Wind River Environmental, a provider of liquid waste management services, is exploring a sale process, four sources familiar with the situation said.

The Gryphon Investors-backed company is working with investment banks William Blair and Baird on the process, said two of the sources. The process has not yet launched, all four sources said.

Marlborough, Massachusetts-based Wind River has over USD 50m in EBITDA, said the first source, with a second source saying the company has EBITDA between USD 50m and USD 60m. Prior to its sale to Gryphon in 2017, Wind River had around 20m in EBITDA, this news service reported at that time.

Financial sponsors are the most likely suitors for Wind River, the second and third sources said, as private equity deal activity is picking up in the waste management sector.

The third source pointed to similar assets including Waste Resource Management (WRM), which was acquired by Ridgewood Infrastructure in January, and Audax portfolio company Liquid Environmental Solutions. Audax is preparing a sale process for Liquid Environmental Solutions, which it acquired in December 2017 and which has EBITDA between USD 35m to USD 45m, according to a recent report by PE Hub.

There has also been deal activity in Europe, including Ardian Infrastructure’s acquisition of Dutch waste treatment and recycling business Attero last year, in a deal worth USD 1.7bn (EUR 1.5bn). Waste management is an attractive space for infrastructure investors due to its non-cyclical nature and predictable cash flows, Mergermarket previously reported.

Gryphon invested in Wind River from its flagship fund. According to the private equity sponsor’s website, the company is the leading provider of inspection, service, installation, repair and maintenance of non-hazardous liquid environmental waste solutions in the US. It provides grease trap cleaning services to commercial restaurants, as well as drain cleaning, septic pumping and other services to the residential and commercial markets. Its municipal and industrials sector services include basin cleaning, sewer repairs, hydro excavation (or soil removal using pressurized water and vacuums), and cleaning lift stations that collect sewage and liquid waste.

Founded in 2009, the company has made more than 100 acquisitions along the Eastern Seaboard, according to a press release. Its most recent purchase was of Cloud 9 Services, a hydro excavation, commercial plumbing, pipelining, and underground utility services provider formerly held by Canopy Capital Management, in February. Terms were undisclosed.

William Blair advised Wind River on Gryphon’s buyout, while the San Francisco-based sponsor worked with Stifel and legal advisor Kirkland & Ellis.

Gryphon, Wind River, William Blair and Baird did not respond to requests for comment.