(1)

In December 2020, we modified the vesting requirements for certain restricted units that we granted in February 2020 which were determined to be improbable of vesting under the original vesting requirements (the "2020 Grants"). The new vesting requirements make it probable the modified restricted units will vest. Also in December 2020, an additional 578,114 restricted units under these modified vesting requirements were granted. The grant date fair value reflects the modification date fair value for those awards that were modified.

(2)

In February 2020, we issued 279,622 unrestricted common units to LTIP participants as a result of satisfying the vesting requirements for 424,486 restricted units that were granted in 2017. The remaining vested units were settled in cash to satisfy tax withholding obligations of the LTIP participants. In December 2020, we accelerated the vesting requirements for 495,038 restricted units that were granted in 2018 (the "2018 Grants") and settled these restricted units in cash.

(3)	In December 2020, 675,302 restricted units that were granted in 2019 (the "2019 Grants") were canceled since it was determined that the vesting requirements for these restricted units were not probable of being satisfied.

(4)	The restricted units granted during 2021 and 2022 have certain minimum-value guarantees per unit, regardless of whether or not the awards vest.

For the years ended December 31, 2022, 2021 and 2020, our LTIP expense for grants of restricted units was $9.4 million, $5.4 million and $8.1 million, respectively. LTIP expense for grants of restricted units for the year ended December 31, 2020 includes the impact of the reversal of the 2019 Grants, the modification of the 2020 Grants and incremental compensation cost associated with the cash settlement of the 2018 Grants. The cash settlement of the 2018 Grants was the first time we have settled restricted units in cash and we currently do not expect to do so again in the future. The cash settlement of the 2018 Grants resulted in $5.4 million in incremental compensation cost. The 2019 Grants were determined to be not probable of vesting therefore $4.8 million of cumulative previously recognized expense was reversed in 2020, offset in part by related DERs for the 2019 Grants previously recorded to equity and then expensed in 2020. The 2020 Grants were determined to be improbable of vesting therefore the Compensation Committee modified the awards to change the vesting requirement, which made the grants probable of vesting, and granted additional restricted units under these modified vesting requirements as previously discussed. As a result, the grant date fair value of the modified awards was changed to reflect the modification date fair value of the awards resulting in a net reduction in LTIP expense of $1.0 million for the year ended December 31, 2020.

The total obligation associated with LTIP grants of restricted units as of December 31, 2022 and 2021 was $16.0 million and $6.7 million, respectively, and is included in the partners' capital Limited partners-common unitholders line item in our consolidated balance sheets. As of December 31, 2022, there was $11.4 million in total unrecognized

compensation expense related to the non-vested LTIP restricted unit grants that are expected to vest. That expense is expected to be recognized over a weighted-average period of 0.8 years.

On January 27, 2023, the Compensation Committee authorized additional grants of 462,225 restricted units, of which 447,225 units were granted. These restricted units have certain minimum-value guarantees, regardless of whether or not the awards vest.

Supplemental Executive Retirement Plan and Directors' Deferred Compensation Plan

A summary of SERP and Directors' Deferred Compensation Plan activity is as follows:


	Number of units	Weighted average grant date fair value per unit		Intrinsic value
				(in thousands)

Phantom units outstanding as of January 1, 2020	631,365	$	25.48	$	6,831
Granted	129,265		5.25
Phantom units outstanding as of December 31, 2020	760,630		22.04		3,408
Granted	46,638		9.45
Issued (1)	(138,570)		25.86
Phantom units outstanding as of December 31, 2021	668,698		20.37		8,452
Granted	73,842		19.44
Phantom units outstanding as of December 31, 2022	742,540		20.28		15,088

(1)	During the year ended December 31, 2021, we purchased 102,962 ARLP common units on the open market to settle the account of a participant under the SERP. Units purchased were net of units settled in cash to satisfy tax-withholding obligations.

Total SERP and Directors' Deferred Compensation Plan expense was $1.4 million, $0.4 million and $0.7 million for the years ended December 31, 2022, 2021 and 2020, respectively. As of December 31, 2022 and 2021, the total obligation associated with the SERP and Directors' Deferred Compensation Plan was $15.1 million and $13.5 million, respectively, and is included in the partners' capital Limited partners-common unitholders line item in our consolidated balance sheets.

See Note 2 – Summary of Significant Accounting Policies for more information on our accounting policy for unit-based compensation.