On March 1, 2016, the Settling Party's freight train derailed at the Site. Two of four derailed train cars transporting ethanol began to leak as a consequence of the derailment. A propane tank car also derailed, but it was not compromised. The Settling Party undertook a removal action at the Site from March 2, 2016, to March 4, 2016. EPA incurred response costs pursuant to Section 104(a) of CERCLA, for its response activities performed at the Site, including assistance in and oversight of the removal action.