Casella Waste Systems (CWST) 10-Q 2 Nov 23 2023 Q3 Quarterly report Financial data

COVER

COVER - shares	9 Months Ended
	Sep. 30, 2023	Oct. 15, 2023
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2023
Document Transition Report	false
Entity File Number	000-23211
Entity Registrant Name	CASELLA WASTE SYSTEMS, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	03-0338873
Entity Address, Address Line One	25 Greens Hill Lane,
Entity Address, City or Town	Rutland,
Entity Address, State or Province	VT
Entity Address, Postal Zip Code	05701
City Area Code	802
Local Phone Number	775-0325
Title of 12(b) Security	Class A common stock, $0.01 par value per share
Trading Symbol	CWST
Security Exchange Name	NASDAQ
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 Central Index Key	0000911177
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
Amendment Flag	false
Class A Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		56,994,524
Class B Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		988,200

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
CURRENT ASSETS:
Cash and cash equivalents	$ 219,089	$ 71,152
Accounts receivable, net of allowance for credit losses of $3,703 and $3,016, respectively	140,332	100,886
Refundable income taxes	3,726	0
Prepaid expenses	20,448	15,182
Inventory	17,519	13,472
Other current assets	12,227	6,787
Total current assets	413,341	207,479
Property, plant and equipment, net of accumulated depreciation and amortization of $1,136,955 and $1,064,756, respectively	935,402	720,550
Operating lease right-of-use assets	103,116	92,063
Goodwill	737,150	274,458
Intangible assets, net	256,689	91,783
Restricted cash and assets	4,658	1,900
Cost method investments	10,967	10,967
Deferred income taxes	6,604	22,903
Other non-current assets	30,088	27,112
Total assets	2,498,015	1,449,215
CURRENT LIABILITIES:
Current maturities of debt	33,957	8,968
Current operating lease liabilities	8,626	7,000
Accounts payable	100,108	74,203
Accrued payroll and related expenses	20,753	23,556
Accrued interest	3,719	2,858
Contract liabilities	18,852	3,742
Current accrued final capping, closure and post-closure costs	13,155	11,036
Other accrued liabilities	54,014	46,237
Total current liabilities	253,184	177,600
Debt, less current portion	1,012,169	585,015
Operating lease liabilities, less current portion	68,584	57,345
Accrued final capping, closure and post-closure costs, less current portion	104,401	102,642
Deferred income taxes	516	437
Other long-term liabilities	28,294	28,276
COMMITMENTS AND CONTINGENCIES
STOCKHOLDERS' EQUITY:
Additional paid-in capital	1,165,517	661,761
Accumulated deficit	(144,710)	(171,920)
Accumulated other comprehensive income, net of tax	9,480	7,542
Total stockholders' equity	1,030,867	497,900
Total liabilities and stockholders' equity	2,498,015	1,449,215
Class A Common Stock
STOCKHOLDERS' EQUITY:
Common stock	570	507
Class B Common Stock
STOCKHOLDERS' EQUITY:
Common stock	$ 10	$ 10

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2023 USD ($) vote $ / shares shares	Dec. 31, 2022 USD ($) vote $ / shares shares
Accounts receivable - trade, allowance for credit losses | $	$ 3,703	$ 3,016
Accumulated depreciation and amortization | $	$ 1,136,955	$ 1,064,756
Class A Common Stock
Common stock, par value (in dollars per share) | $ / shares	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	56,994,000	50,704,000
Common stock, shares outstanding (in shares)	56,994,000	50,704,000
Class B Common Stock
Common stock, par value (in dollars per share) | $ / shares	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	1,000,000	1,000,000
Common stock, shares issued (in shares)	988,000	988,000
Common stock, shares outstanding (in shares)	988,000	988,000
Votes per share held (in votes) | vote	10	10

UNAUDITED CONSOLIDATED STATEMEN

UNAUDITED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Income Statement [Abstract]
Revenues	$ 352,735	$ 295,268	$ 904,975	$ 812,962
Operating expenses:
Cost of operations	226,303	190,285	592,865	538,779
General and administration	41,177	34,348	112,721	97,702
Depreciation and amortization	47,736	32,527	116,095	93,106
Expense from acquisition activities	3,261	816	9,801	3,878
Southbridge Landfill closure charge	70	245	276	563
Legal settlement	0	0	6,150	0
Environmental remediation charge	0	759	0	759
Total operating expenses	318,547	258,980	837,908	734,787
Operating income	34,188	36,288	67,067	78,175
Other expense (income):
Interest income	(5,525)	(178)	(7,820)	(260)
Interest expense	15,748	6,177	31,708	17,078
Loss from termination of bridge financing	0	0	8,191	0
Other income	(225)	(1,523)	(1,019)	(1,978)
Other expense, net	9,998	4,476	31,060	14,840
Income before income taxes	24,190	31,812	36,007	63,335
Provision for income taxes	6,018	9,140	8,797	18,677
Net income	$ 18,172	$ 22,672	$ 27,210	$ 44,658
Basic earnings per share attributable to common stockholders:
Weighted average common shares outstanding, basic (in shares)	57,962	51,677	54,228	51,604
Basic earnings per common share (in dollars per share)	$ 0.31	$ 0.44	$ 0.50	$ 0.87
Diluted earnings per share attributable to common stockholders:
Weighted average common shares outstanding, diluted (in shares)	58,062	51,806	54,325	51,749
Diluted earnings per common share (in dollars per share)	$ 0.31	$ 0.44	$ 0.50	$ 0.86

UNAUDITED CONSOLIDATED STATEM_2

UNAUDITED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Statement of Comprehensive Income [Abstract]
Net income	$ 18,172	$ 22,672	$ 27,210	$ 44,658
Hedging activity:
Interest rate swap settlements	1,763	(129)	4,108	(2,224)
Interest rate swap (income) loss reclassified into interest expense	(1,805)	14	(4,181)	2,136
Unrealized gain resulting from changes in fair value of derivative instruments	2,621	5,493	2,738	17,362
Other comprehensive income, before tax	2,579	5,378	2,665	17,274
Income tax provision related to items of other comprehensive income	707	1,468	727	4,241
Other comprehensive income, net of tax	1,872	3,910	1,938	13,033
Comprehensive income	$ 20,044	$ 26,582	$ 29,148	$ 57,691

UNAUDITED CONSOLIDATED STATEM_3

UNAUDITED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)	Class A Common Stock	Class A Common Stock Common Stock	Class B Common Stock	Class B Common Stock Common Stock
Beginning balance at Dec. 31, 2021	$ 422,457	$ 652,045	$ (224,999)	$ (5,103)		$ 504		$ 10
Beginning balance (in shares) at Dec. 31, 2021						50,423,000		988,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances of Class A common stock	19	17				$ 2
Issuance of Class A common stock (in shares)						227,000
Stock-based compensation	2,241	2,241
Net income	4,190		4,190
Hedging activity	6,143			6,143
Ending balance at Mar. 31, 2022	435,050	654,303	(220,809)	1,040		$ 506		$ 10
Ending balance (in shares) at Mar. 31, 2022						50,650,000		988,000
Beginning balance at Dec. 31, 2021	422,457	652,045	(224,999)	(5,103)		$ 504		$ 10
Beginning balance (in shares) at Dec. 31, 2021						50,423,000		988,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	44,658
Hedging activity	13,033
Ending balance at Sep. 30, 2022	486,559	658,453	(180,341)	7,930		$ 507		$ 10
Ending balance (in shares) at Sep. 30, 2022					50,692,000	50,692,000	988,000	988,000
Beginning balance at Mar. 31, 2022	435,050	654,303	(220,809)	1,040		$ 506		$ 10
Beginning balance (in shares) at Mar. 31, 2022						50,650,000		988,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances of Class A common stock	803	802				$ 1
Issuance of Class A common stock (in shares)						40,000
Stock-based compensation	937	937
Net income	17,796		17,796
Hedging activity	2,980			2,980
Ending balance at Jun. 30, 2022	457,566	656,042	(203,013)	4,020		$ 507		$ 10
Ending balance (in shares) at Jun. 30, 2022						50,690,000		988,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Class A common stock (in shares)						2,000
Stock-based compensation	2,411	2,411
Net income	22,672		22,672
Hedging activity	3,910			3,910
Ending balance at Sep. 30, 2022	486,559	658,453	(180,341)	7,930		$ 507		$ 10
Ending balance (in shares) at Sep. 30, 2022					50,692,000	50,692,000	988,000	988,000
Beginning balance at Dec. 31, 2022	497,900	661,761	(171,920)	7,542		$ 507		$ 10
Beginning balance (in shares) at Dec. 31, 2022					50,704,000	50,704,000	988,000	988,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances of Class A common stock	0	(2)				$ 2
Issuance of Class A common stock (in shares)						194,000
Stock-based compensation	1,976	1,976
Net income	3,548		3,548
Hedging activity	(1,769)			(1,769)
Ending balance at Mar. 31, 2023	501,655	663,735	(168,372)	5,773		$ 509		$ 10
Ending balance (in shares) at Mar. 31, 2023						50,898,000		988,000
Beginning balance at Dec. 31, 2022	497,900	661,761	(171,920)	7,542		$ 507		$ 10
Beginning balance (in shares) at Dec. 31, 2022					50,704,000	50,704,000	988,000	988,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	27,210
Hedging activity	1,938
Ending balance at Sep. 30, 2023	1,030,867	1,165,517	(144,710)	9,480		$ 570		$ 10
Ending balance (in shares) at Sep. 30, 2023					56,994,000	56,994,000	988,000	988,000
Beginning balance at Mar. 31, 2023	501,655	663,735	(168,372)	5,773		$ 509		$ 10
Beginning balance (in shares) at Mar. 31, 2023						50,898,000		988,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Class A common stock - equity offering, net of stock issuance costs	496,238	496,177				$ 61
Issuance of Class A common stock - equity offering, net of stock issuance costs (in shares)						6,053,000
Issuances of Class A common stock	799	799
Issuance of Class A common stock (in shares)						23,000
Stock-based compensation	2,366	2,366
Net income	5,490		5,490
Hedging activity	1,835			1,835
Ending balance at Jun. 30, 2023	1,008,383	1,163,077	(162,882)	7,608		$ 570		$ 10
Ending balance (in shares) at Jun. 30, 2023						56,974,000		988,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Class A common stock - stock issuance costs	(7)	(7)
Issuances of Class A common stock	89	89
Issuance of Class A common stock (in shares)						20,000
Stock-based compensation	2,358	2,358
Net income	18,172		18,172
Hedging activity	1,872			1,872
Ending balance at Sep. 30, 2023	$ 1,030,867	$ 1,165,517	$ (144,710)	$ 9,480		$ 570		$ 10
Ending balance (in shares) at Sep. 30, 2023					56,994,000	56,994,000	988,000	988,000

UNAUDITED CONSOLIDATED STATEM_4

UNAUDITED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Cash Flows from Operating Activities:
Net income	$ 27,210	$ 44,658
Adjustment to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	116,095	93,106
Interest accretion on landfill and environmental remediation liabilities	7,470	6,018
Amortization of debt issuance costs	2,221	1,414
Stock-based compensation	6,699	5,589
Operating lease right-of-use assets expense	10,956	10,405
Disposition of assets, other items and charges, net	279	(282)
Loss from termination of bridge financing	8,191	0
Deferred income taxes	5,233	13,819
Changes in assets and liabilities, net of effects of acquisitions and divestitures:
Accounts receivable	(23,298)	(14,230)
Landfill operating lease contract expenditures	(3,336)	(3,336)
Accounts payable	24,568	7,946
Prepaid expenses, inventories and other assets	(10,112)	(5,799)
Accrued expenses, contract liabilities and other liabilities	(14,351)	(6,877)
Net cash provided by operating activities	157,825	152,431
Cash Flows from Investing Activities:
Acquisitions, net of cash acquired	(847,763)	(73,963)
Additions to property, plant and equipment	(90,364)	(87,667)
Proceeds from sale of property and equipment	971	571
Net cash used in investing activities	(937,156)	(161,059)
Cash Flows from Financing Activities:
Proceeds from debt borrowings	465,000	82,200
Principal payments on debt	(18,563)	(57,407)
Payments of debt issuance costs	(12,759)	(1,232)
Payments of contingent consideration	0	(1,000)
Proceeds from the exercise of share based awards	89	192
Proceeds from the public offering of Class A common stock	496,231	0
Net cash provided by financing activities	929,998	22,753
Net increase in cash and cash equivalents	150,667	14,125
Cash, cash equivalents and restricted cash, beginning of period	71,152	33,809
Cash, cash equivalents and restricted cash, end of period	221,819	47,934
Cash paid during the period for:
Cash interest payments	28,626	14,750
Cash income tax payments	9,689	2,875
Supplemental Disclosure of Non-Cash Investing and Financing Activities:
Non-current assets obtained through long-term financing obligations	8,053	9,420
Right-of-use assets obtained in exchange for operating lease obligations	$ 18,558	$ 7,672

BASIS OF PRESENTATION

BASIS OF PRESENTATION	9 Months Ended
	Sep. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
BASIS OF PRESENTATION	BASIS OF PRESENTATION Casella Waste Systems, Inc. (“Parent”), a Delaware corporation, and its consolidated subsidiaries (collectively, “we”, “us” or “our”), is a regional, vertically integrated solid waste services company. We provide resource management expertise and services to residential, commercial, municipal, institutional and industrial customers, primarily in the areas of solid waste collection and disposal, transfer, recycling and organics services. We provide integrated solid waste services in nine states: Vermont, New Hampshire, New York, Massachusetts, Connecticut, Maine, Pennsylvania, Delaware and Maryland, with our headquarters located in Rutland, Vermont. On June 30, 2023, we acquired the equity interests of four wholly owned subsidiaries of GFL Environmental Inc. ("GFL Subsidiaries"), which are the basis of our newly formed regional operating segment, the Mid-Atlantic region, that expanded our integrated solid waste services into the states of Delaware and Maryland ("GFL Acquisition"). See Note 4, Business Combinations for further disclosure. Operations under the Mid-Atlantic region commenced on July 1, 2023. The GFL Acquisition was funded from financing transactions (see Note 7, Debt for further disclosure), the net proceeds from an equity offering completed June 16, 2023 (see Note 9, Stockholders’ Equity for further disclosure), and cash on hand. We manage our solid waste operations on a geographic basis through regional operating segments, the Eastern, Western and Mid-Atlantic regions, each of which provides a comprehensive range of solid waste services. We manage our resource-renewal operations through the Resource Solutions operating segment, which leverages our core competencies in materials processing, industrial recycling, organics and resource management service offerings to deliver a comprehensive solution for our larger commercial, municipal, institutional and industrial customers that have more diverse waste and recycling needs. Legal, tax, information technology, human resources, certain finance and accounting and other administrative functions are included in our Corporate Entities segment. The accompanying unaudited consolidated financial statements, which include the accounts of the Parent and our wholly-owned subsidiaries, have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”) pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). All significant intercompany accounts and transactions are eliminated in consolidation. Investments in entities in which we do not have a controlling financial interest are accounted for under either the equity method or the cost method of accounting, as appropriate. Our significant accounting policies are more fully discussed in Item 8. " Financial Statements and Supplementary Data " of our Annual Report on Form 10-K for the fiscal year ended December 31, 2022 ("fiscal year 2022"), which was filed with the SEC on February 17, 2023 ("2022 Form 10-K"). Preparation of our consolidated financial statements in accordance with GAAP requires management to make certain estimates and assumptions. These estimates and assumptions affect the accounting for and recognition and disclosure of assets, liabilities, equity, revenues and expenses. We must make these estimates and assumptions because certain information that we use is dependent on future events, cannot be calculated with a high degree of precision given the available data, or simply cannot be readily calculated. In the opinion of management, these consolidated financial statements include all adjustments, including normal recurring and nonrecurring adjustments, as applicable, necessary for a fair presentation of the financial position, results of operations and cash flows for the periods presented. The results for the three and nine months ended September 30, 2023 may not be indicative of the results for any other interim period or the entire fiscal year. The consolidated financial statements presented herein should be read in conjunction with our audited consolidated financial statements included in our 2022 Form 10-K. Certain prior period amounts in the consolidated financial statements are conformed to current period presentation. This includes the presentation of certain adjustments to reconcile net income to net cash provided by operating activities, which have been reclassified within cash flows from operating activities. Subsequent Events We have evaluated subsequent events or transactions that have occurred after the consolidated balance sheet date of September 30, 2023 through the date of filing of the consolidated financial statements with the SEC on this Quarterly Report on Form 10-Q and determined that there have been no material events that have occurred that would require recognition or adjustments to our disclosures in our consolidated financial statements.

ACCOUNTING CHANGES

ACCOUNTING CHANGES	9 Months Ended
	Sep. 30, 2023
Accounting Changes and Error Corrections [Abstract]
ACCOUNTING CHANGES	ACCOUNTING CHANGES The following table provides a brief description of a recent Accounting Standards Update ("ASU") to the Accounting Standards Codification ("ASC") issued by the Financial Accounting Standards Board (“FASB”) that we adopted and is deemed to have a possible material impact on our consolidated financial statements based on current account balances and activity: Standard Description Effect on the Financial Statements or Other Accounting standards adopted effective January 1, 2023 ASU No. 2020-04: Reference Rate Reform (Topic 848), as amended through December 2022 Provides temporary optional guidance to ease the potential burden in applying GAAP to contract modifications and hedging relationships that reference London Inter-Bank Offered Rate ("LIBOR") or another reference rate expected to be discontinued, subject to meeting certain criteria. This guidance provides optional expedients and exceptions for applying GAAP to contracts, hedging relationships and other transactions affected by reference rate reform if certain criteria are met. Effective the quarter ended March 31, 2023, we elected optional expedients under this guidance that allowed us to maintain hedge effectiveness upon modifying contract terms related to reference rate reform in our amended and restated credit agreement, dated as of December 22, 2021, as amended by the first amendment, dated as of February 9, 2023, the second amendment, dated as of February 9, 2023, and the third amendment, dated as of April 25, 2023, collectively with the specified acquisition loan joinder, dated May 25, 2023 ("Loan Joinder") (the "Amended and Restated Credit Agreement") until we transitioned our interest rate derivative agreements from LIBOR to term secured overnight financing rate ("Term SOFR") in the quarter ended June 30, 2023, See Note 7, Debt . This guidance will be in effect through December 31, 2024.

REVENUE RECOGNITION

REVENUE RECOGNITION	9 Months Ended
	Sep. 30, 2023
Revenue from Contract with Customer [Abstract]
REVENUE RECOGNITION	REVENUE RECOGNITION Revenues associated with our solid waste operations are derived mainly from solid waste collection and disposal services, including landfill, transfer station and transportation services, landfill gas-to-energy services and processing services. Revenues associated with our resource-renewal operations are derived from processing services and non-processing services, which we now refer to as our National Accounts business. The following tables set forth revenues disaggregated by service line and timing of revenue recognition by operating segment for each of the three and nine months ended September 30, 2023 and 2022: Three Months Ended September 30, 2023 Eastern Western Mid-Atlantic (1) Resource Solutions Total Revenues Collection $ 68,944 $ 93,924 $ 43,225 $ — $ 206,093 Landfill 7,588 18,563 — — 26,151 Transfer station 16,963 17,491 497 — 34,951 Transportation 1,328 3,907 — — 5,235 Landfill gas-to-energy 208 1,589 — — 1,797 Processing 2,476 545 — 27,782 30,803 National Accounts — — — 47,705 47,705 Total revenues $ 97,507 $ 136,019 $ 43,722 $ 75,487 $ 352,735 Transferred at a point-in-time $ 121 $ 651 $ — $ 8,549 $ 9,321 Transferred over time 97,386 135,368 43,722 66,938 343,414 Total revenues $ 97,507 $ 136,019 $ 43,722 $ 75,487 $ 352,735 Three Months Ended September 30, 2022 Eastern Western Mid-Atlantic (1) Resource Solutions Total Revenues Collection $ 61,875 $ 82,242 $ — $ — $ 144,117 Landfill 7,900 20,240 — — 28,140 Transfer station 19,525 13,230 — — 32,755 Transportation 1,233 4,019 — — 5,252 Landfill gas-to-energy 205 1,438 — — 1,643 Processing 2,399 734 — 32,159 35,292 National Accounts — — — 48,069 48,069 Total revenues $ 93,137 $ 121,903 $ — $ 80,228 $ 295,268 Transferred at a point-in-time $ 115 $ 439 $ — $ 12,380 $ 12,934 Transferred over time 93,022 121,464 — 67,848 282,334 Total revenues $ 93,137 $ 121,903 $ — $ 80,228 $ 295,268 Nine Months Ended September 30, 2023 Eastern Western Mid-Atlantic (1) Resource Solutions Total Revenues Collection $ 194,801 $ 257,891 $ 43,225 $ — $ 495,917 Landfill 21,109 53,943 — — 75,052 Transfer 48,643 42,181 497 — 91,321 Transportation 3,718 11,342 — — 15,060 Landfill gas-to-energy 594 4,448 — — 5,042 Processing 5,875 1,476 — 75,970 83,321 National Accounts — — — 139,262 139,262 Total revenues $ 274,740 $ 371,281 $ 43,722 $ 215,232 $ 904,975 Transferred at a point-in-time $ 339 $ 2,072 $ — $ 23,121 $ 25,532 Transferred over time 274,401 369,209 43,722 192,111 879,443 Total revenues $ 274,740 $ 371,281 $ 43,722 $ 215,232 $ 904,975 Nine Months Ended September 30, 2022 Eastern Western Mid-Atlantic (1) Resource Solutions Total Revenues Collection $ 172,671 $ 228,239 $ — $ — $ 400,910 Landfill 19,819 53,028 — — 72,847 Transfer 48,431 33,055 — — 81,486 Transportation 4,470 10,700 — — 15,170 Landfill gas-to-energy 727 5,323 — — 6,050 Processing 5,602 2,281 — 93,421 101,304 National Accounts — — — 135,195 135,195 Total revenues $ 251,720 $ 332,626 $ — $ 228,616 $ 812,962 Transferred at a point-in-time $ 352 $ 1,467 $ — $ 46,279 $ 48,098 Transferred over time 251,368 331,159 — 182,337 764,864 Total revenues $ 251,720 $ 332,626 $ — $ 228,616 $ 812,962 (1) Operations under the Mid-Atlantic region commenced July 1, 2023. Payments to customers that are not in exchange for a distinct good or service are recorded as a reduction of revenues. Rebates to certain customers associated with payments for recycled or organic materials that are received and subsequently processed and sold to other third-parties amounted to $4,617 and $17,575 in the three and nine months ended September 30, 2023, respectively, and $5,460 and $15,162 in the three and nine months ended September 30, 2022, respectively. Rebates are generally recorded as a reduction of revenues upon the sale of such materials, or upon receipt of the recycled materials at our facilities. We did not record revenues in the three and nine months ended September 30, 2023 or September 30, 2022 from performance obligations satisfied in previous periods. Contract receivables, which are included in accounts receivable, net in our consolidated balance sheets are recorded when billed or when related revenue is earned, if earlier, and represent claims against third-parties that will be settled in cash. Accounts receivable, net includes gross receivables from contracts of $126,672 and $102,234 as of September 30, 2023 and December 31, 2022, respectively. Certain customers are billed in advance and, accordingly, recognition of the related revenues for which payment has been received is deferred as a contract liability until the services are provided and control transferred to the customer. We recognized contract liabilities of $18,852 and $3,742 as of September 30, 2023 and December 31, 2022, respectively. Due to the short term nature of advanced billings, substantially all of the deferred revenue recognized as a contract liability as of December 31, 2022 and December 31, 2021 was recognized as revenue during the nine months ended September 30, 2023 and September 30, 2022, respectively, when the services were performed.

BUSINESS COMBINATIONS

BUSINESS COMBINATIONS	9 Months Ended
	Sep. 30, 2023
Business Combination and Asset Acquisition [Abstract]
BUSINESS COMBINATIONS	BUSINESS COMBINATIONS In the nine months ended September 30, 2023, we acquired five businesses: the GFL Subsidiaries, which includes solid waste collection, transfer and recycling operations in Pennsylvania, Maryland and Delaware and whose assets are allocated between our Mid-Atlantic region and Resource Solutions operating segments; Consolidated Waste Services, LLC and its affiliates (dba Twin Bridges), which was completed on September 1, 2023, consisting of a collection, transfer and recycling business in the greater Albany, New York area whose assets are allocated between our Western region and Resource Solutions operating segments ("Twin Bridges Acquisition"); as well as three solid-waste collection businesses that provide collection, transfer and recycling services. In the nine months ended September 30, 2022, we acquired twelve businesses primarily related to our solid-waste operations, which included solid-waste collection, recycling, transfer station and transportation businesses. The operating results of these businesses have been included in the accompanying unaudited consolidated statements of operations from each date of acquisition, and the purchase price has been allocated to the net assets acquired based on fair values at each date of acquisition with the residual amounts recorded as goodwill. Purchase price allocations are based on information existing at the acquisition dates or upon closing the transactions. Acquired intangible assets other than goodwill that are subject to amortization may include customer relationships, trade names and covenants not-to-compete. Such assets are amortized over a two-year to ten-year period from the date of acquisition. Substantially all amounts recorded to goodwill are expected to be deductible for tax purposes. A summary of the purchase price paid and the purchase price allocation for acquisitions follows: Nine Months Ended 2023 2022 Purchase Price: Cash used in acquisitions, net of cash acquired $ 842,635 $ 72,731 Other non-cash consideration — 1,220 Holdbacks and additional consideration owed to sellers 2,435 4,112 Total consideration $ 845,070 $ 78,063 Allocated as follows: Current assets $ 19,297 $ 7,599 Property, plant and equipment: Land 6,760 3,141 Buildings and improvements 29,636 8,566 Machinery and equipment 175,309 10,296 Operating lease right-of-use assets 11,732 405 Intangible assets: Covenants not-to-compete 37,648 2,034 Customer relationships 145,553 11,417 Other non-current assets — 40 Deferred tax liability (11,013) — Current liabilities (21,724) (3,721) Other long-term liabilities (828) (123) Operating lease liabilities, less current portion (9,939) (282) Fair value of assets acquired and liabilities assumed 382,431 39,372 Excess purchase price allocated to goodwill $ 462,639 $ 38,691 Certain purchase price allocations, including but not limited to the GFL Acquisition and the Twin Bridges Acquisition, which are subject to finalizing the third-party valuations, are preliminary and are based on information existing at the acquisition dates or upon closing the transaction. Accordingly, the purchase price allocations are subject to change. Unaudited pro forma combined information that shows our operational results as though each acquisition completed since the beginning of the prior fiscal year had occurred as of January 1, 2022 is as follows: Three Months Ended Nine Months Ended 2023 2022 2023 2022 Revenues $ 371,139 $ 374,421 $ 1,077,303 $ 1,061,748 Operating income $ 34,584 $ 40,537 $ 75,876 $ 92,345 Net income $ 17,964 $ 24,339 $ 30,318 $ 50,001 Basic earnings per share attributable to common stockholders: Weighted average common shares outstanding 57,962 51,677 54,228 51,604 Basic earnings per common share $ 0.31 $ 0.47 $ 0.56 $ 0.97 Diluted earnings per share attributable to common stockholders: Weighted average common shares outstanding 58,062 51,806 54,325 51,749 Diluted earnings per common share $ 0.31 $ 0.47 $ 0.56 $ 0.97 The unaudited pro forma results set forth in the table above have been prepared for comparative purposes only and are not necessarily indicative of the actual results of operations had the acquisitions occurred as of January 1, 2022 or of the results of our future operations. Furthermore, the unaudited pro forma results do not give effect to all cost savings or incremental costs that may occur as the result of the integration and consolidation of the completed acquisitions.

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS	9 Months Ended
	Sep. 30, 2023
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND INTANGIBLE ASSETS	GOODWILL AND INTANGIBLE ASSETS A summary of the activity and balances related to goodwill by operating segment is as follows: December 31, Acquisitions Measurement Period Adjustments September 30, Eastern $ 52,406 $ 23,947 $ — $ 76,353 Western 183,286 97,905 53 281,244 Mid-Atlantic — 331,975 — 331,975 Resource Solutions 38,766 8,812 — 47,578 $ 274,458 $ 462,639 $ 53 $ 737,150 Summaries of intangible assets by type follows: Covenants Customer Relationships Trade Names Total Balance, September 30, 2023 Intangible assets $ 68,960 $ 272,731 $ 8,405 $ 350,096 Less accumulated amortization (25,713) (61,201) (6,493) (93,407) $ 43,247 $ 211,530 $ 1,912 $ 256,689 Covenants Customer Relationships Trade Names Total Balance, December 31, 2022 Intangible assets $ 31,201 $ 127,179 $ 8,405 $ 166,785 Less accumulated amortization (24,129) (46,162) (4,711) (75,002) $ 7,072 $ 81,017 $ 3,694 $ 91,783 Intangible amortization expense was $10,109 and $18,405 during the three and nine months ended September 30, 2023, respectively, and $4,281 and $12,333 during the three and nine months ended September 30, 2022, respectively. A summary of intangible amortization expense estimated for each of the next five fiscal years following fiscal year 2022 and thereafter is estimated as follows: Estimated Future Amortization Expense as of September 30, 2023 Fiscal year ending December 31, 2023 $ 12,589 Fiscal year ending December 31, 2024 $ 48,250 Fiscal year ending December 31, 2025 $ 44,556 Fiscal year ending December 31, 2026 $ 40,193 Fiscal year ending December 31, 2027 $ 36,053 Thereafter $ 75,048

ACCRUED FINAL CAPPING, CLOSURE

ACCRUED FINAL CAPPING, CLOSURE AND POST CLOSURE	9 Months Ended
	Sep. 30, 2023
Asset Retirement Obligation Disclosure [Abstract]
ACCRUED FINAL CAPPING, CLOSURE AND POST CLOSURE	ACCRUED FINAL CAPPING, CLOSURE AND POST CLOSURE Accrued final capping, closure and post-closure costs include the current and non-current portion of costs associated with obligations for final capping, closure and post-closure of our landfills. We estimate our future final capping, closure and post-closure costs in order to determine the final capping, closure and post-closure expense per ton of waste placed into each landfill. The anticipated time frame for paying these costs varies based on the remaining useful life of each landfill as well as the duration of the post-closure monitoring period. A summary of the changes to accrued final capping, closure and post-closure liabilities follows: Nine Months Ended 2023 2022 Beginning balance $ 113,678 $ 86,914 Obligations incurred 4,023 3,592 Revision in estimates (1) — 1,443 Accretion expense 7,193 5,685 Obligations settled (2) (7,338) (3,027) Ending balance $ 117,556 $ 94,607 (1) Relates to a change in estimates concerning anticipated capping costs at one of our landfills. (2) May include amounts that are being processed through accounts payable as a part of our disbursements cycle.

DEBT

DEBT	9 Months Ended
	Sep. 30, 2023
Debt And Derivatives Disclosure [Abstract]
DEBT	DEBT A summary of debt is as follows: September 30, December 31, Senior Secured Credit Facility: Term loan A facility ("Term Loan Facility") due December 2026; bearing interest at Term SOFR plus 1.385% $ 350,000 $ 350,000 Term loan A facility ("2023 Term Loan Facility") due December 2026; bearing interest at Term SOFR plus 1.885% 424,625 — Revolving credit facility ("Revolving Credit Facility") due December 2026; bearing interest at Term SOFR plus 1.385% — 6,000 Tax-Exempt Bonds: New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014 ("New York Bonds 2014R-1") due December 2044 - fixed rate interest period ending in 2029; bearing interest at 2.875% 25,000 25,000 New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014R-2 ("New York Bonds 2014R-2") due December 2044 - fixed rate interest period ending in 2026; bearing interest at 3.125% 15,000 15,000 New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2020 ("New York Bonds 2020") due September 2050 - fixed rate interest period ending in 2025; bearing interest at 2.750% 40,000 40,000 New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2020R-2 ("New York Bonds 2020R-2") due September 2050 - fixed rate interest period ending in 2030; bearing interest at 5.125% 35,000 — Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2005R-3 ("FAME Bonds 2005R-3") due January 2025 - fixed rate interest period ending in 2025; bearing interest at 5.25% 25,000 25,000 Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015R-1 ("FAME Bonds 2015R-1") due August 2035 - fixed rate interest period ending in 2025; bearing interest at 5.125% 15,000 15,000 Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015R-2 ("FAME Bonds 2015R-2") due August 2035 - fixed rate interest period ending in 2025; bearing interest at 4.375% 15,000 15,000 Vermont Economic Development Authority Solid Waste Disposal Long-Term Revenue Bonds Series 2013 ("Vermont Bonds 2013") due April 2036 - fixed rate interest period ending in 2028; bearing interest at 4.625% 16,000 16,000 Vermont Economic Development Authority Solid Waste Disposal Long-Term Revenue Bonds Series 2022A-1 ("Vermont Bonds 2022A-1") due June 2052 - fixed rate interest period ending in 2027; bearing interest at 5.00% 35,000 35,000 Business Finance Authority of the State of New Hampshire Solid Waste Disposal Revenue Bonds Series 2013 ("New Hampshire Bonds") due April 2029 - fixed rate interest period ending in 2029; bearing interest at 2.95% 11,000 11,000 Other: Finance leases 51,066 49,813 Notes payable maturing through March 2025; bearing interest up to 8.1% 278 664 Principal amount of debt 1,057,969 603,477 Less—unamortized debt issuance costs 11,843 9,494 Debt less unamortized debt issuance costs 1,046,126 593,983 Less—current maturities of debt 33,957 8,968 $ 1,012,169 $ 585,015 Financing Activities In February 2023, we entered into first and second amendments to our Amended and Restated Credit Agreement. The first amendment provides, commencing in the fiscal year ending December 31, 2024, that the interest rate margin applied for drawn and undrawn amounts under the Amended and Restated Credit Agreement shall be separately adjusted based on our achievement of certain thresholds and targets on two sustainability related key performance indicator metrics during the prior fiscal year: (i) metric tons of solid waste materials reduced, reused or recycled through our direct operations or with third-parties in collaboration with customers; and (ii) our total recordable incident rate. The second amendment provides that loans under the Amended and Restated Credit Agreement shall bear interest, at our election, at Term SOFR, including a secured overnight financing rate adjustment of 10 basis points, or at a base rate, in each case, plus or minus any sustainable rate adjustment plus an applicable interest rate margin based upon our consolidated net leverage ratio. In April 2023, we entered into an equity purchase agreement pursuant to which we agreed to the GFL Acquisition. In connection with the GFL Acquisition, we entered into (i) a commitment letter to obtain short-term secured bridge financing of up to $375,000 and (ii) the third amendment to the Amended and Restated Credit Agreement to, among other things, permit the draw down of the short-term secured bridge financing and authorize a delayed draw term loan facility to be executed with customary limited condition provisions. The short-term secured bridge financing was undrawn and subsequently terminated in May 2023 when we entered into the Loan Joinder, which provided for a $430,000 aggregate principal amount 2023 Term Loan Facility under the Amended and Restated Credit Agreement. In June 2023, we borrowed $430,000 under the 2023 Term Loan Facility and paid certain fees and costs due and payable in connection therewith. Borrowings from the 2023 Term Loan Facility were used to fund, in conjunction with the net proceeds from the public offering of our Class A common stock completed on June 16, 2023, cash and cash equivalents and borrowings from our Revolving Credit Facility, the GFL Acquisition. See Note 9, Stockholders' Equity for further disclosure regarding the public offering. In June 2023, we entered into an asset purchase agreement pursuant to which we agreed to the Twin Bridges Acquisition. In connection with the Twin Bridges Acquisition, we entered into a commitment letter to obtain short-term unsecured bridge financing of up to $200,000 that was undrawn and subsequently terminated when we completed the public offering of our Class A common stock on June 16, 2023. Net proceeds from the public equity offering completed on June 16, 2023, together with cash and cash equivalents, were used to fund the Twin Bridges Acquisition. See Note 9, Stockholders' Equity for further disclosure regarding the public offering. In August 2023, we completed the issuance of $35,000 aggregate principal amount of New York Bonds 2020R-2. The New York Bonds 2020R-2, which are unsecured and guaranteed jointly and severally, fully and unconditionally by all of our significant wholly-owned subsidiaries, accrue interest at 5.125% per annum from August 24, 2023 through September 2, 2030, at which time they may be converted to a variable interest rate period or to a new term interest rate period. The New York Bonds 2020R-2 mature on September 1, 2050. As of September 30, 2023, we had $2,730 of remaining cash proceeds from the issuance of the New York Bonds 2020R-2 included in restricted cash and assets that is restricted to finance or reimburse certain noncurrent asset costs associated with capital projects in the State of New York. Credit Facility As of September 30, 2023, we are party to the Amended and Restated Credit Agreement, which provides for a $350,000 aggregate principal amount Term Loan Facility, a $300,000 Revolving Credit Facility, with a $75,000 sublimit for letters of credit, and a $430,000 2023 Term Loan Facility (collectively, the "Credit Facility"). We have the right to request, at our discretion, an increase in the amount of loans under the Credit Facility by an aggregate amount of $125,000, subject to further increase based on the terms and conditions set forth in the Amended and Restated Credit Agreement. The Credit Facility has a 5-year term that matures in December 2026. The Credit Facility shall bear interest, at our election, at Term SOFR, including a secured overnight financing rate adjustment of 10 basis points, or at a base rate, in each case plus or minus any sustainable rate adjustment of up to positive or negative 4.0 basis points per annum, plus an applicable interest rate margin based upon our consolidated net leverage ratio as follows: Term SOFR Loans Base Rate Loans Term Loan Facility 1.125% to 2.125% 0.125% to 1.125% Revolving Credit Facility 1.125% to 2.125% 0.125% to 1.125% 2023 Term Loan Facility 1.625% to 2.625% 0.625% to 1.625% A commitment fee will be charged on undrawn amounts at a rate of Term SOFR, including a secured overnight financing rate adjustment of 10 basis points, plus a margin based upon our consolidated net leverage ratio in the range of 0.20% to 0.40% per annum, plus a sustainability adjustment of up to positive or negative 1.0 basis point per annum. The Amended and Restated Credit Agreement provides that Term SOFR is subject to a zero percent floor. We are also required to pay a fronting fee for each letter of credit of 0.25% per annum. Interest under the Amended and Restated Credit Agreement is subject to increase by 2.00% per annum during the continuance of a payment default and may be subject to increase by 2.00% per annum during the continuance of any other event of default. The Credit Facility is guaranteed jointly and severally, fully and unconditionally by all of our significant wholly-owned subsidiaries and secured by substantially all of our assets. As of September 30, 2023, further advances were available under the Revolving Credit Facility in the amount of $272,267. The available amount is net of outstanding irrevocable letters of credit totaling $27,733, and as of September 30, 2023 no amount had been drawn. Interest Expense The components of interest expense are as follows: Three Months Ended Nine Months Ended 2023 2022 2023 2022 Interest expense on long-term debt and finance leases $ 15,128 $ 5,692 $ 29,565 $ 15,513 Amortization of debt issuance costs (1) 715 489 2,221 1,414 Letter of credit fees 103 117 297 347 Less: capitalized interest (198) (121) (375) (196) Total interest expense $ 15,748 $ 6,177 $ 31,708 $ 17,078 (1) Includes interest expense related to a short-term secured bridge financing entered into in connection with the GFL Acquisition and interest expense related to a short-term unsecured bridge financing entered into in connection with the Twin Bridges Acquisition of $395 and $101, respectively, during the nine months ended September 30, 2023. Loss from Termination of Bridge Financing In the nine months ended September 30, 2023, we wrote-off the unamortized debt issuance costs and recognized a loss from termination of bridge financing upon the extinguishment of both a secured bridge financing agreement in connection with the GFL Acquisition of $3,718, and an unsecured bridge financing agreement in connection with the Twin Bridges Acquisition of $4,473. Cash Flow Hedges Our strategy to reduce exposure to interest rate risk involves entering into interest rate derivative agreements to hedge against adverse movements in interest rates related to the variable rate portion of our long-term debt. We have designated these derivative instruments as highly effective cash flow hedges, and therefore the change in their fair value is recorded in stockholders’ equity as a component of accumulated other comprehensive income, net of tax and included in interest expense at the same time as interest expense is affected by the hedged transactions. Differences paid or received over the life of the agreements are recorded as additions to or reductions of interest expense on the underlying debt and included in cash flows from operating activities. A summary of the changes to the notional amount of interest rate derivative agreements follows: Nine Months Ended Active Forward Starting Total Beginning balance $ 190,000 $ 20,000 $ 210,000 Additions 290,000 — 290,000 Commencements 20,000 (20,000) — Maturities (85,000) — (85,000) Ending balance (1) $ 415,000 $ — $ 415,000 (1) We receive interest based on Term SOFR, restricted by a 0.0% floor, and pay interest at a weighted average rate of approximately 3.41%. These agreements mature between February 2026 and June 2028. A summary of the effect of cash flow hedges related to derivative instruments on the consolidated balance sheets follows: Fair Value Balance Sheet Location September 30, December 31, Interest rate swaps Other current assets $ 7,835 $ 4,345 Interest rate swaps Other non-current assets 8,522 7,461 $ 16,357 $ 11,806 Interest rate swaps Other long-term liabilities $ 1,886 $ — Interest rate swaps Accumulated other comprehensive income, net of tax $ 14,471 $ 11,806 Interest rate swaps - tax effect Accumulated other comprehensive income, net of tax (4,991) (4,264) $ 9,480 $ 7,542

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	9 Months Ended
	Sep. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Legal Proceedings In the ordinary course of our business and as the result of the extensive governmental regulation of the solid waste industry, we are subject to various judicial and administrative proceedings involving state and local agencies. In these proceedings, an agency may seek to impose fines or to revoke or deny renewal of an operating permit held by us. From time to time, we may also be subject to actions brought by special interest or other groups, adjacent landowners or residents in connection with the permitting and licensing of landfills and transfer stations, or allegations of environmental damage or violations of the permits and licenses pursuant to which we operate. In addition, we may be named defendants in various claims and suits pending for alleged damages to persons and property, alleged violations of certain laws and alleged liabilities arising out of matters occurring during the ordinary operation of a waste management business. The plaintiffs in some actions seek unspecified damages or injunctive relief, or both. These actions fall within various procedural stages at any point in time, and some are covered in part by insurance. In accordance with FASB ASC 450 - Contingencies, we accrue for legal proceedings, inclusive of legal costs, when losses become probable and reasonably estimable. We have recorded an aggregate accrual of $6,280 relating to our outstanding legal proceedings as of September 30, 2023. As of the end of each applicable reporting period, we review each of our legal proceedings to determine whether it is probable, reasonably possible or remote that a liability has been incurred and, if it is at least reasonably possible, whether a range of loss can be reasonably estimated under the provisions of FASB ASC 450-20. In instances where we determine that a loss is probable and we can reasonably estimate a range of loss we may incur with respect to such a matter, we record an accrual for the amount within the range that constitutes our best estimate of the possible loss. If we are able to reasonably estimate a range, but no amount within the range appears to be a better estimate than any other, we record an accrual in the amount that is the low end of such range. When a loss is reasonably possible, but not probable, we will not record an accrual, but we will disclose our estimate of the possible range of loss where such estimate can be made in accordance with FASB ASC 450-20. We disclose outstanding matters that we believe could have a material adverse effect on our financial condition, results of operations or cash flows. See Note 11, Other Items and Charges for disclosure regarding a legal settlement charge recorded in the nine months ended September 30, 2023. North Country Environmental Services Expansion Permit The permit for expansion of the Bethlehem, New Hampshire landfill of our subsidiary, North Country Environmental Services, Inc. (“NCES”), known as “Stage VI”, issued in October 2020 (“Permit”), was appealed by the Conservation Law Foundation (“CLF”) to the New Hampshire Waste Management Council (“Council”) on November 9, 2020 on the grounds it failed to meet the public benefit criteria. Following a hearing on the merits during which the Council found that the New Hampshire Department of Environmental Services (“DES”) had reasonably measured and acted lawfully in determining a capacity need for Stage VI, the hearing officer presiding over the proceedings issued an Order on May 11, 2022, without further hearing, determining instead that DES had acted unlawfully in reaching these conclusions (“Hearing Officer’s Order”), and remanded the Permit to DES on this determination. On December 5, 2022, DES and NCES both separately sought review of the Hearing Officer’s Order on appeal to the New Hampshire Supreme Court (“Supreme Court”). The parties presented oral arguments to the Supreme Court on October 3, 2023. A decision has not yet been issued. On December 14, 2022, NCES filed an action in Merrimack Superior Court (“Superior Court”) seeking to invalidate the Hearing Officer’s Order as having been adopted in violation of New Hampshire’s statute governing access to public records and meetings in that the Council did not hold a public meeting to deliberate on the Hearing Officer’s Order. The Superior Court has since dismissed that proceeding, however, NCES appealed that decision to the Supreme Court on April 18, 2023. NCES’s brief on appeal was filed with the Supreme Court on August 11, 2023. On September 26, 2023, CLF filed a Motion to Intervene as well as a memorandum of law asking the Supreme Court to uphold the Superior Court’s dismissal, to which NCES filed an Objection in response on October 23, 2023. The Council submitted its brief on October 25, 2023; NCES’s reply is due November 4, 2023. CLF’s Motion to Intervene remains pending. In the event that the Supreme Court affirms the Hearing Officer’s Order on appeal, the Permit would remand to DES, where NCES would take steps in an effort to avoid or mitigate an adverse determination. If the Stage VI permit is not ultimately approved, NCES capacity could be curtailed. On September 20, 2022, NCES, which has since withdrawn as a party, and our subsidiary, Granite State Landfill, LLC, filed a Petition for Declaratory Judgment ("Petition") in the Superior Court asking the Superior Court for a determination of the meaning and constitutionality of New Hampshire’s public benefit requirement, the same statute at issue in the Hearing Officer’s Order. CLF was granted intervention in the Petition proceeding on June 8, 2023. This matter remains pending before the Superior Court. On April 12, 2023, DES issued approval of construction plans for Stage VI, Phase II to NCES (“DES Approval”). CLF appealed the DES Approval to the Council on May 11, 2023, on the grounds that it failed to meet the public benefit criteria, and that the DES Approval conflicts with the Hearing Officer’s May 11, 2022 Order determining that DES had acted unlawfully in issuing the Permit, and requested expedited review. The Council has denied the request for expedited review and this appeal remains pending before the Council. NCES will continue to vigorously defend the Permit through the appeals to the Supreme Court, will litigate the Petition before the Superior Court, and will defend the DES Approval on appeal before the Council. Cash, Cash Equivalents and Restricted Cash Restricted cash is included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. Beginning-of-period and end-of-period cash, cash equivalents and restricted cash s presented in the statement of cash flows is reconciled as follows: September 30, December 31, Cash and cash equivalents $ 219,089 $ 71,152 Restricted cash - non-current 2,730 — Cash, cash equivalents and restricted cash $ 221,819 $ 71,152 Our restricted cash consists of cash proceeds from the issuance of the New York Bonds 2020R-2 included in restricted cash and assets that is restricted to finance or reimburse certain noncurrent asset costs associated with capital projects in the State of New York. See Note 7, Debt for disclosure regarding New York Bonds 2020R-2. Environmental Remediation Liabilities We are subject to liability for environmental damage, including personal injury and property damage, that our solid waste, recycling and power generation facilities may cause to neighboring property owners, particularly as the result of the contamination of drinking water sources or soil, possibly including damage resulting from conditions that existed before we acquired the facilities. We may also be subject to liability for similar claims arising from off-site environmental contamination caused by pollutants or hazardous substances if we or our predecessors arrange or arranged to transport, treat or dispose of those materials. We accrue for costs associated with environmental remediation obligations when such costs become both probable and reasonably estimable. Determining the method and ultimate cost of remediation requires that a number of assumptions be made. There can sometimes be a range of reasonable estimates of the costs associated with remediation of a site. In these cases, we use the amount within the range that constitutes our best estimate. In the early stages of the remediation process, particular components of the overall liability may not be reasonably estimable; in this instance we use the components of the liability that can be reasonably estimated as a surrogate for the liability. It is reasonably possible that we will need to adjust the liabilities recorded for remediation to reflect the effects of new or additional information, to the extent such information impacts the costs, timing or duration of the required actions. Future changes in our estimates of the cost, timing or duration of the required actions could have a material adverse effect on our consolidated financial position, results of operations and cash flows. We disclose outstanding environmental remediation matters that remain unsettled or are settled in the reporting period that we believe could have a material adverse effect on our financial condition, results of operations or cash flows. We inflate the estimated costs in current dollars to the expected time of payment and discount the total cost to present value using a risk-free interest rate. The risk-free interest rates associated with our environmental remediation liabilities as of September 30, 2023 range between 1.5% and 4.1%. A summary of the changes to the aggregate environmental remediation liabilities for the nine months ended September 30, 2023 and 2022 follows: Nine Months Ended 2023 2022 Beginning balance $ 6,335 $ 5,887 Accretion expense 75 79 Obligations incurred (1) — 759 Obligations settled (2) (338) (353) Ending balance 6,072 6,372 Less: current portion 1,799 646 Long-term portion $ 4,273 $ 5,726 (1) Associated with the investigation of potential remediation at an inactive waste disposal site that adjoins one of the landfills that we operate. (2) May include amounts that are being processed through accounts payable as a part of our disbursement cycle.

STOCKHOLDERS' EQUITY

STOCKHOLDERS' EQUITY	9 Months Ended
	Sep. 30, 2023
Equity [Abstract]
STOCKHOLDERS' EQUITY	STOCKHOLDERS' EQUITY Public Offering of Class A Common Stock On June 16, 2023, we completed a public offering of 6,053 shares of our Class A common stock at a public offering price of $85.50 per share. After deducting stock issuance costs received as of September 30, 2023, including underwriting discounts, commissions and offering expenses, the offering has resulted in net proceeds of $496,231. The net proceeds from this offering were and are to be used to fund acquisition activity, including the GFL Acquisition and the Twin Bridges Acquisition , to pay certain costs associated with acquisition activities, as discussed in Note 11, Other Items and Charges , and to repay borrowings and/or debt securities as discussed Note 7, Debt. Stock Based Compensation Shares Available For Issuance In the fiscal year ended December 31, 2016, we adopted the 2016 Incentive Plan (“2016 Plan”). Under the 2016 Plan, we may grant awards up to an aggregate amount of shares equal to the sum of: (i) 2,250 shares of Class A common stock (subject to adjustment in the event of stock splits and other similar events), plus (ii) such additional number of shares of Class A common stock (up to 2,723 shares) as is equal to the sum of the number of shares of Class A common stock that remained available for grant under the 2006 Stock Incentive Plan (“2006 Plan”) immediately prior to the expiration of the 2006 Plan and the number of shares of Class A common stock subject to awards granted under the 2006 Plan that expire, terminate or are otherwise surrendered, canceled, forfeited or repurchased by us. As of September 30, 2023, there were 625 Class A common stock equivalents available for future grant under the 2016 Plan. On June 1, 2023, our stockholders approved the amendment and restatement of our Amended and Restated 1997 Employee Stock Purchase Plan (as further amended and restated, the “ESPP”) to increase the number of shares of Class A common stock reserved for issuance under the ESPP by 400 shares of Class A common stock. As of September 30, 2023, 444 shares of Class A common stock were available for issuance under the ESPP. Stock Options Stock options are granted at a price equal to the prevailing fair value of our Class A common stock at the date of grant. Generally, stock options granted have a term not to exceed ten years and vest over a one-year to five-year period from the date of grant. The fair value of each stock option granted is estimated using a Black-Scholes option-pricing model, which requires extensive use of accounting judgment and financial estimation, including estimates of the expected term stock option holders will retain their vested stock options before exercising them and the estimated volatility of our Class A common stock price over the expected term. A summary of stock option activity follows: Stock Options Weighted Average Exercise Price Weighted Average Remaining Contractual Term (years) Aggregate Intrinsic Value Outstanding, December 31, 2022 129 $ 55.60 Granted — $ — Exercised (18) $ 4.88 Forfeited — $ — Outstanding, September 30, 2023 111 $ 63.87 7.3 $ 1,846 Exercisable, September 30, 2023 49 $ 40.60 5.4 $ 1,825 Stock-based compensation expense related to stock options was $126 and $374 during the three and nine months ended September 30, 2023, respectively, as compared to $89 and $122 during the three and nine months ended September 30, 2022, respectively. As of September 30, 2023, we had $1,724 of unrecognized stock-based compensation expense related to outstanding stock options to be recognized over a weighted average period of 3.7 years. During the three and nine months ended September 30, 2023, the aggregate intrinsic value of stock options exercised was $1,302 and $1,302, respectively. Other Stock Awards Restricted stock awards, restricted stock units and performance stock units, with the exception of market-based performance stock units, are granted at a price equal to the fair value of our Class A common stock at the date of grant. The fair value of each market-based performance stock unit is estimated using a Monte Carlo pricing model, which requires extensive use of accounting judgment and financial estimation, including the estimated share price appreciation plus, if applicable, the value of dividends of our Class A common stock as compared to the Russell 2000 Index over the requisite service period. Generally, restricted stock awards granted to non-employee directors vest incrementally over a three-year to five-year period beginning on the first anniversary of the date of grant. Restricted stock units granted to non-employee directors vest in full on the first anniversary of the grant date. Restricted stock units granted to employees vest incrementally over an identified service period, typically three A summary of restricted stock award, restricted stock unit and performance stock unit activity follows: Restricted Stock Awards, Restricted Stock Units, and Performance Stock Units (1) Weighted Weighted Average Remaining Contractual Term (years) Aggregate Intrinsic Value Outstanding, December 31, 2022 169 $ 75.52 Granted 119 $ 81.04 Class A Common Stock Vested (65) $ 62.57 Forfeited (6) $ 76.91 Outstanding, September 30, 2023 217 $ 91.51 2.1 $ 16,597 Unvested, September 30, 2023 376 $ 88.63 1.7 $ 28,660 (1) Performance stock unit grants, including market-based performance stock units, are included at the 100% attainment level. Attainment of the maximum performance targets and market achievements would result in the issuance of an additional 159 shares of Class A common stock currently included in unvested. Stock-based compensation expense related to restricted stock awards, restricted stock units and performance stock units was $2,112 and $6,007 during the three and nine months ended September 30, 2023, respectively, as compared to $2,225 and $5,204 during the three and nine months ended September 30, 2022, respectively. During the three and nine months ended September 30, 2023, the total fair value of other stock awards vested was $223 and $5,279, respectively. As of September 30, 2023, total unrecognized stock-based compensation expense related to outstanding restricted stock awards was $12, which will be recognized over a weighted average period of 0.7 years. As of September 30, 2023, total unrecognized stock-based compensation expense related to outstanding restricted stock units was $6,344, which will be recognized over a weighted average period of 2.4 years. As of September 30, 2023, total expected unrecognized stock-based compensation expense related to outstanding performance stock units was $5,655 to be recognized over a weighted average period of 1.7 years. The weighted average fair value of market-based performance stock units granted during the nine months ended September 30, 2023 was $83.16 per award, which was calculated using a Monte Carlo pricing model assuming a risk-free interest rate of 4.31% and an expected volatility of 34.9% assuming no expected dividend yield. Risk-free interest rate is based on the U.S. Treasury yield curve for the expected service period of the award. Expected volatility is calculated using the daily volatility of our Class A common stock over the expected service period of the award. The Monte Carlo pricing model requires extensive use of accounting judgment and financial estimation. Application of alternative assumptions could produce significantly different estimates of the fair value of stock-based compensation and consequently, the related amounts recognized in the consolidated statements of operations. We also recorded $120 and $318 of stock-based compensation expense related to the ESPP during the three and nine months ended September 30, 2023, respectively, as compared to $97 and $262 during the three and nine months ended September 30, 2022, respectively. Accumulated Other Comprehensive Income, Net of Tax A summary of the changes in the balances of each component of accumulated other comprehensive income, net of tax follows: Interest Rate Swaps Balance, December 31, 2022 $ 7,542 Other comprehensive income before reclassifications 6,846 Income reclassified from accumulated other comprehensive income into interest expense (4,181) Income tax provision related to items of other comprehensive income (727) Net current-period other comprehensive income, net of tax 1,938 Balance, September 30, 2023 $ 9,480 A summary of reclassifications out of accumulated other comprehensive income, net of tax into earnings follows: Three Months Ended Nine Months Ended 2023 2022 2023 2022 Details About Accumulated Other Comprehensive Income, Net of Tax Components Amounts Reclassified Out of Accumulated Other Comprehensive Income, Net of Tax Affected Line Item in the Consolidated Interest rate swaps $ (1,805) $ 14 $ (4,181) $ 2,136 Interest expense 1,805 (14) 4,181 (2,136) Income before income taxes 495 — 1,146 (190) Provision for income taxes $ 1,310 $ (14) $ 3,035 $ (1,946) Net income

EARNINGS PER SHARE

EARNINGS PER SHARE	9 Months Ended
	Sep. 30, 2023
Earnings Per Share [Abstract]
EARNINGS PER SHARE	EARNINGS PER SHARE Basic earnings per share is computed by dividing net income by the weighted average number of common shares outstanding during the period. Diluted earnings per share is calculated based on the combined weighted average number of common shares and potentially dilutive shares, which include the assumed exercise of employee stock options, unvested restricted stock awards, unvested restricted stock units and unvested performance stock units, including market-based performance units based on the expected achievement of performance targets. In computing diluted earnings per share, we utilize the treasury stock method. A summary of the numerator and denominators used in the computation of earnings per share follows: Three Months Ended Nine Months Ended 2023 2022 2023 2022 Numerator: Net income $ 18,172 $ 22,672 $ 27,210 $ 44,658 Denominators: Number of shares outstanding, end of period: Class A common stock 56,994 50,692 56,994 50,692 Class B common stock 988 988 988 988 Unvested restricted stock — (1) — (1) Effect of weighted average shares outstanding (1) (20) (2) (3,754) (75) Basic weighted average common shares outstanding 57,962 51,677 54,228 51,604 Impact of potentially dilutive securities: Dilutive effect of stock options and other stock awards 100 129 97 145 Diluted weighted average common shares outstanding 58,062 51,806 54,325 51,749 Anti-dilutive potentially issuable shares 78 84 75 115 (1) The adjustment in the nine months ended September 30, 2023 is primarily associated with the 6,053 shares of Class A common stock issued as part of the public offering, completed on June 16, 2023. See Note 9, Stockholders’ Equity for disclosure regarding the public offering of Class A common stock.

OTHER ITEMS AND CHARGES

OTHER ITEMS AND CHARGES	9 Months Ended
	Sep. 30, 2023
Unusual or Infrequent Items, or Both [Abstract]
OTHER ITEMS AND CHARGES	OTHER ITEMS AND CHARGES Expense from Acquisition Activities In the three and nine months ended September 30, 2023, we recorded charges of $3,261 and $9,801, respectively, and in the three and nine months ended September 30, 2022, we recorded charges of $816 and $3,878, respectively, comprised primarily of legal, consulting and other similar costs associated with due diligence and the acquisition and integration of acquired businesses, including the GFL Acquisition and the Twin Bridges Acquisition in the nine months ended September 30, 2023, or select development projects. Legal Settlement In the nine months ended September 30, 2023, we recorded a charge of $6,150 accrued for in other accrued liabilities due to reaching an agreement at a mediation held on June 20, 2023 with the collective class members of a class action lawsuit relating to certain claims under the Fair Labor Standards Act of 1938 as well as state wage and hours laws. The settlement agreement was executed July 24, 2023 and has received court approval. See Note 8, Commitments and Contingencies for disclosure regarding our aggregate legal proceedings accrual. Environmental Remediation Charge In the three and nine months ended September 30, 2022, we recorded a charge of $759 associated with the investigation of potential remediation at an inactive waste disposal site that adjoins one of the landfills we operate.

FAIR VALUE OF FINANCIAL INSTRUM

FAIR VALUE OF FINANCIAL INSTRUMENTS	9 Months Ended
	Sep. 30, 2023
Fair Value Disclosures [Abstract]
FAIR VALUE OF FINANCIAL INSTRUMENTS	FAIR VALUE OF FINANCIAL INSTRUMENTS We use a three-tier fair value hierarchy to classify and disclose all assets and liabilities measured at fair value on a recurring basis, as well as assets and liabilities measured at fair value on a non-recurring basis, in periods subsequent to their initial measurement. These tiers include: Level 1, defined as quoted market prices in active markets for identical assets or liabilities; Level 2, defined as inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; and Level 3, defined as unobservable inputs that are not corroborated by market data. We use valuation techniques that maximize the use of market prices and observable inputs and minimize the use of unobservable inputs. In measuring the fair value of our financial assets and liabilities, we rely on market data or assumptions that we believe market participants would use in pricing an asset or a liability. Assets and Liabilities Accounted for at Fair Value Our financial instruments include cash and cash equivalents, accounts receivable, restricted investment securities held in trust on deposit with various banks as collateral for our obligations relative to our landfill final capping, closure and post-closure costs, interest rate derivatives, contingent consideration related to acquisitions, trade payables and debt. The carrying values of cash and cash equivalents, restricted cash accounts receivable and trade payables approximate their respective fair values due to their short-term nature. The fair value of restricted investment securities held in trust, which are valued using quoted market prices, are included as restricted assets in the Level 1 tier below. The fair value of the interest rate derivatives included in the Level 2 tier below is calculated using discounted cash flow valuation methodologies based upon Term SOFR yield curves that are observable at commonly quoted intervals for the full term of the swaps. The fair value of contingent consideration - acquisition included in the Level 3 tier below is calculated using a discounted cash flow valuation methodology based upon a probability-weighted analysis of a success payment related to the potential attainment of a transfer station permit expansion. We recognize all derivatives accounted for on the balance sheet at fair value. Recurring Fair Value Measurements Summaries of our financial assets and liabilities that are measured at fair value on a recurring basis follow: Fair Value Measurement at September 30, 2023 Using: Quoted Prices in Significant Other Significant Assets: Restricted investment securities - landfill closure $ 1,928 $ — $ — Interest rate swaps — 16,357 — $ 1,928 $ 16,357 $ — Liabilities: Interest rate swaps — 1,886 — $ — $ 1,886 $ — Fair Value Measurement at December 31, 2022 Using: Quoted Prices in Significant Other Significant Assets: Restricted investment securities - landfill closure $ 1,900 $ — $ — Interest rate swaps — 11,806 — $ 1,900 $ 11,806 $ — Liabilities: Contingent consideration - acquisition (1) $ — $ — $ 965 (1) In the three and nine months ended September 30, 2023, we recorded a gain on resolution of acquisition-related contingent consideration of $376 and $965, respectively, within cost of operations associated with the reversal of a contingency for a transfer station permit expansion that is no longer deemed viable. Fair Value of Debt As of September 30, 2023, the fair value of our fixed rate debt, including our FAME Bonds 2005R-3, FAME Bonds 2015R-1, FAME Bonds 2015R-2, Vermont Bonds 2013, Vermont Bonds 2022A-1, New York Bonds 2014R-1, New York Bonds 2014R-2, New York Bonds 2020, New York Bonds 2020R-2 and New Hampshire Bonds (collectively, the "Industrial Revenue Bonds") was approximately $223,926 and the carrying value was $232,000. The fair value of the Industrial Revenue Bonds is considered to be Level 2 within the fair value hierarchy as the fair value is determined using market approach pricing provided by a third-party that utilizes pricing models and pricing systems, mathematical tools and judgment to determine the evaluated price for the security based on the market information of each of the bonds or securities with similar characteristics. As of September 30, 2023, the carrying values of our Term Loan Facility and 2023 Term Loan Facility were $350,000 and $424,625, respectively, and the carrying value of our Revolving Credit Facility was zero dollars. Their fair values are based on current borrowing rates for similar types of borrowing arrangements, or Level 2 inputs, and approximate their carrying values.

SEGMENT REPORTING

SEGMENT REPORTING	9 Months Ended
	Sep. 30, 2023
Segment Reporting [Abstract]
SEGMENT REPORTING	SEGMENT REPORTING We report selected information about our reportable operating segments in a manner consistent with that used for internal management reporting. We classify our solid waste operations on a geographic basis through regional operating segments, our Eastern, Western and Mid-Atlantic regions. The Mid-Atlantic region, which was formed as a result of the GFL Acquisition on June 30, 2023, commenced operations on July 1, 2023. Revenues associated with our solid waste operations are derived mainly from solid waste collection and disposal services, including landfill, transfer station and transportation services, landfill gas-to-energy services, and processing services in the eastern United States. Our Resource Solutions operating segment leverages our core competencies in materials processing, industrial recycling, organics and resource management service offerings to deliver a comprehensive solution for our larger commercial, municipal, institutional and industrial customers that have more diverse waste and recycling needs. Revenues associated with our Resource Solutions operations are comprised of processing services and services provided by our National Accounts business. Revenues from processing services are derived from customers in the form of processing fees, tipping fees, commodity sales, and organic material sales. Revenues from our National Accounts business are derived from brokerage services and overall resource management services providing a wide range of environmental services and resource management solutions to large and complex organizations, as well as traditional collection, disposal and recycling services provided to large account multi-site customers. Legal, tax, information technology, human resources, certain finance and accounting and other administrative functions are included in our Corporate Entities segment, which is not a reportable operating segment. Corporate Entities results reflect those costs not allocated to our reportable operating segments. Three Months Ended September 30, 2023 Segment Outside Inter-company Depreciation and Operating Total Eastern $ 97,507 $ 24,911 $ 12,381 $ 11,160 $ 417,138 Western 136,019 46,307 20,976 20,462 986,659 Mid-Atlantic 43,722 212 10,182 (747) 557,710 Resource Solutions 75,487 4,172 3,452 4,110 242,413 Corporate Entities — — 745 (797) 294,095 Eliminations — (75,602) — — — $ 352,735 $ — $ 47,736 $ 34,188 $ 2,498,015 Three Months Ended September 30, 2022 Segment Outside Inter-company Depreciation and Operating Total Eastern $ 93,137 $ 23,027 $ 11,907 $ 10,061 $ 361,950 Western 121,903 40,703 16,778 22,405 725,232 Mid-Atlantic — — — — — Resource Solutions 80,228 1,579 3,138 4,526 189,854 Corporate Entities — — 704 (704) 122,311 Eliminations — (65,309) — — — $ 295,268 $ — $ 32,527 $ 36,288 $ 1,399,347 Nine Months Ended September 30, 2023 Segment Outside Inter-company Depreciation and Operating Total Eastern $ 274,740 $ 67,843 $ 36,431 $ 20,819 $ 417,138 Western 371,281 125,208 57,559 51,880 986,659 Mid-Atlantic 43,722 212 10,182 (747) 557,710 Resource Solutions 215,232 10,975 9,618 2,854 242,413 Corporate Entities — — 2,305 (7,739) 294,095 Eliminations — (204,238) — — — $ 904,975 $ — $ 116,095 $ 67,067 $ 2,498,015 Nine Months Ended September 30, 2022 Segment Outside Inter-company Depreciation and Operating Total Eastern $ 251,720 $ 61,842 $ 34,895 $ 13,981 $ 361,950 Western 332,626 112,687 47,376 51,565 725,232 Mid-Atlantic — — — — — Resource Solutions 228,616 2,673 9,011 14,453 189,854 Corporate Entities — — 1,824 (1,824) 122,311 Eliminations — (177,202) — — — $ 812,962 $ — $ 93,106 $ 78,175 $ 1,399,347 A summary of our revenues attributable to services provided follows: Three Months Ended Nine Months Ended 2023 2022 2023 2022 Collection $ 206,093 $ 144,117 $ 495,917 $ 400,910 Disposal 66,337 66,147 181,433 169,503 Power generation 1,797 1,643 5,042 6,050 Processing 3,021 3,133 7,351 7,883 Solid waste operations 277,248 215,040 689,743 584,346 Processing 27,782 32,159 75,970 93,421 National Accounts 47,705 48,069 139,262 135,195 Resource Solutions operations 75,487 80,228 215,232 228,616 Total revenues $ 352,735 $ 295,268 $ 904,975 $ 812,962

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
Pay vs Performance Disclosure
Net income	$ 18,172	$ 5,490	$ 3,548	$ 22,672	$ 17,796	$ 4,190	$ 27,210	$ 44,658

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2023
Trading Arrangements, by Individual
Material Terms of Trading Arrangement		Name (Title) Action Taken (Date of Action) Type of Trading Arrangement Nature of Trading Arrangement Duration of Trading Arrangement Aggregate Number of Securities John W. Casella (Chairman of the Board of Directors, Chief Executive Officer and Secretary) Adoption (08/22/2023) Durable Rule 10b5-1 trading arrangement for sell-to-cover transactions relating to certain equity awards that have or may be granted Sale Until final settlement of any covered RSU or PSU Indeterminable (1) Edmond "Ned" R. Coletta (President and Chief Financial Officer) Adoption (08/02/2023) Durable Rule 10b5-1 trading arrangement for sell-to-cover transactions relating to certain equity awards that have or may be granted Sale Until final settlement of any covered RSU or PSU Indeterminable (1) Shelley E. Sayward (Senior Vice President and General Counsel) Adoption (08/02/2023) Durable Rule 10b5-1 trading arrangement for sell-to-cover transactions relating to certain equity awards that have or may be granted Sale Until final settlement of any covered RSU or PSU Indeterminable (1) Sean M. Steves (Senior Vice President and Chief Operating Officer of Solid Waste Operations) Adoption (08/02/2023) Durable Rule 10b5-1 trading arrangement for sell-to-cover transactions relating to certain equity awards that have or may be granted Sale Until final settlement of any covered RSU or PSU Indeterminable (1) Kevin J. Drohan (Vice President and Chief Accounting Officer) Adoption (08/02/2023) Durable Rule 10b5-1 trading arrangement for sell-to-cover transactions relating to certain equity awards that have or may be granted Sale Until final settlement of any covered RSU or PSU Indeterminable (1) Paul J. Ligon (Senior Vice President Sustainable Growth) Adoption (08/02/2023) Durable Rule 10b5-1 trading arrangement for sell-to-cover transactions relating to certain equity awards that have or may be granted Sale Until final settlement of any covered RSU or PSU Indeterminable (1) Douglas R. Casella (Vice Chairman) Adoption (08/20/2023) Durable Rule 10b5-1 trading arrangement for sell-to-cover transactions relating to certain equity awards that have or may be granted Sale Until final settlement of any covered RSU or PSU Indeterminable (1)
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false
John W. Casella [Member]
Trading Arrangements, by Individual
Name	John W. Casella
Title	Chairman of the Board of Directors, Chief Executive Officer and Secretary
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	08/22/2023
Edmond "Ned" R. Coletta [Member]
Trading Arrangements, by Individual
Name	Edmond "Ned" R. Coletta
Title	President and Chief Financial Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	08/02/2023
Shelley E. Sayward [Member]
Trading Arrangements, by Individual
Name	Shelley E. Sayward
Title	Senior Vice President and General Counsel
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	08/02/2023
Sean M. Steves [Member]
Trading Arrangements, by Individual
Name	Sean M. Steves
Title	Senior Vice President and Chief Operating Officer of Solid Waste Operations
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	08/02/2023
Kevin J. Drohan [Member]
Trading Arrangements, by Individual
Name	Kevin J. Drohan
Title	Vice President and Chief Accounting Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	08/02/2023
Paul J. Ligon [Member]
Trading Arrangements, by Individual
Name	Paul J. Ligon
Title	Senior Vice President Sustainable Growth
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	08/02/2023
Douglas R. Casella [Member]
Trading Arrangements, by Individual
Name	Douglas R. Casella
Title	Vice Chairman
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	08/20/2023

ACCOUNTING CHANGES (Policies)

ACCOUNTING CHANGES (Policies)	9 Months Ended
	Sep. 30, 2023
Accounting Changes and Error Corrections [Abstract]
Basis of Accounting	Casella Waste Systems, Inc. (“Parent”), a Delaware corporation, and its consolidated subsidiaries (collectively, “we”, “us” or “our”), is a regional, vertically integrated solid waste services company. We provide resource management expertise and services to residential, commercial, municipal, institutional and industrial customers, primarily in the areas of solid waste collection and disposal, transfer, recycling and organics services. We provide integrated solid waste services in nine states: Vermont, New Hampshire, New York, Massachusetts, Connecticut, Maine, Pennsylvania, Delaware and Maryland, with our headquarters located in Rutland, Vermont. On June 30, 2023, we acquired the equity interests of four wholly owned subsidiaries of GFL Environmental Inc. ("GFL Subsidiaries"), which are the basis of our newly formed regional operating segment, the Mid-Atlantic region, that expanded our integrated solid waste services into the states of Delaware and Maryland ("GFL Acquisition"). See Note 4, Business Combinations for further disclosure. Operations under the Mid-Atlantic region commenced on July 1, 2023. The GFL Acquisition was funded from financing transactions (see Note 7, Debt for further disclosure), the net proceeds from an equity offering completed June 16, 2023 (see Note 9, Stockholders’ Equity for further disclosure), and cash on hand. We manage our solid waste operations on a geographic basis through regional operating segments, the Eastern, Western and Mid-Atlantic regions, each of which provides a comprehensive range of solid waste services. We manage our resource-renewal operations through the Resource Solutions operating segment, which leverages our core competencies in materials processing, industrial recycling, organics and resource management service offerings to deliver a comprehensive solution for our larger commercial, municipal, institutional and industrial customers that have more diverse waste and recycling needs. Legal, tax, information technology, human resources, certain finance and accounting and other administrative functions are included in our Corporate Entities segment. The accompanying unaudited consolidated financial statements, which include the accounts of the Parent and our wholly-owned subsidiaries, have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”) pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). All significant intercompany accounts and transactions are eliminated in consolidation. Investments in entities in which we do not have a controlling financial interest are accounted for under either the equity method or the cost method of accounting, as appropriate. Our significant accounting policies are more fully discussed in Item 8. " Financial Statements and Supplementary Data " of our Annual Report on Form 10-K for the fiscal year ended December 31, 2022 ("fiscal year 2022"), which was filed with the SEC on February 17, 2023 ("2022 Form 10-K").
Use of Estimates	Preparation of our consolidated financial statements in accordance with GAAP requires management to make certain estimates and assumptions. These estimates and assumptions affect the accounting for and recognition and disclosure of assets, liabilities, equity, revenues and expenses. We must make these estimates and assumptions because certain information that we use is dependent on future events, cannot be calculated with a high degree of precision given the available data, or simply cannot be readily calculated. In the opinion of management, these consolidated financial statements include all adjustments, including normal recurring and nonrecurring adjustments, as applicable, necessary for a fair presentation of the financial position, results of operations and cash flows for the periods presented. The results for the three and nine months ended September 30, 2023 may not be indicative of the results for any other interim period or the entire fiscal year.
Subsequent Events	We have evaluated subsequent events or transactions that have occurred after the consolidated balance sheet date of September 30, 2023 through the date of filing of the consolidated financial statements with the SEC on this Quarterly Report on Form 10-Q and determined that there have been no material events that have occurred that would require recognition or adjustments to our disclosures in our consolidated financial statements.
Accounting Standards Adopted and Pending Adoption	The following table provides a brief description of a recent Accounting Standards Update ("ASU") to the Accounting Standards Codification ("ASC") issued by the Financial Accounting Standards Board (“FASB”) that we adopted and is deemed to have a possible material impact on our consolidated financial statements based on current account balances and activity: Standard Description Effect on the Financial Statements or Other Accounting standards adopted effective January 1, 2023 ASU No. 2020-04: Reference Rate Reform (Topic 848), as amended through December 2022 Provides temporary optional guidance to ease the potential burden in applying GAAP to contract modifications and hedging relationships that reference London Inter-Bank Offered Rate ("LIBOR") or another reference rate expected to be discontinued, subject to meeting certain criteria. This guidance provides optional expedients and exceptions for applying GAAP to contracts, hedging relationships and other transactions affected by reference rate reform if certain criteria are met. Effective the quarter ended March 31, 2023, we elected optional expedients under this guidance that allowed us to maintain hedge effectiveness upon modifying contract terms related to reference rate reform in our amended and restated credit agreement, dated as of December 22, 2021, as amended by the first amendment, dated as of February 9, 2023, the second amendment, dated as of February 9, 2023, and the third amendment, dated as of April 25, 2023, collectively with the specified acquisition loan joinder, dated May 25, 2023 ("Loan Joinder") (the "Amended and Restated Credit Agreement") until we transitioned our interest rate derivative agreements from LIBOR to term secured overnight financing rate ("Term SOFR") in the quarter ended June 30, 2023, See Note 7, Debt . This guidance will be in effect through December 31, 2024.
Accrued Final Capping, Closure and Post Closure	Accrued final capping, closure and post-closure costs include the current and non-current portion of costs associated with obligations for final capping, closure and post-closure of our landfills. We estimate our future final capping, closure and post-closure costs in order to determine the final capping, closure and post-closure expense per ton of waste placed into each landfill. The anticipated time frame for paying these costs varies based on the remaining useful life of each landfill as well as the duration of the post-closure monitoring period.
Fair Value of Financial Instruments	We use a three-tier fair value hierarchy to classify and disclose all assets and liabilities measured at fair value on a recurring basis, as well as assets and liabilities measured at fair value on a non-recurring basis, in periods subsequent to their initial measurement. These tiers include: Level 1, defined as quoted market prices in active markets for identical assets or liabilities; Level 2, defined as inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; and Level 3, defined as unobservable inputs that are not corroborated by market data. We use valuation techniques that maximize the use of market prices and observable inputs and minimize the use of unobservable inputs. In measuring the fair value of our financial assets and liabilities, we rely on market data or assumptions that we believe market participants would use in pricing an asset or a liability. Assets and Liabilities Accounted for at Fair Value Our financial instruments include cash and cash equivalents, accounts receivable, restricted investment securities held in trust on deposit with various banks as collateral for our obligations relative to our landfill final capping, closure and post-closure costs, interest rate derivatives, contingent consideration related to acquisitions, trade payables and debt. The carrying values of cash and cash equivalents, restricted cash accounts receivable and trade payables approximate their respective fair values due to their short-term nature. The fair value of restricted investment securities held in trust, which are valued using quoted market prices, are included as restricted assets in the Level 1 tier below. The fair value of the interest rate derivatives included in the Level 2 tier below is calculated using discounted cash flow valuation methodologies based upon Term SOFR yield curves that are observable at commonly quoted intervals for the full term of the swaps. The fair value of contingent consideration - acquisition included in the Level 3 tier below is calculated using a discounted cash flow valuation methodology based upon a probability-weighted analysis of a success payment related to the potential attainment of a transfer station permit expansion. We recognize all derivatives accounted for on the balance sheet at fair value.
Segment Reporting	We report selected information about our reportable operating segments in a manner consistent with that used for internal management reporting. We classify our solid waste operations on a geographic basis through regional operating segments, our Eastern, Western and Mid-Atlantic regions. The Mid-Atlantic region, which was formed as a result of the GFL Acquisition on June 30, 2023, commenced operations on July 1, 2023. Revenues associated with our solid waste operations are derived mainly from solid waste collection and disposal services, including landfill, transfer station and transportation services, landfill gas-to-energy services, and processing services in the eastern United States. Our Resource Solutions operating segment leverages our core competencies in materials processing, industrial recycling, organics and resource management service offerings to deliver a comprehensive solution for our larger commercial, municipal, institutional and industrial customers that have more diverse waste and recycling needs. Revenues associated with our Resource Solutions operations are comprised of processing services and services provided by our National Accounts business. Revenues from processing services are derived from customers in the form of processing fees, tipping fees, commodity sales, and organic material sales. Revenues from our National Accounts business are derived from brokerage services and overall resource management services providing a wide range of environmental services and resource management solutions to large and complex organizations, as well as traditional collection, disposal and recycling services provided to large account multi-site customers. Legal, tax, information technology, human resources, certain finance and accounting and other administrative functions are included in our Corporate Entities segment, which is not a reportable operating segment. Corporate Entities results reflect those costs not allocated to our reportable operating segments.

ACCOUNTING CHANGES (Tables)

ACCOUNTING CHANGES (Tables)	9 Months Ended
	Sep. 30, 2023
Accounting Changes and Error Corrections [Abstract]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles	The following table provides a brief description of a recent Accounting Standards Update ("ASU") to the Accounting Standards Codification ("ASC") issued by the Financial Accounting Standards Board (“FASB”) that we adopted and is deemed to have a possible material impact on our consolidated financial statements based on current account balances and activity: Standard Description Effect on the Financial Statements or Other Accounting standards adopted effective January 1, 2023 ASU No. 2020-04: Reference Rate Reform (Topic 848), as amended through December 2022 Provides temporary optional guidance to ease the potential burden in applying GAAP to contract modifications and hedging relationships that reference London Inter-Bank Offered Rate ("LIBOR") or another reference rate expected to be discontinued, subject to meeting certain criteria. This guidance provides optional expedients and exceptions for applying GAAP to contracts, hedging relationships and other transactions affected by reference rate reform if certain criteria are met. Effective the quarter ended March 31, 2023, we elected optional expedients under this guidance that allowed us to maintain hedge effectiveness upon modifying contract terms related to reference rate reform in our amended and restated credit agreement, dated as of December 22, 2021, as amended by the first amendment, dated as of February 9, 2023, the second amendment, dated as of February 9, 2023, and the third amendment, dated as of April 25, 2023, collectively with the specified acquisition loan joinder, dated May 25, 2023 ("Loan Joinder") (the "Amended and Restated Credit Agreement") until we transitioned our interest rate derivative agreements from LIBOR to term secured overnight financing rate ("Term SOFR") in the quarter ended June 30, 2023, See Note 7, Debt . This guidance will be in effect through December 31, 2024.

REVENUE RECOGNITION (Tables)

REVENUE RECOGNITION (Tables)	9 Months Ended
	Sep. 30, 2023
Revenue from Contract with Customer [Abstract]
Schedule of Disaggregation of Revenue	The following tables set forth revenues disaggregated by service line and timing of revenue recognition by operating segment for each of the three and nine months ended September 30, 2023 and 2022: Three Months Ended September 30, 2023 Eastern Western Mid-Atlantic (1) Resource Solutions Total Revenues Collection $ 68,944 $ 93,924 $ 43,225 $ — $ 206,093 Landfill 7,588 18,563 — — 26,151 Transfer station 16,963 17,491 497 — 34,951 Transportation 1,328 3,907 — — 5,235 Landfill gas-to-energy 208 1,589 — — 1,797 Processing 2,476 545 — 27,782 30,803 National Accounts — — — 47,705 47,705 Total revenues $ 97,507 $ 136,019 $ 43,722 $ 75,487 $ 352,735 Transferred at a point-in-time $ 121 $ 651 $ — $ 8,549 $ 9,321 Transferred over time 97,386 135,368 43,722 66,938 343,414 Total revenues $ 97,507 $ 136,019 $ 43,722 $ 75,487 $ 352,735 Three Months Ended September 30, 2022 Eastern Western Mid-Atlantic (1) Resource Solutions Total Revenues Collection $ 61,875 $ 82,242 $ — $ — $ 144,117 Landfill 7,900 20,240 — — 28,140 Transfer station 19,525 13,230 — — 32,755 Transportation 1,233 4,019 — — 5,252 Landfill gas-to-energy 205 1,438 — — 1,643 Processing 2,399 734 — 32,159 35,292 National Accounts — — — 48,069 48,069 Total revenues $ 93,137 $ 121,903 $ — $ 80,228 $ 295,268 Transferred at a point-in-time $ 115 $ 439 $ — $ 12,380 $ 12,934 Transferred over time 93,022 121,464 — 67,848 282,334 Total revenues $ 93,137 $ 121,903 $ — $ 80,228 $ 295,268 Nine Months Ended September 30, 2023 Eastern Western Mid-Atlantic (1) Resource Solutions Total Revenues Collection $ 194,801 $ 257,891 $ 43,225 $ — $ 495,917 Landfill 21,109 53,943 — — 75,052 Transfer 48,643 42,181 497 — 91,321 Transportation 3,718 11,342 — — 15,060 Landfill gas-to-energy 594 4,448 — — 5,042 Processing 5,875 1,476 — 75,970 83,321 National Accounts — — — 139,262 139,262 Total revenues $ 274,740 $ 371,281 $ 43,722 $ 215,232 $ 904,975 Transferred at a point-in-time $ 339 $ 2,072 $ — $ 23,121 $ 25,532 Transferred over time 274,401 369,209 43,722 192,111 879,443 Total revenues $ 274,740 $ 371,281 $ 43,722 $ 215,232 $ 904,975 Nine Months Ended September 30, 2022 Eastern Western Mid-Atlantic (1) Resource Solutions Total Revenues Collection $ 172,671 $ 228,239 $ — $ — $ 400,910 Landfill 19,819 53,028 — — 72,847 Transfer 48,431 33,055 — — 81,486 Transportation 4,470 10,700 — — 15,170 Landfill gas-to-energy 727 5,323 — — 6,050 Processing 5,602 2,281 — 93,421 101,304 National Accounts — — — 135,195 135,195 Total revenues $ 251,720 $ 332,626 $ — $ 228,616 $ 812,962 Transferred at a point-in-time $ 352 $ 1,467 $ — $ 46,279 $ 48,098 Transferred over time 251,368 331,159 — 182,337 764,864 Total revenues $ 251,720 $ 332,626 $ — $ 228,616 $ 812,962 (1) Operations under the Mid-Atlantic region commenced July 1, 2023.

BUSINESS COMBINATIONS (Tables)

BUSINESS COMBINATIONS (Tables)	9 Months Ended
	Sep. 30, 2023
Business Combination and Asset Acquisition [Abstract]
Summary of Purchase Price Paid for Acquisitions	A summary of the purchase price paid and the purchase price allocation for acquisitions follows: Nine Months Ended 2023 2022 Purchase Price: Cash used in acquisitions, net of cash acquired $ 842,635 $ 72,731 Other non-cash consideration — 1,220 Holdbacks and additional consideration owed to sellers 2,435 4,112 Total consideration $ 845,070 $ 78,063 Allocated as follows: Current assets $ 19,297 $ 7,599 Property, plant and equipment: Land 6,760 3,141 Buildings and improvements 29,636 8,566 Machinery and equipment 175,309 10,296 Operating lease right-of-use assets 11,732 405 Intangible assets: Covenants not-to-compete 37,648 2,034 Customer relationships 145,553 11,417 Other non-current assets — 40 Deferred tax liability (11,013) — Current liabilities (21,724) (3,721) Other long-term liabilities (828) (123) Operating lease liabilities, less current portion (9,939) (282) Fair value of assets acquired and liabilities assumed 382,431 39,372 Excess purchase price allocated to goodwill $ 462,639 $ 38,691
Schedule of Unaudited Pro forma Combined Information	Unaudited pro forma combined information that shows our operational results as though each acquisition completed since the beginning of the prior fiscal year had occurred as of January 1, 2022 is as follows: Three Months Ended Nine Months Ended 2023 2022 2023 2022 Revenues $ 371,139 $ 374,421 $ 1,077,303 $ 1,061,748 Operating income $ 34,584 $ 40,537 $ 75,876 $ 92,345 Net income $ 17,964 $ 24,339 $ 30,318 $ 50,001 Basic earnings per share attributable to common stockholders: Weighted average common shares outstanding 57,962 51,677 54,228 51,604 Basic earnings per common share $ 0.31 $ 0.47 $ 0.56 $ 0.97 Diluted earnings per share attributable to common stockholders: Weighted average common shares outstanding 58,062 51,806 54,325 51,749 Diluted earnings per common share $ 0.31 $ 0.47 $ 0.56 $ 0.97

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS (Tables)	9 Months Ended
	Sep. 30, 2023
Goodwill and Intangible Assets Disclosure [Abstract]
Summary of Goodwill Activity	A summary of the activity and balances related to goodwill by operating segment is as follows: December 31, Acquisitions Measurement Period Adjustments September 30, Eastern $ 52,406 $ 23,947 $ — $ 76,353 Western 183,286 97,905 53 281,244 Mid-Atlantic — 331,975 — 331,975 Resource Solutions 38,766 8,812 — 47,578 $ 274,458 $ 462,639 $ 53 $ 737,150
Summary of Intangible Assets by Type	Summaries of intangible assets by type follows: Covenants Customer Relationships Trade Names Total Balance, September 30, 2023 Intangible assets $ 68,960 $ 272,731 $ 8,405 $ 350,096 Less accumulated amortization (25,713) (61,201) (6,493) (93,407) $ 43,247 $ 211,530 $ 1,912 $ 256,689 Covenants Customer Relationships Trade Names Total Balance, December 31, 2022 Intangible assets $ 31,201 $ 127,179 $ 8,405 $ 166,785 Less accumulated amortization (24,129) (46,162) (4,711) (75,002) $ 7,072 $ 81,017 $ 3,694 $ 91,783
Summary of Intangible Amortization Expense Estimated	A summary of intangible amortization expense estimated for each of the next five fiscal years following fiscal year 2022 and thereafter is estimated as follows: Estimated Future Amortization Expense as of September 30, 2023 Fiscal year ending December 31, 2023 $ 12,589 Fiscal year ending December 31, 2024 $ 48,250 Fiscal year ending December 31, 2025 $ 44,556 Fiscal year ending December 31, 2026 $ 40,193 Fiscal year ending December 31, 2027 $ 36,053 Thereafter $ 75,048

ACCRUED FINAL CAPPING, CLOSUR_2

ACCRUED FINAL CAPPING, CLOSURE AND POST CLOSURE (Tables)	9 Months Ended
	Sep. 30, 2023
Asset Retirement Obligation Disclosure [Abstract]
Summary of Changes to Accrued Capping, Closure and Post-Closure Liabilities	A summary of the changes to accrued final capping, closure and post-closure liabilities follows: Nine Months Ended 2023 2022 Beginning balance $ 113,678 $ 86,914 Obligations incurred 4,023 3,592 Revision in estimates (1) — 1,443 Accretion expense 7,193 5,685 Obligations settled (2) (7,338) (3,027) Ending balance $ 117,556 $ 94,607 (1) Relates to a change in estimates concerning anticipated capping costs at one of our landfills. (2) May include amounts that are being processed through accounts payable as a part of our disbursements cycle.

DEBT (Tables)

DEBT (Tables)	9 Months Ended
	Sep. 30, 2023
Debt And Derivatives Disclosure [Abstract]
Schedule of Debt	A summary of debt is as follows: September 30, December 31, Senior Secured Credit Facility: Term loan A facility ("Term Loan Facility") due December 2026; bearing interest at Term SOFR plus 1.385% $ 350,000 $ 350,000 Term loan A facility ("2023 Term Loan Facility") due December 2026; bearing interest at Term SOFR plus 1.885% 424,625 — Revolving credit facility ("Revolving Credit Facility") due December 2026; bearing interest at Term SOFR plus 1.385% — 6,000 Tax-Exempt Bonds: New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014 ("New York Bonds 2014R-1") due December 2044 - fixed rate interest period ending in 2029; bearing interest at 2.875% 25,000 25,000 New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014R-2 ("New York Bonds 2014R-2") due December 2044 - fixed rate interest period ending in 2026; bearing interest at 3.125% 15,000 15,000 New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2020 ("New York Bonds 2020") due September 2050 - fixed rate interest period ending in 2025; bearing interest at 2.750% 40,000 40,000 New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2020R-2 ("New York Bonds 2020R-2") due September 2050 - fixed rate interest period ending in 2030; bearing interest at 5.125% 35,000 — Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2005R-3 ("FAME Bonds 2005R-3") due January 2025 - fixed rate interest period ending in 2025; bearing interest at 5.25% 25,000 25,000 Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015R-1 ("FAME Bonds 2015R-1") due August 2035 - fixed rate interest period ending in 2025; bearing interest at 5.125% 15,000 15,000 Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015R-2 ("FAME Bonds 2015R-2") due August 2035 - fixed rate interest period ending in 2025; bearing interest at 4.375% 15,000 15,000 Vermont Economic Development Authority Solid Waste Disposal Long-Term Revenue Bonds Series 2013 ("Vermont Bonds 2013") due April 2036 - fixed rate interest period ending in 2028; bearing interest at 4.625% 16,000 16,000 Vermont Economic Development Authority Solid Waste Disposal Long-Term Revenue Bonds Series 2022A-1 ("Vermont Bonds 2022A-1") due June 2052 - fixed rate interest period ending in 2027; bearing interest at 5.00% 35,000 35,000 Business Finance Authority of the State of New Hampshire Solid Waste Disposal Revenue Bonds Series 2013 ("New Hampshire Bonds") due April 2029 - fixed rate interest period ending in 2029; bearing interest at 2.95% 11,000 11,000 Other: Finance leases 51,066 49,813 Notes payable maturing through March 2025; bearing interest up to 8.1% 278 664 Principal amount of debt 1,057,969 603,477 Less—unamortized debt issuance costs 11,843 9,494 Debt less unamortized debt issuance costs 1,046,126 593,983 Less—current maturities of debt 33,957 8,968 $ 1,012,169 $ 585,015 Term SOFR Loans Base Rate Loans Term Loan Facility 1.125% to 2.125% 0.125% to 1.125% Revolving Credit Facility 1.125% to 2.125% 0.125% to 1.125% 2023 Term Loan Facility 1.625% to 2.625% 0.625% to 1.625%
Components of Interest Expense	The components of interest expense are as follows: Three Months Ended Nine Months Ended 2023 2022 2023 2022 Interest expense on long-term debt and finance leases $ 15,128 $ 5,692 $ 29,565 $ 15,513 Amortization of debt issuance costs (1) 715 489 2,221 1,414 Letter of credit fees 103 117 297 347 Less: capitalized interest (198) (121) (375) (196) Total interest expense $ 15,748 $ 6,177 $ 31,708 $ 17,078 (1) Includes interest expense related to a short-term secured bridge financing entered into in connection with the GFL Acquisition and interest expense related to a short-term unsecured bridge financing entered into in connection with the Twin Bridges Acquisition of $395 and $101, respectively, during the nine months ended September 30, 2023.
Summary of Cash Flow Hedges	A summary of the effect of cash flow hedges related to derivative instruments on the consolidated balance sheets follows: Fair Value Balance Sheet Location September 30, December 31, Interest rate swaps Other current assets $ 7,835 $ 4,345 Interest rate swaps Other non-current assets 8,522 7,461 $ 16,357 $ 11,806 Interest rate swaps Other long-term liabilities $ 1,886 $ — Interest rate swaps Accumulated other comprehensive income, net of tax $ 14,471 $ 11,806 Interest rate swaps - tax effect Accumulated other comprehensive income, net of tax (4,991) (4,264) $ 9,480 $ 7,542
Summary of Notional Amounts	A summary of the changes to the notional amount of interest rate derivative agreements follows: Nine Months Ended Active Forward Starting Total Beginning balance $ 190,000 $ 20,000 $ 210,000 Additions 290,000 — 290,000 Commencements 20,000 (20,000) — Maturities (85,000) — (85,000) Ending balance (1) $ 415,000 $ — $ 415,000 (1) We receive interest based on Term SOFR, restricted by a 0.0% floor, and pay interest at a weighted average rate of approximately 3.41%. These agreements mature between February 2026 and June 2028.

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	9 Months Ended
	Sep. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Summary of Environmental Liability	A summary of the changes to the aggregate environmental remediation liabilities for the nine months ended September 30, 2023 and 2022 follows: Nine Months Ended 2023 2022 Beginning balance $ 6,335 $ 5,887 Accretion expense 75 79 Obligations incurred (1) — 759 Obligations settled (2) (338) (353) Ending balance 6,072 6,372 Less: current portion 1,799 646 Long-term portion $ 4,273 $ 5,726 (1) Associated with the investigation of potential remediation at an inactive waste disposal site that adjoins one of the landfills that we operate. (2) May include amounts that are being processed through accounts payable as a part of our disbursement cycle.
Schedule of Cash and Cash Equivalents	Beginning-of-period and end-of-period cash, cash equivalents and restricted cash s presented in the statement of cash flows is reconciled as follows: September 30, December 31, Cash and cash equivalents $ 219,089 $ 71,152 Restricted cash - non-current 2,730 — Cash, cash equivalents and restricted cash $ 221,819 $ 71,152
Schedule of Restricted Cash	Beginning-of-period and end-of-period cash, cash equivalents and restricted cash s presented in the statement of cash flows is reconciled as follows: September 30, December 31, Cash and cash equivalents $ 219,089 $ 71,152 Restricted cash - non-current 2,730 — Cash, cash equivalents and restricted cash $ 221,819 $ 71,152

STOCKHOLDERS' EQUITY (Tables)

STOCKHOLDERS' EQUITY (Tables)	9 Months Ended
	Sep. 30, 2023
Equity [Abstract]
Summary of Stock Option Activity	A summary of stock option activity follows: Stock Options Weighted Average Exercise Price Weighted Average Remaining Contractual Term (years) Aggregate Intrinsic Value Outstanding, December 31, 2022 129 $ 55.60 Granted — $ — Exercised (18) $ 4.88 Forfeited — $ — Outstanding, September 30, 2023 111 $ 63.87 7.3 $ 1,846 Exercisable, September 30, 2023 49 $ 40.60 5.4 $ 1,825
Summary of Restricted Stock, Restricted Stock Unit and Performance Stock Unit Activity	A summary of restricted stock award, restricted stock unit and performance stock unit activity follows: Restricted Stock Awards, Restricted Stock Units, and Performance Stock Units (1) Weighted Weighted Average Remaining Contractual Term (years) Aggregate Intrinsic Value Outstanding, December 31, 2022 169 $ 75.52 Granted 119 $ 81.04 Class A Common Stock Vested (65) $ 62.57 Forfeited (6) $ 76.91 Outstanding, September 30, 2023 217 $ 91.51 2.1 $ 16,597 Unvested, September 30, 2023 376 $ 88.63 1.7 $ 28,660 (1) Performance stock unit grants, including market-based performance stock units, are included at the 100% attainment level. Attainment of the maximum performance targets and market achievements would result in the issuance of an additional 159 shares of Class A common stock currently included in unvested.
Summary of Changes in Balances of Each Component of Accumulated Other Comprehensive Loss	A summary of the changes in the balances of each component of accumulated other comprehensive income, net of tax follows: Interest Rate Swaps Balance, December 31, 2022 $ 7,542 Other comprehensive income before reclassifications 6,846 Income reclassified from accumulated other comprehensive income into interest expense (4,181) Income tax provision related to items of other comprehensive income (727) Net current-period other comprehensive income, net of tax 1,938 Balance, September 30, 2023 $ 9,480
Summary of Reclassifications Out of Accumulated Other Comprehensive Loss	A summary of reclassifications out of accumulated other comprehensive income, net of tax into earnings follows: Three Months Ended Nine Months Ended 2023 2022 2023 2022 Details About Accumulated Other Comprehensive Income, Net of Tax Components Amounts Reclassified Out of Accumulated Other Comprehensive Income, Net of Tax Affected Line Item in the Consolidated Interest rate swaps $ (1,805) $ 14 $ (4,181) $ 2,136 Interest expense 1,805 (14) 4,181 (2,136) Income before income taxes 495 — 1,146 (190) Provision for income taxes $ 1,310 $ (14) $ 3,035 $ (1,946) Net income

EARNINGS PER SHARE (Tables)

EARNINGS PER SHARE (Tables)	9 Months Ended
	Sep. 30, 2023
Earnings Per Share [Abstract]
Summary of Earnings per Share Computation	A summary of the numerator and denominators used in the computation of earnings per share follows: Three Months Ended Nine Months Ended 2023 2022 2023 2022 Numerator: Net income $ 18,172 $ 22,672 $ 27,210 $ 44,658 Denominators: Number of shares outstanding, end of period: Class A common stock 56,994 50,692 56,994 50,692 Class B common stock 988 988 988 988 Unvested restricted stock — (1) — (1) Effect of weighted average shares outstanding (1) (20) (2) (3,754) (75) Basic weighted average common shares outstanding 57,962 51,677 54,228 51,604 Impact of potentially dilutive securities: Dilutive effect of stock options and other stock awards 100 129 97 145 Diluted weighted average common shares outstanding 58,062 51,806 54,325 51,749 Anti-dilutive potentially issuable shares 78 84 75 115 (1) The adjustment in the nine months ended September 30, 2023 is primarily associated with the 6,053 shares of Class A common stock issued as part of the public offering, completed on June 16, 2023. See Note 9, Stockholders’ Equity for disclosure regarding the public offering of Class A common stock.

FAIR VALUE OF FINANCIAL INSTR_2

FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)	9 Months Ended
	Sep. 30, 2023
Fair Value Disclosures [Abstract]
Summary of Financial Assets and Liabilities Measured at Fair Value	Summaries of our financial assets and liabilities that are measured at fair value on a recurring basis follow: Fair Value Measurement at September 30, 2023 Using: Quoted Prices in Significant Other Significant Assets: Restricted investment securities - landfill closure $ 1,928 $ — $ — Interest rate swaps — 16,357 — $ 1,928 $ 16,357 $ — Liabilities: Interest rate swaps — 1,886 — $ — $ 1,886 $ — Fair Value Measurement at December 31, 2022 Using: Quoted Prices in Significant Other Significant Assets: Restricted investment securities - landfill closure $ 1,900 $ — $ — Interest rate swaps — 11,806 — $ 1,900 $ 11,806 $ — Liabilities: Contingent consideration - acquisition (1) $ — $ — $ 965 (1) In the three and nine months ended September 30, 2023, we recorded a gain on resolution of acquisition-related contingent consideration of $376 and $965, respectively, within cost of operations associated with the reversal of a contingency for a transfer station permit expansion that is no longer deemed viable.

SEGMENT REPORTING (Tables)

SEGMENT REPORTING (Tables)	9 Months Ended
	Sep. 30, 2023
Segment Reporting [Abstract]
Summary of Segment Reporting Information by Segment	Three Months Ended September 30, 2023 Segment Outside Inter-company Depreciation and Operating Total Eastern $ 97,507 $ 24,911 $ 12,381 $ 11,160 $ 417,138 Western 136,019 46,307 20,976 20,462 986,659 Mid-Atlantic 43,722 212 10,182 (747) 557,710 Resource Solutions 75,487 4,172 3,452 4,110 242,413 Corporate Entities — — 745 (797) 294,095 Eliminations — (75,602) — — — $ 352,735 $ — $ 47,736 $ 34,188 $ 2,498,015 Three Months Ended September 30, 2022 Segment Outside Inter-company Depreciation and Operating Total Eastern $ 93,137 $ 23,027 $ 11,907 $ 10,061 $ 361,950 Western 121,903 40,703 16,778 22,405 725,232 Mid-Atlantic — — — — — Resource Solutions 80,228 1,579 3,138 4,526 189,854 Corporate Entities — — 704 (704) 122,311 Eliminations — (65,309) — — — $ 295,268 $ — $ 32,527 $ 36,288 $ 1,399,347 Nine Months Ended September 30, 2023 Segment Outside Inter-company Depreciation and Operating Total Eastern $ 274,740 $ 67,843 $ 36,431 $ 20,819 $ 417,138 Western 371,281 125,208 57,559 51,880 986,659 Mid-Atlantic 43,722 212 10,182 (747) 557,710 Resource Solutions 215,232 10,975 9,618 2,854 242,413 Corporate Entities — — 2,305 (7,739) 294,095 Eliminations — (204,238) — — — $ 904,975 $ — $ 116,095 $ 67,067 $ 2,498,015 Nine Months Ended September 30, 2022 Segment Outside Inter-company Depreciation and Operating Total Eastern $ 251,720 $ 61,842 $ 34,895 $ 13,981 $ 361,950 Western 332,626 112,687 47,376 51,565 725,232 Mid-Atlantic — — — — — Resource Solutions 228,616 2,673 9,011 14,453 189,854 Corporate Entities — — 1,824 (1,824) 122,311 Eliminations — (177,202) — — — $ 812,962 $ — $ 93,106 $ 78,175 $ 1,399,347
Summary of Revenue Attributable to Services	A summary of our revenues attributable to services provided follows: Three Months Ended Nine Months Ended 2023 2022 2023 2022 Collection $ 206,093 $ 144,117 $ 495,917 $ 400,910 Disposal 66,337 66,147 181,433 169,503 Power generation 1,797 1,643 5,042 6,050 Processing 3,021 3,133 7,351 7,883 Solid waste operations 277,248 215,040 689,743 584,346 Processing 27,782 32,159 75,970 93,421 National Accounts 47,705 48,069 139,262 135,195 Resource Solutions operations 75,487 80,228 215,232 228,616 Total revenues $ 352,735 $ 295,268 $ 904,975 $ 812,962

BASIS OF PRESENTATION (Details)

BASIS OF PRESENTATION (Details)	Jun. 30, 2023 subsidiary	Sep. 30, 2023 state
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of states in which entity operates | state		9
Number of wholly owned subsidiaries acquired | subsidiary	4

REVENUE RECOGNITION - Disaggreg

REVENUE RECOGNITION - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Disaggregation of Revenue [Line Items]
Total revenues	$ 352,735	$ 295,268	$ 904,975	$ 812,962
Transferred at a point-in-time
Disaggregation of Revenue [Line Items]
Total revenues	9,321	12,934	25,532	48,098
Transferred over time
Disaggregation of Revenue [Line Items]
Total revenues	343,414	282,334	879,443	764,864
Collection
Disaggregation of Revenue [Line Items]
Total revenues	206,093	144,117	495,917	400,910
Landfill
Disaggregation of Revenue [Line Items]
Total revenues	26,151	28,140	75,052	72,847
Transfer station
Disaggregation of Revenue [Line Items]
Total revenues	34,951	32,755	91,321	81,486
Transportation
Disaggregation of Revenue [Line Items]
Total revenues	5,235	5,252	15,060	15,170
Landfill gas-to-energy
Disaggregation of Revenue [Line Items]
Total revenues	1,797	1,643	5,042	6,050
Processing
Disaggregation of Revenue [Line Items]
Total revenues	30,803	35,292	83,321	101,304
National Accounts
Disaggregation of Revenue [Line Items]
Total revenues	47,705	48,069	139,262	135,195
Eastern
Disaggregation of Revenue [Line Items]
Total revenues	97,507	93,137	274,740	251,720
Eastern | Transferred at a point-in-time
Disaggregation of Revenue [Line Items]
Total revenues	121	115	339	352
Eastern | Transferred over time
Disaggregation of Revenue [Line Items]
Total revenues	97,386	93,022	274,401	251,368
Eastern | Collection
Disaggregation of Revenue [Line Items]
Total revenues	68,944	61,875	194,801	172,671
Eastern | Landfill
Disaggregation of Revenue [Line Items]
Total revenues	7,588	7,900	21,109	19,819
Eastern | Transfer station
Disaggregation of Revenue [Line Items]
Total revenues	16,963	19,525	48,643	48,431
Eastern | Transportation
Disaggregation of Revenue [Line Items]
Total revenues	1,328	1,233	3,718	4,470
Eastern | Landfill gas-to-energy
Disaggregation of Revenue [Line Items]
Total revenues	208	205	594	727
Eastern | Processing
Disaggregation of Revenue [Line Items]
Total revenues	2,476	2,399	5,875	5,602
Eastern | National Accounts
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Western
Disaggregation of Revenue [Line Items]
Total revenues	136,019	121,903	371,281	332,626
Western | Transferred at a point-in-time
Disaggregation of Revenue [Line Items]
Total revenues	651	439	2,072	1,467
Western | Transferred over time
Disaggregation of Revenue [Line Items]
Total revenues	135,368	121,464	369,209	331,159
Western | Collection
Disaggregation of Revenue [Line Items]
Total revenues	93,924	82,242	257,891	228,239
Western | Landfill
Disaggregation of Revenue [Line Items]
Total revenues	18,563	20,240	53,943	53,028
Western | Transfer station
Disaggregation of Revenue [Line Items]
Total revenues	17,491	13,230	42,181	33,055
Western | Transportation
Disaggregation of Revenue [Line Items]
Total revenues	3,907	4,019	11,342	10,700
Western | Landfill gas-to-energy
Disaggregation of Revenue [Line Items]
Total revenues	1,589	1,438	4,448	5,323
Western | Processing
Disaggregation of Revenue [Line Items]
Total revenues	545	734	1,476	2,281
Western | National Accounts
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Mid-Atlantic
Disaggregation of Revenue [Line Items]
Total revenues	43,722	0	43,722	0
Mid-Atlantic | Transferred at a point-in-time
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Mid-Atlantic | Transferred over time
Disaggregation of Revenue [Line Items]
Total revenues	43,722	0	43,722	0
Mid-Atlantic | Collection
Disaggregation of Revenue [Line Items]
Total revenues	43,225	0	43,225	0
Mid-Atlantic | Landfill
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Mid-Atlantic | Transfer station
Disaggregation of Revenue [Line Items]
Total revenues	497	0	497	0
Mid-Atlantic | Transportation
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Mid-Atlantic | Landfill gas-to-energy
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Mid-Atlantic | Processing
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Mid-Atlantic | National Accounts
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Resource Solutions
Disaggregation of Revenue [Line Items]
Total revenues	75,487	80,228	215,232	228,616
Resource Solutions | Transferred at a point-in-time
Disaggregation of Revenue [Line Items]
Total revenues	8,549	12,380	23,121	46,279
Resource Solutions | Transferred over time
Disaggregation of Revenue [Line Items]
Total revenues	66,938	67,848	192,111	182,337
Resource Solutions | Collection
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Resource Solutions | Landfill
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Resource Solutions | Transfer station
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Resource Solutions | Transportation
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Resource Solutions | Landfill gas-to-energy
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Resource Solutions | Processing
Disaggregation of Revenue [Line Items]
Total revenues	27,782	32,159	75,970	93,421
Resource Solutions | National Accounts
Disaggregation of Revenue [Line Items]
Total revenues	$ 47,705	$ 48,069	$ 139,262	$ 135,195

REVENUE RECOGNITION - Narrative

REVENUE RECOGNITION - Narrative (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Disaggregation of Revenue [Line Items]
Rebates	$ (352,735,000)	$ (295,268,000)	$ (904,975,000)	$ (812,962,000)
Revenue recognized fro performance obligation satisfied in previous period	0	0	0	0
Gross receivables from contracts	126,672,000		126,672,000		$ 102,234,000
Contract liabilities	18,852,000		18,852,000		$ 3,742,000
Rebate for Recycled or Returned Organic Materials
Disaggregation of Revenue [Line Items]
Rebates	$ 4,617,000	$ 5,460,000	$ 17,575,000	$ 15,162,000

BUSINESS COMBINATIONS - Narrati

BUSINESS COMBINATIONS - Narrative (Details) - business		9 Months Ended
	Sep. 01, 2023	Sep. 30, 2023	Sep. 30, 2022
Business Acquisition [Line Items]
Number of businesses acquired		5	12
Solid-waste collection businesses
Business Acquisition [Line Items]
Number of businesses acquired	3
Minimum
Business Acquisition [Line Items]
Useful life of finite lived intangible assets		2 years
Maximum
Business Acquisition [Line Items]
Useful life of finite lived intangible assets		10 years

BUSINESS COMBINATIONS - Summary

BUSINESS COMBINATIONS - Summary of Purchase Price Paid for Acquisitions (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Purchase Price:
Cash used in acquisitions, net of cash acquired	$ 847,763	$ 73,963
Allocated as follows:
Excess purchase price allocated to goodwill	737,150		$ 274,458
Waste Collection Acquisitions
Purchase Price:
Cash used in acquisitions, net of cash acquired	842,635	72,731
Other non-cash consideration	0	1,220
Holdbacks and additional consideration owed to sellers	2,435	4,112
Total consideration	845,070	78,063
Allocated as follows:
Current assets	19,297	7,599
Land	6,760	3,141
Buildings and improvements	29,636	8,566
Machinery and equipment	175,309	10,296
Operating lease right-of-use assets	11,732	405
Other non-current assets	0	40
Deferred tax liability	(11,013)	0
Current liabilities	(21,724)	(3,721)
Other long-term liabilities	(828)	(123)
Operating lease liabilities, less current portion	(9,939)	(282)
Fair value of assets acquired and liabilities assumed	382,431	39,372
Excess purchase price allocated to goodwill	462,639	38,691
Waste Collection Acquisitions | Covenants Not-to-Compete
Allocated as follows:
Intangible assets	37,648	2,034
Waste Collection Acquisitions | Customer Relationships
Allocated as follows:
Intangible assets	$ 145,553	$ 11,417

BUSINESS COMBINATIONS - Schedul

BUSINESS COMBINATIONS - Schedule of Unaudited Pro forma Combined Information (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Business Combination and Asset Acquisition [Abstract]
Revenues	$ 371,139	$ 374,421	$ 1,077,303	$ 1,061,748
Operating income	34,584	40,537	75,876	92,345
Net income	$ 17,964	$ 24,339	$ 30,318	$ 50,001
Weighted average common shares outstanding, basic (in shares)	57,962	51,677	54,228	51,604
Basic earnings per common share (in dollars per share)	$ 0.31	$ 0.47	$ 0.56	$ 0.97
Weighted average common shares outstanding, diluted (in shares)	58,062	51,806	54,325	51,749
Diluted earnings per common share (in dollars per share)	$ 0.31	$ 0.47	$ 0.56	$ 0.97

GOODWILL AND INTANGIBLE ASSET_2

GOODWILL AND INTANGIBLE ASSETS - Summary of Goodwill Activity (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2023 USD ($)
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 274,458
Acquisitions	462,639
Measurement Period Adjustments	53
Goodwill, ending balance	737,150
Eastern
Goodwill [Roll Forward]
Goodwill, beginning balance	52,406
Acquisitions	23,947
Measurement Period Adjustments	0
Goodwill, ending balance	76,353
Western
Goodwill [Roll Forward]
Goodwill, beginning balance	183,286
Acquisitions	97,905
Measurement Period Adjustments	53
Goodwill, ending balance	281,244
Mid-Atlantic
Goodwill [Roll Forward]
Goodwill, beginning balance	0
Acquisitions	331,975
Measurement Period Adjustments	0
Goodwill, ending balance	331,975
Resource Solutions
Goodwill [Roll Forward]
Goodwill, beginning balance	38,766
Acquisitions	8,812
Measurement Period Adjustments	0
Goodwill, ending balance	$ 47,578

GOODWILL AND INTANGIBLE ASSET_3

GOODWILL AND INTANGIBLE ASSETS - Summary of Intangible Assets by Type (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Finite-Lived Intangible Assets [Line Items]
Intangible assets	$ 350,096	$ 166,785
Less accumulated amortization	(93,407)	(75,002)
Intangible assets, net	256,689	91,783
Covenants Not-to-Compete
Finite-Lived Intangible Assets [Line Items]
Intangible assets	68,960	31,201
Less accumulated amortization	(25,713)	(24,129)
Intangible assets, net	43,247	7,072
Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Intangible assets	272,731	127,179
Less accumulated amortization	(61,201)	(46,162)
Intangible assets, net	211,530	81,017
Trade Names
Finite-Lived Intangible Assets [Line Items]
Intangible assets	8,405	8,405
Less accumulated amortization	(6,493)	(4,711)
Intangible assets, net	$ 1,912	$ 3,694

GOODWILL AND INTANGIBLE ASSET_4

GOODWILL AND INTANGIBLE ASSETS - Narrative (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible amortization expense	$ 10,109	$ 4,281	$ 18,405	$ 12,333

GOODWILL AND INTANGIBLE ASSET_5

GOODWILL AND INTANGIBLE ASSETS - Summary of Intangible Amortization Expense Estimated (Detail) $ in Thousands	Sep. 30, 2023 USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
Fiscal year ending December 31, 2023	$ 12,589
Fiscal year ending December 31, 2024	48,250
Fiscal year ending December 31, 2025	44,556
Fiscal year ending December 31, 2026	40,193
Fiscal year ending December 31, 2027	36,053
Thereafter	$ 75,048

ACCRUED FINAL CAPPING, CLOSUR_3

ACCRUED FINAL CAPPING, CLOSURE AND POST CLOSURE - Summary of Changes to Accrued Capping, Closure and Post-Closure Liabilities (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance	$ 113,678	$ 86,914
Obligations incurred	4,023	3,592
Revision in estimates	0	1,443
Accretion expense	7,193	5,685
Obligations settled	(7,338)	(3,027)
Ending balance	$ 117,556	$ 94,607

DEBT - Summary of Debt (Details

DEBT - Summary of Debt (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Weighted-average discount rate - finance leases	3.90%
Finance leases maturing through December 2107; bearing interest at a weighted average of 3.9%	$ 51,066	$ 49,813
Principal amount of debt	1,057,969	603,477
Less - unamortized debt issuance costs	11,843	9,494
Debt less unamortized debt issuance costs	1,046,126	593,983
Less—current maturities of debt	33,957	8,968
Debt, less current portion	$ 1,012,169	$ 585,015
Finance Lease, Liability, Statement of Financial Position [Extensible Enumeration]	Debt, less current portion	Debt, less current portion
Secured Debt | Term loan A facility ("Term Loan Facility") due December 2026; bearing interest at Term SOFR plus 1.385%
Debt Instrument [Line Items]
Principal amount of debt	$ 350,000	$ 350,000
Secured Debt | Term loan A facility ("Term Loan Facility") due December 2026; bearing interest at Term SOFR plus 1.385% | SOFR
Debt Instrument [Line Items]
Variable rate margin	1.385%
Secured Debt | Term loan A facility ("2023 Term Loan Facility") due December 2026; bearing interest at Term SOFR plus 1.885%
Debt Instrument [Line Items]
Principal amount of debt	$ 424,625	0
Secured Debt | Term loan A facility ("2023 Term Loan Facility") due December 2026; bearing interest at Term SOFR plus 1.885% | SOFR
Debt Instrument [Line Items]
Variable rate margin	1.885%
Secured Debt | Revolving credit facility ("Revolving Credit Facility") due December 2026; bearing interest at Term SOFR plus 1.385% | SOFR
Debt Instrument [Line Items]
Variable rate margin	1.385%
Line of Credit | Revolving credit facility ("Revolving Credit Facility") due December 2026; bearing interest at Term SOFR plus 1.385%
Debt Instrument [Line Items]
Principal amount of debt	$ 0	6,000
Unsecured Debt | New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014 ("New York Bonds 2014R-1") due December 2044 - fixed rate interest period ending in 2029; bearing interest at 2.875%
Debt Instrument [Line Items]
Stated interest rate	2.875%
Principal amount of debt	$ 25,000	25,000
Unsecured Debt | New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014R-2 ("New York Bonds 2014R-2") due December 2044 - fixed rate interest period ending in 2026; bearing interest at 3.125%
Debt Instrument [Line Items]
Stated interest rate	3.125%
Principal amount of debt	$ 15,000	15,000
Unsecured Debt | New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2020 ("New York Bonds 2020") due September 2050 - fixed rate interest period ending in 2025; bearing interest at 2.750%
Debt Instrument [Line Items]
Stated interest rate	2.75%
Principal amount of debt	$ 40,000	40,000
Unsecured Debt | New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2020R-2 ("New York Bonds 2020R-2") due September 2050 - fixed rate interest period ending in 2030; bearing interest at 5.125%
Debt Instrument [Line Items]
Stated interest rate	5.125%
Principal amount of debt	$ 35,000	0
Unsecured Debt | Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2005R-3 ("FAME Bonds 2005R-3") due January 2025 - fixed rate interest period ending in 2025; bearing interest at 5.25%
Debt Instrument [Line Items]
Stated interest rate	5.25%
Principal amount of debt	$ 25,000	25,000
Unsecured Debt | Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015R-1 ("FAME Bonds 2015R-1") due August 2035 - fixed rate interest period ending in 2025; bearing interest at 5.125%
Debt Instrument [Line Items]
Stated interest rate	5.125%
Principal amount of debt	$ 15,000	15,000
Unsecured Debt | Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015R-2 ("FAME Bonds 2015R-2") due August 2035 - fixed rate interest period ending in 2025; bearing interest at 4.375%
Debt Instrument [Line Items]
Stated interest rate	4.375%
Principal amount of debt	$ 15,000	15,000
Unsecured Debt | Vermont Economic Development Authority Solid Waste Disposal Long-Term Revenue Bonds Series 2013 ("Vermont Bonds 2013") due April 2036 - fixed rate interest period ending in 2028; bearing interest at 4.625%
Debt Instrument [Line Items]
Stated interest rate	4.625%
Principal amount of debt	$ 16,000	16,000
Unsecured Debt | Vermont Economic Development Authority Solid Waste Disposal Long-Term Revenue Bonds Series 2022A-1 ("Vermont Bonds 2022A-1") due June 2052 - fixed rate interest period ending in 2027; bearing interest at 5.00%
Debt Instrument [Line Items]
Stated interest rate	5%
Principal amount of debt	$ 35,000	35,000
Unsecured Debt | Business Finance Authority of the State of New Hampshire Solid Waste Disposal Revenue Bonds Series 2013 ("New Hampshire Bonds") due April 2029 - fixed rate interest period ending in 2029; bearing interest at 2.95%
Debt Instrument [Line Items]
Stated interest rate	2.95%
Principal amount of debt	$ 11,000	11,000
Notes payable maturing through March 2025; bearing interest up to 8.1%
Debt Instrument [Line Items]
Stated interest rate	8.10%
Principal amount of debt	$ 278	$ 664

DEBT - Financing Activities (De

DEBT - Financing Activities (Details) - USD ($) $ in Thousands	1 Months Ended	9 Months Ended
	Jun. 30, 2023	Sep. 30, 2023	Sep. 30, 2022	Aug. 31, 2023	May 31, 2023	Apr. 30, 2023	Dec. 31, 2022
Line of Credit Facility [Line Items]
Proceeds from debt borrowings		$ 465,000	$ 82,200
Restricted cash and assets		$ 4,658					$ 1,900
Credit Facility | SOFR
Line of Credit Facility [Line Items]
Variable rate adjustment		0.10%
Secured Debt
Line of Credit Facility [Line Items]
Bridge loan						$ 375,000
Secured Debt | 2023 Term Loan Facility
Line of Credit Facility [Line Items]
Aggregate principal amount issued		$ 430,000			$ 430,000
Proceeds from debt borrowings	$ 430,000
Unsecured Debt
Line of Credit Facility [Line Items]
Bridge loan	$ 200,000
Unsecured Debt | New York Bonds 2020R-2
Line of Credit Facility [Line Items]
Aggregate principal amount issued				$ 35,000
Stated interest rate		5.125%
Restricted cash and assets		$ 2,730

DEBT - Credit Facility Narrativ

DEBT - Credit Facility Narrative (Details) - USD ($)	9 Months Ended
	Sep. 30, 2023	May 31, 2023
Line of Credit Facility [Line Items]
Additional revolver capacity	$ 125,000,000
Line of Credit
Line of Credit Facility [Line Items]
Facility term	5 years
Remaining capacity	$ 272,267,000
Line of credit drawn	$ 0
Credit Facility
Line of Credit Facility [Line Items]
Commitment fee adjustment	0.01%
Floor interest rate	0%
Interest rate, annual increase upon payment default	2%
Interest rate, annual increase upon other event of default	2%
Credit Facility | Minimum
Line of Credit Facility [Line Items]
Commitment fee, margin percent	0.20%
Credit Facility | Maximum
Line of Credit Facility [Line Items]
Commitment fee, margin percent	0.40%
Credit Facility | SOFR
Line of Credit Facility [Line Items]
Variable rate adjustment	0.10%
Credit Facility | Base Rate
Line of Credit Facility [Line Items]
Variable rate adjustment	0.04%
Secured Debt | Term loan A facility ("Term Loan Facility") due December 2026; bearing interest at Term SOFR plus 1.385%
Line of Credit Facility [Line Items]
Aggregate principal amount issued	$ 350,000,000
Secured Debt | Term loan A facility ("2023 Term Loan Facility") due December 2026; bearing interest at Term SOFR plus 1.885%
Line of Credit Facility [Line Items]
Aggregate principal amount issued	430,000,000	$ 430,000,000
Revolving Credit Facility | Revolving credit facility ("Revolving Credit Facility") due December 2026; bearing interest at Term SOFR plus 1.385% | Line of Credit
Line of Credit Facility [Line Items]
Credit facility maximum	300,000,000
Outstanding irrevocable letters of credit totaling	27,733,000
Revolving Credit Facility | Revolving credit facility ("Revolving Credit Facility") due December 2026; bearing interest at Term SOFR plus 1.385% | Letter of Credit
Line of Credit Facility [Line Items]
Letters of credit sublimit	$ 75,000,000
Line of Credit | Credit Facility | Letter of Credit
Line of Credit Facility [Line Items]
Fronting fee	0.25%

DEBT - Variable Rate Margins (D

DEBT - Variable Rate Margins (Details)	9 Months Ended
	Sep. 30, 2023
Term loan A facility ("Term Loan Facility") due December 2026; bearing interest at Term SOFR plus 1.385% | SOFR | Secured Debt
Debt Instrument [Line Items]
Variable rate margin	1.385%
Term loan A facility ("Term Loan Facility") due December 2026; bearing interest at Term SOFR plus 1.385% | SOFR | Minimum | Secured Debt
Debt Instrument [Line Items]
Variable rate margin	1.125%
Term loan A facility ("Term Loan Facility") due December 2026; bearing interest at Term SOFR plus 1.385% | SOFR | Maximum | Secured Debt
Debt Instrument [Line Items]
Variable rate margin	2.125%
Term loan A facility ("Term Loan Facility") due December 2026; bearing interest at Term SOFR plus 1.385% | Base Rate | Minimum | Secured Debt
Debt Instrument [Line Items]
Variable rate margin	0.125%
Term loan A facility ("Term Loan Facility") due December 2026; bearing interest at Term SOFR plus 1.385% | Base Rate | Maximum | Secured Debt
Debt Instrument [Line Items]
Variable rate margin	1.125%
Revolving credit facility ("Revolving Credit Facility") due December 2026; bearing interest at Term SOFR plus 1.385% | SOFR | Secured Debt
Debt Instrument [Line Items]
Variable rate margin	1.385%
Revolving credit facility ("Revolving Credit Facility") due December 2026; bearing interest at Term SOFR plus 1.385% | SOFR | Minimum | Line of Credit
Debt Instrument [Line Items]
Variable rate margin	1.125%
Revolving credit facility ("Revolving Credit Facility") due December 2026; bearing interest at Term SOFR plus 1.385% | SOFR | Maximum | Line of Credit
Debt Instrument [Line Items]
Variable rate margin	2.125%
Revolving credit facility ("Revolving Credit Facility") due December 2026; bearing interest at Term SOFR plus 1.385% | Base Rate | Minimum | Line of Credit
Debt Instrument [Line Items]
Variable rate margin	0.125%
Revolving credit facility ("Revolving Credit Facility") due December 2026; bearing interest at Term SOFR plus 1.385% | Base Rate | Maximum | Line of Credit
Debt Instrument [Line Items]
Variable rate margin	1.125%
Term loan A facility ("2023 Term Loan Facility") due December 2026; bearing interest at Term SOFR plus 1.885% | SOFR | Secured Debt
Debt Instrument [Line Items]
Variable rate margin	1.885%
Term loan A facility ("2023 Term Loan Facility") due December 2026; bearing interest at Term SOFR plus 1.885% | SOFR | Minimum | Secured Debt
Debt Instrument [Line Items]
Variable rate margin	1.625%
Term loan A facility ("2023 Term Loan Facility") due December 2026; bearing interest at Term SOFR plus 1.885% | SOFR | Maximum | Secured Debt
Debt Instrument [Line Items]
Variable rate margin	2.625%
Term loan A facility ("2023 Term Loan Facility") due December 2026; bearing interest at Term SOFR plus 1.885% | Base Rate | Minimum | Secured Debt
Debt Instrument [Line Items]
Variable rate margin	0.625%
Term loan A facility ("2023 Term Loan Facility") due December 2026; bearing interest at Term SOFR plus 1.885% | Base Rate | Maximum | Secured Debt
Debt Instrument [Line Items]
Variable rate margin	1.625%

DEBT - Components of Interest E

DEBT - Components of Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Debt Instrument [Line Items]
Interest expense on long-term debt and finance leases	$ 15,128	$ 5,692	$ 29,565	$ 15,513
Amortization of debt issuance costs	715	489	2,221	1,414
Letter of credit fees	103	117	297	347
Less: capitalized interest	(198)	(121)	(375)	(196)
Total interest expense	$ 15,748	$ 6,177	31,708	$ 17,078
GFL Acquisition
Debt Instrument [Line Items]
Amortization of debt issuance costs			395
Twin Bridges Acquisition
Debt Instrument [Line Items]
Amortization of debt issuance costs			$ 101

DEBT - Loss from Termination of

DEBT - Loss from Termination of Bridge Financing (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Debt Instrument [Line Items]
Loss from termination of bridge financing	$ 0	$ 0	$ 8,191	$ 0
GFL Acquisition
Debt Instrument [Line Items]
Loss from termination of bridge financing			3,718
Twin Bridges Acquisition
Debt Instrument [Line Items]
Loss from termination of bridge financing			$ 4,473

DEBT - Summary of Notional Amou

DEBT - Summary of Notional Amounts (Details) - Cash Flow Hedging $ in Thousands	9 Months Ended
	Sep. 30, 2023 USD ($)
Total
Derivative, Notional Amount [Roll Forward]
Beginning balance	$ 210,000
Additions	290,000
Commencements	0
Maturities	(85,000)
Ending balance	$ 415,000
Floor interest rate (as a percent)	0%
Weighted average percentage rate paid (as a percent)	3.41%
Active
Derivative, Notional Amount [Roll Forward]
Beginning balance	$ 190,000
Additions	290,000
Commencements	20,000
Maturities	(85,000)
Ending balance	415,000
Forward Starting
Derivative, Notional Amount [Roll Forward]
Beginning balance	20,000
Additions	0
Commencements	(20,000)
Maturities	0
Ending balance	$ 0

DEBT - Summary of Cash Flow Hed

DEBT - Summary of Cash Flow Hedges (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Derivatives, Fair Value [Line Items]
Accumulated other comprehensive income, net of tax	$ 9,480	$ 7,542
Designated as Hedging Instrument | Interest rate swaps
Derivatives, Fair Value [Line Items]
Cash flow hedge derivatives, gross asset	16,357	11,806
Designated as Hedging Instrument | Interest rate swaps | Accumulated gain (loss), cash flow hedge
Derivatives, Fair Value [Line Items]
Accumulated other comprehensive income, before tax	14,471	11,806
Accumulated other comprehensive income, tax	(4,991)	(4,264)
Accumulated other comprehensive income, net of tax	9,480	7,542
Other current assets | Designated as Hedging Instrument | Interest rate swaps
Derivatives, Fair Value [Line Items]
Cash flow hedge derivatives, gross asset	7,835	4,345
Other non-current assets | Designated as Hedging Instrument | Interest rate swaps
Derivatives, Fair Value [Line Items]
Cash flow hedge derivatives, gross asset	8,522	7,461
Other long-term liabilities | Designated as Hedging Instrument | Interest rate swaps
Derivatives, Fair Value [Line Items]
Cash flow hedge derivatives, gross liability	$ 1,886	$ 0

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - Narrative (Detail) $ in Thousands	Sep. 30, 2023 USD ($)
Loss Contingencies [Line Items]
Loss contingency accrual	$ 6,280
Minimum
Loss Contingencies [Line Items]
Risk free interest (as a percent)	1.50%
Maximum
Loss Contingencies [Line Items]
Risk free interest (as a percent)	4.10%

COMMITMENTS AND CONTINGENCIES_2

COMMITMENTS AND CONTINGENCIES - Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Dec. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Cash and cash equivalents	$ 219,089	$ 71,152
Restricted cash - non-current	2,730	0
Cash, cash equivalents and restricted cash	$ 221,819	$ 71,152	$ 47,934	$ 33,809

COMMITMENTS AND CONTINGENCIES_3

COMMITMENTS AND CONTINGENCIES - Environmental Remediation Liability (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	$ 6,335	$ 5,887
Obligations settled	(338)	(353)
Ending balance	6,072	6,372
Less: current portion	1,799	646
Long-term portion	4,273	5,726
Other environmental remediation sites
Accrual for Environmental Loss Contingencies [Roll Forward]
Obligations incurred	75	79
Inactive waste disposal site
Accrual for Environmental Loss Contingencies [Roll Forward]
Obligations incurred	$ 0	$ 759

STOCKHOLDERS' EQUITY - Narrativ

STOCKHOLDERS' EQUITY - Narrative (Detail) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended		9 Months Ended
	Jun. 16, 2023	Jun. 01, 2023	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Limited Partners' Capital Account [Line Items]
Unrecognized stock-based compensation, weighted average period					3 years 8 months 12 days
Fair value of stock awards vested			$ 223		$ 5,279
Stock Options
Limited Partners' Capital Account [Line Items]
Stock-based compensation expense			126	$ 89	374	$ 122
Unrecognized stock-based compensation expense, stock options			1,724		1,724
Aggregate intrinsic value of options exercised			1,302		1,302
Restricted Stock Awards, Restricted Stock Units And Performance Stock Units
Limited Partners' Capital Account [Line Items]
Stock-based compensation expense			2,112	2,225	6,007	5,204
Restricted Stock
Limited Partners' Capital Account [Line Items]
Unrecognized stock-based compensation expense			12		12
Restricted Stock Unit
Limited Partners' Capital Account [Line Items]
Unrecognized stock-based compensation expense			6,344		6,344
Performance Stock Unit
Limited Partners' Capital Account [Line Items]
Unrecognized stock-based compensation expense			5,655		$ 5,655
Market-based Performance Stock Units
Limited Partners' Capital Account [Line Items]
Weighted average fair value of market-based performance (in dollars per share)					$ 83.16
Risk-free interest rate					4.31%
Expected volatility					34.90%
Minimum | Restricted Stock | Non Employee Director
Limited Partners' Capital Account [Line Items]
Award vesting period					3 years
Minimum | Restricted Stock Unit | Non Employee Director
Limited Partners' Capital Account [Line Items]
Award service period					3 years
Maximum | Restricted Stock | Non Employee Director
Limited Partners' Capital Account [Line Items]
Award vesting period					5 years
Maximum | Restricted Stock Unit | Non Employee Director
Limited Partners' Capital Account [Line Items]
Award service period					5 years
Weighted average | Restricted Stock
Limited Partners' Capital Account [Line Items]
Unrecognized stock-based compensation, weighted average period					8 months 12 days
Weighted average | Restricted Stock Unit
Limited Partners' Capital Account [Line Items]
Unrecognized stock-based compensation, weighted average period					2 years 4 months 24 days
Weighted average | Performance Stock Unit
Limited Partners' Capital Account [Line Items]
Unrecognized stock-based compensation, weighted average period					1 year 8 months 12 days
2016 Plan
Limited Partners' Capital Account [Line Items]
Expiration period					10 years
2016 Plan | Minimum
Limited Partners' Capital Account [Line Items]
Award vesting period					1 year
2016 Plan | Maximum
Limited Partners' Capital Account [Line Items]
Award vesting period					5 years
Amended and Restated 1997 Employee Stock Purchase Plan
Limited Partners' Capital Account [Line Items]
Stock-based compensation expense			$ 120	$ 97	$ 318	$ 262
Class A Common Stock
Limited Partners' Capital Account [Line Items]
Number of shares issued (in shares)	6,053,000				6,053,000
Public offering price (in dollars per share)	$ 85.50
Net proceeds	$ 496,231
Class A Common Stock | 2016 Plan
Limited Partners' Capital Account [Line Items]
Common stock, authorized shares (in shares)			2,250,000		2,250,000
Number of shares available for future grant (in shares)			625,000		625,000
Class A Common Stock | 2006 Incentive Plan
Limited Partners' Capital Account [Line Items]
Common stock, additional authorized shares (in shares)					2,723,000
Class A Common Stock | Amended and Restated 1997 Employee Stock Purchase Plan
Limited Partners' Capital Account [Line Items]
Common stock, additional authorized shares (in shares)		400,000
Number of shares available for future grant (in shares)			444,000		444,000

STOCKHOLDERS' EQUITY - Summary

STOCKHOLDERS' EQUITY - Summary of Stock Option Activity (Detail) $ / shares in Units, shares in Thousands, $ in Thousands	9 Months Ended
	Sep. 30, 2023 USD ($) $ / shares shares
Stock Options
Beginning balance, outstanding (in shares) | shares	129
Granted (in shares) | shares	0
Exercised (in shares) | shares	(18)
Forfeited (in shares) | shares	0
Ending balance, outstanding (in shares) | shares	111
Exercisable at end of period (in shares) | shares	49
Weighted Average Exercise Price
Beginning balance, outstanding (in dollars per share) | $ / shares	$ 55.60
Granted (in dollars per share) | $ / shares	0
Exercised (in dollars per share) | $ / shares	4.88
Forfeited (in dollars per share) | $ / shares	0
Ending balance, outstanding (in dollars per share) | $ / shares	63.87
Exercisable at end of period (in dollars per share) | $ / shares	$ 40.60
Weighted Average Remaining Contractual Term (years) and Aggregate Intrinsic Value
Outstanding contractual term	7 years 3 months 18 days
Exercisable contractual term	5 years 4 months 24 days
Outstanding aggregate intrinsic value | $	$ 1,846
Exercisable aggregate intrinsic value | $	$ 1,825

STOCKHOLDERS' EQUITY - Summar_2

STOCKHOLDERS' EQUITY - Summary of Restricted Stock Awards, Restricted Stock Unit and Performance-based Stock Unit Activity (Detail) $ / shares in Units, shares in Thousands, $ in Thousands	9 Months Ended
	Sep. 30, 2023 USD ($) $ / shares shares
Performance Stock Unit
Weighted Average Remaining Contractual Term (years) and Aggregate Intrinsic Value
Percentage of attainment level (as a percent)	100%
Performance Stock Unit | Class A Common Stock
Weighted Average Remaining Contractual Term (years) and Aggregate Intrinsic Value
Number of additional shares (in shares)	159
Restricted Stock Awards, Restricted Stock Units And Performance Stock Units
Restricted Stock, Restricted Stock Units, and Performance Stock Units
Outstanding, beginning of period (in shares)	169
Granted (in shares)	119
Forfeited (in shares)	(6)
Outstanding, end of period (in shares)	217
Weighted Average Grant Date Fair Value
Outstanding at beginning of period (in dollars per share) | $ / shares	$ 75.52
Granted (in dollars per share) | $ / shares	81.04
Forfeited (in dollars per share) | $ / shares	76.91
Outstanding at end of period (in dollars per share) | $ / shares	$ 91.51
Weighted Average Remaining Contractual Term (years) and Aggregate Intrinsic Value
Contractual term (in years)	2 years 1 month 6 days
Aggregate intrinsic value | $	$ 16,597
Restricted Stock Awards, Restricted Stock Units And Performance Stock Units | Class A Common Stock
Restricted Stock, Restricted Stock Units, and Performance Stock Units
Class A Common Stock Vested (in shares)	(65)
Weighted Average Grant Date Fair Value
Class A Common Stock Vested (in dollars per share) | $ / shares	$ 62.57
Unvested | Restricted Stock Awards, Restricted Stock Units And Performance Stock Units
Restricted Stock, Restricted Stock Units, and Performance Stock Units
Outstanding, end of period (in shares)	376
Weighted Average Grant Date Fair Value
Outstanding at end of period (in dollars per share) | $ / shares	$ 88.63
Weighted Average Remaining Contractual Term (years) and Aggregate Intrinsic Value
Contractual term (in years)	1 year 8 months 12 days
Aggregate intrinsic value | $	$ 28,660

STOCKHOLDERS' EQUITY - Summar_3

STOCKHOLDERS' EQUITY - Summary of Changes in Balances of Each Component of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 1,008,383	$ 501,655	$ 497,900	$ 457,566	$ 435,050	$ 422,457	$ 497,900	$ 422,457
Other comprehensive income, net of tax	1,872	1,835	(1,769)	3,910	2,980	6,143	1,938	13,033
Ending balance	1,030,867	$ 1,008,383	501,655	$ 486,559	$ 457,566	$ 435,050	1,030,867	$ 486,559
Accumulated gain (loss), cash flow hedge
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance			$ 7,542				7,542
Other comprehensive income before reclassifications							6,846
Income reclassified from accumulated other comprehensive income into interest expense							(4,181)
Income tax provision related to items of other comprehensive income							(727)
Other comprehensive income, net of tax							1,938
Ending balance	$ 9,480						$ 9,480

STOCKHOLDERS' EQUITY - Summar_4

STOCKHOLDERS' EQUITY - Summary of Reclassifications Out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	$ 15,748			$ 6,177			$ 31,708	$ 17,078
Income before income taxes	24,190			31,812			36,007	63,335
Provision for income taxes	6,018			9,140			8,797	18,677
Net income	18,172	$ 5,490	$ 3,548	22,672	$ 17,796	$ 4,190	27,210	44,658
Accumulated gain (loss), cash flow hedge | Amounts Reclassified Out of Accumulated Other Comprehensive Income, Net of Tax
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	1,805			(14)			4,181	(2,136)
Provision for income taxes	495			0			1,146	(190)
Net income	1,310			(14)			3,035	(1,946)
Interest rate swaps | Accumulated gain (loss), cash flow hedge | Amounts Reclassified Out of Accumulated Other Comprehensive Income, Net of Tax
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	$ (1,805)			$ 14			$ (4,181)	$ 2,136

EARNINGS PER SHARE (Details)

EARNINGS PER SHARE (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	Jun. 16, 2023	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Numerator:
Net income		$ 18,172	$ 22,672	$ 27,210	$ 44,658
Denominators:
Unvested restricted stock (in shares)		0	(1,000)	0	(1,000)
Effect of weighted average shares outstanding (in shares)		(20,000)	(2,000)	(3,754,000)	(75,000)
Basic weighted average common shares outstanding (in shares)		57,962,000	51,677,000	54,228,000	51,604,000
Impact of potentially dilutive securities:
Dilutive effect of stock options and other stock awards (in shares)		100,000	129,000	97,000	145,000
Diluted weighted average common shares outstanding (in shares)		58,062,000	51,806,000	54,325,000	51,749,000
Anti-dilutive potentially issuable shares (in shares)		78,000	84,000	75,000	115,000
Class A Common Stock
Denominators:
Common stock, shares outstanding (in shares)		56,994,000	50,692,000	56,994,000	50,692,000	50,704,000
Impact of potentially dilutive securities:
Number of shares issued (in shares)	6,053,000			6,053,000
Class B Common Stock
Denominators:
Common stock, shares outstanding (in shares)		988,000	988,000	988,000	988,000	988,000

OTHER ITEMS AND CHARGES (Detail

OTHER ITEMS AND CHARGES (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Unusual or Infrequent Items, or Both [Abstract]
Expense from acquisition activities	$ 3,261	$ 816	$ 9,801	$ 3,878
Legal settlement	0	0	6,150	0
Environmental remediation charge	$ 0	$ 759	$ 0	$ 759

FAIR VALUE OF FINANCIAL INSTR_3

FAIR VALUE OF FINANCIAL INSTRUMENTS - Recurring Fair Value Measurements (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2023	Dec. 31, 2022
Assets:
Restricted investment securities - landfill closure	$ 4,658	$ 4,658	$ 1,900
Liabilities:
Derivative Asset, Statement Of Financial Position Extensible Enumeration, Not Disclosed Flag		Interest rate swaps	Interest rate swaps
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Interest rate swaps	0	$ 0	$ 0
Total assets	1,928	1,928	1,900
Liabilities:
Interest rate swaps	0	0
Contingent consideration - acquisition			0
Total	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Landfill
Assets:
Restricted investment securities - landfill closure	1,928	1,928	1,900
Recurring | Significant Other Observable Inputs (Level 2)
Assets:
Interest rate swaps	16,357	16,357	11,806
Total assets	16,357	16,357	11,806
Liabilities:
Interest rate swaps	1,886	1,886
Contingent consideration - acquisition			0
Total	1,886	1,886
Recurring | Significant Other Observable Inputs (Level 2) | Landfill
Assets:
Restricted investment securities - landfill closure	0	0	0
Recurring | Significant Unobservable Inputs (Level 3)
Assets:
Interest rate swaps	0	0	0
Total assets	0	0	0
Liabilities:
Interest rate swaps	0	0
Contingent consideration - acquisition			965
Total	0	0
Contingent consideration, decrease for reversal of contingency	376	965
Recurring | Significant Unobservable Inputs (Level 3) | Landfill
Assets:
Restricted investment securities - landfill closure	$ 0	$ 0	$ 0

FAIR VALUE OF FINANCIAL INSTR_4

FAIR VALUE OF FINANCIAL INSTRUMENTS - Narrative (Detail) - USD ($)	Sep. 30, 2023	Dec. 31, 2022
Term loan A facility ("Term Loan Facility") due December 2026; bearing interest at Term SOFR plus 1.385% | Secured Debt
Debt Instrument [Line Items]
Principal amount of debt	$ 350,000,000	$ 350,000,000
Term loan A facility ("2023 Term Loan Facility") due December 2026; bearing interest at Term SOFR plus 1.885% | Secured Debt
Debt Instrument [Line Items]
Principal amount of debt	424,625,000	$ 0
Fair Value | Fixed Rate Bonds
Debt Instrument [Line Items]
Fixed rate debt	223,926,000
Carrying Value
Debt Instrument [Line Items]
Revolving credit facility	0
Carrying Value | Fixed Rate Bonds
Debt Instrument [Line Items]
Fixed rate debt	$ 232,000,000

SEGMENT REPORTING - Summary of

SEGMENT REPORTING - Summary of Financial Information by Reportable Segment (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Segment Reporting Information [Line Items]
Revenues	$ 352,735	$ 295,268	$ 904,975	$ 812,962
Depreciation and amortization	47,736	32,527	116,095	93,106
Operating income (loss)	34,188	36,288	67,067	78,175
Total assets	2,498,015	1,399,347	2,498,015	1,399,347	$ 1,449,215
Operating | Eastern
Segment Reporting Information [Line Items]
Revenues	97,507	93,137	274,740	251,720
Depreciation and amortization	12,381	11,907	36,431	34,895
Operating income (loss)	11,160	10,061	20,819	13,981
Total assets	417,138	361,950	417,138	361,950
Operating | Western
Segment Reporting Information [Line Items]
Revenues	136,019	121,903	371,281	332,626
Depreciation and amortization	20,976	16,778	57,559	47,376
Operating income (loss)	20,462	22,405	51,880	51,565
Total assets	986,659	725,232	986,659	725,232
Operating | Mid-Atlantic
Segment Reporting Information [Line Items]
Revenues	43,722	0	43,722	0
Depreciation and amortization	10,182	0	10,182	0
Operating income (loss)	(747)	0	(747)	0
Total assets	557,710	0	557,710	0
Operating | Resource Solutions
Segment Reporting Information [Line Items]
Revenues	75,487	80,228	215,232	228,616
Depreciation and amortization	3,452	3,138	9,618	9,011
Operating income (loss)	4,110	4,526	2,854	14,453
Total assets	242,413	189,854	242,413	189,854
Corporate Entities
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Depreciation and amortization	745	704	2,305	1,824
Operating income (loss)	(797)	(704)	(7,739)	(1,824)
Total assets	294,095	122,311	294,095	122,311
Inter-company revenues
Segment Reporting Information [Line Items]
Revenues	(75,602)	(65,309)	(204,238)	(177,202)
Inter-company revenues | Eastern
Segment Reporting Information [Line Items]
Revenues	(24,911)	(23,027)	(67,843)	(61,842)
Inter-company revenues | Western
Segment Reporting Information [Line Items]
Revenues	(46,307)	(40,703)	(125,208)	(112,687)
Inter-company revenues | Mid-Atlantic
Segment Reporting Information [Line Items]
Revenues	(212)	0	(212)	0
Inter-company revenues | Resource Solutions
Segment Reporting Information [Line Items]
Revenues	$ (4,172)	$ (1,579)	$ (10,975)	$ (2,673)

SEGMENT REPORTING - Summary o_2

SEGMENT REPORTING - Summary of Revenues Attributable to Services Provided by Company (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Revenue from External Customer [Line Items]
Revenues	$ 352,735	$ 295,268	$ 904,975	$ 812,962
Solid waste operations
Revenue from External Customer [Line Items]
Revenues	277,248	215,040	689,743	584,346
Collection
Revenue from External Customer [Line Items]
Revenues	206,093	144,117	495,917	400,910
Disposal
Revenue from External Customer [Line Items]
Revenues	66,337	66,147	181,433	169,503
Power generation
Revenue from External Customer [Line Items]
Revenues	1,797	1,643	5,042	6,050
Processing
Revenue from External Customer [Line Items]
Revenues	3,021	3,133	7,351	7,883
Resource Solutions operations
Revenue from External Customer [Line Items]
Revenues	75,487	80,228	215,232	228,616
Processing
Revenue from External Customer [Line Items]
Revenues	27,782	32,159	75,970	93,421
National Accounts
Revenue from External Customer [Line Items]
Revenues	$ 47,705	$ 48,069	$ 139,262	$ 135,195