A Texas oil refinery featured in a joint Center for Public Integrity-ABC News investigation into the dangers of hydrofluoric acid has agreed to pay $303,000 to settle pollution violations stemming from a 2009 accident.

In an order issued Wednesday, the Texas Commission on Environmental Quality found that some 46,000 pounds of the acid, known as HF, were released over nine days in July 2009 from the Citgo East refinery in Corpus Christi. The finding exceeds previous estimates by federal investigators.

The U.S. Chemical Safety Board has estimated that at least 4,000 pounds of HF went beyond plant boundaries.

Citgo maintains that only 30 pounds escaped.

The order calls the accident an “avoidable emissions event,” and says Citgo committed six violations of state air and water pollution rules.

The commission charged, among other things, that Citgo filed an incomplete report on the incident, leaving out “emission estimates of products of combustion” resulting from a fire that persisted for two days.

It also found that Citgo “failed to prevent the unauthorized discharge of wastewater,” a product of its efforts to disperse the HF cloud with a “water curtain.” The Chemical Safety Board found those efforts to be lacking.

A Citgo spokesman did not respond to requests for comment Thursday.  Since the incident, Citgo has replaced some equipment, modified some operating procedures, and stepped up training and inspections, the order states.

The joint investigation by the Center and ABC found that 50 U.S. refineries that continue to use HF despite the acid’s extreme toxicity and the availability of a safer alternative. Worst-case scenarios filed by companies with the federal government show that at least 16 million Americans live in the potential path of the chemical.