US Ecology (ECOL) 10-Q 4 Nov 19 2019 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2019	Oct. 29, 2019
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Sep. 30, 2019
Entity File Number	000-11688
Entity Registrant Name	US ECOLOGY, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	95-3889638
Entity Address, Address Line One	101 S. Capitol Blvd., Suite 1000
Entity Address, City or Town	Boise
Entity Address, State or Province	ID
Entity Address, Postal Zip Code	83702
City Area Code	208
Local Phone Number	331-8400
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		22,093,904
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Entity Central Index Key	0001783400
Amendment Flag	false
Common Stock
Title of 12(b) Security	Common Stock
Trading Symbol	ECOL
Security Exchange Name	NASDAQ
Warrants
Title of 12(b) Security	Warrants to Purchase Common Stock
Trading Symbol	ECOLW
Security Exchange Name	NASDAQ

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current Assets:
Cash and cash equivalents	$ 21,074	$ 31,969
Receivables, net	155,826	144,690
Prepaid expenses and other current assets	16,014	10,938
Income taxes receivable	4,786	7,071
Total current assets	197,700	194,668
Property and equipment, net	273,781	258,443
Operating lease assets	17,496
Restricted cash and investments	5,045	4,941
Intangible assets, net	275,983	279,666
Goodwill	219,181	207,177
Other assets	10,963	3,003
Total assets	1,000,149	947,898
Current Liabilities:
Accounts payable	23,162	17,754
Deferred revenue	12,278	10,451
Accrued liabilities	33,369	35,524
Accrued salaries and benefits	19,469	16,732
Income taxes payable	275	505
Short-term borrowings	1,535
Current portion of closure and post-closure obligations	2,196	2,266
Current portion of operating lease liabilities	4,914
Total current liabilities	97,198	83,232
Long-term debt	354,000	364,000
Long-term closure and post-closure obligations	78,203	76,097
Long-term operating lease liabilities	12,590
Other long-term liabilities	3,792	2,146
Deferred income taxes, net	68,399	63,206
Total liabilities	614,182	588,681
Commitments and contingencies
Stockholders' Equity:
Common stock $0.01 par value, 50,000 authorized; 22,094 and 22,040 shares issued and outstanding, respectively	221	220
Additional paid-in capital	185,940	183,834
Retained earnings	214,013	189,324
Treasury stock, at cost, 13 and 8 shares, respectively	(772)	(370)
Accumulated other comprehensive loss	(13,435)	(13,791)
Total stockholders' equity	385,967	359,217
Total liabilities and stockholders' equity	$ 1,000,149	$ 947,898

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares shares in Thousands	Sep. 30, 2019	Dec. 31, 2018
CONSOLIDATED BALANCE SHEETS
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	50,000	50,000
Common stock, shares issued	22,094	22,040
Common stock, shares outstanding	22,094	22,040
Treasury stock, shares	13	8

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
CONSOLIDATED STATEMENTS OF OPERATIONS
Revenue	$ 167,402	$ 151,416	$ 454,241	$ 408,387
Direct operating costs	110,862	104,116	312,877	283,968
Gross profit	56,540	47,300	141,364	124,419
Selling, general and administrative expenses	33,329	23,649	77,683	67,037
Impairment charges		3,666		3,666
Operating income	23,211	19,985	63,681	53,716
Other income (expense):
Interest income	158	34	567	97
Interest expense	(3,891)	(3,066)	(11,509)	(8,782)
Foreign currency loss	(90)	(303)	(613)	(456)
Other	110	177	342	2,493
Total other expense	(3,713)	(3,158)	(11,213)	(6,648)
Income before income taxes	19,498	16,827	52,468	47,068
Income tax expense	6,428	3,400	15,864	11,178
Net income	$ 13,070	$ 13,427	$ 36,604	$ 35,890
Earnings per share:
Basic (in dollars per share)	$ 0.59	$ 0.61	$ 1.66	$ 1.64
Diluted (in dollars per share)	$ 0.59	$ 0.61	$ 1.65	$ 1.63
Shares used in earnings per share calculation:
Basic (in shares)	22,013	21,928	22,002	21,866
Diluted (in shares)	22,231	22,099	22,212	22,027

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
Net income	$ 13,070	$ 13,427	$ 36,604	$ 35,890
Other comprehensive income (loss):
Foreign currency translation gain (loss)	(995)	1,590	2,374	(1,878)
Net changes in interest rate hedge, net of taxes of $(40), $114, $(537) and $706, respectively	(150)	428	(2,018)	2,651
Comprehensive income, net of tax	$ 11,925	$ 15,445	$ 36,960	$ 36,663

CONSOLIDATED STATEMENTS OF CO_2

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Other comprehensive income (loss):
Net changes in interest rate hedge, tax	$ (40)	$ 114	$ (537)	$ 706

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities:
Net income	$ 36,604	$ 35,890
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of property and equipment	26,656	20,991
Amortization of intangible assets	8,600	6,925
Accretion of closure and post-closure obligations	3,397	3,242
Property and equipment impairment charges	25
Goodwill and intangible asset impairment charges		3,666
Unrealized foreign currency loss (gain)	(361)	899
Deferred income taxes	3,873	4,730
Share-based compensation expense	3,713	3,272
Unrecognized tax benefits	(238)	674
Net loss (gain) on disposition of assets	665	(57)
Gain on insurance proceeds from damaged property and equipment	(9,651)
Amortization of debt issuance costs	613	607
Changes in assets and liabilities (net of effects of business acquisitions):
Receivables	(9,449)	(27,573)
Income taxes receivable	2,292	(7,878)
Other assets	(7,206)	(2,355)
Accounts payable and accrued liabilities	1,873	11,218
Deferred revenue	1,770	3,579
Accrued salaries and benefits	2,665	1,576
Income taxes payable	(425)	(2,884)
Closure and post-closure obligations	(1,414)	(1,026)
Net cash provided by operating activities	64,002	55,496
Cash flows from investing activities:
Purchases of property and equipment	(38,443)	(25,791)
Business acquisitions (net of cash acquired)	(17,851)	(21,253)
Insurance proceeds from damaged property and equipment	10,000
Minority interest investment	(7,870)
Proceeds from sale of property and equipment	549	307
Purchases of restricted investments	(798)	(673)
Proceeds from sale of restricted investments	751	583
Net cash used in investing activities	(53,662)	(46,827)
Cash flows from financing activities:
Proceeds from long-term debt	20,000
Payments on long-term debt	(30,000)
Payments on short-term borrowings	(51,018)
Proceeds from short-term borrowings	52,553
Dividends paid	(11,915)	(11,838)
Payment of equipment financing obligations	(619)	(326)
Proceeds from exercise of stock options	63	2,427
Other	(915)	(314)
Net cash used in financing activities	(21,851)	(10,051)
Effect of foreign exchange rate changes on cash	673	(578)
Decrease in Cash and cash equivalents and restricted cash	(10,838)	(1,960)
Cash and cash equivalents and restricted cash at beginning of period	32,753	28,799
Cash and cash equivalents and restricted cash at end of period	21,915	26,839
Supplemental Disclosures:
Income taxes paid, net of receipts	10,422	17,842
Interest paid	10,340	8,001
Non-cash investing and financing activities:
Capital expenditures in accounts payable	558	2,684
Restricted stock issued from treasury shares	$ 514	$ 11

CONSOLIDATED STATEMENTS OF CA_2

CONSOLIDATED STATEMENTS OF CASH FLOWS - (Restricted cash and investments) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Reconciliation of Cash and cash equivalents and restricted cash
Cash and cash equivalents	$ 21,074	$ 31,969	$ 26,076	$ 27,042
Restricted cash	841	784	763	1,757
Cash and cash equivalents and restricted cash	$ 21,915	$ 32,753	$ 26,839	$ 28,799

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Additional Paid-In Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Total
Beginning balances at Dec. 31, 2017	$ 218	$ 177,498	$ 155,533	$ (68)	$ (9,104)	$ 324,077
Increase (Decrease) in Stockholders' Equity
Net income			35,890			35,890
Other comprehensive income (loss)					773
Share-based compensation		3,272
Stock option exercised and issuance of common stock and restricted common stock	2	1,978
Dividends paid			(11,838)
Repurchase of common stock				(313)
Issuance of restricted common stock from treasury shares		(11)		11
Ending balances at Sep. 30, 2018	220	182,737	179,585	(370)	(8,331)	353,841
Beginning balances at Jun. 30, 2018	220	180,687	170,112	(370)	(10,349)	340,300
Increase (Decrease) in Stockholders' Equity
Net income			13,427			13,427
Other comprehensive income (loss)					2,018
Share-based compensation		1,193
Stock option exercised and issuance of common stock and restricted common stock		857
Dividends paid			(3,954)
Ending balances at Sep. 30, 2018	220	182,737	179,585	(370)	(8,331)	353,841
Beginning balances at Dec. 31, 2018	220	183,834	189,324	(370)	(13,791)	$ 359,217
Balance (in shares) at Dec. 31, 2018						22,040,000
Increase (Decrease) in Stockholders' Equity
Net income			36,604			$ 36,604
Other comprehensive income (loss)					356
Share-based compensation		3,713
Stock option exercised and issuance of common stock and restricted common stock	1	(1,093)
Dividends paid			(11,915)
Repurchase of common stock				(916)
Issuance of restricted common stock from treasury shares		(514)		514
Issuance of restricted stock from treasury stock (in shares)						8,900
Ending balances at Sep. 30, 2019	221	185,940	214,013	(772)	(13,435)	$ 385,967
Balance (in shares) at Sep. 30, 2019						22,094,000
Beginning balances at Jun. 30, 2019	221	184,747	204,916	(835)	(12,290)	$ 376,759
Increase (Decrease) in Stockholders' Equity
Net income			13,070			13,070
Other comprehensive income (loss)					(1,145)
Share-based compensation		1,246
Stock option exercised and issuance of common stock and restricted common stock		10
Dividends paid			(3,973)
Issuance of restricted common stock from treasury shares		(63)		63
Ending balances at Sep. 30, 2019	$ 221	$ 185,940	$ 214,013	$ (772)	$ (13,435)	$ 385,967
Balance (in shares) at Sep. 30, 2019						22,094,000

GENERAL

GENERAL	9 Months Ended
	Sep. 30, 2019
GENERAL
GENERAL	NOTE 1. GENERAL ​ Basis of Presentation ​ The accompanying unaudited consolidated financial statements include the results of operations, financial position and cash flows of US Ecology, Inc. and its wholly-owned subsidiaries. All inter-company balances have been eliminated. Throughout these consolidated financial statements words such as “we,” “us,” “our,” “US Ecology” and “the Company” refer to US Ecology, Inc. and its subsidiaries. ​ In the opinion of management, the accompanying unaudited consolidated financial statements include all adjustments (consisting only of normal recurring adjustments) necessary to present fairly, in all material respects, the results of the Company for the periods presented. These consolidated financial statements have been prepared by the Company pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) have been omitted pursuant to the rules and regulations of the SEC. These consolidated financial statements should be read in conjunction with the consolidated financial statements and accompanying notes included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2018. The results of operations for the three and nine months ended September 30, 2019 are not necessarily indicative of the results to be expected for the entire year ending December 31, 2019. ​ The Company’s consolidated balance sheet as of December 31, 2018 has been derived from the Company’s audited consolidated balance sheet as of that date. ​ Use of Estimates ​ The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements, as well as the reported amounts of revenue and expenses during the reporting period. Actual results could differ materially from the estimates and assumptions that we use in the preparation of our consolidated financial statements. As it relates to estimates and assumptions in amortization rates and environmental obligations, significant engineering, operations and accounting judgments are required. We review these estimates and assumptions no less than annually. In many circumstances, the ultimate outcome of these estimates and assumptions will not be known for decades into the future. Actual results could differ materially from these estimates and assumptions due to changes in applicable regulations, changes in future operational plans and inherent imprecision associated with estimating environmental impacts far into the future. ​ Recently Issued Accounting Pronouncements ​ In August 2018, the SEC adopted the final rule under SEC Release No. 33-10532, “Disclosure Update and Simplification,” adopting amendments to certain disclosure rules that were redundant, duplicative, overlapping, outdated, or superseded, in light of other SEC disclosure requirements, GAAP or changes in the information environment. In addition, the amendments expanded the disclosure requirements relating to the analysis of equity for interim financial statements. Under the amendments, an analysis of the changes in each caption of shareholders’ equity and noncontrolling interests presented in the balance sheet must be provided in a note or separate statement. The analysis must present a reconciliation of the beginning balance to the ending balance of each period for which a statement of earnings is required to be filed. The final rule was effective on November 5, 2018. The Company adopted the final rule effective for the first quarter of 2019. The adoption of the final rule did not have an impact on the Company’s consolidated financial position or results of operations. In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815). through changes to both the designation and measurement guidance for qualifying hedging relationships and the presentation of hedge results. The guidance is effective for annual and interim reporting periods beginning after December 15, 2018, with early adoption permitted. The Company adopted ASU 2017-12 on January 1, 2019 and the standard did not have a material impact on its consolidated financial statements. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) ​ Adoption of ASU 2016-02 resulted in the recognition of right-of-use assets and lease liabilities for operating leases of $18.1 million on its consolidated balance sheet as of March 31, 2019, with no material impact on its consolidated statement of stockholders’ equity or consolidated statements of operations. See Note 9 for additional information and disclosure on our leases. ​ NRCG Merger ​ On June 23, 2019, US Ecology, Inc. entered into an Agreement and Plan of Merger (the “Merger Agreement”) with NRC Group Holdings Corp., a Delaware corporation (“NRCG”), US Ecology Holdings, Inc. (f/k/a US Ecology, Inc.) (“Predecessor US Ecology”), Rooster Merger Sub, Inc., a Delaware corporation (“NRCG Merger Sub”), and ECOL Merger Sub, Inc., a Delaware corporation (“ECOL Merger Sub”). ​ On November 1, 2019, pursuant to and subject to the conditions set forth in the Merger Agreement, ECOL Merger Sub merged with and into US Ecology Holdings, Inc. (“Predecessor US Ecology”) (the “ECOL Merger”), with Predecessor US Ecology continuing as the surviving company and as a wholly-owned subsidiary of the Company. Substantially concurrently therewith, NRCG Merger Sub merged with and into NRCG (the “NRCG Merger,” and, together with the ECOL Merger, the “Mergers”), with NRCG continuing as the surviving company and as a wholly-owned subsidiary of the Company. Following the completion of the Mergers, the Company contributed all of the issued and outstanding equity interests of NRCG to Predecessor US Ecology so that, after such contribution, NRCG became a wholly-owned subsidiary of Predecessor US Ecology. ​ In the ECOL Merger, each share of common stock, par value $0.01 per share, of Predecessor US Ecology (“Predecessor US Ecology Common Stock”) issued and outstanding immediately prior to the Effective Time (other than cancelled shares) was converted into one share of common stock, par value $0.01 per share, of the Company (“Company Common Stock”). Each share of Predecessor US Ecology Common Stock that was held by Predecessor US Ecology as treasury stock or that was owned by Predecessor US Ecology, ECOL Merger Sub, or any other subsidiary of the Company, immediately prior to the effective time of the Mergers (the “Effective Time”) ceased to be outstanding and was cancelled and ceased to exist, and no consideration was delivered in exchange therefor. At the Effective Time, outstanding equity awards of Predecessor US Ecology were automatically assumed by the Company and converted into equity awards of the Company on a one-for-one basis as set forth in the Merger Agreement. ​ In the NRCG Merger, each share of common stock, par value $0.0001 per share, of NRCG (“NRCG Common Stock”) issued and outstanding immediately prior to the Effective Time (other than cancelled shares) was converted into: (1) 0.196 (the “NRCG Exchange Ratio”) of a share of Company Common Stock, (2) cash in lieu of fractional shares of Company Common Stock payable pursuant to the Merger Agreement and (3) any dividends or other distributions to which the holder thereof became entitled to upon the surrender of such shares of NRCG Common Stock in accordance with the Merger Agreement. Outstanding shares of NRCG equity awards were converted into equity awards of the Company pursuant to the mechanics set forth in the Merger Agreement. In the NRCG Merger, each share of NRCG Common Stock that was held by NRCG as treasury stock or that is owned by NRCG, NRCG Merger Sub or any other subsidiary of Predecessor US Ecology or NRCG immediately prior to the Effective Time ceased to be outstanding and was cancelled and ceased to exist, and no consideration was delivered in exchange therefor. At the Effective Time, outstanding equity awards of NRCG were automatically assumed by the Company and converted into equity awards of the Company pursuant to the terms of the Merger Agreement. ​ In addition, in the NRCG Merger, each share of 7.00% Series A Convertible Cumulative Preferred Stock, par value $0.0001 per share, of NRCG (the “NRCG Series A Preferred Stock”) was converted into, and became exchangeable for 1.7506 shares of Company Common Stock in accordance with the Merger Agreement. ​ At the closing of the NRCG Merger, in respect of each outstanding warrant to purchase NRCG Common Stock (each, a “NRCG Warrant”) issued pursuant to that certain Warrant Agreement, dated as of June 22, 2017 (the “NRCG Warrant Agreement”), between Continental Stock Transfer & Trust Company and NRCG, the Company issued a replacement warrant (each, a “Replacement Warrant”) to each holder of such NRCG Warrant that complies with and satisfies that applicable terms and conditions under the NRCG Warrant Agreement and is exercisable for a number of shares of Company Common Stock equal to the product (rounded to the nearest whole number) of (1) the number of shares of NRCG Common Stock that would have been issuable upon the exercise of the NRCG Warrant immediately prior to the effective time of the NRCG Merger and (2) the NRCG Exchange Ratio, at an exercise price equal to $58.67. ​ At the Effective Time, Predecessor US Ecology caused all shares of the Company issued and outstanding immediately prior to the Effective Time to be surrendered and cancelled and cease to exist, with no consideration delivered in exchange therefor. ​ Effective as of the close of market on October 31, 2019, each of the Predecessor US Ecology Common Stock, the NRCG Common Stock and the NRCG Warrants ceased to be traded on the Nasdaq Global Select Market and NYSE American, respectively. As a consequence of the Mergers, Form 25s were filed to (i) remove of the Predecessor US Ecology Common Stock from listing and registration on Nasdaq and from registration under the Exchange Act and (ii) remove the NRCG Common Stock and NRCG Warrants from listing and registration on NYSE American, and each of Predecessor US Ecology and NRCG intend to file a Form 15 with the SEC to terminate the registration under the Exchange Act of the Predecessor US Ecology Common Stock and the NRCG Common Stock and NRCG Warrants, respectively, and suspend all of their respective reporting obligations under Section 15(d) of the Exchange Act. ​ Effective as of November 1, 2019, the Company changed its name from “US Ecology Parent, Inc.” to “US Ecology, Inc.,” the Company Common Stock and the Replacement Warrants began trading on the Nasdaq Global Select Market under the symbol “ECOL” and “ECOLW,” respectively. Also effective as of November 1, 2019, Predecessor US Ecology changed its name from “US Ecology, Inc.” to “US Ecology Holdings, Inc.” ​ See Note 18 for additional information on the NRCG Merger. ​

REVENUES

REVENUES	9 Months Ended
	Sep. 30, 2019
REVENUES
REVENUES	NOTE 2. REVENUES ​ Our operations are managed in two reportable segments, Environmental Services and Field & Industrial Services, reflecting our internal reporting structure and nature of services offered. See Note 17 for additional information on our operating segments. ​ Effective December 31, 2018, we changed our presentation of disaggregated revenues to align with changes in how we manage our service lines within our Field & Industrial Services segment. Revenues previously combined and reported as Technical Services are now disaggregated into two service lines, Small Quantity Generation (“SQG”) and Total Waste Management (“TWM”) and certain revenues formerly classified as Technical Services are now included in Remediation. Also, marine terminal services revenues, formerly classified as Other, are now included in Industrial Services. Effective January 1, 2019, Emergency Response revenues, formerly classified as Other, are now presented as a discrete service line. We also conformed the allocation of intercompany revenues between Treatment & Disposal Revenue and Services Revenue to be consistent across both segments. Throughout this Quarterly Report on Form 10-Q, our disaggregated revenues for all periods presented have been recast to reflect these changes. ​ The following table presents our revenue disaggregated by our reportable segments and service lines: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, 2019 ​ ​ ​ ​ Field & ​ ​ ​ ​ ​ Environmental ​ Industrial ​ ​ ​ $s in thousands Services Services Total Treatment & Disposal Revenue (1) ​ $ 98,554 ​ $ 3,312 ​ $ 101,866 Services Revenue: ​ ​ ​ ​ ​ ​ ​ ​ ​ Transportation and Logistics (2) ​ ​ 23,658 ​ ​ 12,070 ​ ​ 35,728 Industrial Services (3) ​ ​ — ​ ​ 4,850 ​ ​ 4,850 Small Quantity Generation (4) ​ ​ — ​ ​ 10,001 ​ ​ 10,001 Total Waste Management (5) ​ ​ — ​ ​ 8,674 ​ ​ 8,674 Remediation (6) ​ ​ — ​ ​ 1,388 ​ ​ 1,388 Emergency Response (7) ​ ​ — ​ ​ 3,294 ​ ​ 3,294 Other (8) ​ ​ — ​ ​ 1,601 ​ ​ 1,601 Revenue ​ $ 122,212 ​ $ 45,190 ​ $ 167,402 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, 2018 ​ ​ ​ ​ Field & ​ ​ ​ ​ ​ Environmental ​ Industrial ​ ​ ​ $s in thousands Services Services Total Treatment & Disposal Revenue (1) ​ $ 82,768 ​ $ 3,221 ​ $ 85,989 Services Revenue: ​ ​ ​ ​ ​ ​ ​ ​ ​ Transportation and Logistics (2) ​ ​ 24,429 ​ ​ 9,345 ​ ​ 33,774 Industrial Services (3) ​ ​ — ​ ​ 6,052 ​ ​ 6,052 Small Quantity Generation (4) ​ ​ — ​ ​ 8,611 ​ ​ 8,611 Total Waste Management (5) ​ ​ — ​ ​ 10,054 ​ ​ 10,054 Remediation (6) ​ ​ — ​ ​ 2,296 ​ ​ 2,296 Emergency Response (7) ​ ​ — ​ ​ 2,794 ​ ​ 2,794 Other (8) ​ ​ — ​ ​ 1,846 ​ ​ 1,846 Revenue ​ $ 107,197 ​ $ 44,219 ​ $ 151,416 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2019 ​ ​ ​ ​ Field & ​ ​ ​ ​ ​ Environmental ​ Industrial ​ ​ ​ $s in thousands Services Services Total Treatment & Disposal Revenue (1) ​ $ 266,646 ​ $ 9,241 ​ $ 275,887 Services Revenue: ​ ​ ​ ​ ​ ​ ​ ​ ​ Transportation and Logistics (2) ​ ​ 60,743 ​ ​ 31,922 ​ ​ 92,665 Industrial Services (3) ​ ​ — ​ ​ 15,830 ​ ​ 15,830 Small Quantity Generation (4) ​ ​ — ​ ​ 27,516 ​ ​ 27,516 Total Waste Management (5) ​ ​ — ​ ​ 25,393 ​ ​ 25,393 Remediation (6) ​ ​ — ​ ​ 4,003 ​ ​ 4,003 Emergency Response (7) ​ ​ — ​ ​ 9,520 ​ ​ 9,520 Other (8) ​ ​ — ​ ​ 3,427 ​ ​ 3,427 Revenue ​ $ 327,389 ​ $ 126,852 ​ $ 454,241 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2018 ​ ​ ​ ​ Field & ​ ​ ​ ​ ​ Environmental ​ Industrial ​ ​ ​ $s in thousands Services Services Total Treatment & Disposal Revenue (1) ​ $ 233,570 ​ $ 8,770 ​ $ 242,340 Services Revenue: ​ ​ ​ ​ ​ ​ ​ ​ ​ Transportation and Logistics (2) ​ ​ 59,058 ​ ​ 22,593 ​ ​ 81,651 Industrial Services (3) ​ ​ — ​ ​ 14,437 ​ ​ 14,437 Small Quantity Generation (4) ​ ​ — ​ ​ 26,075 ​ ​ 26,075 Total Waste Management (5) ​ ​ — ​ ​ 29,295 ​ ​ 29,295 Remediation (6) ​ ​ — ​ ​ 8,454 ​ ​ 8,454 Emergency Response (7) ​ ​ — ​ ​ 4,185 ​ ​ 4,185 Other (8) ​ ​ — ​ ​ 1,950 ​ ​ 1,950 Revenue ​ $ 292,628 ​ $ 115,759 ​ $ 408,387 (1) We categorize our treatment and disposal revenue as either “Base Business” or “Event Business” based on the underlying nature of the revenue source. We define Event Business as non-recurring projects that are expected to equal or exceed 1,000 tons, with Base Business defined as all other business not meeting the definition of Event Business. For the three months ended September 30, 2019 and 2018, 25% and 22% , respectively, of our treatment and disposal revenue was derived from Event Business projects. Base Business revenue accounted for 75% and 78% of our treatment and disposal revenue for the three months ended September 30, 2019 and 2018, respectively. For the nine months ended September 30, 2019 and 2018, 22% and 20% , respectively, of our treatment and disposal revenue was derived from Event Business projects. Base Business revenue accounted for 78% and 80% of our treatment and disposal revenue for the nine months ended September 30, 2019 and 2018, respectively. (2) Includes collection and transportation of non-hazardous and hazardous waste. (3) Includes industrial cleaning and maintenance for refineries, chemical plants, steel and automotive plants, marine terminals and refinery services such as tank cleaning and temporary storage. (4) Includes retail services, laboratory packing, less-than-truck-load service and household hazardous waste collection. Contracts for Small Quantity Generation may extend beyond one year and a portion of the transaction price can be fixed. (5) Through our TWM program, customers outsource the management of their waste compliance program to us, allowing us to organize and coordinate their waste management disposal activities and environmental compliance. TWM contracts may extend beyond one year and a portion of the transaction price can be fixed. (6) Includes site assessment, onsite treatment, project management and remedial action planning and execution. Contracts for Remediation may extend beyond one year and a portion of the transaction price can be fixed. (7) Includes spill response, waste analysis and treatment and disposal planning. (8) Includes equipment rental and other miscellaneous services. ​ We provide services in the United States and Canada. The following table presents our revenue disaggregated by our reportable segments and geographic location where the underlying services were performed: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, 2019 ​ Three Months Ended September 30, 2018 ​ ​ ​ ​ Field & ​ ​ ​ ​ ​ ​ Field & ​ ​ ​ ​ ​ Environmental ​ Industrial ​ ​ ​ ​ Environmental ​ Industrial ​ ​ ​ $s in thousands Services Services ​ Total ​ Services Services ​ Total United States ​ $ 99,554 ​ $ 44,332 ​ $ 143,886 ​ $ 85,183 ​ $ 44,219 ​ $ 129,402 Canada ​ 22,658 ​ 858 ​ 23,516 ​ 22,014 ​ — ​ 22,014 Total revenue ​ $ 122,212 ​ $ 45,190 ​ $ 167,402 ​ $ 107,197 ​ $ 44,219 ​ $ 151,416 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2019 ​ Nine Months Ended September 30, 2018 ​ ​ ​ ​ Field & ​ ​ ​ ​ ​ ​ Field & ​ ​ ​ ​ ​ Environmental ​ Industrial ​ ​ ​ ​ Environmental ​ Industrial ​ ​ ​ $s in thousands Services Services ​ Total ​ Services Services ​ Total United States ​ $ 262,699 ​ $ 125,994 ​ $ 388,693 ​ $ 245,086 ​ $ 115,759 ​ $ 360,845 Canada ​ 64,690 ​ 858 ​ 65,548 ​ 47,542 ​ — ​ 47,542 Total revenue ​ $ 327,389 ​ $ 126,852 ​ $ 454,241 ​ $ 292,628 ​ $ 115,759 ​ $ 408,387 ​ Deferred Revenue We record deferred revenue when cash payments are received, or advance billings are charged, prior to performance of services. Deferred revenue includes waste that has been received but not yet treated or disposed, and is recognized when services are performed. During the three months ended September 30, 2019 and 2018, we recognized $738,000 and $496,000 of revenue, respectively, that was included in the deferred revenue balance at the beginning of each year. During the nine months ended September 30, 2019 and 2018, we recognized $9.7 million and $8.3 million of revenue, respectively, that was included in the deferred revenue balance at the beginning of each year. ​ Receivables ​ Our receivables include invoiced and unbilled amounts where the Company has an unconditional right to payment. ​ Principal versus Agent Considerations ​ The Company commonly contracts with third-parties to perform certain waste-related services that we have promised in our customer contracts. We consider ourselves the principal in these arrangements as we direct the timing, nature and pricing of the services ultimately provided by the third-party to the customer. ​ Costs to obtain a contract ​ The Company pays sales commissions to employees, which qualify as costs to obtain a contract. Sales commissions are expensed as incurred as the commissions are earned by the employee and paid by the Company over time as the related revenue is recognized. ​ Practical Expedients and Optional Exemptions ​ Our payment terms may vary based on type of service or customer; however, we do not adjust the promised amount of consideration in our contracts for the time value of money as payment terms extended to our customers do not exceed one year and are not considered a significant financing component in our contracts. ​ We do not disclose the value of unsatisfied performance obligations as contracts with an original expected length of more than one year and contracts for which we do not recognize revenue at the amount to which we have the right to invoice for services performed is insignificant and the aggregate amount of fixed consideration allocated to unsatisfied performance obligations is not material.

BUSINESS COMBINATIONS

BUSINESS COMBINATIONS	9 Months Ended
	Sep. 30, 2019
BUSINESS COMBINATIONS
BUSINESS COMBINATIONS	NOTE 3. BUSINESS COMBINATIONS ​ NRC Group Holdings Corp. ​ On November 1, 2019, we completed our previously announced merger transaction with NRCG. See Note 1 and Note 18 for additional information. ​ W.I.S.E. Environmental Solutions Inc. ​ On August 1, 2019, we acquired 100% of the outstanding shares of W.I.S.E. Environmental Services Inc. (“US Ecology Sarnia”), an equipment rental and waste services company based in Sarnia, Ontario, Canada for 23.5 million Canadian dollars, which translated to $17.9 million at the time of transaction. The purchase price is subject to post-closing adjustments based on agreed upon working capital requirements, which are expected to be finalized and settled in the fourth quarter of 2019. US Ecology Sarnia is reported as part of our Field & Industrial Services segment. The Company assessed the revenues, net income, earnings per share and total assets of US Ecology Sarnia and concluded they are not material to our consolidated financial position or results of operations. ​ We allocated the purchase price to the assets acquired and liabilities assumed based on estimates of the fair value at the date of the acquisition, resulting in $9.0 million allocated to goodwill and $4.3 million allocated to intangible assets (primarily customer relationships) to be amortized over a weighted average life of approximately 14 years. All of the goodwill recognized was assigned to our Field & Industrial Services segment and is not expected to be deductible for income tax purposes. ​ Ecoserv Industrial Disposal, LLC ​ On November 14, 2018, the Company acquired Ecoserv Industrial Disposal, LLC (“Winnie”), which provides non-hazardous industrial wastewater disposal solutions and employs deep-well injection technology in the southern United States. ​ The following table summarizes the consideration paid for Winnie and the fair value estimates of assets acquired and liabilities assumed, recognized at the acquisition date, with purchase price allocation adjustments since the preliminary purchase price allocation as previously disclosed as of December 31, 2018: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Purchase Price Allocation ​ ​ December 31, ​ ​ ​ ​ September 30, $s in thousands 2018 ​ Adjustments ​ 2019 Current assets ​ $ 1,923 ​ $ (63) ​ $ 1,860 Property and equipment ​ ​ 6,300 ​ ​ (2,324) ​ ​ 3,976 Identifiable intangible assets ​ ​ 66,600 ​ ​ (100) ​ ​ 66,500 Current liabilities ​ ​ (755) ​ ​ — ​ ​ (755) Other liabilities ​ ​ (512) ​ ​ — ​ ​ (512) Total identifiable net assets ​ ​ 73,556 ​ ​ (2,487) ​ ​ 71,069 Goodwill ​ ​ 13,573 ​ ​ 2,586 ​ ​ 16,159 Total purchase price ​ $ 87,129 ​ $ 99 ​ $ 87,228 ​ Purchase price allocation adjustments relate primarily to the receipt of additional information regarding the fair values of property and equipment, a post-closing price adjustment based on working capital requirements and residual goodwill.

ACCUMULATED OTHER COMPREHENSIVE

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	9 Months Ended
	Sep. 30, 2019
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS).
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	NOTE 4. ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) ​ Changes in accumulated other comprehensive income (loss) (“AOCI”) consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Foreign ​ Unrealized Gain ​ ​ ​ ​ ​ Currency ​ (Loss) on Interest ​ ​ ​ $s in thousands Translation Rate Hedge Total Balance at December 31, 2018 ​ $ (14,697) ​ $ 906 ​ $ (13,791) Other comprehensive income (loss) before reclassifications, net of tax ​ 2,374 ​ (1,780) ​ 594 Amounts reclassified out of AOCI, net of tax (1) ​ — ​ (238) ​ (238) Other comprehensive income, net ​ 2,374 ​ (2,018) ​ 356 Balance at September 30, 2019 ​ $ (12,323) ​ $ (1,112) ​ $ (13,435) (1) Before-tax reclassifications of $ 35,000 ($27,000 after-tax) and $301,000 ($238,000 after-tax) for the three and nine months ended September 30, 2019, respectively, were included as a reduction of Interest expense in the Company’s consolidated statements of operations. Amounts relate to the Company’s interest rate swap which is designated as a cash flow hedge. Changes in fair value of the swap recognized in AOCI are reclassified to interest expense when hedged interest payments on the underlying long-term debt are made. Amounts in AOCI expected to be recognized as a reduction of interest expense over the next 12 months total approximately $ 139,000 ($110,000 after-tax). ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Foreign ​ Unrealized Gain ​ ​ ​ ​ ​ Currency ​ (Loss) on Interest ​ ​ ​ $s in thousands Translation Rate Hedge Total Balance at December 31, 2017 ​ $ (8,603) ​ $ (501) ​ $ (9,104) Other comprehensive income (loss) before reclassifications, net of tax ​ (1,878) ​ 2,310 ​ 432 Amounts reclassified out of AOCI, net of tax (2) ​ — ​ 341 ​ 341 Other comprehensive income, net ​ (1,878) ​ 2,651 ​ 773 Balance at September 30, 2018 ​ $ (10,481) ​ $ 2,150 ​ $ (8,331) (2) Before-tax reclassifications of $40,000 ($31,000 after-tax) and $432,000 ($341,000 after-tax) for the three and nine months ended September 30, 2018, respectively, were included in Interest expense in the Company’s consolidated statements of operations. Amounts relate to the Company’s interest rate swap which is designated as a cash flow hedge. Changes in fair value of the swap recognized in AOCI are reclassified to interest expense when hedged interest payments on the underlying long-term debt are made.

CONCENTRATIONS AND CREDIT RISK

CONCENTRATIONS AND CREDIT RISK	9 Months Ended
	Sep. 30, 2019
CONCENTRATIONS AND CREDIT RISK
CONCENTRATIONS AND CREDIT RISK	NOTE 5. CONCENTRATIONS AND CREDIT RISK ​ Major Customers ​ No customer accounted for more than 10% of total revenue for the three or nine months ended September 30, 2019 or 2018, respectively. No customer accounted for more than 10% of total trade receivables as of September 30, 2019 or December 31, 2018. ​ Credit Risk Concentration ​ We maintain most of our cash and cash equivalents with nationally recognized financial institutions. Substantially all balances are uninsured and are not used as collateral for other obligations. Concentrations of credit risk on accounts receivable are believed to be limited due to the number, diversification and character of the obligors and our credit evaluation process. ​

RECEIVABLES

RECEIVABLES	9 Months Ended
	Sep. 30, 2019
RECEIVABLES
RECEIVABLES	NOTE 6. RECEIVABLES ​ Receivables consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, $s in thousands ​ 2019 2018 Trade ​ $ 117,913 ​ $ 118,909 Unbilled revenue ​ 30,810 ​ 26,538 Other ​ 9,739 ​ 2,241 Total receivables ​ 158,462 ​ 147,688 Allowance for doubtful accounts ​ (2,636) ​ (2,998) Receivables, net ​ $ 155,826 ​ $ 144,690 ​

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	9 Months Ended
	Sep. 30, 2019
FAIR VALUE MEASUREMENTS
FAIR VALUE MEASUREMENTS	NOTE 7. FAIR VALUE MEASUREMENTS ​ Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Assets and liabilities recorded at fair value are categorized using defined hierarchical levels directly related to the amount of subjectivity associated with the inputs to fair value measurements, as follows: ​ Level 1 - Quoted prices in active markets for identical assets or liabilities; ​ Level 2 - Inputs other than quoted prices included within Level 1 that are either directly or indirectly observable; ​ Level 3 - Unobservable inputs in which little or no market activity exists, requiring an entity to develop its own assumptions that market participants would use to value the asset or liability. ​ The Company’s financial instruments consist of cash and cash equivalents, accounts receivable, restricted cash and investments, accounts payable, accrued liabilities, debt and interest rate swap agreements. The estimated fair value of cash and cash equivalents, accounts receivable, accounts payable and accrued liabilities approximate their carrying value due to the short-term nature of these instruments. ​ On September 19, 2019, the Company invested $7.9 million in the preferred stock of a privately held company which is included in Other assets in the Company’s consolidated balance sheets. The investment does not have a readily determinable fair value therefore the investment is valued at cost, less impairment, plus or minus observable price changes of an identical or similar investment of the same issuer, if any. As of September 30, 2019, there have been no identified events or changes in circumstances that would indicate the cost method investment should be impaired nor have there been any observable price changes of an identical or similar investment of the same issuer. ​ The Company estimates the fair value of its variable-rate debt using Level 2 inputs, such as interest rates, related terms and maturities of similar obligations. At September 30, 2019, the carrying value of the Company’s variable-rate debt approximates fair value due to the short-term nature of the interest rates. ​ The Company’s assets and liabilities measured at fair value on a recurring basis consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2019 ​ ​ Quoted Prices in ​ Other Observable ​ Unobservable ​ ​ ​ ​ ​ Active Markets ​ Inputs ​ Inputs ​ ​ ​ $s in thousands (Level 1) (Level 2) (Level 3) Total Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fixed-income securities (1) ​ $ 1,980 ​ $ 2,224 ​ $ — ​ $ 4,204 Money market funds (2) ​ ​ 841 ​ ​ — ​ ​ — ​ ​ 841 Total ​ $ 2,821 ​ $ 2,224 ​ $ — ​ $ 5,045 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Interest rate swap agreement (3) ​ $ — ​ $ 1,408 ​ $ — ​ $ 1,408 Total ​ $ — ​ $ 1,408 ​ $ — ​ $ 1,408 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2018 ​ ​ Quoted Prices in ​ Other Observable ​ Unobservable ​ ​ ​ ​ ​ Active Markets ​ Inputs ​ Inputs ​ ​ ​ $s in thousands (Level 1) (Level 2) (Level 3) Total Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fixed-income securities (1) ​ $ 1,561 ​ $ 2,596 ​ $ — ​ $ 4,157 Money market funds (2) ​ ​ 784 ​ ​ — ​ ​ — ​ ​ 784 Interest rate swap agreement (3) ​ ​ — ​ ​ 1,147 ​ ​ ​ ​ ​ 1,147 Total ​ $ 2,345 ​ $ 3,743 ​ $ — ​ $ 6,088 (1) We invest a portion of our Restricted cash and investments in fixed-income securities, including U.S. Treasury and U.S. agency securities. We measure the fair value of U.S. Treasury securities using quoted prices for identical assets in active markets. We measure the fair value of U.S. agency securities using observable market activity for similar assets. The fair value of our fixed-income securities approximates our cost basis in the investments. ​ (2) We invest a portion of our Restricted cash and investments in money market funds. We measure the fair value of these money market fund investments using quoted prices for identical assets in active markets. Money market funds are considered restricted cash for purposes of reconciling the beginning-of-period and end-of-period amounts presented in the Company’s consolidated statements of cash flows. ​ (3) In order to manage interest rate exposure, we entered into an interest rate swap agreement in October 2014 that effectively converts a portion of our variable-rate debt to a fixed interest rate. The swap is designated as a cash flow hedge, with gains and losses deferred in other comprehensive income to be recognized as an adjustment to interest expense in the same period that the hedged interest payments affect earnings. The interest rate swap has an effective date of December 31, 2014 with an initial notional amount of $250.0 million. The fair value of the interest rate swap agreement represents the difference in the present value of cash flows calculated at the contracted interest rates and at current market interest rates at the end of the period. We calculate the fair value of the interest rate swap agreement quarterly based on the quoted market price for the same or similar financial instruments. The fair value of the interest rate swap agreement is included in Other long-term liabilities and Other assets in the Company’s consolidated balance sheet as of September 30, 2019 and December 31, 2018, respectively .

PROPERTY AND EQUIPMENT

PROPERTY AND EQUIPMENT	9 Months Ended
	Sep. 30, 2019
PROPERTY AND EQUIPMENT
PROPERTY AND EQUIPMENT	NOTE 8. PROPERTY AND EQUIPMENT ​ Property and equipment consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, $s in thousands ​ 2019 2018 Cell development costs ​ $ 146,861 ​ $ 146,155 Land and improvements ​ 51,997 ​ 50,481 Buildings and improvements ​ 92,389 ​ 91,358 Railcars ​ 17,299 ​ 17,299 Vehicles and other equipment ​ 169,454 ​ 154,014 Construction in progress ​ 36,303 ​ 14,554 Total property and equipment ​ 514,303 ​ 473,861 Accumulated depreciation and amortization ​ (240,522) ​ (215,418) Property and equipment, net ​ $ 273,781 ​ $ 258,443 ​ Depreciation and amortization expense for the three months ended September 30, 2019 and 2018 was $9.4 million and $7.3 million, respectively. Depreciation and amortization expense for the nine months ended September 30, 2019 and 2018 was $26.7 million and $21.0 million, respectively.

LEASES

LEASES	9 Months Ended
	Sep. 30, 2019
LEASES
LEASES	NOTE 9. LEASES ​ We lease certain facilities, office space, land and equipment. Our lease payments are primarily fixed, but also include variable payments that are based on usage of the leased asset. Initial lease terms range from one to 15 years, and may include one or more options to renew, with renewal terms extending a lease up to 40 years. None of our renewal options are considered reasonably certain to be exercised. Provisions for residual value guarantees exist in some of our equipment leases, however amounts associated with these provisions are not material. Our leases do not include any material restrictive covenants. ​ Leases with an initial term of 12 months or less are not recorded on the balance sheet and expense is recognized on a straight-line basis over the lease term. We combine lease and nonlease components in our leases, except for equipment leases that include maintenance related services. We use the rate implicit in the lease, when available, to discount lease payments to present value. However, many of our leases do not provide a readily determinable implicit rate and we estimate our incremental borrowing rate to discount payments based on information available at lease commencement. ​ Lease assets and liabilities consisted of the following: ​ ​ ​ ​ ​ $s in thousands September 30, 2019 Assets: ​ ​ ​ Operating right-of-use assets (1) ​ $ 17,496 Finance right-of-use assets (2) ​ ​ 2,780 Total ​ $ 20,276 ​ ​ ​ ​ Liabilities: ​ ​ ​ Current: ​ ​ ​ Operating (3) ​ $ 4,914 Finance (4) ​ ​ 774 Long-term: ​ ​ ​ Operating (5) ​ ​ 12,590 Finance (6) ​ ​ 2,118 Total ​ $ 20,396 (1) Included in Operating lease assets in the Company’s consolidated balance sheets. (2) Included in Property and equipment, net in the Company’s consolidated balance sheets. Finance right-of-use assets are recorded net of accumulated amortization of $1.8 million as of September 30, 2019. (3) Included in Current portion of operating lease liabilities in the Company’s consolidated balance sheets. (4) Included in Accrued liabilities in the Company’s consolidated balance sheets. (5) Included in Long-term operating lease liabilities in the Company’s consolidated balance sheets. (6) Included in Other long-term liabilities in the Company’s consolidated balance sheets. ​ Lease expense consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended $s in thousands September 30, 2019 September 30, 2019 Operating lease cost (1) ​ $ 1,691 ​ $ 5,146 Finance lease cost: ​ ​ ​ ​ ​ ​ Amortization of leased assets (2) ​ ​ 249 ​ ​ 725 Interest on lease liabilities (3) ​ ​ 28 ​ ​ 78 Total ​ $ 1,968 ​ $ 5,949 (1) Included in Direct operating costs and Selling, general, and administrative expenses in the Company’s consolidated statements of operations. Operating lease cost includes short-term leases, excluding expenses relating to leases with a term of one month or less, which are not material. Operating lease cost excludes variable lease costs which are not material. (2) Included in Direct operating costs in the Company’s consolidated statements of operations. (3) Included in Interest expense in the Company’s consolidated statements of operations. ​ Supplemental cash flow information related to our leases is as follows: ​ ​ ​ ​ ​ ​ ​ Nine Months Ended $s in thousands September 30, 2019 Cash paid for amounts included in the measurement of lease liabilities: ​ ​ ​ Operating cash flows from operating leases ​ $ 4,868 Operating cash flows from finance leases ​ ​ 78 Financing cash flows from finance leases ​ ​ 619 ​ ​ ​ ​ Non-cash investing and financing activities: ​ ​ ​ Right-of-use assets obtained in exchange for new operating lease liabilities ​ $ 3,817 Right-of-use assets obtained in exchange for new finance lease liabilities ​ ​ 1,844 ​ Other information related to our leases is as follows: ​ ​ ​ ​ ​ ​ ​ September 30, 2019 Weighted-average remaining lease term (years): ​ ​ ​ ​ Operating leases ​ ​ 5.5 ​ Finance leases ​ ​ 3.5 ​ Weighted-average discount rate: ​ ​ ​ ​ Operating leases ​ ​ 4.38 % Finance leases ​ ​ 3.80 % ​ The Company’s maturity analysis of its lease liabilities as of September 30, 2019 is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating ​ Finance ​ ​ $s in thousands Leases ​ Leases ​ Total 2019 (excluding the nine months ended September 30, 2019) ​ $ 1,546 ​ $ 242 ​ $ 1,788 2020 ​ ​ 4,584 ​ ​ 792 ​ ​ 5,376 2021 ​ 4,035 ​ 619 ​ 4,654 2022 ​ 2,589 ​ 548 ​ 3,137 2023 ​ 2,092 ​ 612 ​ 2,704 Thereafter ​ 5,209 ​ 354 ​ 5,563 Total ​ $ 20,055 ​ $ 3,167 ​ $ 23,222 Less: Interest ​ ​ 2,551 ​ ​ 275 ​ ​ 2,826 Present value of lease liabilities ​ $ 17,504 ​ $ 2,892 ​ $ 20,396 ​ Future minimum lease payments on non-cancellable operating leases as of December 31, 2018 are as follows: ​ ​ ​ ​ ​ $s in thousands Payments 2019 ​ $ 5,638 2020 ​ 3,644 2021 ​ 3,184 2022 ​ 1,885 2023 ​ 1,457 Thereafter ​ 5,065 ​ ​ $ 20,873 ​

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS	9 Months Ended
	Sep. 30, 2019
GOODWILL AND INTANGIBLE ASSETS
GOODWILL AND INTANGIBLE ASSETS	NOTE 10. GOODWILL AND INTANGIBLE ASSETS ​ Changes in goodwill for the nine months ended September 30, 2019 consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Field & ​ ​ ​ ​ ​ Environmental ​ Industrial ​ ​ ​ ​ Services ​ Services ​ ​ ​ ​ ​ ​ ​ Accumulated ​ ​ ​ Accumulated ​ ​ ​ $s in thousands ​ Gross ​ Impairment ​ Gross ​ Impairment ​ Total Balance at December 31, 2018 ​ $ 162,816 ​ $ (6,870) ​ $ 51,231 ​ $ — ​ $ 207,177 US Ecology Sarnia acquisition ​ ​ — ​ ​ — ​ ​ 8,975 ​ ​ — ​ ​ 8,975 Winnie purchase price allocation adjustment ​ ​ 2,586 ​ ​ — ​ ​ — ​ ​ — ​ ​ 2,586 Foreign currency translation ​ 503 ​ ​ — ​ (60) ​ ​ — ​ 443 Balance at September 30, 2019 ​ $ 165,905 ​ $ (6,870) ​ $ 60,146 ​ $ — ​ $ 219,181 ​ Intangible assets, net consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2019 ​ December 31, 2018 ​ ​ ​ ​ ​ Accumulated ​ ​ ​ ​ ​ ​ ​ Accumulated ​ ​ ​ $s in thousands Cost Amortization Net Cost Amortization Net Amortizing intangible assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Permits, licenses and lease ​ $ 165,355 ​ $ (17,642) ​ $ 147,713 ​ $ 164,840 ​ $ (14,804) ​ $ 150,036 Customer relationships ​ ​ 103,203 ​ ​ (30,609) ​ ​ 72,594 ​ ​ 99,241 ​ ​ (25,676) ​ ​ 73,565 Technology - formulae and processes ​ 6,872 ​ (1,931) ​ 4,941 ​ 6,672 ​ (1,714) ​ 4,958 Customer backlog ​ 3,652 ​ (1,930) ​ 1,722 ​ 3,652 ​ (1,656) ​ 1,996 Developed software ​ ​ 2,891 ​ ​ (1,807) ​ ​ 1,084 ​ ​ 2,884 ​ ​ (1,581) ​ ​ 1,303 Non-compete agreements ​ 1,995 ​ (1,191) ​ 804 ​ 1,542 ​ (875) ​ 667 Internet domain and website ​ ​ 536 ​ ​ (149) ​ ​ 387 ​ ​ 536 ​ ​ (128) ​ ​ 408 Database ​ ​ 387 ​ ​ (185) ​ ​ 202 ​ ​ 384 ​ ​ (167) ​ ​ 217 Total amortizing intangible assets ​ 284,891 ​ (55,444) ​ 229,447 ​ 279,751 ​ (46,601) ​ 233,150 Non-amortizing intangible assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Permits and licenses ​ 46,408 ​ ​ — ​ 46,408 ​ 46,391 ​ ​ — ​ 46,391 Tradename ​ 128 ​ ​ — ​ ​ 128 ​ 125 ​ ​ — ​ ​ 125 Total intangible assets ​ $ 331,427 ​ $ (55,444) ​ $ 275,983 ​ $ 326,267 ​ $ (46,601) ​ $ 279,666 ​ During the nine months ended September 30, 2019, the Company acquired US Ecology Sarnia and recorded $9.0 million of goodwill and $4.3 million of amortizing intangible assets (consisting primarily of customer relationships). See Note 3 for additional information. ​ Amortization expense for the three months ended September 30, 2019 and 2018 was $2.9 million and $2.3 million, respectively. Amortization expense for the nine months ended September 30, 2019 and 2018 was $8.6 million and $6.9 million, respectively. Foreign intangible asset carrying amounts are affected by foreign currency translation.

DEBT

DEBT	9 Months Ended
	Sep. 30, 2019
DEBT
DEBT	NOTE 11. DEBT ​ Long-term debt consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, $s in thousands 2019 2018 Revolving credit facility ​ $ 354,000 ​ $ 364,000 Long-term debt ​ $ 354,000 ​ $ 364,000 ​ 2017 Credit Agreement ​ On April 18, 2017, Predecessor US Ecology, a wholly-owned subsidiary of the Company, entered into a senior secured credit agreement (the “2017 Credit Agreement”) with Wells Fargo Bank, National Association (“Wells Fargo”), as administrative agent for the lenders, swingline lender and issuing lender, and Bank of America, N.A., as an issuing lender, that provides for a $500.0 million, five-year revolving credit facility (the “Revolving Credit Facility”), including a $75.0 million sublimit for the issuance of standby letters of credit and a $25.0 million sublimit for the issuance of swingline loans used to fund short-term working capital requirements. The 2017 Credit Agreement also contains an accordion feature whereby Predecessor US Ecology may request up to $200.0 million of additional funds through an increase to the Revolving Credit Facility, through incremental term loans, or some combination thereof. As described below, the 2017 Credit Agreement was amended in November 2019 in connection with Mergers. In addition, as a result of the consummation of the Mergers, the borrower under the 2017 Credit Facility is Predecessor US Ecology, a wholly-owned subsidiary of the Company. ​ The Revolving Credit Facility provides up to $500.0 million of revolving credit loans or letters of credit with the use of proceeds restricted solely for working capital and other general corporate purposes (including acquisitions and capital expenditures). Under the Revolving Credit Facility, revolving credit loans are available based on a base rate (as defined in the 2017 Credit Agreement) or LIBOR, at Predecessor US Ecology’s option, plus an applicable margin which is determined according to a pricing grid under which the interest rate decreases or increases based on our ratio of funded debt to consolidated earnings before interest, taxes, depreciation and amortization (as defined in the 2017 Credit Agreement), as set forth in the table below: ​ Total Net Leverage Ratio LIBOR Rate Loans Interest Margin Base Rate Loans Interest Margin Equal to or greater than 3.25 to 1.00 2.00% 1.00% Equal to or greater than 2.50 to 1.00, but less than 3.25 to 1.00 1.75% 0.75% Equal to or greater than 1.75 to 1.00, but less than 2.50 to 1.00 1.50% 0.50% Equal to or greater than 1.00 to 1.00, but less than 1.75 to 1.00 1.25% 0.25% Less than 1.00 to 1.00 1.00% 0.00% ​ At September 30, 2019, the effective interest rate on the Revolving Credit Facility, after giving effect to the impact of our interest rate swap, was 3.62%. Interest only payments are due either quarterly or on the last day of any interest period, as applicable. ​ In October 2014, Predecessor US Ecology entered into an interest rate swap agreement, effectively fixing the interest rate on $155.0 million, or 44%, of the Revolving Credit Facility borrowings as of September 30, 2019. ​ Predecessor US Ecology is required to pay a commitment fee ranging from 0.175% to 0.35% on the average daily unused portion of the Revolving Credit Facility, with such commitment fee to be reduced based upon Predecessor US Ecology’s total net leverage ratio (as defined in the 2017 Credit Agreement). The maximum letter of credit capacity under the Revolving Credit Facility is $75.0 million and the 2017 Credit Agreement provides for a letter of credit fee equal to the applicable margin for LIBOR loans under the Revolving Credit Facility. At September 30, 2019, there were $354.0 million of revolving credit loans outstanding on the Revolving Credit Facility. These revolving credit loans are due upon the earliest to occur of (a) April 18, 2022 (or, with respect to any lender, such later date as requested by us and accepted by such lender), (b) the date of termination of the entire revolving credit commitment (as defined in the 2017 Credit Agreement) by us, and (c) the date of termination of the revolving credit commitment and are presented as Long-term debt in the consolidated balance sheets. ​ Predecessor US Ecology has entered into a sweep arrangement whereby day-to-day cash requirements in excess of available cash balances are advanced to the Company on an as-needed basis with repayments of these advances automatically made from subsequent deposits to our cash operating accounts (the “Sweep Arrangement”). Total advances outstanding under the Sweep Arrangement are subject to the $25.0 million swingline loan sublimit under the Revolving Credit Facility. The Company’s revolving credit loans outstanding under the Revolving Credit Facility are not subject to repayment through the Sweep Arrangement. As of September 30, 2019, there were $1.5 million in borrowings outstanding subject to the Sweep Arrangement, which are presented as Short-term borrowings in the consolidated balance sheet. ​ As of September 30, 2019, the availability under the Revolving Credit Facility was $138.7 million with $5.7 million of the Revolving Credit Facility issued in the form of standby letters of credit utilized as collateral for closure and post-closure financial assurance and other assurance obligations. ​ Predecessor US Ecology may at any time and from time to time prepay revolving credit loans and swingline loans, in whole or in part, without premium or penalty, subject to the obligation to indemnify each of the lenders against any actual loss or expense (including any loss or expense arising from the liquidation or reemployment of funds obtained by it to maintain a LIBOR rate loan (as defined in the 2017 Credit Agreement) or from fees payable to terminate the deposits from which such funds were obtained) with respect to the early termination of any LIBOR rate loan. The 2017 Credit Agreement provides for mandatory prepayment at any time if the revolving credit outstanding exceeds the revolving credit commitment (as such terms are defined in the 2017 Credit Agreement), in an amount equal to such excess. Subject to certain exceptions, the 2017 Credit Agreement provides for mandatory prepayment upon certain asset dispositions, casualty events and issuances of indebtedness. ​ Pursuant to (i) an unconditional guarantee agreement and (ii) a collateral agreement, each entered into by Predecessor US Ecology and its domestic subsidiaries on April 18, 2017, Predecessor US Ecology’s obligations under the 2017 Credit Agreement are (or will be) jointly and severally and fully and unconditionally guaranteed on a senior basis by all of the Company’s existing and certain future domestic subsidiaries and are secured by substantially all of the assets of Predecessor US Ecology and the Company’s existing and certain future domestic subsidiaries (subject to certain exclusions), including 100% of the equity interests of the Company’s domestic subsidiaries and 65% of the voting equity interests of the Company’s directly owned foreign subsidiaries (and 100% of the non-voting equity interests of the Company’s directly owned foreign subsidiaries). ​ The 2017 Credit Agreement contains customary restrictive covenants, subject to certain permitted amounts and exceptions, including covenants limiting the ability of the Company to incur additional indebtedness, pay dividends and make other restricted payments, repurchase shares of our outstanding stock and create certain liens. Upon the occurrence of an event of default (as defined in the 2017 Credit Agreement), among other things, amounts outstanding under the 2017 Credit Agreement may be accelerated and the commitments may be terminated. ​ The 2017 Credit Agreement also contains financial maintenance covenants, a maximum consolidated total net leverage ratio and a consolidated interest coverage ratio (as such terms are defined in the 2017 Credit Agreement). Our consolidated total net leverage ratio as of the last day of any fiscal quarter may not exceed 3.50 to 1.00, subject to certain exceptions. Our consolidated interest coverage ratio as of the last day of any fiscal quarter may not be less than 3.00 to 1.00. ​ At September 30, 2019, we were in compliance with all of the financial covenants in the 2017 Credit Agreement. ​ Amendments to the 2017 Credit Agreement ​ On August 6, 2019, Predecessor US Ecology entered into the first amendment (the “First Amendment”) to the 2017 Credit Agreement, by and among Predecessor US Ecology, the subsidiaries of Predecessor US Ecology party thereto, the lenders referred to therein and Wells Fargo, as issuing lender, swingline lender and administrative agent. Effective November 1, 2019, the First Amendment, among other things, extended the expiration of the Revolving Credit Facility to November 1, 2024, permitted the issuance of a $400.0 million incremental term loan to be used to refinance existing indebtedness of NRCG and pay related transaction expenses in connection with the Mergers, modified the accordion feature allowing the Company to request up to the greater of (x) $250.0 million and (y) 100% of consolidated EBITDA plus certain additional amounts, increased the sublimit for the issuance of swingline loans to $40.0 million and increased the maximum consolidated total net leverage ratio to 4.00 to 1.00. ​ On November 1, 2019, Predecessor US Ecology entered into the lender joinder agreement and second amendment (the “Second Amendment”) to the 2017 Credit Agreement. Effective November 1, 2019, the Second Amendment, among other things, amended the 2017 Credit Agreement to increase the capacity for incremental term loans by $50.0 million and provided for Wells Fargo lending $450.0 million in incremental term loans to Predecessor US Ecology to pay off the existing debt of NRCG in connection with the Mergers, to pay certain fees, costs and expenses incurred in connection with the Mergers and to repay outstanding borrowings under the Revolving Credit Facility. The seven-year incremental term loan matures November 1, 2026, requires principal repayment of 1% annually, and bears interest at LIBOR plus 2.25% or a base rate plus 1.25% (with a step-up to LIBOR plus 2.50% or a base rate plus 1.50% in the event that US Ecology credit ratings are not BB (with a stable or better outlook) or better from S&P and Ba2 (with a stable or better outlook) or better from Moody’s).

CLOSURE AND POST-CLOSURE OBLIGA

CLOSURE AND POST-CLOSURE OBLIGATIONS	9 Months Ended
	Sep. 30, 2019
CLOSURE AND POST-CLOSURE OBLIGATIONS
CLOSURE AND POST-CLOSURE OBLIGATIONS	NOTE 12. CLOSURE AND POST-CLOSURE OBLIGATIONS ​ Our accrued closure and post-closure liability represents the expected future costs, including corrective actions, associated with closure and post-closure of our operating and non-operating disposal facilities. We record the fair value of our closure and post-closure obligations as a liability in the period in which the regulatory obligation to retire a specific asset is triggered. For our individual landfill cells, the required closure and post-closure obligations under the terms of our permits and our intended operation of the landfill cell are triggered and recorded when the cell is placed into service and waste is initially disposed in the landfill cell. The fair value is based on the total estimated costs to close the landfill cell and perform post-closure activities once the landfill cell has reached capacity and is no longer accepting waste. We perform periodic reviews of both non-operating and operating facilities and revise accruals for estimated closure and post-closure, remediation or other costs as necessary. Recorded liabilities are based on our best estimates of current costs and are updated periodically to include the effects of existing technology, presently enacted laws and regulations, inflation and other economic factors. ​ Changes to closure and post-closure obligations consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ $s in thousands September 30, 2019 ​ September 30, 2019 ​ Closure and post-closure obligations, beginning of period ​ $ 79,919 ​ $ 78,363 ​ Accretion expense ​ 1,139 ​ 3,397 ​ Payments ​ (638) ​ (1,413) ​ Foreign currency translation ​ (21) ​ 52 ​ Closure and post-closure obligations, end of period ​ 80,399 ​ 80,399 ​ Less current portion ​ (2,196) ​ (2,196) ​ Long-term portion ​ $ 78,203 ​ $ 78,203 ​ ​

INCOME TAXES

INCOME TAXES	9 Months Ended
	Sep. 30, 2019
INCOME TAXES
INCOME TAXES	NOTE 13. INCOME TAXES ​ Our effective tax rate for the three months ended September 30, 2019 was 33.0%, up from 20.2% for the three months ended September 30, 2018. Our effective tax rate for the nine months ended September 30, 2019 was 30.2%, up from 23.7% for the nine months ended September 30, 2018. These increases were primarily due to higher non-deductible expenses during the three and nine months ended September 30, 2019 compared to the three and nine months ended September 30, 2018. In addition, the Company implemented various one-time federal and state tax planning strategies during the three months ended September 30, 2018 that favorably impacted the effective tax rate. ​ Gross unrecognized tax benefits, included in Other long-term liabilities in the consolidated balance sheets, were $247,000 and $555,000 as of September 30, 2019 and December 31, 2018, respectively. The decrease in the gross unrecognized tax benefits was the result of the state of Idaho audit completion, as well as federal statute of limitations expirations. The gross unrecognized tax benefits, if recognized by the Company, will result in a reduction of approximately $236,000 to the provision for income taxes thereby favorably impacting the Company’s effective tax rate. We do not anticipate our total unrecognized tax benefits to increase or decrease materially within the next twelve months. We recognize interest assessed by taxing authorities or interest associated with uncertain tax positions as a component of interest expense. We recognize any penalties assessed by taxing authorities or penalties associated with uncertain tax positions as a component of Selling, general and administrative expenses. ​ We file a consolidated U.S. federal income tax return with the Internal Revenue Service (“IRS”) as well as tax returns in various states, Canada, and Mexico. The Company is subject to examination by the IRS for tax years 2015 through 2018. The Company is currently under examination by the state of Texas for the year 2014. During the third quarter of 2019, the state of Idaho examination for the years 2014 through 2018 concluded with no material changes. We may be subject to examinations by various state and local taxing jurisdictions for tax years 2014 through 2018. The tax years 2015 through 2018 remain subject to examination by foreign jurisdictions. We are currently not aware of any other significant examinations by taxing authorities. ​

EARNINGS PER SHARE

EARNINGS PER SHARE	9 Months Ended
	Sep. 30, 2019
EARNINGS PER SHARE
EARNINGS PER SHARE	NOTE 14. EARNINGS PER SHARE ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ ​ 2019 ​ 2018 $s and shares in thousands, except per share amounts Basic Diluted Basic Diluted Net income ​ $ 13,070 ​ $ 13,070 ​ $ 13,427 ​ $ 13,427 Weighted average basic shares outstanding ​ 22,013 ​ 22,013 ​ 21,928 ​ 21,928 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Dilutive effect of share-based awards ​ ​ ​ ​ 218 ​ ​ ​ ​ 171 Weighted average diluted shares outstanding ​ ​ ​ ​ 22,231 ​ ​ ​ ​ 22,099 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Earnings per share ​ $ 0.59 ​ $ 0.59 ​ $ 0.61 ​ $ 0.61 Anti-dilutive shares excluded from calculation ​ ​ ​ ​ 80 ​ ​ ​ ​ 16 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, ​ ​ 2019 ​ 2018 $s and shares in thousands, except per share amounts Basic Diluted Basic Diluted Net income ​ $ 36,604 ​ $ 36,604 ​ $ 35,890 ​ $ 35,890 Weighted average basic shares outstanding ​ 22,002 ​ 22,002 ​ 21,866 ​ 21,866 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Dilutive effect of share-based awards ​ ​ ​ ​ 210 ​ ​ ​ ​ 161 Weighted average diluted shares outstanding ​ ​ ​ ​ 22,212 ​ ​ ​ ​ 22,027 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Earnings per share ​ $ 1.66 ​ $ 1.65 ​ $ 1.64 ​ $ 1.63 Anti-dilutive shares excluded from calculation ​ ​ ​ ​ 84 ​ ​ ​ ​ 56 ​

EQUITY

EQUITY	9 Months Ended
	Sep. 30, 2019
EQUITY
EQUITY	NOTE 15. EQUITY ​ Stock Repurchase Program ​ On June 1, 2016, Predecessor US Ecology’s Board of Directors authorized the repurchase of $25.0 million of the Company’s outstanding common stock. Repurchases may be made from time to time in the open market or through privately negotiated transactions. The timing of any repurchases will be based upon prevailing market conditions and other factors. The Company did not repurchase any shares of common stock under the repurchase program during the three or nine months ended September 30, 2019. On May 29, 2018 the repurchase program was extended and will remain in effect until June 6, 2020, unless further extended by our Board of Directors. ​ Omnibus Incentive Plan ​ On May 27, 2015, our stockholders approved the Omnibus Incentive Plan (“Omnibus Plan”), which was approved by our Board of Directors on April 7, 2015. The Omnibus Plan was developed to provide additional incentives through equity ownership in the Company and, as a result, encourage employees and directors to contribute to our success. The Omnibus Plan provides, among other things, the ability for the Company to grant restricted stock, performance stock, options, stock appreciation rights, restricted stock units (“RSUs”), performance stock units (“PSUs”) and other share-based awards or cash awards to officers, employees, consultants and non-employee directors. Subsequent to the approval of the Omnibus Plan in May 2015, we stopped granting equity awards under our 2008 Stock Option Incentive Plan and our 2006 Restricted Stock Plan (collectively, the “Previous Plans”). The Previous Plans will remain in effect solely for the settlement of awards granted under the Previous Plans. No shares that are reserved but unissued under the Previous Plans or that are outstanding under the Previous Plans and reacquired by the Company for any reason will be available for issuance under the Omnibus Plan. The Omnibus Plan expires on April 7, 2025 and authorizes 1,500,000 shares of common stock for grant over the life of the Omnibus Plan. As of September 30, 2019, 873,163 shares of common stock remain available for grant under the Omnibus Plan. ​ PSUs, RSUs and Restricted Stock ​ On March 1, 2019, the Company granted 17,111 PSUs to certain employees. Each PSU represents the right to receive, on the settlement date, one share of the Company’s common stock. The total number of PSUs each participant is eligible to earn ranges from 0% to 300% of the target number of PSUs granted. The actual number of PSUs that will vest and be settled in shares is determined at the end of a three-year performance period beginning January 1, 2019, based on adjusted earnings per share and return on invested capital relative to established targets with an additional adjustment based on total stockholder return relative to a set of peer companies. The fair value of the PSUs estimated on the grant date using a Monte Carlo simulation was $58.20 per unit. Compensation expense is recorded over the awards’ vesting period. ​ Assumptions used in the Monte Carlo simulation to calculate the fair value of the PSUs granted in 2019 are as follows: ​ ​ ​ ​ ​ ​ ​ 2019 Stock price on grant date ​ $ 58.40 ​ Expected term ​ 3.0 years Expected volatility ​ ​ 30 % Risk-free interest rate ​ 2.5 % Expected dividend yield ​ 1.1 % ​ A summary of our PSU, restricted stock and RSU activity for the nine months ended September 30, 2019 is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ PSUs ​ Restricted Stock ​ RSUs ​ ​ ​ ​ Weighted ​ ​ ​ Weighted ​ ​ ​ Weighted ​ ​ ​ ​ Average ​ ​ ​ Average ​ ​ ​ Average ​ ​ ​ ​ Grant Date ​ ​ ​ Grant Date ​ ​ ​ Grant Date ​ Shares Fair Value Shares Fair Value ​ Shares Fair Value Outstanding as of December 31, 2018 39,200 ​ $ 55.48 74,988 ​ $ 46.74 ​ 66,785 ​ $ 53.77 Granted 17,111 ​ ​ 58.20 28,900 ​ ​ 62.59 ​ 33,020 ​ ​ 56.21 Vested (13,600) ​ 41.22 (39,234) ​ 43.77 ​ (29,772) ​ 51.15 Cancelled, expired or forfeited — ​ — — ​ — ​ (1,389) ​ 52.54 Outstanding as of September 30, 2019 42,711 ​ $ 61.11 64,654 ​ $ 55.62 ​ 68,644 ​ $ 56.11 ​ During the nine months ended September 30, 2019, 13,600 PSUs vested and PSU holders earned 19,414 shares of the Company’s common stock. ​ Stock Options ​ A summary of our stock option activity for the nine months ended September 30, 2019 is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ Average ​ ​ ​ ​ Exercise ​ Shares Price Outstanding as of December 31, 2018 236,503 ​ $ 44.93 Granted 41,100 ​ ​ 63.36 Exercised (6,272) ​ 40.75 Cancelled, expired or forfeited (1,540) ​ 43.55 Outstanding as of September 30, 2019 269,791 ​ $ 47.84 Exercisable as of September 30, 2019 188,730 ​ $ 43.91 ​ During the nine months ended September 30, 2019, option holders tendered 3,136 options in connection with options exercised via net share settlement. ​ Treasury Stock ​ During the nine months ended September 30, 2019, the Company repurchased 14,462 shares of the Company’s common stock in connection with the net share settlement of employee equity awards at an average cost of $63.34 per share. During the nine months ended September 30, 2019, the Company issued 8,900 treasury shares related to restricted stock awards at an average cost of $57.77 per share. ​ Dividends ​ The Company paid dividends of $0.18 per common share during each of the three months ended September 30, 2019 and 2018 and paid dividends of $0.54 per common share during each of the nine months ended September 30, 2019 and 2018.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	9 Months Ended
	Sep. 30, 2019
COMMITMENTS AND CONTINGENCIES
COMMITMENTS AND CONTINGENCIES	NOTE 16. COMMITMENTS AND CONTINGENCIES ​ Litigation and Regulatory Proceedings ​ In the ordinary course of business, we are involved in judicial and administrative proceedings involving federal, state, provincial or local governmental authorities, including regulatory agencies that oversee and enforce compliance with permits. Fines or penalties may be assessed by our regulators for non-compliance. Actions may also be brought by individuals or groups in connection with permitting of planned facilities, modification or alleged violations of existing permits, or alleged damages suffered from exposure to hazardous substances purportedly released from our operated sites, as well as other litigation. We maintain insurance intended to cover property and damage claims asserted as a result of our operations. Periodically, management reviews and may establish reserves for legal and administrative matters, or other fees expected to be incurred in relation to these matters. On November 17, 2018, an explosion occurred at our Grand View, Idaho facility, resulting in one employee fatality and injuries to other employees. The incident severely damaged the facility’s primary waste-treatment building as well as surrounding waste handling, waste storage, maintenance and administrative support structures, resulting in the closure of the entire facility that remained in effect through January 2019. We resumed landfill operations at our Grand View, Idaho facility in first quarter of 2019 and resumed operations of our secondary waste-treatment facility in the second quarter of 2019. Reconstruction of the primary waste-treatment building is currently underway. In addition to conducting our own investigation into the incident, we are fully cooperating with government agencies, including Idaho Department of Environmental Quality (“IDEQ”) and the U.S. Environmental Protection Agency (“USEPA”) to support their comprehensive and independent investigations of the incident. We cannot presently estimate the potential liability related to the incident and, therefore, no amounts related to such claims have been recorded in our financial statements as of September 30, 2019. We have not been named as a defendant in any civil action relating to the incident. As a result of the Occupational Safety and Health Administration’s (“OSHA”) inspection following the incident, OSHA issued a Citation and Notification of Penalty on May 6, 2019. We are currently contesting the Citation and Notification of Penalty before the Occupational Safety and Health Review Commission and the contested penalty is not material. We maintain workers’ compensation insurance, business interruption insurance and liability insurance for personal injury, property and casualty damage. We believe that any potential third-party claims associated with the explosion, in excess of our deductibles, are expected to be resolved primarily through our insurance policies. Although we carry business interruption insurance, a disruption of our business caused by a casualty event, including the full and partial closure of our Grand View, Idaho facility, may result in the loss of business, profits or customers during the time of such closure. Accordingly, our insurance policies may not fully compensate us for these losses. ​ The Company is actively working with its insurance companies on comprehensive property and business interruption insurance claims related to the incident at our Grand View, Idaho facility in the fourth quarter of 2018. The Company has received $10.0 million of property-related insurance payments in the first nine months of 2019 and has recognized $498,000 and $9.7 million of property-related insurance recovery gains for the three and nine months ended September 30, 2019, respectively. The Company has also recognized insurance recoveries of $699,000 and $4.7 million for the three and nine months ended September 30, 2019, respectively, related to expenses incurred to continue limited operations at the facility and $2.6 million for both the three and nine months ended September 30, 2019, related to lost profits as a result of lost business or customers. ​ Other than as described above, during the period covered by this Quarterly Report on Form 10-Q, we have not been a party to any material legal proceedings.

OPERATING SEGMENTS

OPERATING SEGMENTS	9 Months Ended
	Sep. 30, 2019
OPERATING SEGMENTS
OPERATING SEGMENTS	NOTE 17. OPERATING SEGMENTS ​ Financial Information by Segment ​ Our operations are managed in two reportable segments reflecting our internal reporting structure and nature of services offered as follows: ​ Environmental Services ​ Field & Industrial Services ​ The operations not managed through our two reportable segments are recorded as “Corporate.” Corporate selling, general and administrative expenses include typical corporate items such as legal, accounting and other items of a general corporate nature. Income taxes are assigned to Corporate, but all other items are included in the segment where they originated. Inter-company transactions have been eliminated from the segment information and are not significant between segments. ​ Summarized financial information of our reportable segments is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, 2019 ​ ​ ​ ​ Field & ​ ​ ​ ​ ​ ​ ​ ​ Environmental ​ Industrial ​ ​ ​ ​ ​ ​ $s in thousands Services Services Corporate Total Revenue ​ $ 122,212 ​ $ 45,190 ​ $ — ​ $ 167,402 Depreciation, amortization and accretion ​ $ 10,790 ​ $ 2,319 ​ $ 358 ​ $ 13,467 Capital expenditures ​ $ 12,188 ​ $ 1,018 ​ $ 579 ​ $ 13,785 Total assets ​ $ 750,915 ​ $ 167,996 ​ $ 81,238 ​ $ 1,000,149 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, 2018 ​ ​ ​ ​ Field & ​ ​ ​ ​ ​ ​ ​ ​ Environmental ​ Industrial ​ ​ ​ ​ ​ ​ $s in thousands Services Services Corporate Total Revenue ​ $ 107,197 ​ $ 44,219 ​ $ — ​ $ 151,416 Depreciation, amortization and accretion ​ $ 8,903 ​ $ 1,537 ​ $ 316 ​ $ 10,756 Capital expenditures ​ $ 9,878 ​ $ 573 ​ $ 379 ​ $ 10,830 Total assets ​ $ 614,228 ​ $ 157,989 ​ $ 80,957 ​ $ 853,174 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2019 ​ ​ ​ ​ Field & ​ ​ ​ ​ ​ ​ ​ ​ Environmental ​ Industrial ​ ​ ​ ​ ​ ​ $s in thousands Services Services Corporate Total Revenue ​ $ 327,389 ​ $ 126,852 ​ $ — ​ $ 454,241 Depreciation, amortization and accretion ​ $ 30,793 ​ $ 6,601 ​ $ 1,259 ​ $ 38,653 Capital expenditures ​ $ 33,485 ​ $ 3,126 ​ $ 1,832 ​ $ 38,443 Total assets ​ $ 750,915 ​ $ 167,996 ​ $ 81,238 ​ $ 1,000,149 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2018 ​ ​ ​ ​ Field & ​ ​ ​ ​ ​ ​ ​ ​ Environmental ​ Industrial ​ ​ ​ ​ ​ ​ $s in thousands Services Services Corporate Total Revenue ​ $ 292,628 ​ $ 115,759 ​ $ — ​ $ 408,387 Depreciation, amortization and accretion ​ $ 26,089 ​ $ 4,307 ​ $ 762 ​ $ 31,158 Capital expenditures ​ $ 20,818 ​ $ 3,460 ​ $ 1,513 ​ $ 25,791 Total assets ​ $ 614,228 ​ $ 157,989 ​ $ 80,957 ​ $ 853,174 ​ ​ Adjusted Earnings Before Interest, Taxes, Depreciation and Amortization (“Adjusted EBITDA”) ​ Management uses Adjusted EBITDA as a financial measure to assess segment performance. Adjusted EBITDA is defined as net income before interest expense, interest income, income tax expense, depreciation, amortization, share-based compensation, accretion of closure and post-closure liabilities, foreign currency gain/loss, non-cash property and equipment impairment charges, non-cash goodwill and intangible asset impairment charges, property insurance recoveries and other income/expense. Adjusted EBITDA is a complement to results provided in accordance with GAAP and we believe that such information provides additional useful information to analysts, stockholders and other users to understand the Company’s operating performance. Since Adjusted EBITDA is not a measurement determined in accordance with GAAP and is thus susceptible to varying calculations, Adjusted EBITDA as presented may not be comparable to other similarly titled measures of other companies. Items excluded from Adjusted EBITDA are significant components in understanding and assessing our financial performance. Adjusted EBITDA should not be considered in isolation or as an alternative to, or substitute for, net income, cash flows generated by operations, investing or financing activities, or other financial statement data presented in the consolidated financial statements as indicators of financial performance or liquidity. Adjusted EBITDA has limitations as an analytical tool and should not be considered in isolation or a substitute for analyzing our results as reported under GAAP. Some of the limitations are: ​ ● Adjusted EBITDA does not reflect changes in, or cash requirements for, our working capital needs; ​ ● Adjusted EBITDA does not reflect our interest expense, or the requirements necessary to service interest or principal payments on our debt; ​ ● Adjusted EBITDA does not reflect our income tax expenses or the cash requirements to pay our taxes; ​ ● Adjusted EBITDA does not reflect our cash expenditures or future requirements for capital expenditures or contractual commitments; and ​ ● Although depreciation and amortization charges are non-cash charges, the assets being depreciated and amortized will often have to be replaced in the future, and Adjusted EBITDA does not reflect any cash requirements for such replacements. ​ A reconciliation of Net income to Adjusted EBITDA is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, $s in thousands 2019 2018 2019 2018 Net income ​ $ 13,070 ​ $ 13,427 ​ $ 36,604 ​ $ 35,890 Income tax expense ​ ​ 6,428 ​ ​ 3,400 ​ ​ 15,864 ​ ​ 11,178 Interest expense ​ ​ 3,891 ​ ​ 3,066 ​ ​ 11,509 ​ ​ 8,782 Interest income ​ ​ (158) ​ ​ (34) ​ ​ (567) ​ ​ (97) Foreign currency loss ​ ​ 90 ​ ​ 303 ​ ​ 613 ​ ​ 456 Other income ​ ​ (110) ​ ​ (177) ​ ​ (342) ​ ​ (2,493) Property and equipment impairment charges ​ ​ — ​ ​ — ​ ​ 25 ​ ​ — Goodwill and intangible asset impairment charges ​ ​ — ​ ​ 3,666 ​ ​ — ​ ​ 3,666 Depreciation and amortization of plant and equipment ​ ​ 9,402 ​ ​ 7,342 ​ ​ 26,656 ​ ​ 20,991 Amortization of intangible assets ​ ​ 2,926 ​ ​ 2,327 ​ ​ 8,600 ​ ​ 6,925 Share-based compensation ​ ​ 1,246 ​ ​ 1,193 ​ ​ 3,713 ​ ​ 3,272 Accretion and non-cash adjustment of closure & post-closure liabilities ​ ​ 1,139 ​ ​ 1,087 ​ ​ 3,397 ​ ​ 3,242 Property insurance recoveries ​ ​ (498) ​ ​ — ​ ​ (9,651) ​ ​ — Adjusted EBITDA ​ $ 37,426 ​ $ 35,600 ​ $ 96,421 ​ $ 91,812 ​ Adjusted EBITDA, by operating segment, is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, Nine Months Ended September 30, $s in thousands ​ 2019 2018 ​ 2019 2018 Environmental Services $ 51,409 ​ $ 43,210 $ 133,725 ​ $ 117,742 Field & Industrial Services 5,848 ​ 6,236 13,424 ​ 13,143 Corporate (19,831) ​ (13,846) (50,728) ​ (39,073) Total $ 37,426 ​ $ 35,600 $ 96,421 ​ $ 91,812 ​ Property and Equipment and Intangible Assets Outside of the United States ​ We provide services in the United States and Canada. Long-lived assets, comprised of property and equipment and intangible assets net of accumulated depreciation and amortization, by geographic location are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, $s in thousands ​ 2019 2018 United States ​ $ 491,904 ​ $ 480,322 Canada ​ 57,860 ​ 57,787 Total long-lived assets ​ $ 549,764 ​ $ 538,109 ​

SUBSEQUENT EVENTS

SUBSEQUENT EVENTS	9 Months Ended
	Sep. 30, 2019
SUBSEQUENT EVENTS
SUBSEQUENT EVENTS	NOTE 18. SUBSEQUENT EVENTS ​ Quarterly Dividend ​ On October 1, 2019, we declared a quarterly dividend of $0.18 per common share to stockholders of record on October 18, 2019. The dividend was paid using cash on hand on October 25, 2019 in an aggregate amount of $4.0 million. ​ NRCG Merger ​ As discussed above in Note 1, on November 1, 2019, upon the terms and subject to the conditions set forth in the Merger Agreement, the Mergers were completed. Following the completion of the Mergers, the Company contributed all of the issued and outstanding equity interests of NRCG to Predecessor US Ecology so that, after such contribution, NRCG became a wholly-owned subsidiary of Predecessor US Ecology. ​ Also on November 1, 2019, the Company entered into the Second Amendment to the 2017 Credit Agreement. Effective November 1, 2019, the Second Amendment, among other things, amended the 2017 Credit Agreement to increase the capacity for incremental term loans by $50.0 million and provided for Wells Fargo lending $450.0 million in incremental term loans to Predecessor US Ecology to pay off the existing debt of NRCG in connection with the Mergers, to pay certain fees, costs and expenses incurred in connection with the Mergers and to repay outstanding borrowings under the Revolving Credit Facility. The seven-year incremental term loan matures November 1, 2026, requires principal repayment of 1% annually, and bears interest at LIBOR plus 2.25% or a base rate plus 1.25% (with a step-up to LIBOR plus 2.50% or a base rate plus 1.50% in the event that US Ecology credit ratings are not BB (with a stable or better outlook) or better from S&P and Ba2 (with a stable or better outlook) or better from Moody’s). ​

GENERAL (Policies)

GENERAL (Policies)	9 Months Ended
	Sep. 30, 2019
GENERAL
Basis of Presentation	Basis of Presentation ​ The accompanying unaudited consolidated financial statements include the results of operations, financial position and cash flows of US Ecology, Inc. and its wholly-owned subsidiaries. All inter-company balances have been eliminated. Throughout these consolidated financial statements words such as “we,” “us,” “our,” “US Ecology” and “the Company” refer to US Ecology, Inc. and its subsidiaries. ​ In the opinion of management, the accompanying unaudited consolidated financial statements include all adjustments (consisting only of normal recurring adjustments) necessary to present fairly, in all material respects, the results of the Company for the periods presented. These consolidated financial statements have been prepared by the Company pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) have been omitted pursuant to the rules and regulations of the SEC. These consolidated financial statements should be read in conjunction with the consolidated financial statements and accompanying notes included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2018. The results of operations for the three and nine months ended September 30, 2019 are not necessarily indicative of the results to be expected for the entire year ending December 31, 2019. ​ The Company’s consolidated balance sheet as of December 31, 2018 has been derived from the Company’s audited consolidated balance sheet as of that date.
Use of Estimates	Use of Estimates ​ The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements, as well as the reported amounts of revenue and expenses during the reporting period. Actual results could differ materially from the estimates and assumptions that we use in the preparation of our consolidated financial statements. As it relates to estimates and assumptions in amortization rates and environmental obligations, significant engineering, operations and accounting judgments are required. We review these estimates and assumptions no less than annually. In many circumstances, the ultimate outcome of these estimates and assumptions will not be known for decades into the future. Actual results could differ materially from these estimates and assumptions due to changes in applicable regulations, changes in future operational plans and inherent imprecision associated with estimating environmental impacts far into the future.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements ​ In August 2018, the SEC adopted the final rule under SEC Release No. 33-10532, “Disclosure Update and Simplification,” adopting amendments to certain disclosure rules that were redundant, duplicative, overlapping, outdated, or superseded, in light of other SEC disclosure requirements, GAAP or changes in the information environment. In addition, the amendments expanded the disclosure requirements relating to the analysis of equity for interim financial statements. Under the amendments, an analysis of the changes in each caption of shareholders’ equity and noncontrolling interests presented in the balance sheet must be provided in a note or separate statement. The analysis must present a reconciliation of the beginning balance to the ending balance of each period for which a statement of earnings is required to be filed. The final rule was effective on November 5, 2018. The Company adopted the final rule effective for the first quarter of 2019. The adoption of the final rule did not have an impact on the Company’s consolidated financial position or results of operations. In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815). through changes to both the designation and measurement guidance for qualifying hedging relationships and the presentation of hedge results. The guidance is effective for annual and interim reporting periods beginning after December 15, 2018, with early adoption permitted. The Company adopted ASU 2017-12 on January 1, 2019 and the standard did not have a material impact on its consolidated financial statements. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) ​ Adoption of ASU 2016-02 resulted in the recognition of right-of-use assets and lease liabilities for operating leases of $18.1 million on its consolidated balance sheet as of March 31, 2019, with no material impact on its consolidated statement of stockholders’ equity or consolidated statements of operations. See Note 9 for additional information and disclosure on our leases. ​

REVENUES (Tables)

REVENUES (Tables)	9 Months Ended
	Sep. 30, 2019
REVENUES
Schedule of disaggregation of revenues	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, 2019 ​ ​ ​ ​ Field & ​ ​ ​ ​ ​ Environmental ​ Industrial ​ ​ ​ $s in thousands Services Services Total Treatment & Disposal Revenue (1) ​ $ 98,554 ​ $ 3,312 ​ $ 101,866 Services Revenue: ​ ​ ​ ​ ​ ​ ​ ​ ​ Transportation and Logistics (2) ​ ​ 23,658 ​ ​ 12,070 ​ ​ 35,728 Industrial Services (3) ​ ​ — ​ ​ 4,850 ​ ​ 4,850 Small Quantity Generation (4) ​ ​ — ​ ​ 10,001 ​ ​ 10,001 Total Waste Management (5) ​ ​ — ​ ​ 8,674 ​ ​ 8,674 Remediation (6) ​ ​ — ​ ​ 1,388 ​ ​ 1,388 Emergency Response (7) ​ ​ — ​ ​ 3,294 ​ ​ 3,294 Other (8) ​ ​ — ​ ​ 1,601 ​ ​ 1,601 Revenue ​ $ 122,212 ​ $ 45,190 ​ $ 167,402 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, 2018 ​ ​ ​ ​ Field & ​ ​ ​ ​ ​ Environmental ​ Industrial ​ ​ ​ $s in thousands Services Services Total Treatment & Disposal Revenue (1) ​ $ 82,768 ​ $ 3,221 ​ $ 85,989 Services Revenue: ​ ​ ​ ​ ​ ​ ​ ​ ​ Transportation and Logistics (2) ​ ​ 24,429 ​ ​ 9,345 ​ ​ 33,774 Industrial Services (3) ​ ​ — ​ ​ 6,052 ​ ​ 6,052 Small Quantity Generation (4) ​ ​ — ​ ​ 8,611 ​ ​ 8,611 Total Waste Management (5) ​ ​ — ​ ​ 10,054 ​ ​ 10,054 Remediation (6) ​ ​ — ​ ​ 2,296 ​ ​ 2,296 Emergency Response (7) ​ ​ — ​ ​ 2,794 ​ ​ 2,794 Other (8) ​ ​ — ​ ​ 1,846 ​ ​ 1,846 Revenue ​ $ 107,197 ​ $ 44,219 ​ $ 151,416 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2019 ​ ​ ​ ​ Field & ​ ​ ​ ​ ​ Environmental ​ Industrial ​ ​ ​ $s in thousands Services Services Total Treatment & Disposal Revenue (1) ​ $ 266,646 ​ $ 9,241 ​ $ 275,887 Services Revenue: ​ ​ ​ ​ ​ ​ ​ ​ ​ Transportation and Logistics (2) ​ ​ 60,743 ​ ​ 31,922 ​ ​ 92,665 Industrial Services (3) ​ ​ — ​ ​ 15,830 ​ ​ 15,830 Small Quantity Generation (4) ​ ​ — ​ ​ 27,516 ​ ​ 27,516 Total Waste Management (5) ​ ​ — ​ ​ 25,393 ​ ​ 25,393 Remediation (6) ​ ​ — ​ ​ 4,003 ​ ​ 4,003 Emergency Response (7) ​ ​ — ​ ​ 9,520 ​ ​ 9,520 Other (8) ​ ​ — ​ ​ 3,427 ​ ​ 3,427 Revenue ​ $ 327,389 ​ $ 126,852 ​ $ 454,241 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2018 ​ ​ ​ ​ Field & ​ ​ ​ ​ ​ Environmental ​ Industrial ​ ​ ​ $s in thousands Services Services Total Treatment & Disposal Revenue (1) ​ $ 233,570 ​ $ 8,770 ​ $ 242,340 Services Revenue: ​ ​ ​ ​ ​ ​ ​ ​ ​ Transportation and Logistics (2) ​ ​ 59,058 ​ ​ 22,593 ​ ​ 81,651 Industrial Services (3) ​ ​ — ​ ​ 14,437 ​ ​ 14,437 Small Quantity Generation (4) ​ ​ — ​ ​ 26,075 ​ ​ 26,075 Total Waste Management (5) ​ ​ — ​ ​ 29,295 ​ ​ 29,295 Remediation (6) ​ ​ — ​ ​ 8,454 ​ ​ 8,454 Emergency Response (7) ​ ​ — ​ ​ 4,185 ​ ​ 4,185 Other (8) ​ ​ — ​ ​ 1,950 ​ ​ 1,950 Revenue ​ $ 292,628 ​ $ 115,759 ​ $ 408,387 (1) We categorize our treatment and disposal revenue as either “Base Business” or “Event Business” based on the underlying nature of the revenue source. We define Event Business as non-recurring projects that are expected to equal or exceed 1,000 tons, with Base Business defined as all other business not meeting the definition of Event Business. For the three months ended September 30, 2019 and 2018, 25% and 22% , respectively, of our treatment and disposal revenue was derived from Event Business projects. Base Business revenue accounted for 75% and 78% of our treatment and disposal revenue for the three months ended September 30, 2019 and 2018, respectively. For the nine months ended September 30, 2019 and 2018, 22% and 20% , respectively, of our treatment and disposal revenue was derived from Event Business projects. Base Business revenue accounted for 78% and 80% of our treatment and disposal revenue for the nine months ended September 30, 2019 and 2018, respectively. (2) Includes collection and transportation of non-hazardous and hazardous waste. (3) Includes industrial cleaning and maintenance for refineries, chemical plants, steel and automotive plants, marine terminals and refinery services such as tank cleaning and temporary storage. (4) Includes retail services, laboratory packing, less-than-truck-load service and household hazardous waste collection. Contracts for Small Quantity Generation may extend beyond one year and a portion of the transaction price can be fixed. (5) Through our TWM program, customers outsource the management of their waste compliance program to us, allowing us to organize and coordinate their waste management disposal activities and environmental compliance. TWM contracts may extend beyond one year and a portion of the transaction price can be fixed. (6) Includes site assessment, onsite treatment, project management and remedial action planning and execution. Contracts for Remediation may extend beyond one year and a portion of the transaction price can be fixed. (7) Includes spill response, waste analysis and treatment and disposal planning. (8) Includes equipment rental and other miscellaneous services. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, 2019 ​ Three Months Ended September 30, 2018 ​ ​ ​ ​ Field & ​ ​ ​ ​ ​ ​ Field & ​ ​ ​ ​ ​ Environmental ​ Industrial ​ ​ ​ ​ Environmental ​ Industrial ​ ​ ​ $s in thousands Services Services ​ Total ​ Services Services ​ Total United States ​ $ 99,554 ​ $ 44,332 ​ $ 143,886 ​ $ 85,183 ​ $ 44,219 ​ $ 129,402 Canada ​ 22,658 ​ 858 ​ 23,516 ​ 22,014 ​ — ​ 22,014 Total revenue ​ $ 122,212 ​ $ 45,190 ​ $ 167,402 ​ $ 107,197 ​ $ 44,219 ​ $ 151,416 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2019 ​ Nine Months Ended September 30, 2018 ​ ​ ​ ​ Field & ​ ​ ​ ​ ​ ​ Field & ​ ​ ​ ​ ​ Environmental ​ Industrial ​ ​ ​ ​ Environmental ​ Industrial ​ ​ ​ $s in thousands Services Services ​ Total ​ Services Services ​ Total United States ​ $ 262,699 ​ $ 125,994 ​ $ 388,693 ​ $ 245,086 ​ $ 115,759 ​ $ 360,845 Canada ​ 64,690 ​ 858 ​ 65,548 ​ 47,542 ​ — ​ 47,542 Total revenue ​ $ 327,389 ​ $ 126,852 ​ $ 454,241 ​ $ 292,628 ​ $ 115,759 ​ $ 408,387

BUSINESS COMBINATIONS (Tables)

BUSINESS COMBINATIONS (Tables)	9 Months Ended
	Sep. 30, 2019
BUSINESS COMBINATIONS
Summary of preliminary fair value estimates of assets acquired and liabilities assumed	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Purchase Price Allocation ​ ​ December 31, ​ ​ ​ ​ September 30, $s in thousands 2018 ​ Adjustments ​ 2019 Current assets ​ $ 1,923 ​ $ (63) ​ $ 1,860 Property and equipment ​ ​ 6,300 ​ ​ (2,324) ​ ​ 3,976 Identifiable intangible assets ​ ​ 66,600 ​ ​ (100) ​ ​ 66,500 Current liabilities ​ ​ (755) ​ ​ — ​ ​ (755) Other liabilities ​ ​ (512) ​ ​ — ​ ​ (512) Total identifiable net assets ​ ​ 73,556 ​ ​ (2,487) ​ ​ 71,069 Goodwill ​ ​ 13,573 ​ ​ 2,586 ​ ​ 16,159 Total purchase price ​ $ 87,129 ​ $ 99 ​ $ 87,228

ACCUMULATED OTHER COMPREHENSI_2

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Tables)	9 Months Ended
	Sep. 30, 2019
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS).
Schedule of changes in accumulated other comprehensive income (loss)	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Foreign ​ Unrealized Gain ​ ​ ​ ​ ​ Currency ​ (Loss) on Interest ​ ​ ​ $s in thousands Translation Rate Hedge Total Balance at December 31, 2018 ​ $ (14,697) ​ $ 906 ​ $ (13,791) Other comprehensive income (loss) before reclassifications, net of tax ​ 2,374 ​ (1,780) ​ 594 Amounts reclassified out of AOCI, net of tax (1) ​ — ​ (238) ​ (238) Other comprehensive income, net ​ 2,374 ​ (2,018) ​ 356 Balance at September 30, 2019 ​ $ (12,323) ​ $ (1,112) ​ $ (13,435) (1) Before-tax reclassifications of $ 35,000 ($27,000 after-tax) and $301,000 ($238,000 after-tax) for the three and nine months ended September 30, 2019, respectively, were included as a reduction of Interest expense in the Company’s consolidated statements of operations. Amounts relate to the Company’s interest rate swap which is designated as a cash flow hedge. Changes in fair value of the swap recognized in AOCI are reclassified to interest expense when hedged interest payments on the underlying long-term debt are made. Amounts in AOCI expected to be recognized as a reduction of interest expense over the next 12 months total approximately $ 139,000 ($110,000 after-tax). ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Foreign ​ Unrealized Gain ​ ​ ​ ​ ​ Currency ​ (Loss) on Interest ​ ​ ​ $s in thousands Translation Rate Hedge Total Balance at December 31, 2017 ​ $ (8,603) ​ $ (501) ​ $ (9,104) Other comprehensive income (loss) before reclassifications, net of tax ​ (1,878) ​ 2,310 ​ 432 Amounts reclassified out of AOCI, net of tax (2) ​ — ​ 341 ​ 341 Other comprehensive income, net ​ (1,878) ​ 2,651 ​ 773 Balance at September 30, 2018 ​ $ (10,481) ​ $ 2,150 ​ $ (8,331) (2) Before-tax reclassifications of $40,000 ($31,000 after-tax) and $432,000 ($341,000 after-tax) for the three and nine months ended September 30, 2018, respectively, were included in Interest expense in the Company’s consolidated statements of operations. Amounts relate to the Company’s interest rate swap which is designated as a cash flow hedge. Changes in fair value of the swap recognized in AOCI are reclassified to interest expense when hedged interest payments on the underlying long-term debt are made.

RECEIVABLES (Tables)

RECEIVABLES (Tables)	9 Months Ended
	Sep. 30, 2019
RECEIVABLES
Schedule of receivables	​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, $s in thousands ​ 2019 2018 Trade ​ $ 117,913 ​ $ 118,909 Unbilled revenue ​ 30,810 ​ 26,538 Other ​ 9,739 ​ 2,241 Total receivables ​ 158,462 ​ 147,688 Allowance for doubtful accounts ​ (2,636) ​ (2,998) Receivables, net ​ $ 155,826 ​ $ 144,690

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	9 Months Ended
	Sep. 30, 2019
FAIR VALUE MEASUREMENTS
Schedule of assets and liabilities measured at fair value on a recurring basis	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2019 ​ ​ Quoted Prices in ​ Other Observable ​ Unobservable ​ ​ ​ ​ ​ Active Markets ​ Inputs ​ Inputs ​ ​ ​ $s in thousands (Level 1) (Level 2) (Level 3) Total Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fixed-income securities (1) ​ $ 1,980 ​ $ 2,224 ​ $ — ​ $ 4,204 Money market funds (2) ​ ​ 841 ​ ​ — ​ ​ — ​ ​ 841 Total ​ $ 2,821 ​ $ 2,224 ​ $ — ​ $ 5,045 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Interest rate swap agreement (3) ​ $ — ​ $ 1,408 ​ $ — ​ $ 1,408 Total ​ $ — ​ $ 1,408 ​ $ — ​ $ 1,408 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2018 ​ ​ Quoted Prices in ​ Other Observable ​ Unobservable ​ ​ ​ ​ ​ Active Markets ​ Inputs ​ Inputs ​ ​ ​ $s in thousands (Level 1) (Level 2) (Level 3) Total Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fixed-income securities (1) ​ $ 1,561 ​ $ 2,596 ​ $ — ​ $ 4,157 Money market funds (2) ​ ​ 784 ​ ​ — ​ ​ — ​ ​ 784 Interest rate swap agreement (3) ​ ​ — ​ ​ 1,147 ​ ​ ​ ​ ​ 1,147 Total ​ $ 2,345 ​ $ 3,743 ​ $ — ​ $ 6,088 (1) We invest a portion of our Restricted cash and investments in fixed-income securities, including U.S. Treasury and U.S. agency securities. We measure the fair value of U.S. Treasury securities using quoted prices for identical assets in active markets. We measure the fair value of U.S. agency securities using observable market activity for similar assets. The fair value of our fixed-income securities approximates our cost basis in the investments. ​ (2) We invest a portion of our Restricted cash and investments in money market funds. We measure the fair value of these money market fund investments using quoted prices for identical assets in active markets. Money market funds are considered restricted cash for purposes of reconciling the beginning-of-period and end-of-period amounts presented in the Company’s consolidated statements of cash flows. ​ (3) In order to manage interest rate exposure, we entered into an interest rate swap agreement in October 2014 that effectively converts a portion of our variable-rate debt to a fixed interest rate. The swap is designated as a cash flow hedge, with gains and losses deferred in other comprehensive income to be recognized as an adjustment to interest expense in the same period that the hedged interest payments affect earnings. The interest rate swap has an effective date of December 31, 2014 with an initial notional amount of $250.0 million. The fair value of the interest rate swap agreement represents the difference in the present value of cash flows calculated at the contracted interest rates and at current market interest rates at the end of the period. We calculate the fair value of the interest rate swap agreement quarterly based on the quoted market price for the same or similar financial instruments. The fair value of the interest rate swap agreement is included in Other long-term liabilities and Other assets in the Company’s consolidated balance sheet as of September 30, 2019 and December 31, 2018, respectively .

PROPERTY AND EQUIPMENT (Tables)

PROPERTY AND EQUIPMENT (Tables)	9 Months Ended
	Sep. 30, 2019
PROPERTY AND EQUIPMENT
Schedule of property and equipment	​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, $s in thousands ​ 2019 2018 Cell development costs ​ $ 146,861 ​ $ 146,155 Land and improvements ​ 51,997 ​ 50,481 Buildings and improvements ​ 92,389 ​ 91,358 Railcars ​ 17,299 ​ 17,299 Vehicles and other equipment ​ 169,454 ​ 154,014 Construction in progress ​ 36,303 ​ 14,554 Total property and equipment ​ 514,303 ​ 473,861 Accumulated depreciation and amortization ​ (240,522) ​ (215,418) Property and equipment, net ​ $ 273,781 ​ $ 258,443

LEASES (Tables)

LEASES (Tables)	9 Months Ended
	Sep. 30, 2019
LEASES
Summary of leased assets and liabilities	​ ​ ​ ​ ​ $s in thousands September 30, 2019 Assets: ​ ​ ​ Operating right-of-use assets (1) ​ $ 17,496 Finance right-of-use assets (2) ​ ​ 2,780 Total ​ $ 20,276 ​ ​ ​ ​ Liabilities: ​ ​ ​ Current: ​ ​ ​ Operating (3) ​ $ 4,914 Finance (4) ​ ​ 774 Long-term: ​ ​ ​ Operating (5) ​ ​ 12,590 Finance (6) ​ ​ 2,118 Total ​ $ 20,396 (1) Included in Operating lease assets in the Company’s consolidated balance sheets. (2) Included in Property and equipment, net in the Company’s consolidated balance sheets. Finance right-of-use assets are recorded net of accumulated amortization of $1.8 million as of September 30, 2019. (3) Included in Current portion of operating lease liabilities in the Company’s consolidated balance sheets. (4) Included in Accrued liabilities in the Company’s consolidated balance sheets. (5) Included in Long-term operating lease liabilities in the Company’s consolidated balance sheets. (6) Included in Other long-term liabilities in the Company’s consolidated balance sheets.
Summary of lease cost	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended $s in thousands September 30, 2019 September 30, 2019 Operating lease cost (1) ​ $ 1,691 ​ $ 5,146 Finance lease cost: ​ ​ ​ ​ ​ ​ Amortization of leased assets (2) ​ ​ 249 ​ ​ 725 Interest on lease liabilities (3) ​ ​ 28 ​ ​ 78 Total ​ $ 1,968 ​ $ 5,949 (1) Included in Direct operating costs and Selling, general, and administrative expenses in the Company’s consolidated statements of operations. Operating lease cost includes short-term leases, excluding expenses relating to leases with a term of one month or less, which are not material. Operating lease cost excludes variable lease costs which are not material. (2) Included in Direct operating costs in the Company’s consolidated statements of operations. (3) Included in Interest expense in the Company’s consolidated statements of operations.
Schedule of cash flow supplemental information	​ ​ ​ ​ ​ ​ ​ Nine Months Ended $s in thousands September 30, 2019 Cash paid for amounts included in the measurement of lease liabilities: ​ ​ ​ Operating cash flows from operating leases ​ $ 4,868 Operating cash flows from finance leases ​ ​ 78 Financing cash flows from finance leases ​ ​ 619 ​ ​ ​ ​ Non-cash investing and financing activities: ​ ​ ​ Right-of-use assets obtained in exchange for new operating lease liabilities ​ $ 3,817 Right-of-use assets obtained in exchange for new finance lease liabilities ​ ​ 1,844
Summary of weighted-average remaining lease term and discount rate	​ ​ ​ ​ ​ ​ ​ September 30, 2019 Weighted-average remaining lease term (years): ​ ​ ​ ​ Operating leases ​ ​ 5.5 ​ Finance leases ​ ​ 3.5 ​ Weighted-average discount rate: ​ ​ ​ ​ Operating leases ​ ​ 4.38 % Finance leases ​ ​ 3.80 %
Summary of future maturity of lease liability and its present value	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating ​ Finance ​ ​ $s in thousands Leases ​ Leases ​ Total 2019 (excluding the nine months ended September 30, 2019) ​ $ 1,546 ​ $ 242 ​ $ 1,788 2020 ​ ​ 4,584 ​ ​ 792 ​ ​ 5,376 2021 ​ 4,035 ​ 619 ​ 4,654 2022 ​ 2,589 ​ 548 ​ 3,137 2023 ​ 2,092 ​ 612 ​ 2,704 Thereafter ​ 5,209 ​ 354 ​ 5,563 Total ​ $ 20,055 ​ $ 3,167 ​ $ 23,222 Less: Interest ​ ​ 2,551 ​ ​ 275 ​ ​ 2,826 Present value of lease liabilities ​ $ 17,504 ​ $ 2,892 ​ $ 20,396 ​ ​ ​ ​ ​ $s in thousands Payments 2019 ​ $ 5,638 2020 ​ 3,644 2021 ​ 3,184 2022 ​ 1,885 2023 ​ 1,457 Thereafter ​ 5,065 ​ ​ $ 20,873

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS (Tables)	9 Months Ended
	Sep. 30, 2019
GOODWILL AND INTANGIBLE ASSETS
Schedule of changes in goodwill	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Field & ​ ​ ​ ​ ​ Environmental ​ Industrial ​ ​ ​ ​ Services ​ Services ​ ​ ​ ​ ​ ​ ​ Accumulated ​ ​ ​ Accumulated ​ ​ ​ $s in thousands ​ Gross ​ Impairment ​ Gross ​ Impairment ​ Total Balance at December 31, 2018 ​ $ 162,816 ​ $ (6,870) ​ $ 51,231 ​ $ — ​ $ 207,177 US Ecology Sarnia acquisition ​ ​ — ​ ​ — ​ ​ 8,975 ​ ​ — ​ ​ 8,975 Winnie purchase price allocation adjustment ​ ​ 2,586 ​ ​ — ​ ​ — ​ ​ — ​ ​ 2,586 Foreign currency translation ​ 503 ​ ​ — ​ (60) ​ ​ — ​ 443 Balance at September 30, 2019 ​ $ 165,905 ​ $ (6,870) ​ $ 60,146 ​ $ — ​ $ 219,181
Schedule of intangible assets, net	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2019 ​ December 31, 2018 ​ ​ ​ ​ ​ Accumulated ​ ​ ​ ​ ​ ​ ​ Accumulated ​ ​ ​ $s in thousands Cost Amortization Net Cost Amortization Net Amortizing intangible assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Permits, licenses and lease ​ $ 165,355 ​ $ (17,642) ​ $ 147,713 ​ $ 164,840 ​ $ (14,804) ​ $ 150,036 Customer relationships ​ ​ 103,203 ​ ​ (30,609) ​ ​ 72,594 ​ ​ 99,241 ​ ​ (25,676) ​ ​ 73,565 Technology - formulae and processes ​ 6,872 ​ (1,931) ​ 4,941 ​ 6,672 ​ (1,714) ​ 4,958 Customer backlog ​ 3,652 ​ (1,930) ​ 1,722 ​ 3,652 ​ (1,656) ​ 1,996 Developed software ​ ​ 2,891 ​ ​ (1,807) ​ ​ 1,084 ​ ​ 2,884 ​ ​ (1,581) ​ ​ 1,303 Non-compete agreements ​ 1,995 ​ (1,191) ​ 804 ​ 1,542 ​ (875) ​ 667 Internet domain and website ​ ​ 536 ​ ​ (149) ​ ​ 387 ​ ​ 536 ​ ​ (128) ​ ​ 408 Database ​ ​ 387 ​ ​ (185) ​ ​ 202 ​ ​ 384 ​ ​ (167) ​ ​ 217 Total amortizing intangible assets ​ 284,891 ​ (55,444) ​ 229,447 ​ 279,751 ​ (46,601) ​ 233,150 Non-amortizing intangible assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Permits and licenses ​ 46,408 ​ ​ — ​ 46,408 ​ 46,391 ​ ​ — ​ 46,391 Tradename ​ 128 ​ ​ — ​ ​ 128 ​ 125 ​ ​ — ​ ​ 125 Total intangible assets ​ $ 331,427 ​ $ (55,444) ​ $ 275,983 ​ $ 326,267 ​ $ (46,601) ​ $ 279,666

DEBT (Tables)

DEBT (Tables)	9 Months Ended
	Sep. 30, 2019
DEBT
Schedule of long-term debt	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, $s in thousands 2019 2018 Revolving credit facility ​ $ 354,000 ​ $ 364,000 Long-term debt ​ $ 354,000 ​ $ 364,000
Schedule of interest margins based on the total net leverage ratio	​ Total Net Leverage Ratio LIBOR Rate Loans Interest Margin Base Rate Loans Interest Margin Equal to or greater than 3.25 to 1.00 2.00% 1.00% Equal to or greater than 2.50 to 1.00, but less than 3.25 to 1.00 1.75% 0.75% Equal to or greater than 1.75 to 1.00, but less than 2.50 to 1.00 1.50% 0.50% Equal to or greater than 1.00 to 1.00, but less than 1.75 to 1.00 1.25% 0.25% Less than 1.00 to 1.00 1.00% 0.00%

CLOSURE AND POST-CLOSURE OBLI_2

CLOSURE AND POST-CLOSURE OBLIGATIONS (Tables)	9 Months Ended
	Sep. 30, 2019
CLOSURE AND POST-CLOSURE OBLIGATIONS
Schedule of changes to reported closure and post closure obligations	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ $s in thousands September 30, 2019 ​ September 30, 2019 ​ Closure and post-closure obligations, beginning of period ​ $ 79,919 ​ $ 78,363 ​ Accretion expense ​ 1,139 ​ 3,397 ​ Payments ​ (638) ​ (1,413) ​ Foreign currency translation ​ (21) ​ 52 ​ Closure and post-closure obligations, end of period ​ 80,399 ​ 80,399 ​ Less current portion ​ (2,196) ​ (2,196) ​ Long-term portion ​ $ 78,203 ​ $ 78,203 ​

EARNINGS PER SHARE (Tables)

EARNINGS PER SHARE (Tables)	9 Months Ended
	Sep. 30, 2019
EARNINGS PER SHARE
Schedule of earnings per share	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ ​ 2019 ​ 2018 $s and shares in thousands, except per share amounts Basic Diluted Basic Diluted Net income ​ $ 13,070 ​ $ 13,070 ​ $ 13,427 ​ $ 13,427 Weighted average basic shares outstanding ​ 22,013 ​ 22,013 ​ 21,928 ​ 21,928 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Dilutive effect of share-based awards ​ ​ ​ ​ 218 ​ ​ ​ ​ 171 Weighted average diluted shares outstanding ​ ​ ​ ​ 22,231 ​ ​ ​ ​ 22,099 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Earnings per share ​ $ 0.59 ​ $ 0.59 ​ $ 0.61 ​ $ 0.61 Anti-dilutive shares excluded from calculation ​ ​ ​ ​ 80 ​ ​ ​ ​ 16 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, ​ ​ 2019 ​ 2018 $s and shares in thousands, except per share amounts Basic Diluted Basic Diluted Net income ​ $ 36,604 ​ $ 36,604 ​ $ 35,890 ​ $ 35,890 Weighted average basic shares outstanding ​ 22,002 ​ 22,002 ​ 21,866 ​ 21,866 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Dilutive effect of share-based awards ​ ​ ​ ​ 210 ​ ​ ​ ​ 161 Weighted average diluted shares outstanding ​ ​ ​ ​ 22,212 ​ ​ ​ ​ 22,027 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Earnings per share ​ $ 1.66 ​ $ 1.65 ​ $ 1.64 ​ $ 1.63 Anti-dilutive shares excluded from calculation ​ ​ ​ ​ 84 ​ ​ ​ ​ 56

EQUITY (Tables)

EQUITY (Tables)	9 Months Ended
	Sep. 30, 2019
EQUITY
Schedule of assumptions for determining the fair value for PSU awards using Monte Carlo simulation models	​ ​ ​ ​ ​ ​ ​ 2019 Stock price on grant date ​ $ 58.40 ​ Expected term ​ 3.0 years Expected volatility ​ ​ 30 % Risk-free interest rate ​ 2.5 % Expected dividend yield ​ 1.1 %
Summary of PSU, restricted stock and RSU activity	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ PSUs ​ Restricted Stock ​ RSUs ​ ​ ​ ​ Weighted ​ ​ ​ Weighted ​ ​ ​ Weighted ​ ​ ​ ​ Average ​ ​ ​ Average ​ ​ ​ Average ​ ​ ​ ​ Grant Date ​ ​ ​ Grant Date ​ ​ ​ Grant Date ​ Shares Fair Value Shares Fair Value ​ Shares Fair Value Outstanding as of December 31, 2018 39,200 ​ $ 55.48 74,988 ​ $ 46.74 ​ 66,785 ​ $ 53.77 Granted 17,111 ​ ​ 58.20 28,900 ​ ​ 62.59 ​ 33,020 ​ ​ 56.21 Vested (13,600) ​ 41.22 (39,234) ​ 43.77 ​ (29,772) ​ 51.15 Cancelled, expired or forfeited — ​ — — ​ — ​ (1,389) ​ 52.54 Outstanding as of September 30, 2019 42,711 ​ $ 61.11 64,654 ​ $ 55.62 ​ 68,644 ​ $ 56.11
Summary of stock option activity	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ Average ​ ​ ​ ​ Exercise ​ Shares Price Outstanding as of December 31, 2018 236,503 ​ $ 44.93 Granted 41,100 ​ ​ 63.36 Exercised (6,272) ​ 40.75 Cancelled, expired or forfeited (1,540) ​ 43.55 Outstanding as of September 30, 2019 269,791 ​ $ 47.84 Exercisable as of September 30, 2019 188,730 ​ $ 43.91

OPERATING SEGMENTS (Tables)

OPERATING SEGMENTS (Tables)	9 Months Ended
	Sep. 30, 2019
OPERATING SEGMENTS
Summary of financial information of our reportable segments	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, 2019 ​ ​ ​ ​ Field & ​ ​ ​ ​ ​ ​ ​ ​ Environmental ​ Industrial ​ ​ ​ ​ ​ ​ $s in thousands Services Services Corporate Total Revenue ​ $ 122,212 ​ $ 45,190 ​ $ — ​ $ 167,402 Depreciation, amortization and accretion ​ $ 10,790 ​ $ 2,319 ​ $ 358 ​ $ 13,467 Capital expenditures ​ $ 12,188 ​ $ 1,018 ​ $ 579 ​ $ 13,785 Total assets ​ $ 750,915 ​ $ 167,996 ​ $ 81,238 ​ $ 1,000,149 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, 2018 ​ ​ ​ ​ Field & ​ ​ ​ ​ ​ ​ ​ ​ Environmental ​ Industrial ​ ​ ​ ​ ​ ​ $s in thousands Services Services Corporate Total Revenue ​ $ 107,197 ​ $ 44,219 ​ $ — ​ $ 151,416 Depreciation, amortization and accretion ​ $ 8,903 ​ $ 1,537 ​ $ 316 ​ $ 10,756 Capital expenditures ​ $ 9,878 ​ $ 573 ​ $ 379 ​ $ 10,830 Total assets ​ $ 614,228 ​ $ 157,989 ​ $ 80,957 ​ $ 853,174 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2019 ​ ​ ​ ​ Field & ​ ​ ​ ​ ​ ​ ​ ​ Environmental ​ Industrial ​ ​ ​ ​ ​ ​ $s in thousands Services Services Corporate Total Revenue ​ $ 327,389 ​ $ 126,852 ​ $ — ​ $ 454,241 Depreciation, amortization and accretion ​ $ 30,793 ​ $ 6,601 ​ $ 1,259 ​ $ 38,653 Capital expenditures ​ $ 33,485 ​ $ 3,126 ​ $ 1,832 ​ $ 38,443 Total assets ​ $ 750,915 ​ $ 167,996 ​ $ 81,238 ​ $ 1,000,149 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2018 ​ ​ ​ ​ Field & ​ ​ ​ ​ ​ ​ ​ ​ Environmental ​ Industrial ​ ​ ​ ​ ​ ​ $s in thousands Services Services Corporate Total Revenue ​ $ 292,628 ​ $ 115,759 ​ $ — ​ $ 408,387 Depreciation, amortization and accretion ​ $ 26,089 ​ $ 4,307 ​ $ 762 ​ $ 31,158 Capital expenditures ​ $ 20,818 ​ $ 3,460 ​ $ 1,513 ​ $ 25,791 Total assets ​ $ 614,228 ​ $ 157,989 ​ $ 80,957 ​ $ 853,174 ​
Reconciliation of Net Income to Adjusted EBITDA and adjusted EBITDA by operating segment	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, $s in thousands 2019 2018 2019 2018 Net income ​ $ 13,070 ​ $ 13,427 ​ $ 36,604 ​ $ 35,890 Income tax expense ​ ​ 6,428 ​ ​ 3,400 ​ ​ 15,864 ​ ​ 11,178 Interest expense ​ ​ 3,891 ​ ​ 3,066 ​ ​ 11,509 ​ ​ 8,782 Interest income ​ ​ (158) ​ ​ (34) ​ ​ (567) ​ ​ (97) Foreign currency loss ​ ​ 90 ​ ​ 303 ​ ​ 613 ​ ​ 456 Other income ​ ​ (110) ​ ​ (177) ​ ​ (342) ​ ​ (2,493) Property and equipment impairment charges ​ ​ — ​ ​ — ​ ​ 25 ​ ​ — Goodwill and intangible asset impairment charges ​ ​ — ​ ​ 3,666 ​ ​ — ​ ​ 3,666 Depreciation and amortization of plant and equipment ​ ​ 9,402 ​ ​ 7,342 ​ ​ 26,656 ​ ​ 20,991 Amortization of intangible assets ​ ​ 2,926 ​ ​ 2,327 ​ ​ 8,600 ​ ​ 6,925 Share-based compensation ​ ​ 1,246 ​ ​ 1,193 ​ ​ 3,713 ​ ​ 3,272 Accretion and non-cash adjustment of closure & post-closure liabilities ​ ​ 1,139 ​ ​ 1,087 ​ ​ 3,397 ​ ​ 3,242 Property insurance recoveries ​ ​ (498) ​ ​ — ​ ​ (9,651) ​ ​ — Adjusted EBITDA ​ $ 37,426 ​ $ 35,600 ​ $ 96,421 ​ $ 91,812 ​ Adjusted EBITDA, by operating segment, is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, Nine Months Ended September 30, $s in thousands ​ 2019 2018 ​ 2019 2018 Environmental Services $ 51,409 ​ $ 43,210 $ 133,725 ​ $ 117,742 Field & Industrial Services 5,848 ​ 6,236 13,424 ​ 13,143 Corporate (19,831) ​ (13,846) (50,728) ​ (39,073) Total $ 37,426 ​ $ 35,600 $ 96,421 ​ $ 91,812
Schedule of long-lived assets by geographic location	​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, $s in thousands ​ 2019 2018 United States ​ $ 491,904 ​ $ 480,322 Canada ​ 57,860 ​ 57,787 Total long-lived assets ​ $ 549,764 ​ $ 538,109

GENERAL (Details)

GENERAL (Details) - USD ($) $ in Thousands	Jan. 01, 2019	Sep. 30, 2019	Mar. 31, 2019
Recently issued accounting pronouncements
Operating lease, right-of-use asset		$ 17,496
Operating lease liability		$ 17,504
ASU 2016-02
Recently issued accounting pronouncements
Practical expedients - Package	true
Practical expedients - Land easements	true
Practical expedients - Hindsight	false
Operating lease, right-of-use asset			$ 18,100
Operating lease liability			$ 18,100

GENERAL - NRCG Merger (Details)

GENERAL - NRCG Merger (Details) - USD ($)	Nov. 01, 2019	Sep. 30, 2019	Dec. 31, 2018
Acquisition
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01	$ 0.01
US Ecology
Acquisition
Common stock, par value (in dollars per share)	$ 0.01
Number of shares of stock to be received of Company's for each share of stock held	1
US Ecology | Treasury Stock
Acquisition
Acquisition price	$ 0
NRCG
Acquisition
Common stock, par value (in dollars per share)	$ 0.0001
Number of shares of stock to be received of Company's for each share of stock held	0.196
NRCG | Replacement warrants
Acquisition
Exercise price	$ 58.67
NRCG | 7.00% Series A Convertible Cumulative Preferred Stock
Acquisition
Number of shares of stock to be received of Company's for each share of stock held	1.7506
Preferred stock, par value (in dollars per share)	$ 0.0001
Preferred stock, percentage	7.00%
NRCG | Treasury Stock
Acquisition
Acquisition price	$ 0

REVENUES (Details)

REVENUES (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)segment	Sep. 30, 2018USD ($)	Dec. 31, 2018item
Disaggregation of revenue
Number of reportable segments | segment			2
Revenue	$ 167,402	$ 151,416	$ 454,241	$ 408,387
Field and Industrial Services
Disaggregation of revenue
Number of service lines | item					2
Treatment and disposal
Disaggregation of revenue
Revenue	101,866	85,989	275,887	242,340
Transportation and Logistics
Disaggregation of revenue
Revenue	35,728	33,774	92,665	81,651
Industrial Services
Disaggregation of revenue
Revenue	4,850	6,052	15,830	14,437
Small Quantity Generation
Disaggregation of revenue
Revenue	10,001	8,611	27,516	26,075
Total Waste Management
Disaggregation of revenue
Revenue	8,674	10,054	25,393	29,295
Remediation
Disaggregation of revenue
Revenue	1,388	2,296	4,003	8,454
Emergency Response
Disaggregation of revenue
Revenue	3,294	2,794	9,520	4,185
Other
Disaggregation of revenue
Revenue	1,601	1,846	3,427	1,950
Operating Segment | Environmental Services
Disaggregation of revenue
Revenue	122,212	107,197	327,389	292,628
Operating Segment | Field and Industrial Services
Disaggregation of revenue
Revenue	45,190	44,219	126,852	115,759
Operating Segment | Treatment and disposal | Environmental Services
Disaggregation of revenue
Revenue	98,554	82,768	266,646	233,570
Operating Segment | Treatment and disposal | Field and Industrial Services
Disaggregation of revenue
Revenue	3,312	3,221	9,241	8,770
Operating Segment | Transportation and Logistics | Environmental Services
Disaggregation of revenue
Revenue	23,658	24,429	60,743	59,058
Operating Segment | Transportation and Logistics | Field and Industrial Services
Disaggregation of revenue
Revenue	12,070	9,345	31,922	22,593
Operating Segment | Industrial Services | Field and Industrial Services
Disaggregation of revenue
Revenue	4,850	6,052	15,830	14,437
Operating Segment | Small Quantity Generation | Field and Industrial Services
Disaggregation of revenue
Revenue	10,001	8,611	27,516	26,075
Operating Segment | Total Waste Management | Field and Industrial Services
Disaggregation of revenue
Revenue	8,674	10,054	25,393	29,295
Operating Segment | Remediation | Field and Industrial Services
Disaggregation of revenue
Revenue	1,388	2,296	4,003	8,454
Operating Segment | Emergency Response | Field and Industrial Services
Disaggregation of revenue
Revenue	3,294	2,794	9,520	4,185
Operating Segment | Other | Field and Industrial Services
Disaggregation of revenue
Revenue	$ 1,601	$ 1,846	$ 3,427	$ 1,950

REVENUES - Treatment and Dispos

REVENUES - Treatment and Disposal Revenue (Details) - Treatment and disposal - T	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Event Business
Disaggregation of revenue
Threshold Tons of Non-recurring projects			1,000
Revenue (in percent)	25.00%	22.00%	22.00%	20.00%
Base Business
Disaggregation of revenue
Revenue (in percent)	75.00%	78.00%	78.00%	80.00%

REVENUES - Geography (Details)

REVENUES - Geography (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of revenue
Revenue	$ 167,402	$ 151,416	$ 454,241	$ 408,387
United States
Disaggregation of revenue
Revenue	143,886	129,402	388,693	360,845
Canada
Disaggregation of revenue
Revenue	23,516	22,014	65,548	47,542
Operating Segment | Environmental Services
Disaggregation of revenue
Revenue	122,212	107,197	327,389	292,628
Operating Segment | Environmental Services | United States
Disaggregation of revenue
Revenue	99,554	85,183	262,699	245,086
Operating Segment | Environmental Services | Canada
Disaggregation of revenue
Revenue	22,658	22,014	64,690	47,542
Operating Segment | Field and Industrial Services
Disaggregation of revenue
Revenue	45,190	44,219	126,852	115,759
Operating Segment | Field and Industrial Services | United States
Disaggregation of revenue
Revenue	44,332	$ 44,219	125,994	$ 115,759
Operating Segment | Field and Industrial Services | Canada
Disaggregation of revenue
Revenue	$ 858		$ 858

REVENUES - Practical Expedients

REVENUES - Practical Expedients (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
REVENUES
Deferred revenue recognized in revenue	$ 738	$ 496	$ 9,700	$ 8,300
Revenue, Practical Expedient, Financing Component			true
Revenue, Practical Expedient, Initial Application and Transition, Nonrestatement of Modified Contract			true

BUSINESS COMBINATIONS (Details)

BUSINESS COMBINATIONS (Details) $ in Thousands, $ in Millions	Aug. 01, 2019CAD ($)	Aug. 01, 2019USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Dec. 31, 2018USD ($)
Acquisition
Payment to acquire business, net of cash acquired			$ 17,851	$ 21,253
Consideration paid and the fair value of assets acquired and liabilities assumed
Goodwill			219,181		$ 207,177
Field and Industrial Services
Consideration paid and the fair value of assets acquired and liabilities assumed
Goodwill			60,146		51,231
Winnie
Acquisition
Acquisition price			87,228		87,129
Consideration paid and the fair value of assets acquired and liabilities assumed
Current assets			1,860		1,923
Property and equipment			3,976		6,300
Identifiable intangible assets			66,500		66,600
Current liabilities			(755)		(755)
Other liabilities			(512)		(512)
Total identifiable net assets			71,069		73,556
Goodwill			16,159		13,573
Total purchase price			87,228		$ 87,129
Adjustments
Current assets - adjustment			(63)
Property and equipment - adjustment			(2,324)
Identifiable intangible assets - adjustment			(100)
Total identifiable net assets - adjustment			(2,487)
Goodwill - adjustment			2,586
Total purchase price - adjustment			99
US Ecology Sarnia
Acquisition
Percentage of outstanding shares acquired		100.00%
Acquisition price	$ 23.5	$ 17,900
Consideration paid and the fair value of assets acquired and liabilities assumed
Identifiable intangible assets		4,300
Goodwill		9,000	$ 9,000
Total purchase price	$ 23.5	$ 17,900
Adjustments
Weighted average amortization period	14 years	14 years

ACCUMULATED OTHER COMPREHENSI_3

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Changes in AOCI (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Accumulated other comprehensive income (loss)
Beginning balances	$ 376,759	$ 340,300	$ 359,217	$ 324,077
Ending balances	385,967	353,841	385,967	353,841
Foreign Currency Translation
Accumulated other comprehensive income (loss)
Beginning balances			(14,697)	(8,603)
Other comprehensive income (loss) before reclassifications, net of tax			2,374	(1,878)
Other comprehensive income, net			2,374	(1,878)
Ending balances	(12,323)	(10,481)	(12,323)	(10,481)
Unrealized Gain (Loss) on Interest Rate Hedge
Accumulated other comprehensive income (loss)
Beginning balances			906	(501)
Other comprehensive income (loss) before reclassifications, net of tax			(1,780)	2,310
Amounts reclassified out of AOCI, net of tax			(238)	341
Other comprehensive income, net			(2,018)	2,651
Ending balances	(1,112)	2,150	(1,112)	2,150
Accumulated Other Comprehensive Income (Loss)
Accumulated other comprehensive income (loss)
Beginning balances	(12,290)	(10,349)	(13,791)	(9,104)
Other comprehensive income (loss) before reclassifications, net of tax			594	432
Amounts reclassified out of AOCI, net of tax			(238)	341
Other comprehensive income, net	(1,145)	2,018	356	773
Ending balances	$ (13,435)	$ (8,331)	$ (13,435)	$ (8,331)

ACCUMULATED OTHER COMPREHENSI_4

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) -Reclassifications Line Items (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Reclassification adjustments
Interest expense	$ 3,891,000	$ 3,066,000	$ 11,509,000	$ 8,782,000
Unrealized Gain (Loss) on Interest Rate Hedge | Interest rate swap agreement
Reclassification adjustments
Amounts in AOCI expected to be recognized over the next 12 months before tax	139,000		139,000
Amounts in AOCI expected to be recognized over the next 12 months, net of taxes	110,000		110,000
Unrealized Gain (Loss) on Interest Rate Hedge | Interest rate swap agreement | Reclassification out of accumulated other comprehensive income
Reclassification adjustments
Interest expense	35,000	40,000	301,000	432,000
Interest expense, net of tax	$ 27,000	$ 31,000	$ 238,000	$ 341,000

RECEIVABLES (Details)

RECEIVABLES (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
RECEIVABLES
Trade	$ 117,913	$ 118,909
Unbilled revenue	30,810	26,538
Other	9,739	2,241
Total receivables	158,462	147,688
Allowance for doubtful accounts	(2,636)	(2,998)
Receivables, net	$ 155,826	$ 144,690

FAIR VALUE MEASUREMENTS (Detail

FAIR VALUE MEASUREMENTS (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 19, 2019	Dec. 31, 2018	Dec. 31, 2014
Interest rate swap agreement
Assets measured at fair value on a recurring basis
Initial notional amount				$ 250,000
Preferred Stock | Other Assets
Equity securities without readily determinable fair value
Investment in privately held company		$ 7,900
Recurring
Assets measured at fair value on a recurring basis
Assets fair value disclosure	$ 5,045		$ 6,088
Liabilities fair value disclosure	1,408
Recurring | Interest rate swap agreement
Assets measured at fair value on a recurring basis
Assets fair value disclosure			1,147
Liabilities fair value disclosure	1,408
Recurring | Fixed-income securities
Assets measured at fair value on a recurring basis
Assets fair value disclosure	4,204		4,157
Recurring | Money market funds
Assets measured at fair value on a recurring basis
Assets fair value disclosure	841		784
Recurring | Quoted Prices in Active Markets (Level 1)
Assets measured at fair value on a recurring basis
Assets fair value disclosure	2,821		2,345
Recurring | Quoted Prices in Active Markets (Level 1) | Fixed-income securities
Assets measured at fair value on a recurring basis
Assets fair value disclosure	1,980		1,561
Recurring | Quoted Prices in Active Markets (Level 1) | Money market funds
Assets measured at fair value on a recurring basis
Assets fair value disclosure	841		784
Recurring | Other Observable Inputs (Level 2)
Assets measured at fair value on a recurring basis
Assets fair value disclosure	2,224		3,743
Liabilities fair value disclosure	1,408
Recurring | Other Observable Inputs (Level 2) | Interest rate swap agreement
Assets measured at fair value on a recurring basis
Assets fair value disclosure			1,147
Liabilities fair value disclosure	1,408
Recurring | Other Observable Inputs (Level 2) | Fixed-income securities
Assets measured at fair value on a recurring basis
Assets fair value disclosure	$ 2,224		$ 2,596

PROPERTY AND EQUIPMENT (Details

PROPERTY AND EQUIPMENT (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
PROPERTY AND EQUIPMENT
Total property and equipment	$ 514,303		$ 514,303		$ 473,861
Accumulated depreciation and amortization	(240,522)		(240,522)		(215,418)
Property and equipment, net	273,781		273,781		258,443
Depreciation and amortization of plant and equipment	9,402	$ 7,342	26,656	$ 20,991
Cell development costs
PROPERTY AND EQUIPMENT
Total property and equipment	146,861		146,861		146,155
Land and improvements
PROPERTY AND EQUIPMENT
Total property and equipment	51,997		51,997		50,481
Buildings and improvements
PROPERTY AND EQUIPMENT
Total property and equipment	92,389		92,389		91,358
Railcars
PROPERTY AND EQUIPMENT
Total property and equipment	17,299		17,299		17,299
Vehicles and other equipment
PROPERTY AND EQUIPMENT
Total property and equipment	169,454		169,454		154,014
Construction in progress
PROPERTY AND EQUIPMENT
Total property and equipment	$ 36,303		$ 36,303		$ 14,554

LEASES (Details)

LEASES (Details)	9 Months Ended
	Sep. 30, 2019
Leases
Operating lease - existence of option to renew	true
Finance lease - existence of option to renew	true
Minimum
Leases
Operating lease - term	1 year
Finance lease - term	1 year
Maximum
Leases
Operating lease - term	15 years
Operating lease - renewal term	40 years
Finance lease - term	15 years
Finance lease - renewal term	40 years

LEASES - Leased assets and liab

LEASES - Leased assets and liabilities (Details) $ in Thousands	Sep. 30, 2019USD ($)
Assets:
Operating lease assets	$ 17,496
Finance right-of-use lease assets	2,780
Total	20,276
Finance leased assets - accumulated amortization	1,800
Liabilities:
Operating lease, current	4,914
Finance lease, current	774
Long-term operating lease liabilities	12,590
Finance lease, long term	2,118
Total	$ 20,396

LEASES - Lease cost (Details)

LEASES - Lease cost (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019
Lease cost
Operating lease cost	$ 1,691	$ 5,146
Amortization of leased assets	249	725
Interest on lease liabilities	28	78
Total	$ 1,968	$ 5,949

LEASES - Supplemental Cash Flow

LEASES - Supplemental Cash Flow information (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019USD ($)
LEASES
Operating cash flows from operating leases	$ 4,868
Operating cash flows from finance leases	78
Financing cash flows from finance leases	619
Right-of-use assets obtained in exchange for new operating lease liabilities	3,817
Right-of-use assets obtained in exchange for new finance lease liabilities	$ 1,844

LEASES - Weighted-average remai

LEASES - Weighted-average remaining lease term and discount rate (Details)	Sep. 30, 2019
LEASES
Weighted-average remaining lease term, operating leases	5 years 6 months
Weighted-average remaining lease term, finance leases	3 years 6 months
Weighted-average discount rate, operating leases	4.38%
Weighted-average discount rate, finance leases	3.80%

LEASES - Future maturity of lea

LEASES - Future maturity of lease liability and its present value (Details) $ in Thousands	Sep. 30, 2019USD ($)
Operating Leases
2019 (excluding the nine months ended September 30, 2019)	$ 1,546
2020	4,584
2021	4,035
2022	2,589
2023	2,092
Thereafter	5,209
Total	20,055
Less: Interest	2,551
Present Value of Lease Liabilities	17,504
Finance Leases
2019 (excluding the six months ended June 30, 2019)	242
2020	792
2021	619
2022	548
2023	612
Thereafter	354
Total	3,167
Less: Interest	275
Present Value of Lease Liabilities	2,892
Operating And Finance Leases
2019 (excluding the six months ended June 30, 2019)	1,788
2020	5,376
2021	4,654
2022	3,137
2023	2,704
Thereafter	5,563
Total	23,222
Less: Interest	2,826
Present Value of Lease Liabilities	$ 20,396

LEASES - Operating Leases (Deta

LEASES - Operating Leases (Details) $ in Thousands	Dec. 31, 2018USD ($)
Future minimum lease payments on non-cancellable operating leases
2019	$ 5,638
2020	3,644
2021	3,184
2022	1,885
2023	1,457
Thereafter	5,065
Total	$ 20,873

GOODWILL AND INTANGIBLE ASSET_2

GOODWILL AND INTANGIBLE ASSETS - Goodwill (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019USD ($)
Changes in goodwill
Balance at the beginning of the period	$ 207,177
Foreign currency translation	443
Balance at the end of the period	219,181
US Ecology Sarnia
Changes in goodwill
Acquisition	8,975
Balance at the end of the period	9,000
Winnie
Changes in goodwill
Balance at the beginning of the period	13,573
Purchase price allocation adjustment	2,586
Balance at the end of the period	16,159
Environmental Services
Changes in goodwill
Balance at the beginning of the period	162,816
Foreign currency translation	503
Balance at the end of the period	165,905
Accumulated Impairment
Accumulated impairment at the beginning	(6,870)
Accumulated impairment at the ending	(6,870)
Environmental Services | Winnie
Changes in goodwill
Purchase price allocation adjustment	2,586
Field and Industrial Services
Changes in goodwill
Balance at the beginning of the period	51,231
Foreign currency translation	(60)
Balance at the end of the period	60,146
Field and Industrial Services | US Ecology Sarnia
Changes in goodwill
Acquisition	$ 8,975

GOODWILL AND INTANGIBLE ASSET_3

GOODWILL AND INTANGIBLE ASSETS - Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Aug. 01, 2019	Dec. 31, 2018
Intangible Assets
Amortizing intangible assets, Cost	$ 284,891		$ 284,891			$ 279,751
Accumulated amortization	(55,444)		(55,444)			(46,601)
Amortizing intangible assets, Net	229,447		229,447			233,150
Total intangible assets, cost	331,427		331,427			326,267
Total intangible assets, net	275,983		275,983			279,666
Amortization of intangible assets	2,926	$ 2,327	8,600	$ 6,925
Goodwill	219,181		219,181			207,177
Permits and licenses
Intangible Assets
Non-amortizing intangible assets	46,408		46,408			46,391
Tradename
Intangible Assets
Non-amortizing intangible assets	128		128			125
Permits, licenses and lease
Intangible Assets
Amortizing intangible assets, Cost	165,355		165,355			164,840
Accumulated amortization	(17,642)		(17,642)			(14,804)
Amortizing intangible assets, Net	147,713		147,713			150,036
Customer relationships
Intangible Assets
Amortizing intangible assets, Cost	103,203		103,203			99,241
Accumulated amortization	(30,609)		(30,609)			(25,676)
Amortizing intangible assets, Net	72,594		72,594			73,565
Technology - formulae and processes
Intangible Assets
Amortizing intangible assets, Cost	6,872		6,872			6,672
Accumulated amortization	(1,931)		(1,931)			(1,714)
Amortizing intangible assets, Net	4,941		4,941			4,958
Customer backlog
Intangible Assets
Amortizing intangible assets, Cost	3,652		3,652			3,652
Accumulated amortization	(1,930)		(1,930)			(1,656)
Amortizing intangible assets, Net	1,722		1,722			1,996
Developed software
Intangible Assets
Amortizing intangible assets, Cost	2,891		2,891			2,884
Accumulated amortization	(1,807)		(1,807)			(1,581)
Amortizing intangible assets, Net	1,084		1,084			1,303
Non-compete agreements
Intangible Assets
Amortizing intangible assets, Cost	1,995		1,995			1,542
Accumulated amortization	(1,191)		(1,191)			(875)
Amortizing intangible assets, Net	804		804			667
Internet domain and website
Intangible Assets
Amortizing intangible assets, Cost	536		536			536
Accumulated amortization	(149)		(149)			(128)
Amortizing intangible assets, Net	387		387			408
Database
Intangible Assets
Amortizing intangible assets, Cost	387		387			384
Accumulated amortization	(185)		(185)			(167)
Amortizing intangible assets, Net	202		202			217
Winnie
Intangible Assets
Goodwill	16,159		16,159			13,573
US Ecology Sarnia
Intangible Assets
Amortizing intangible assets, Cost	4,300		4,300
Goodwill	9,000		9,000		$ 9,000
Environmental Services
Intangible Assets
Goodwill	165,905		165,905			162,816
Field and Industrial Services
Intangible Assets
Goodwill	$ 60,146		$ 60,146			$ 51,231

DEBT - Schedule (Details)

DEBT - Schedule (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Long-term debt
Loan amount	$ 354,000	$ 364,000
Long-term debt	354,000	364,000
2017 Revolving Credit Facility
Long-term debt
Loan amount	$ 354,000	$ 364,000

DEBT - Paragraph (Details)

DEBT - Paragraph (Details) $ in Thousands	Nov. 01, 2019USD ($)	Aug. 06, 2019USD ($)	Apr. 18, 2017USD ($)	Sep. 30, 2019USD ($)	Dec. 31, 2018USD ($)
DEBT
Loan amount				$ 354,000	$ 364,000
2017 Revolving Credit Facility
DEBT
Maximum borrowing capacity			$ 500,000
Loan amount				$ 354,000	$ 364,000
Contractual term			5 years
Accordion feature			$ 200,000
Effective interest rate (as a percent)				3.62%
Amount of debt hedged				$ 155,000
Availability for borrowings under line of credit				138,700
Line of credit issued in the form of a standby letters of credit				$ 5,700
Equity interest in domestic subsidiaries pledged as security (as a percent)			100.00%
Voting equity interest in foreign subsidiaries pledged as security (as a percent)			65.00%
Non-voting equity interest in foreign subsidiaries pledged as security (as a percent)			100.00%
Debt instrument hedged (as a percent)				44.00%
Total leverage ratio		4	3.50
Interest coverage ratio			3
2017 Revolving Credit Facility | Subsequent events
DEBT
Accordion feature	$ 250,000
Percentage of EBITDA plus certain additional amounts used to determine additonal borrowing capicity	100.00%
2017 Revolving Credit Facility | Sweep Arrangements
DEBT
Loan amount				$ 1,500
2017 Revolving Credit Facility | Minimum
DEBT
Commitment fee (as a percent)			0.175%
2017 Revolving Credit Facility | Maximum
DEBT
Commitment fee (as a percent)			0.35%
2017 Revolving Credit Facility | Equal To Or Greater Than 3.25 to 1.00
DEBT
Minimum consolidated senior secured leverage ratio			3.25
2017 Revolving Credit Facility | Equal To Or Greater Than 2.50 to 1.00, But Less Than 3.25 to 1.00
DEBT
Minimum consolidated senior secured leverage ratio			2.50
Maximum consolidated senior secured leverage ratio			3.25
2017 Revolving Credit Facility | Equal To Or Greater Than 1.75 to 1.00, But Less Than 2.50 to 1.00
DEBT
Minimum consolidated senior secured leverage ratio			1.75
Maximum consolidated senior secured leverage ratio			2.50
2017 Revolving Credit Facility | Equal To Or Greater Than 1.00 to 1.00, But Less Than 1.75 to 1.00
DEBT
Minimum consolidated senior secured leverage ratio			1
Maximum consolidated senior secured leverage ratio			1.75
2017 Revolving Credit Facility | Less Than 1.00 to 1.00
DEBT
Maximum consolidated senior secured leverage ratio			1
2017 Revolving Credit Facility | LIBOR | Equal To Or Greater Than 3.25 to 1.00
DEBT
Percentage points added to the reference rate			2.00%
2017 Revolving Credit Facility | LIBOR | Equal To Or Greater Than 2.50 to 1.00, But Less Than 3.25 to 1.00
DEBT
Percentage points added to the reference rate			1.75%
2017 Revolving Credit Facility | LIBOR | Equal To Or Greater Than 1.75 to 1.00, But Less Than 2.50 to 1.00
DEBT
Percentage points added to the reference rate			1.50%
2017 Revolving Credit Facility | LIBOR | Equal To Or Greater Than 1.00 to 1.00, But Less Than 1.75 to 1.00
DEBT
Percentage points added to the reference rate			1.25%
2017 Revolving Credit Facility | LIBOR | Less Than 1.00 to 1.00
DEBT
Percentage points added to the reference rate			1.00%
2017 Revolving Credit Facility | Base rate | Equal To Or Greater Than 3.25 to 1.00
DEBT
Percentage points added to the reference rate			1.00%
2017 Revolving Credit Facility | Base rate | Equal To Or Greater Than 2.50 to 1.00, But Less Than 3.25 to 1.00
DEBT
Percentage points added to the reference rate			0.75%
2017 Revolving Credit Facility | Base rate | Equal To Or Greater Than 1.75 to 1.00, But Less Than 2.50 to 1.00
DEBT
Percentage points added to the reference rate			0.50%
2017 Revolving Credit Facility | Base rate | Equal To Or Greater Than 1.00 to 1.00, But Less Than 1.75 to 1.00
DEBT
Percentage points added to the reference rate			0.25%
2017 Revolving Credit Facility | Base rate | Less Than 1.00 to 1.00
DEBT
Percentage points added to the reference rate			0.00%
2017 Credit Agreement, Letter Of Credit
DEBT
Maximum borrowing capacity			$ 75,000
2017 Credit Agreement, Swingline Loans
DEBT
Maximum borrowing capacity		$ 40,000	$ 25,000
Incremental Term Loans | Subsequent events
DEBT
Increase in capacity	$ 50,000
Maximum borrowing capacity	450,000
Loan amount	$ 400,000
Contractual term	7 years
Required annual principal repayment (as a percent)	1.00%
Incremental Term Loans | LIBOR | Subsequent events
DEBT
Percentage points added to the reference rate	2.25%
Incremental Term Loans | LIBOR | Step Up Rate Based on Credit Ratings | Subsequent events
DEBT
Percentage points added to the reference rate	2.50%
Incremental Term Loans | Base rate | Subsequent events
DEBT
Percentage points added to the reference rate	1.25%
Incremental Term Loans | Base rate | Step Up Rate Based on Credit Ratings | Subsequent events
DEBT
Percentage points added to the reference rate	1.50%

CLOSURE AND POST-CLOSURE OBLI_3

CLOSURE AND POST-CLOSURE OBLIGATIONS - Rollforward (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Changes to reported closure and post-closure obligations
Closure and post-closure obligations, beginning of period	$ 79,919	$ 78,363
Accretion expense	1,139	3,397	$ 3,242
Payments	(638)	(1,413)
Adjustments	(21)	52
Closure and post-closure obligations, end of period	80,399	80,399
Less current portion	(2,196)	(2,196)		$ (2,266)
Long-term portion	$ 78,203	$ 78,203		$ 76,097

INCOME TAXES (Details)

INCOME TAXES (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
INCOME TAXES
Effective tax rate (as a percent)	33.00%	20.20%	30.20%	23.70%
Unrecognized Tax Benefits	$ 247		$ 247		$ 555
Possible reduction in the provision for income taxes if the unrecognized tax benefits were recognized			$ 236

EARNINGS PER SHARE (Details)

EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
EARNINGS PER SHARE
Net income	$ 13,070	$ 13,427	$ 36,604	$ 35,890
Basic
Weighted average basic shares outstanding	22,013	21,928	22,002	21,866
Earnings per share (in dollars per share)	$ 0.59	$ 0.61	$ 1.66	$ 1.64
Diluted
Net income, diluted	$ 13,070	$ 13,427	$ 36,604	$ 35,890
Dilutive effect of share-based awards (in shares)	218	171	210	161
Weighted average diluted shares outstanding	22,231	22,099	22,212	22,027
Earnings per share (in dollars per share)	$ 0.59	$ 0.61	$ 1.65	$ 1.63
Anti-dilutive shares excluded from calculation	80	16	84	56

EQUITY - Stock Repurchase Progr

EQUITY - Stock Repurchase Program (Details) $ in Millions	Jun. 01, 2016USD ($)
EQUITY
Authorized repurchase amount of outstanding common stock	$ 25

EQUITY - Omnibus Incentive Plan

EQUITY - Omnibus Incentive Plan (Details) - Omnibus Plan - shares	Sep. 30, 2019	May 27, 2015
Stock-Based Compensation Plans
Number of shares authorized for grant		1,500,000
Number of shares available for future grant	873,163

EQUITY - PSUs, Restricted Stock

EQUITY - PSUs, Restricted Stock and RSU (Details) - USD ($)	Mar. 01, 2019	Sep. 30, 2019	Dec. 31, 2018
Assumptions used in Monte Carlo simulation
Common stock, shares issued		22,094,000	22,040,000
PSUs
Stock-Based Compensation Plans
Number of common shares each PSU represents (in shares)	1
Vesting period	3 years
Shares
Outstanding at the beginning of the year (in shares)		39,200
Granted (in shares)	17,111	17,111
Vested (in shares)		(13,600)
Outstanding at the end of the year (in shares)		42,711
Weighted Average Grant Date Fair Value
Outstanding at the beginning of the period (in dollars per share)		$ 55.48
Granted (in dollars per share)	$ 58.20	58.20
Vested (in dollars per share)		41.22
Outstanding at the end of the period (in dollars per share)		$ 61.11
Assumptions used in Monte Carlo simulation
Stock price on grant date		$ 58.40
Expected term (years)		3 years
Expected volatility (as a percent)		30.00%
Risk-free interest rate (as a percent)		2.50%
Expected dividend yield (as a percent)		1.10%
Common stock, shares issued		19,414
PSUs | Minimum
Stock-Based Compensation Plans
Percentage payout rate	0.00%
PSUs | Maximum
Stock-Based Compensation Plans
Percentage payout rate	300.00%
Restricted stock
Shares
Outstanding at the beginning of the year (in shares)		74,988
Granted (in shares)		28,900
Vested (in shares)		(39,234)
Outstanding at the end of the year (in shares)		64,654
Weighted Average Grant Date Fair Value
Outstanding at the beginning of the period (in dollars per share)		$ 46.74
Granted (in dollars per share)		62.59
Vested (in dollars per share)		43.77
Outstanding at the end of the period (in dollars per share)		$ 55.62
RSUs
Shares
Outstanding at the beginning of the year (in shares)		66,785
Granted (in shares)		33,020
Vested (in shares)		(29,772)
Cancelled, expired or forfeited (in shares)		(1,389)
Outstanding at the end of the year (in shares)		68,644
Weighted Average Grant Date Fair Value
Outstanding at the beginning of the period (in dollars per share)		$ 53.77
Granted (in dollars per share)		56.21
Vested (in dollars per share)		51.15
Cancelled, expired or forfeited (in dollars per share)		52.54
Outstanding at the end of the period (in dollars per share)		$ 56.11

EQUITY - Stock Options (Details

EQUITY - Stock Options (Details)	9 Months Ended
	Sep. 30, 2019$ / sharesshares
Additional disclosures
Number of options exercised via net share settlement	3,136
Stock options
Shares
Outstanding at the beginning of the period (in shares)	236,503
Granted (in shares)	41,100
Exercised (in shares)	(6,272)
Cancelled, expired or forfeited (in shares)	(1,540)
Outstanding at the end of the period (in shares)	269,791
Exercisable at the end of the period (in shares)	188,730
Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share) | $ / shares	$ 44.93
Granted (in dollars per share) | $ / shares	63.36
Exercised (in dollars per share) | $ / shares	40.75
Cancelled, expired or forfeited (in dollars per share) | $ / shares	43.55
Outstanding at the end of the period (in dollars per share) | $ / shares	47.84
Exercisable at the end of the period (in dollars per share) | $ / shares	$ 43.91

EQUITY - Treasury Stock (Detail

EQUITY - Treasury Stock (Details) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Treasury Stock
Issuance of restricted stock from treasury stock (in shares)			8,900
Average cost (in dollars per share)	$ 57.77		$ 57.77
Repurchase of common stock (in shares)			14,462
Average cost of repurchase (in dollars per share)			$ 63.34
Dividends
Dividends paid per share (in dollars per share)	$ 0.18	$ 0.18	$ 0.54	$ 0.54

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - Litigation and Regulatory Proceedings (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019USD ($)	Sep. 30, 2019USD ($)	Dec. 31, 2018USD ($)	Nov. 17, 2018item
Litigation and Regulatory Proceedings
Insurance proceeds from damaged property and equipment		$ 10,000
Property insurance recoveries	$ 498	9,651
Explosion at the Grand View, Idaho Facility
Litigation and Regulatory Proceedings
Number of fatalities | item				1
Estimated liability			$ 0
Insurance proceeds from damaged property and equipment		10,000
Property insurance recoveries	498	9,700
Continued limited operations insurance recoveries	699	4,700
Lost profits insurance recoveries	$ 2,600	$ 2,600

OPERATING SEGMENTS - Summarized

OPERATING SEGMENTS - Summarized Financial Information (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)segment	Sep. 30, 2018USD ($)	Dec. 31, 2018USD ($)
OPERATING SEGMENTS
Number of reportable segments | segment			2
Revenue	$ 167,402	$ 151,416	$ 454,241	$ 408,387
Depreciation, amortization and accretion	13,467	10,756	38,653	31,158
Capital expenditures	13,785	10,830	38,443	25,791
Total assets	1,000,149	853,174	1,000,149	853,174	$ 947,898
Treatment and disposal
OPERATING SEGMENTS
Revenue	101,866	85,989	275,887	242,340
Transportation and Logistics
OPERATING SEGMENTS
Revenue	35,728	33,774	92,665	81,651
Remediation
OPERATING SEGMENTS
Revenue	1,388	2,296	4,003	8,454
Other
OPERATING SEGMENTS
Revenue	1,601	1,846	3,427	1,950
Corporate
OPERATING SEGMENTS
Depreciation, amortization and accretion	358	316	1,259	762
Capital expenditures	579	379	1,832	1,513
Total assets	81,238	80,957	81,238	80,957
Environmental Services | Operating Segment
OPERATING SEGMENTS
Revenue	122,212	107,197	327,389	292,628
Depreciation, amortization and accretion	10,790	8,903	30,793	26,089
Capital expenditures	12,188	9,878	33,485	20,818
Total assets	750,915	614,228	750,915	614,228
Environmental Services | Operating Segment | Treatment and disposal
OPERATING SEGMENTS
Revenue	98,554	82,768	266,646	233,570
Environmental Services | Operating Segment | Transportation and Logistics
OPERATING SEGMENTS
Revenue	23,658	24,429	60,743	59,058
Field and Industrial Services | Operating Segment
OPERATING SEGMENTS
Revenue	45,190	44,219	126,852	115,759
Depreciation, amortization and accretion	2,319	1,537	6,601	4,307
Capital expenditures	1,018	573	3,126	3,460
Total assets	167,996	157,989	167,996	157,989
Field and Industrial Services | Operating Segment | Treatment and disposal
OPERATING SEGMENTS
Revenue	3,312	3,221	9,241	8,770
Field and Industrial Services | Operating Segment | Transportation and Logistics
OPERATING SEGMENTS
Revenue	12,070	9,345	31,922	22,593
Field and Industrial Services | Operating Segment | Remediation
OPERATING SEGMENTS
Revenue	1,388	2,296	4,003	8,454
Field and Industrial Services | Operating Segment | Other
OPERATING SEGMENTS
Revenue	$ 1,601	$ 1,846	$ 3,427	$ 1,950

OPERATING SEGMENTS - Reconcilia

OPERATING SEGMENTS - Reconciliation of EBITDA (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Reconciliation of Net Income to Adjusted EBITDA
Net income	$ 13,070	$ 13,427	$ 36,604	$ 35,890
Income tax expense	6,428	3,400	15,864	11,178
Interest expense	3,891	3,066	11,509	8,782
Interest income	(158)	(34)	(567)	(97)
Foreign currency loss	90	303	613	456
Other income	(110)	(177)	(342)	(2,493)
Property and equipment impairment charges			25
Goodwill and intangible asset impairment charges		3,666		3,666
Depreciation and amortization of plant and equipment	9,402	7,342	26,656	20,991
Amortization of intangibles assets	2,926	2,327	8,600	6,925
Share-based compensation	1,246	1,193	3,713	3,272
Accretion and non-cash adjustment of closure & post-closure liabilities	1,139	1,087	3,397	3,242
Property insurance recoveries	(498)		(9,651)
Adjusted EBITDA	37,426	35,600	96,421	91,812
Operating Segment | Environmental Services
Reconciliation of Net Income to Adjusted EBITDA
Adjusted EBITDA	51,409	43,210	133,725	117,742
Operating Segment | Field and Industrial Services
Reconciliation of Net Income to Adjusted EBITDA
Adjusted EBITDA	5,848	6,236	13,424	13,143
Corporate
Reconciliation of Net Income to Adjusted EBITDA
Adjusted EBITDA	$ (19,831)	$ (13,846)	$ (50,728)	$ (39,073)

OPERATING SEGMENTS - Revenue an

OPERATING SEGMENTS - Revenue and Long-lived Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Revenue and Long-Lived Assets Outside of the United States
Total long- lived assets	$ 549,764	$ 538,109
United States
Revenue and Long-Lived Assets Outside of the United States
Total long- lived assets	491,904	480,322
Canada
Revenue and Long-Lived Assets Outside of the United States
Total long- lived assets	$ 57,860	$ 57,787

SUBSEQUENT EVENTS (Details)

SUBSEQUENT EVENTS (Details) - USD ($) $ / shares in Units, $ in Thousands	Nov. 01, 2019	Oct. 25, 2019	Oct. 01, 2019	Apr. 18, 2017	Sep. 30, 2019	Sep. 30, 2018
Subsequent events
Dividend paid in cash					$ 11,915	$ 11,838
2017 Revolving Credit Facility
Second Amendment
Maximum borrowing capacity				$ 500,000
Contractual term				5 years
Subsequent events
Subsequent events
Quarterly dividend declared (in dollars per share)			$ 0.18
Dividend paid in cash		$ 4,000
Subsequent events | Incremental Term Loans
Second Amendment
Increase in capacity	$ 50,000
Maximum borrowing capacity	$ 450,000
Contractual term	7 years
Required annual principal repayment (as a percent)	1.00%
Subsequent events | Incremental Term Loans | LIBOR
Second Amendment
Percentage points added to the reference rate	2.25%
Subsequent events | Incremental Term Loans | LIBOR | Step Up Rate Based on Credit Ratings
Second Amendment
Percentage points added to the reference rate	2.50%
Subsequent events | Incremental Term Loans | Base rate
Second Amendment
Percentage points added to the reference rate	1.25%
Subsequent events | Incremental Term Loans | Base rate | Step Up Rate Based on Credit Ratings
Second Amendment
Percentage points added to the reference rate	1.50%