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Asset Retirement Obligations (Tables)
 12 Months Ended
Dec. 31, 2018
Asset Retirement Obligations  
Schedule of reconciliation of asset retirement obligations

The following is a reconciliation of the Company’s asset retirement obligations for the years ended December 31, 2017 and 2018 (in thousands):

 

 

 

 

 

 

 

 

 

 

2017

 

2018

 

Asset retirement obligations—beginning of year

 

$

32,736

 

 

34,610

 

Obligations settled

 

 

(22)

 

 

 —

 

Obligations incurred

 

 

4,044

 

 

9,981

 

Revisions to prior estimates

 

 

(4,758)

 

 

11,569

 

Accretion expense

 

 

2,610

 

 

2,819

 

Asset retirement obligations—end of year

 

$

34,610

 

 

58,979