ST. PETERSBURG — The city wants the state to change its environmental rules to make legal an illegal maneuver it has relied on a lot lately: flushing wastewater down into the aquifer.

The idea was proposed by a consulting firm the city is paying $4 million to create a master plan to guide revamping the sewage system and other water utilities.

Jacobs Engineering project manager Leisha Pica told the City Council on Jan. 4 that this could help improve St. Petersburg's image after its mishandling of 1 billion gallons of sewage spilled during the 2015-16 sewage crisis.

Legalizing that tactic, she said, would give the city "operational flexibility."

"It seems to be a better perception of the city's management when you're doing something that's not a violation," Pica said at the council meeting, using air quotes when she said "violation."

"So that's what we're going for ... It's a perception of an approach."

The Tampa Bay Times asked the Florida Department of Environmental Protection whether it would consider such a request.

The answer was an emphatic no.

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Injecting partly-treated sewage or "reject water" deep underground had been part of St. Petersburg's approach for nearly half a century until the Environmental Protection Agency banned the practice in 2005, fearing that sewage pumped into the aquifer could seep into the drinking water supply.

During emergencies in recent years, the city opted to flush sewage underground rather than have it spill into local waterways or streets. The proposal seeks to make that policy legal.

City officials said that they would still alert the state whenever it flushed dirty wastewater into the aquifer. The change, they said, would be aimed at protecting plant operators from potentially losing their licenses.

And flushing sewage hundreds of feet underground into an oxygen-free environment poses far less risks than the alternatives, said Public Works spokesman Bill Logan.

"It would clean itself," he said.

City Council vice chairman Steve Kornell questioned the city's plan, saying it doesn't make sense why the city would want legalize what is illegal.

"I don't see why environmental regulations should change because you're violating them," Kornell said.

Using injection wells to send sewage below ground was a hot-button issue during the sewage crisis. A Florida Fish and Wildlife Conservation Commission investigation found that the city flushed up to 800 million gallons of sewage underground during storms, a violation of state law which requires that only reclaimed-quality wastewater (the same thing sprinkled on lawns and parks) be sent down the wells. The other 200 million gallons ended up in Tampa Bay and some neighborhoods.

Leaky pipes saturated with groundwater lead to heavy flows during storms, overwhelming plants. Operators, instead of allowing tanks to overflow or sending the excess sewage to Tampa Bay, chose to flush sewage into the aquifer down the wells.

Part of Mayor Rick Kriseman's plan to fix the sewage system involved digging new wells to increase the capacity of the plants to dispose of treated wastewater, allowing the city to treat more sewage during emergencies.

But after Hurricane Irma in September, the city was forced to flush millions of gallons of sewage underground. After that storm, the Northeast sewage plant injected more than 15 million gallons of sewage into its wells, a fact not fully reported by the city until Kornell voiced concerns on social media.

City sewer officials later said they should have been more forthcoming.

The proposed rule change will not reduce transparency, said Water Resources director John Palenchar. He said public reporting requirements would stay the same.

All that the city wants to do is gather data, he said, and prepare documentation to present to DEP to "have a discussion."

The city believes the better option for public health and the environment is to flush the sewage underground if necessary, Palenchar said. And he said plant operators shouldn't be forced to put their careers at risk.

"The intent is not to expose operators to losing their license for choosing between two bad choices," he said, explaining the city's rationale.

The proposal is part of a contract with Jacobs Engineering to craft a integrated plan to improve its sewers, reclaimed water, stormwater and potable water systems. The DEP required the plan as part of its $326 million consent order for the city to repair its aging sewer system.

The original proposal contained in a 63-page scope of services agreement with Jacobs contained this language: "The consultant will prepare justification for the city to present to FDEP to permit disposal of reject water via the city's existing deep well injection wells as an appropriate emergency practice provided certain protocols are in place to make this a last resort to avoid significant sewer overflows."

After Kornell's objections, the council agreed to modify that language to state that Jacobs would prepare an analysis for council members to consider.

When asked if changing the law to allow sewage to be flushed underground without violating the city's wastewater permit could make it easier to comply with the consent decree, Palenchar declined to offer an opinion, saying only:

"It would not count against us as a violation."

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Meanwhile, DEP is deciding what additional penalties the city will have to pay in a new "short-order" consent decree being negotiated with the city over the post-Irma flushings.

The consultant's plan for St. Petersburg won't be finished until December 2019. But DEP officials already know their answer to the city's request to legalize an illegal practice: No.

Flushing anything less than fully treated wastewater down injection wells will always run afoul of state law, said spokeswoman Shannon Herbon.

"That's never going to change," she said. "It will always be a violation."

Contact Charlie Frago at cfrago@tampabay.com or (727)893-8459. Follow@CharlieFrago.