


thousands	Estimated Useful Life	March 31, 2022		December 31, 2021
Land	N/A	$	10,955	$	10,955
Gathering systems – pipelines	30 years	5,429,779		5,386,003
Gathering systems – compressors	15 years	2,203,895		2,172,953
Processing complexes and treating facilities	25 years	3,380,819		3,375,317
Transportation pipeline and equipment	6 to 45 years	169,380		169,356
Produced-water disposal systems	20 years	885,265		882,527
Assets under construction	N/A	91,268		98,473
Other	3 to 40 years	758,997		750,494
Total property, plant, and equipment		12,930,358		12,846,078
Less accumulated depreciation		4,455,162		4,333,171
Net property, plant, and equipment		$	8,475,196	$	8,512,907

The cost of property classified as “Assets under construction” is excluded from capitalized costs being depreciated. These amounts represent property that is not yet placed into productive service as of the respective balance sheet date.

Long-lived asset and other impairments. During the three months ended March 31, 2021, the Partnership recognized impairments of $14.9 million, primarily attributable to $13.5 million of impairments at the DJ Basin complex due to cancellation of projects.