Federal officials have reached an agreement with operators of one of the nation’s largest discount retail chains over safety issues at their stores.

U.S. Department of Labor’s Occupational Safety and Health Administration said the agreement requires Dollar Tree and Family Dollar to conduct a nationwide assessment of violations OSHA has repeatedly cited at multiple stores. The agreement requires the companies to make immediate corrections on things such as blocked exits, issues with access to fire extinguishers and electrical panels and improper storage of materials or face fines up to $100,000 per day of violation, up to $500,000.

The companies have also agreed to pay $1.35 million in penalties to settle similar alleged violations.

“This agreement focuses on improving working conditions at thousands of stores nationwide,” said Assistant Secretary for Occupational Safety and Health Doug Parker. “Dollar Tree and Family Dollar have agreed to significant investments to more effectively identify and correct the root causes of the hazards most commonly found during OSHA inspections, including blocked exits and unstable stacking of materials.”

Larger “operational” changes must be made over the next two years, OSHA said, including the development of an audit program, hiring additional safety personnel and creating a new employee training program. Dollar Tree has also agreed to establish a 24-hour hotline to receive safety complaints and tracking to ensure those complaints are addressed.

According to Parker, OSHA has issued 403 violations at Dollar Tree and Family Dollar stores since 2017, resulting in more than $13.1 million in fines to date. The company made improvements in worker safety following a 2015 settlement that expired in 2018 but continued violations show more work need to be done, the AP reported.

Virginia-based Dollar Tree operates more than 16,000 Dollar Tree and Family Dollar stores in 48 states. The company employs more than 193,000 people.