Houston-based R360 specializes in nonhazardous oilfield waste treatment, recovery and disposal services. The company generates about $300 million in annual sales operating from 26 facilities spread across six states, including a presence in the oil-rich Permian, Bakken and Eagle Ford Basins.

West Connections, also of Houston, called the deal a "natural extension" of its existing disposal offerings. The company, which provides solid waste collection and disposal to more than two million residential and commercial customers in 30 states, said it expects services like what R360 offers to grow faster than its core municipal waste business.

"Through acquisitions and new facility development, R360 has created leading positions in key basins, providing closed loop oilfield waste services within an increasingly stringent regulatory environment," Waste Connections chairman and CEO Ronald J. Mittelstaedt said in a statement. "While a tepid economy has impacted [municipal solid waste] volumes, increased drilling activity in unconventional areas is fueling impressive organic growth within the E&P waste sector."

Founded in 1997, Waste Connections has long been an active consolidator. The company completed more than 139 deals in its first five years in business but has slowed down of late, in 2011 acquiring Hudson Valley Waste Holding Inc. from Clairvest Equity Partners III LP for $300 million and Alaska Waste Inc. for an undisclosed sum.

Waste Connection said it expects the deal to add about 4% to its consolidated Ebitda, and contribute to free cash flow margins.

R360 was founded in 2010 when investment firms Paine & Partners LLC and Tinicum Capital Partners LP acquired and merged U.S. Liquids of Louisiana, Controlled Recovery Inc., Calpet, R&G and J.Scott. The investor group acquired USLL from Three Cities Research Inc. and the Calpet group from its family owners.

R360 CEO Troy Thacker, a former partner at Paine, in a statement said that the sale to Waste Connections is "a terrific opportunity that should enable us to grow more rapidly" by giving his company access to Waste Connection's resources.

"By combining our business and expertise with the scale, breadth and financial resources of Waste Connections, we will be able to enhance the environmental solutions we bring to our customers," Thacker said.