PROPERTY, PLANT, AND EQUIPMENT

12 Months Ended

Dec. 31, 2020

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, 2020		December 31, 2019
Land	$	139,776	$	131,023
Asset retirement costs (non-landfill)	16,407		15,924
Landfill assets	191,687		182,276
Buildings and improvements (1)	509,804		499,159
Camp equipment	159,021		158,277
Vehicles (2)	844,026		785,056
Equipment (3)	1,807,235		1,779,366
Furniture and fixtures	7,082		6,054
Construction in progress	24,378		36,679
	3,699,416		3,593,814
Less - accumulated depreciation and amortization	2,174,118		2,005,663
Total property, plant and equipment, net	$	1,525,298	$	1,588,151

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(1) Balances inclusive of gross ROU assets classified as finance leases of $8.9 million and $31.0 million, respectively.

(2) Balances inclusive of gross ROU assets classified as finance leases of $47.2 million and $2.4 million, respectively.

(3) December 31, 2020 balance inclusive of gross ROU assets classified as finance leases of $9.3 million.

Depreciation expense, inclusive of landfill and finance lease amortization was $257.1 million, $265.5 million and $264.3 million for the years ended December 31, 2020, 2019 and 2018, respectively.