Culligan International Co. is closing its longtime manufacturing operation in suburban Chicago. The company is selling the 40-acre property, which also includes its corporate headquarters, and the 300 workers at the company's head office will be shifted to another location in the Chicago area. Some 200 other employees who do manufacturing at the site will be laid off by year-end. Culligan president Mark Seals says that the layoffs are not a sign of financial stress, but a shift away from in-house manufacturing of items such as filters, valves, tanks and pumps.