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ASSET RETIREMENT AND ENVIRONMENTAL OBLIGATIONS | 12 Months Ended
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Dec. 31, 2022
Asset Retirement Obligation And Environmental Remediation Obligations [Abstract] |
ASSET RETIREMENT AND ENVIRONMENTAL OBLIGATIONS | ASSET RETIREMENT AND ENVIRONMENTAL OBLIGATIONS Asset Retirement Obligations The Company estimates ARO based on the requirements to reclaim certain land and facilities associated with mining activity at Mountain Pass. Minor reclamation activities related to discrete portions of the Company’s operations are ongoing. As of December 31, 2022, the Company estimated a significant portion of the cash outflows for major reclamation activities including the retirement of Mountain Pass will be incurred beginning in 2056 and 2057. In June 2021, San Bernardino County approved a re-zoning request for certain of the Company’s properties such that certain of the Company’s processing and separations facilities would be zoned for industrial end uses as opposed to the prior “resource conservation” designation. In September 2022, and as a result of the re-zoning of this land, the Company received final approval from San Bernardino County and the Division of Mine Reclamation (California) on a revised reclamation plan. The revision removed from the regulatory oversight under The Surface Mining and Reclamation Act of 1975 the majority of the buildings and equipment used in the processing and separations facilities, including the land underlying such buildings and equipment. As a result of the final approval of the reclamation plan, in the third quarter of 2022, the Company revised its estimated cash flows pertaining to the settlement of the reclamation and removal activities associated with Mountain Pass, including removing the previous estimates of the cash flows associated with the processing and separations facilities that no longer require reclamation. The changes in estimates resulted in an ARO decrement of $13.1 million, of which $10.4 million reduced the carrying amounts of the associated property, plant and equipment, and $2.7 million, reflecting the excess of the decrement over the carrying amount of the related property, plant and equipment, was recorded as a reduction to depreciation expense for the year ended December 31, 2022. In the fourth quarter of 2021, the Company revised its estimated timing and cash flows pertaining to the settlement of the reclamation and removal activities associated with Mountain Pass as a result of an updated life of mine where the Company determined that the estimated commencement of the reclamation and removal activities will now occur in 2056 and 2057 for a significant portion of the assets requiring reclamation at the time. The changes in estimates resulted in an ARO decrement of $9.8 million, of which $8.7 million reduced the carrying amounts of the associated property, plant and equipment, and $1.1 million, reflecting the excess of the decrement over the carrying amount of the related property, plant and equipment, was recorded as a reduction to depreciation expense for the year ended December 31, 2021. The following is a summary of the Company’s ARO:
| December 31,
(in thousands) | 2022 |  | 2021
Beginning balance | $ | 17,757 |  |  | $ | 25,646 |
Obligations settled | (144) |  |  | (199) |
Accretion expense | 976 |  |  | 1,876 |
Additional ARO | — |  |  | 213 |
Revisions in estimated cash flows | (13,114) |  |  | (9,779) |
Ending balance | $ | 5,475 |  |  | $ | 17,757 |
The balance as of December 31, 2022 and 2021, included current portions of $0.2 million and $0.1 million, respectively. The total estimated future undiscounted cash flows required to satisfy the Company’s ARO as of December 31, 2022 and 2021, were $50.4 million and $167.3 million, respectively. As of December 31, 2022, the credit-adjusted risk-free rate ranged between 6.5% and 12.0% depending on the timing of expected settlement and when the increment was recognized. There were no significant increments for the years ended December 31, 2022 and 2021, and there were no significant increments or decrements for the year ended December 31, 2020. Environmental Obligations The Company has certain environmental remediation liabilities related to the monitoring of groundwater contamination. The Company engaged an environmental consultant to develop a remediation plan and remediation cost projections based upon that plan. Utilizing the remediation plan developed by the environmental consultant, the Company developed an estimate of future cash payments for the remediation plan. As of December 31, 2022, the Company estimated the cash outflows related to these environmental activities will be incurred annually over the next 25 years. The Company’s environmental remediation liabilities are measured at the expected value of future cash outflows discounted to their present value using a discount rate of 2.93%. There were no significant changes in the estimated remaining remediation costs for the years ended December 31, 2022, 2021 and 2020. The total estimated aggregate undiscounted cost of $27.2 million and $27.7 million as of December 31, 2022 and 2021, respectively, principally related to water monitoring activities required by state and local agencies. Based on the Company’s estimate of the cost and timing and the assumption that payments are considered to be fixed and reliably determinable, the Company has discounted the liability. The balance as of December 31, 2022 and 2021, included current portions of $0.5 million. As of December 31, 2022, the total environmental remediation costs were as follows (in thousands):
Year ending December 31, |
2023 | $ | 520 |
2024 | 536 |
2025 | 552 |
2026 | 569 |
2027 | 587 |
Thereafter | 24,411 |
Total | 27,175 |
Effect of discounting | (10,075) |
Total environmental obligations | $ | 17,100 |
Financial Assurances The Company is required to provide the applicable government agencies with financial assurances relating to the closure and reclamation obligations. As of December 31, 2022 and 2021, the Company had financial assurance requirements of $43.5 million and $39.0 million, respectively, which were satisfied with surety bonds placed with California state and regional agencies.

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