STOCK-BASED COMPENSATION

6 Months Ended

Jun. 30, 2020

Share-based Payment Arrangement [Abstract]

On June 3, 2020, our shareholders approved the Clean Harbor's Inc. 2020 Stock Incentive Plan (the "2020 Plan"), which became effective on that date. The 2020 Plan provides for future awards of up to 2.5 million shares of the Company’s common stock (subject to certain anti-dilution adjustments) in the form of stock options, stock appreciation rights, restricted stock, restricted stock units and other stock-based awards. The 2020 Plan is administered by the Compensation Committee of the Company’s Board of Directors. The Company's previous stock incentive plan (the "2010 Plan") expired on May 10, 2020. In connection with the adoption of the 2020 Plan, no further awards will be made under the 2010 Plan.

Total stock-based compensation cost charged to selling, general and administrative expenses for the three and six months ended June 30, 2020 was $2.8 million and $6.1 million, respectively. Total stock-based compensation cost charged to selling, general and administrative expenses for the three and six months ended June 30, 2019 was $3.8 million and $9.6 million, respectively. The total income tax benefit recognized in the consolidated statements of operations from stock-based compensation expense for the three and six months ended June 30, 2020 was $0.4 million and $1.2 million, respectively. The total income tax benefit recognized in the consolidated statements of operations from stock-based compensation expense for the three and six months ended June 30, 2019 was $0.7 million and $1.8 million, respectively.

Restricted Stock Awards

The following table summarizes information about restricted stock awards for the six months ended June 30, 2020:


Restricted Stock	Number of Shares	Weighted Average Grant-Date Fair Value
Balance at January 1, 2020	522,597	$	59.57
Granted	52,078	59.07
Vested	(147,197)	57.33
Forfeited	(31,640)	58.64
Balance at June 30, 2020	395,838	60.42

As of June 30, 2020, there was $16.5 million of total unrecognized compensation cost arising from restricted stock awards. This cost is expected to be recognized over a weighted average period of 2.3 years. The total fair value of restricted stock vested during the three and six months ended June 30, 2020 was $4.4 million and $9.7 million, respectively. The total fair value of restricted stock vested during the three and six months ended June 30, 2019 was $7.9 million and $11.1 million, respectively.

Performance Stock Awards

Performance stock awards are subject to performance criteria established by the Compensation Committee of the Company's Board of Directors prior to or at the date of grant. The vesting of the performance stock awards is based on achieving targets typically based on revenue, Adjusted EBITDA margin, Adjusted Free Cash Flow and Total Recordable Incident Rate. In addition, performance stock awards include continued service conditions.

The following table summarizes information about performance stock awards for the six months ended June 30, 2020:


Performance Stock	Number of Shares	Weighted Average Grant-Date Fair Value
Balance at January 1, 2020	204,553	$	64.78
Granted	—	—
Vested	(23,222)	55.75
Forfeited	(11,976)	65.71
Balance at June 30, 2020	169,355	65.95

As of June 30, 2020, there was $1.6 million of total unrecognized compensation cost arising from unvested performance stock awards deemed probable of vesting. No performance awards vested during the three months ended June 30, 2020 and June 30, 2019. The total fair value of performance awards vested during the six months ended June 30, 2020 and June 30, 2019 was $1.3 million and $2.9 million, respectively.