The Maine Department of Environmental Protection is warning the railroad company whose freight train derailed in Somerset County last weekend that they need to improve their clean-up efforts.

According to CBS 13, Canadian Pacific Kansas City received a letter from the DEP Thursday saying that while the company has made progress in cleaning up the crash site, it has failed to meet the department’s expectations.

The derailment caused around 500 gallons of diesel fuel to be spilled into the surrounding environment. The DEP warns the CPKC that if their cleanup efforts are not improved, the department will take over at the company’s expense.