"The City has still not received a report from Valero and has instead had to rely on media reports from KQED and others," Young said in an email. "Significant questions remain unanswered."
Valero rejects the notion that it has not been forthcoming.
"We find Mayor Patterson's statements puzzling," said company spokeswoman Lillian Riojas in an email. "We've been very up front and open with the city as well as other regulators about what we know."
The May 5 outage led to shelter-in-place and evacuation orders throughout the city, and at least a dozen people sought medical treatment for breathing difficulties.
The refinery released more than 80,00 pounds of sulfur dioxide on the day of the outage and in the weeks afterward.
Two investigations, one by California's Division of Occupational Safety and Health (Cal/OSHA) and another by the Solano County Environmental Health Division, cleared Valero of wrongdoing. Another probe, by the Bay Area Air Quality Management District, is yet to be completed.
City officials became aware of the county's investigative findings only after KQED obtained them and asked for a comment, according to Patterson.
The mayor says an industrial safety ordinance would get the city that kind of information directly.
Patterson and a coalition of local environmental and community groups want the city to move forward on an industrial safety ordinance. A town hall meeting to educate the public on the proposal is scheduled for Tuesday night (Nov. 14).
The ordinance would allow Benicia to audit Valero's safety plans and take part in inspections of its refinery.
Valero is lobbying against the proposal.
"A local ISO would not have prevented this power outage," Don Wilson, the refinery's vice president and general manager, wrote the City Council in a letter in June. "A local ISO will be costly and duplicative of existing state and local programs."
The company has blamed Pacific Gas and Electric and has sued the San Francisco-based utility, seeking $75 million in damages and lost revenue.
"Let's remember, PG&E abruptly shut off all power to the refinery without any notice," said Riojas, the Valero spokeswoman.
PG&E hired a third party to investigate the outage. That report has been submitted to the California Public Utilities Commission.
In October California adopted new statewide refinery oversight regulations. Refineries are now required to adopt safety designs and systems, conduct periodic workplace safety culture assessments and investigate causes of serious refinery malfunctions.
Councilman Young, Councilman Tom Campbell and Terry Schmidtbauer, assistant director of Solano County's Department of Resource Management, which conducts audits on the refinery, say they're unclear on whether a city ordinance would add anything that the state's new rules don't already cover.
"An ISO may be a great idea but I don't want it to somehow get in the road of other already existing state and federal regulations," said Campbell in an email.
"My only hesitation revolves around my desire not to have an ordinance that overlaps with recent Cal-OSHA requirements," said Young.
Mayor Patterson says a local ordinance would go further: It would require Valero to report information directly to the city about a refinery malfunction and the company's proposed actions to prevent a similar incident.
"The ISO would give us a seat at the table," Patterson said.
Tuesday's town hall meeting takes place at the Benicia Public Library at 7 p.m.
