PROPERTY, PLANT AND EQUIPMENT

9 Months Ended

Sep. 30, 2019

Property, Plant and Equipment [Abstract]

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



	September 30, 2019		December 31, 2018
Land	$	134,809	$	123,734
Asset retirement costs (non-landfill)	15,349		15,148
Landfill assets	172,453		154,918
Buildings and improvements ⁽¹⁾	485,686		440,188
Camp equipment	156,786		152,998
Vehicles	786,575		721,735
Equipment	1,745,483		1,697,490
Furniture and fixtures	5,373		5,453
Construction in progress	37,290		20,931
	3,539,804		3,332,595
Less - accumulated depreciation and amortization	1,945,811		1,770,617
Total property, plant and equipment, net	$	1,593,993	$	1,561,978

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(1) September 30, 2019 balance inclusive of ROU assets classified as finance leases.

Interest in the amount of $0.1 million and $0.3 million was capitalized to property, plant and equipment during the three and nine months ended September 30, 2019, respectively. 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. Depreciation expense, inclusive of landfill and finance lease amortization, was $65.3 million and $196.7 million for the three and nine months ended September 30, 2019, 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.