PROPERTY, PLANT AND EQUIPMENT

9 Months Ended

Sep. 30, 2018

Property, Plant and Equipment [Abstract]

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



	September 30, 2018		December 31, 2017
Land	$	125,804	$	121,658
Asset retirement costs (non-landfill)	14,857		14,593
Landfill assets	149,748		144,539
Buildings and improvements	443,908		414,384
Camp equipment	163,427		170,012
Vehicles	723,872		617,959
Equipment	1,697,920		1,644,102
Furniture and fixtures	5,652		5,708
Construction in progress	29,373		57,618
	3,354,561		3,190,573
Less - accumulated depreciation and amortization	1,740,132		1,603,208
Total property, plant and equipment, net	$	1,614,429	$	1,587,365

Interest in the amount of $0.1 million and $0.5 million was capitalized to property, plant and equipment during the three and nine months ended September 30, 2018, respectively. Interest in the amount of $0.2 million and $0.4 million was capitalized to property, plant and equipment during the three and nine months ended September 30, 2017, respectively. Depreciation expense, inclusive of landfill amortization, was $64.9 million and $194.7 million for the three and nine months ended September 30, 2018, respectively. Depreciation expense, inclusive of landfill amortization, was $64.0 million and $189.2 million for the three and nine months ended September 30, 2017, respectively.