The ARO is initially set up as in Example 1. After 15 years, it is determined that the actual cost to remove the tank requires adding 10,000 in current dollars. Click on the ARO, then choose Add layer to enter a new layer on the existing ARO, with a current start date of July 15, 2028 and the same January 31, 2033 end date as originally. Use current inflation and risk-free rates. (If the estimated cost should be reduced, you would use the original 6.5% risk-free rate.)