power outage was beyond anyone’s expectations and/or planning scenarios.”
[Read the full report]
When the power went out, two city sewage pump stations failed because they each relied on electrical feeds from two separate San Diego Gas & Electric substations and don’t have onsite generators. One facility was on Roselle Street near Los Penasquitos Lagoon and the other was near Interstate 5 and state Route 54 in the South Bay.
While the blackout was still affecting parts of the region, San Diego County’s Department of Environmental Health reported the Los Penasquitos spill at 3.2 million gallons but quickly revised the estimate to 1.9 million gallons, the number that the city reported to the San Diego Regional Water Quality Control Board. The other spill has been consistently characterized as 120,000 gallons until the latest report for the City Council.
The updated figures show 2.6 million gallons spilled in Los Penasquitos Creek and 870,000 gallons were released into the Sweetwater River and ultimately to San Diego Bay.
Beaches in both areas were closed for days afterwards until pollution decreased below levels of concern, but the incidents raised alarms for some residents.
At Wednesday’s meeting, lawyers from San Diego Coastkeeper will push for upgrades.
“Now is the time for the city to rectify its mistakes handling this sewage crisis and take the proper steps to ensure it won’t happen again,” said Gabriel Solmer, advocacy director for the nonprofit group. “Our human and environmental health and economy depend on the city taking discrete and proactive action.”
Jeremy Haas, a senior scientist with the regional board’s compliance unit, said Tuesday that he had not seen the city’s latest numbers but that initial spill figures commonly change.
“Spill volume estimates often get revised from initial emergency reports after collections agency staff have time to review logs from flow meters at pump stations or treatment plants,” he said. “Sometimes estimates go up, other times down.”
Sasaki said the city is investigating the use of backup power generators at the failed pump stations but it could be another month before she can provide general cost estimates and longer before detailed figures are available.
To mitigate the environmental damage of the pollution, San Diego reported pumping more than 14 million gallons of from Los Penasquitos Creek. The city also is working with the regional board to conduct what’s likely to be months of biological monitoring at the site.
When the City Council committee takes up the topic Wednesday, it will also look at power failures at city water pump stations that lead to precautionary boil water orders for thousands of residents in 13 neighborhoods. The staff report said the power outage affected about 10 percent of the city’s water customers, the result of not having emergency generators at each of the pump stations.
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