At the end of August, Casella Resource Solutions quietly closed the gates at its almost 40-year-old, award-winning composting facility in Unity Township, Maine. Since the Hawk Ridge Composting Facility opened in 1989, Casella has processed about 1.5 million cubic yards of sewage sludges as well as 240,000 cubic yards of papermill sludges and 130,000 cubic yards of other feedstocks in making its compost.

Under current Maine state law, it is illegal to sell or use biosolids-based compost. That put a dent in Hawk Ridge’s compost business, with Casella having to find other places to market its products. Sources from the company say the uncertain regional market – especially in states like Massachusetts – was one of the drivers for closing Hawk Ridge. Casella was also looking at significant capital improvements to Hawk Ridge’s 30+ year old composting infrastructure. In the end, the company decided it wasn’t worth it. They stopped taking wastewater sludges as of August 30th. Casella is honoring their existing contracts and finding homes for their customers’ sludge elsewhere at no additional cost, or disruption to service.

According to news reports, the Maine Department of Environmental Protection is concerned with PFAS levels in impoundment water at the Hawk Ridge site and has concerns with the site going forward, specifically PFAS in surface waters on and adjacent to the composting facility. What the media has not picked up on is that Hawk Ridge site received biosolids for land application that were industrially impacted. The same source of biosolids that was the cause of significant contamination at dozens of other farms in the greater Fairfield area. The PFAS contamination up gradient of the Hawk Ridge composting operation is just as high as on those other farms, and is a likely contributor to contamination down gradient of the compost facility. Casella is in the process of cleaning up the site and will completely cease operations in the Spring, although they may still use the site for storage and non-regulated activities as negotiations with DEP continue. Casella submitted its closure plan to the DEP in late August. The facility closure is slated for June 30th 2026.

The loss in regional biosolids processing capacity from the closure of Hawk Ridge in Maine is very significant. It could substantially affect Massachusetts which is vulnerable in the short term, being mainly reliant on out-of-state outlets to manage their sludges. Massachusetts’ study of biosolids management [download] shows that 10,322 dry tons of biosolids from Massachusetts went to Hawk Ridge in 2023. That is over 6% of the total 165,000 or so tons being generated in Massachusetts.

The Hawk Ridge composting facility shut down comes at a time when Maine is still struggling to find suitable solutions for managing its own biosolids. Back in June, the legislature approved another temporary measure to allow for the continued import of bulky wastes to mix with biosolids at landfill, where an estimated 90% of Maine wastewater sludges are ending up. According to a state study by Brown and Caldwell (see previous article: Maine Biosolids Study — NEBRA), the state-owned (and Casella run) Juniper Ridge landfill will run out of space in 2028 unless something is done. Although the Maine DEP is supportive of the request to expand the landfill, that application is already facing push back, especially from its neighbors, the Penobscot Nation.  

Meanwhile, Maine’s wastewater operators are stepping up efforts to get legislators to understand and revisit the law that limits in-state options for biosolids to landfilling. And they may be getting some traction: Maine's wastewater industry urges state to stop landfilling biosolids. The Maine Water Environment Association cites numerous reports that point to answers and mention effective regulatory models in other states. See the full press release here: Maine's Wastewater Industry Calls for Policy Changes on Biosolids.pdf.