CLEAN HARBORS, INC. AND SUBSIDIARIES

SCHEDULE II

VALUATION AND QUALIFYING ACCOUNTS

For the Three Years Ended December 31, 2012

(in thousands)



Allowance for Doubtful Accounts	Balance Beginning of Period		Additions Charged to Operating Expense		Deductions from Reserves(a)			Balance End of Period
2010	$	832	$	1,245	$	(7	)	$	2,084
2011	$	2,084	$	759	$	1,013		$	1,830
2012	$	1,830	$	1,213	$	1,797		$	1,246

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(a)	Amounts deemed uncollectible, net of recoveries.



Revenue Allowance(b)	Balance Beginning of Period		Additions Charged to Revenue		Deductions from Reserves		Balance End of Period
2010	$	7,423	$	29,497	$	15,300	$	21,620
2011	$	21,620	$	13,846	$	24,613	$	10,853
2012	$	10,853	$	18,847	$	19,821	$	9,879

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(b)

Due to the nature of the Company's business and the complex invoices that result from the services provided, customers may withhold payments and attempt to renegotiate amounts invoiced. In addition, for some of the services provided, the Company's invoices are based on quotes that can either generate credits or debits when the actual revenue amount is known. Based on industry knowledge and historical trends, the Company records a revenue allowance accordingly. This practice causes the volume of activity flowing through the revenue allowance during the year to be higher than the balance at the end of the year. Increases in overall sales volumes and the expansion of the customer base in recent years have also increased the volume of additions and deductions to the allowance during the year, as well as increased the amount of the allowance at the end of the year.

The revenue allowance is intended to cover the net amount of revenue adjustments that may need to be credited to customers' accounts in future periods. Management determines the appropriate total revenue allowance by evaluating the following factors on a customer-by-customer basis as well as on a consolidated level: historical collection trends, age of outstanding receivables, existing economic conditions and other information as deemed applicable. Revenue allowance estimates can differ materially from the actual adjustments, but historically the revenue allowance has been sufficient to cover the net amount of the reserve adjustments issued in subsequent reporting periods.



Valuation Allowance on Deferred Tax Assets	Balance Beginning of Period		Additions (Deductions) Charged to (from) Income Tax Expense			Other Changes to Reserves(a)		Balance End of Period
2010	$	11,242	$	1,677		$	—	$	12,919
2011	$	12,919	$	(1,593	)	$	147	$	11,473
2012	$	11,473	$	(196	)	$	14,358	$	25,635

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(a)	The Safety-Kleen acquisition accounted for $12.5 million of the increase in the valuation allowance as of December 31, 2012.