Suffolk Construction, NorthStar Contracting fined nearly $700,000 following May incident at South Boston site

A police car patrolled the site where three workers were injured in South Boston on May 5.Erin Clark/Globe Staff

Suffolk Construction Co. and NorthStar Contracting are facing a combined total of nearly $700,000 in fines for federal workplace safety violations following a May 5 incident in which a man lost his legs and two other workers were injured after a mezzanine collapsed at a South Boston work site, officials said Thursday.

The Occupational Safety and Health Administration found that Suffolk, the region’s largest construction company, and NorthStar “failed to ensure adequate demolition and asbestos safeguards for their employees” at the former Boston Edison plant, according to an OSHA statement.

NorthStar, which is headquartered in New York and has a local office in Everett, according to its website, did not respond to a request for comment. Suffolk, in a statement, said it was “disappointed” and disagrees with the preliminary findings.

“We will continue to work closely with the demolition contractor NorthStar and all parties involved in this project to maintain the highest level of safety on the jobsite,” the company said. “As always, safety is our number one priority and we are committed to working with stakeholders throughout the industry to improve construction safety and ensure all workers return home safely at the end of the work day.”

James Mulligan, an area director for OSHA based in Braintree, said the companies had “exposed employees to the immediate hazard of structural collapse and the potential long-term consequences of asbestos exposure.”

“These hazards are preventable and employers can control and eliminate them,” Mulligan said in the statement. “Had they ensured proper planning — including engineering surveys and frequent and regular jobsite inspections, effective safety procedures, personal protective equipment and employee training — was in place, this incident and the violations that followed might have been avoided.”

OSHA proposed $292,116 in fines for Suffolk Construction and cited the company for two willful and three serious violations of workplace safety standards, according to the statement.

The agency found that Suffolk did not have a plan in place to prevent the mezzanine’s collapse and had not conspicuously posted the weight limit for the mezzanine, where asbestos and other debris was being stored, the statement said. Officials also said Suffolk had failed to properly inspect work inside the asbestos containment area and to ensure employees were wearing respirators properly.

OSHA proposed $399,864 in penalties for NorthStar and cited the company for three willful violations, four serious violations, and one other-than-serious violation of workplace safety standards, the statement said.

NorthStar had not conducted an engineering survey on the mezzanine to determine its safety, nor had the firm conspicuously posted the safe weight limit for the mezzanine, according to the statement. The company hadn’t adequately trained employees about hazards or ensured that employees were wearing respirators properly, and it hadn’t designated a competent worker to perform or oversee duties in the asbestos containment area, officials said.

OSHA said NorthStar officials had also failed to remove asbestos waste at the end of each shift and to provide its OSHA logs to investigators within four business hours, as required by federal regulation.

This story was updated to reflect a statement from Suffolk Friday morning.