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Accrued Capping, Closure and Post Closure (Tables)
12 Months Ended
Apr. 30, 2013
Changes to Accrued Capping, Closure and Post-Closure Liabilities

The changes to accrued capping, closure and post-closure liabilities are as follows:

 

     Fiscal Year Ended April 30,  
     2013     2012  

Beginning balance

   $ 39,629      $ 36,407   

Obligations incurred

     3,188        3,123   

Revisions in estimates (1)

     (694     (1,682

Accretion expense

     3,538        3,341   

Payments

     (2,491     (1,560
  

 

 

   

 

 

 

Ending balance

   $ 43,170      $ 39,629   
  

 

 

   

 

 

 

 

(1) The revisions in estimates for capping, closure and post-closure for the years ended April 30, 2013 and 2012 consist of changes in cost estimates and timing of capping and closure events as well as changes to expansion airspace and tonnage placement assumptions.