PROPERTY, PLANT, AND EQUIPMENT

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

PROPERTY, PLANT, AND EQUIPMENT

PROPERTY, PLANT AND EQUIPMENT

Property, plant and equipment consisted of the following (in thousands):

	December 31, 2017		December 31, 2016
Land	$	121,658	$	120,575
Asset retirement costs (non-landfill)	14,593		14,567
Landfill assets	144,539		139,708
Buildings and improvements	414,384		373,160
Camp equipment	170,012		152,740
Vehicles	617,959		541,022
Equipment	1,644,102		1,483,736
Furniture and fixtures	5,708		5,492
Construction in progress	57,618		146,904
	3,190,573		2,977,904
Less - accumulated depreciation and amortization	1,603,208		1,366,077
Total property, plant and equipment, net	$	1,587,365	$	1,611,827

Interest in the amount of $0.6 million, $5.5 million and $2.0 million was capitalized to fixed assets during the years ended December 31, 2017, 2016 and 2015, respectively. Depreciation expense, inclusive of landfill amortization was $251.4 million, $247.0 million and $234.0 million for the years ended December 31, 2017, 2016 and 2015, respectively.