11.

Asset retirement obligations ("ARO") relate to the Lost Creek mine and Pathfinder projects and are equal to the present value of all estimated future costs required to remediate any environmental disturbances that exist as of the end of the period discounted using discount rates ranging from 0.33% to 7.25%. Included in this liability are the costs of closure, reclamation, demolition and stabilization of the mines, processing plants, infrastructure, aquifer restoration, waste dumps and ongoing post-closure environmental monitoring and maintenance costs.

At September 30, 2020, the current, non-inflated, closure cost estimate was $29.4 million and the estimated future cost to complete the reclamation, including inflation, is $39.5 million. The schedule of payments required to settle the future reclamation extends through 2033. The present value of the estimated future closure estimate is presented in the following table.

Change in estimated reclamation costs

Accretion expense

The restricted cash discussed in note 6 relates to the surety bonds provided to the governmental agencies for these obligations.