Members of Local 542 of operation engineers are picketing on Schantz Road in Upper Macungie Township, stating that is unfair to union workers.
The employees, who asked to remain anonymous, said the company ruled out using union engineers to help build its 215,000-square-foot warehouse in the township.
Jim Reilly, president of Local 542, was not available for comment. Calls to Ocean Spray's headquarters in Bordentown, N.J., were not returned.
Township supervisors recently approved a plan to to 215,000 square feet from its original 315,000 square feet.
The cost of bulding the plant is $110 million and is expected to bring hundreds of jobs to the Lehigh Valley.