PROPERTY, PLANT, AND EQUIPMENT (Tables)

12 Months Ended

Dec. 31, 2016

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

The Company depreciates and amortizes the cost of these assets, using the straight-line method as follows:

Asset Classification	Estimated Useful Life
Buildings and building improvements
Buildings	30–42 years
Leasehold and building improvements	2–45 years
Camp equipment	8–15 years
Vehicles	3–15 years
Equipment
Capitalized software and computer equipment	3–5 years
Solar equipment	30 years
Containers and railcars	15–20 years
All other equipment	8–25 years
Furniture and fixtures	5–8 years

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

	December 31, 2016		December 31, 2015
Land	$	120,575	$	100,582
Asset retirement costs (non-landfill)	14,567		12,434
Landfill assets	139,708		136,624
Buildings and improvements	373,160		344,209
Camp equipment	152,740		149,361
Vehicles	541,022		500,619
Equipment	1,483,736		1,328,915
Furniture and fixtures	5,492		5,337
Construction in progress	146,904		113,657
	2,977,904		2,691,738
Less - accumulated depreciation and amortization	1,366,077		1,159,271
Total property, plant and equipment, net	$	1,611,827	$	1,532,467