NORWELL, MASSACHUSETTS – Clean Harbors, Inc. (“Clean Harbors”) (NYSE: CLH), the leading provider of environmental, energy and industrial services throughout North America, today announced it has signed a definitive agreement to acquire Safety-Kleen, Inc. (“Safety-Kleen”), the largest re-refiner and recycler of used oil in North America and a leading provider of parts cleaning and environmental services. Under the terms of the agreement, Clean Harbors will purchase Safety-Kleen in an all-cash transaction valued at $1.25 billion. The acquisition is subject to approval by U.S. and Canadian regulators, as well as other customary closing conditions. The transaction is expected to be completed by year-end.