CLEAN HARBORS INC

The changes toremedial liabilities from January 1, 2022 through December 31, 2023 were as follows (in thousands):

In the year ended December 31, 2023, the Company increased its remedial liabilities for an inactive site and an active site by $1.1 million each due to changes in the estimates of the related liabilities to account for new information obtained regarding the ultimate remediation of these sites. In the year ended December 31, 2022, the $8.1 million liability assumed in acquisition relates to real estate that the Company acquired in 2022. In purchasing the property, the Company assumed a known associated remedial liability, which was contemplated in the purchase price.

Anticipated payments at December 31, 2023 (based on current estimated costs and anticipated timing of necessary regulatory approvals to commence work on remedial activities) for each of the next five years and thereafter were as follows (in thousands):

The following table presents the Company's estimated remedial liabilities and reasonably possible additional liabilities as of December 31, 2023 disaggregated by facility/site type (in thousands, except percentages):

(1)Amounts represent the high end of the range of management's best estimate of the reasonably possible additional liabilities.

The following table presents the Company's estimated remedial liabilities and reasonably possible additional liabilities as of December 31, 2023 disaggregated by facilities/sites which represent at least 5% of the total and with all other facilities/ sites combined (in thousands, except percentages):

(1)$25.0 million of the $111.2 million remedial liabilities include estimates related to the legal and administrative proceedings discussed in Note 18, "Commitments and Contingencies."

(2)Amounts represent the high end of the range of management's best estimate of the reasonably possible additional liabilities.

Revisions to remediation reserve requirements may result in upward or downward adjustments to income from operations in any given period. The Company believes that its extensive experience in the environmental services business, as well as its involvement with a large number of sites, provides a reasonable basis for estimating its aggregate liability. It is possible, however, that future changes in available technology, regulatory or enforcement developments, the results of environmental studies or other factors could necessitate the recording of additional liabilities or the revision of currently recorded liabilities that could be material. Since the Company's satisfaction of the liabilities will occur over many years, the Company cannot reasonably predict the nature or extent of possible future events or the impact that those events, if any, might have on the current estimates of remedial liabilities.