The state of Texas is suing BP for a huge release of toxic chemicals—including benzene, a carcinogen—that went on for 40 days at the company’s Texas City refinery last spring. The lawsuit could result in civil penalties reaching into the millions.

The release, as we have reported, started April 6, just two weeks before the Deepwater Horizon explosion, when a key piece of equipment failed and, rather than stopping production to fix it, BP attempted repairs while operations were continuing — resulting in a release of 538,000 pounds of toxic chemicals.

“Proper maintenance could have prevented the event,” reads the state’s lawsuit. “BP made very little attempt to minimize the emission of air contaminants caused by its actions, once again prioritizing profits over environmental compliance.” (Read the full lawsuit in our document viewer.)

The lawsuit calls for civil penalties to be assessed for each day of the release. Pursuant to the Texas Water Code, that penalty would be between $50 and $25,000 for each pollutant released per day. (The lawsuit lists six contaminants, and the toxic release went on for 40 days. By our rough calculation, the penalties could be as much as $6 million if the judge or jury decides to get tough on the company. Even so, when compared with the $2.8 million in profit that BP averages in an hour, whatever BP shells out won't hurt it too much.)

This isn’t the only lawsuit BP faces over safety issues at Texas City. The state sued BP just last year for “poor operating and maintenance practices” resulting in 72 violations—7 of which involved the same unit of equipment as the emission in this latest suit.

Texas City refinery workers and nearby residents have also filed lawsuits, alleging the 40-day release harmed their health.

BP spokesman Scott Dean, when asked about the worker lawsuits, told ProPublica last week that "the community air-monitoring network did not show elevated readings" during the equipment failure in April and May. Regarding the new lawsuit filed by the state of Texas, he told the Houston Chronicle that the company would cooperate with the Attorney General's Office and the Texas Commission on Environmental Quality to resolve the concerns.

Follow @mariancw