SIGNIFICANT ACCOUNTING POLICIES (Tables)

12 Months Ended

Dec. 31, 2015

Accounting Policies [Abstract]

Schedule of estimated useful lives of property, plant and equipment

Following are the estimated useful lives of our property, plant and equipment:

	Useful Lives (in Years)
Building and land improvements including assets under capital lease	10 – 39
Mineral reserves	N/A*
Tanks and equipment	7 – 40
Railroad and related improvements	20 – 40
Machinery and equipment	5 – 10
Plant equipment including assets under capital lease	5 – 7
Industrial vehicles	3 – 7
Furniture, office equipment and software	3 – 7
Leasehold improvements	3 – 5 or lease term, whichever is less

*    Depletion calculated using units-of-production method

Schedule of changes in the asset retirement obligations

Changes in the asset retirement obligations are as follows:

	Year Ended December 31,
	2015			2014
	($ in thousands)
Beginning balance	$	2,386		$	1,414
Additions	113			934
Accretion	80			38
Reclamation costs	(9		)	—
Ending balance	$	2,570		$	2,386