Property, plant and equipment consists primarily of pipeline, pipeline-related equipment, storage tanks and processing equipment. We state property, plant and equipment at cost except for certain acquired assets recorded at fair value on their respective acquisition dates and impaired assets. We record impaired assets at fair value on the last impairment evaluation date for which an adjustment was required.

We assign asset lives based on reasonable estimates when we place an asset into service. Subsequent events could cause us to change our estimates, which would affect the future calculation of depreciation expense.

When we sell or retire property, plant and equipment, we remove its carrying value and the related accumulated depreciation from our accounts and record any associated gains or losses in our consolidated statements of income in the period of sale or disposition.

We capitalize expenditures to replace existing assets and retire the replaced assets. We capitalize expenditures when they extend the useful life, increase the productivity or capacity, or improve the safety or efficiency of the asset. We capitalize direct project costs such as labor and materials as incurred. Indirect project costs, such as overhead, are capitalized based on a percentage of direct labor charged to the respective capital project. We charge expenditures for routine maintenance, repairs and minor replacements to operating expense in the period incurred.

During construction, we capitalize interest on construction projects undergoing preparation for use and when total budgeted project costs exceed $0.5 million. The interest we capitalize is based on the weighted average interest rate of our debt. The weighted average rates used to capitalize interest on borrowed funds were 4.4%, 4.4% and 4.3% for the years ended December 31, 2020, 2021 and 2022, respectively.


					Estimated Depreciable Lives
	December 31,
	2021		2022
Construction work-in-progress	$	89.5	$	93.9
Land	111.5		121.9
Buildings	121.8		124.2		10 to 53 years
Storage tanks	1,986.7		1,985.4		10 to 49 years
Pipeline and station equipment	3,386.0		3,430.7		10 to 59 years
Processing equipment	1,826.4		1,875.7		3 to 56 years
Rights-of-way and other	524.0		532.1		3 to 53 years
Property, plant and equipment, gross	$	8,045.9	$	8,163.9

Other includes total interest capitalized on assets placed in service as of December 31, 2021 and 2022 of $98.7 million and $100.1 million, respectively. Depreciation expense for the years ended December 31, 2020, 2021 and 2022 was $240.5 million, $225.2 million and $218.7 million, respectively.

Long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying value may not be recoverable. In reviewing for impairment, the carrying value of such assets is compared to the estimated undiscounted future cash flows expected from the use of the assets and their eventual disposition. If such cash flows are not sufficient to support the asset’s recorded value, an impairment charge is recognized to reduce the carrying value of the long-lived asset to its estimated fair value. The determination of future cash flows as well as the estimated fair value of long-lived assets involves significant estimates on the part of management.

In accordance with ASC, 360 Property, Plant and Equipment, we ceased recording depreciation and amortization for all assets upon their designation as assets held for sale.

We record the excess of purchase price over the fair value of the tangible and identifiable intangible assets acquired and liabilities assumed in a business acquisition (or combination) as goodwill. The goodwill relating to each of our reporting units is tested for impairment annually as well as when an event or change in circumstances indicates an impairment may have occurred.

For purposes of performing the impairment test for goodwill, our reporting units are our refined products and crude oil segments. In 2021, we elected to bypass the qualitative assessment of our annual goodwill impairment test and perform the quantitative assessment. Based on this assessment, we concluded goodwill was not impaired as calculated fair value of each of our reporting units was greater than the carrying amount. In 2020 and 2022, we elected to complete the qualitative goodwill impairment test and concluded it was more likely than not that the fair value of each of our reporting units was greater than its carrying amount.

Other intangible assets with finite lives are amortized over their estimated useful lives of 7 years up to 30 years. The weighted average asset life of our other intangible assets at December 31, 2022 was approximately 15 years. We adjust the useful lives of our other intangible assets if events or circumstances indicate there has been a change in the remaining useful lives. We eliminate from our balance sheets the gross carrying amount and the related accumulated amortization for any fully amortized intangibles in the year they are fully amortized. During the years ended December 31, 2020, 2021 and 2022, amortization of other intangible assets was $2.7 million, $2.7 million and $2.8 million, respectively.