RUMFORD – NewPage Corp. said this week that it’s complying with federal safety standards after its Rumford paper mill was cited for a chemical reaction last May that injured nine workers.

NewPage paid a $5,000 fine to the Occupational Safety and Health Administration for failing to segregate incompatible chemicals muriatic acid and sodium hypochlorite, a strong bleaching agent, inside a warehouse and beater room in the basement of the mill’s North End building.

A beater room is a preparation area where substances are mixed before going to paper machines. Incompatible chemicals are ones that, if accidentally mixed, could react and cause toxic vapor release or fire.

The misidentified acid was accidentally mixed with bleach in a holding tank on May 17, causing a heat reaction that released chlorine gas and hydrochloric acid vapors.

Seven men and two women suffered chemical inhalation or respiratory problems, but none were critically injured. Six were treated and released that night at Rumford Hospital while the other three were hospitalized overnight.

Additionally, two vendors, Hercules Inc. of Wilmington, Del., and PSC Industrial Outsourcing Inc. of Bangor, were cited and fined. However, the fine against PSC was rescinded as of Sept. 24, but Hercules, a specialty chemical company, paid a $4,500 fine, according to Hercules public affairs director John Riley.

“We were fined because one of our employees was involved in the mixing process,” Riley said Friday.

Hercules did not supply NewPage with the chemicals used in the accident, he said.

OSHA initially levied a total of $29,250 in fines on Aug. 29 against all three companies, of which NewPage was tagged with $17,500, Hercules with $6,750, and PSC $5,000.

According to the violations, all three companies were cited for failing to provide employees with a work place that was free of recognized hazards that could cause death or serious injuries, in that employees were exposed to the mixing or storing of incompatible chemicals.

OSHA contends that the accident would have been prevented had the acid-containing drums that were being stored with bleach drums been promptly removed to another storage area.

According to NewPage spokesman Tony Lyons, the mill’s response to additional violations and fines that OSHA rescinded following an informal settlement meeting on Sept. 17 included enhancing its alarm system to provide automatic messages telling evacuating employees how best to avoid problem areas, adding signs and reorganizing the warehouse.

Additionally, employees with numeric pagers will get text pagers, and employees and visitors will be required to carry escape respirators, something that was done in certain areas, but not in the area where the May 17 incident occurred.

“We’re working continuously to improve our emergency system throughout the mill,” Lyons said.