A major Walmart subcontractor has agreed to a $21 million settlement in a class action brought by warehouse workers who said they were forced to work as long as 16 hours a day, sometimes seven days a week and in sweltering conditions, without overtime pay.

As many as 1,600 workers at Walmart’s three warehouses in Mira Loma, Calif., could share in the settlement fund to be set up by Schneider Logistics, Inc., as agreed to in a preliminary settlement filed May 13 in U.S. District Court for the Central District of California. Schneider Logistics and its subsidiaries deny any wrongdoing or liability.