Casella Waste Systems (CWST) 10-Q28 Oct 222022 Q3 Quarterly reportFinancial data

Company Profile

COVER

COVER - shares	9 Months Ended
COVER - shares	Sep. 30, 2022	Oct. 15, 2022
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2022
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	2022
Document Fiscal Period Focus	Q3
Amendment Flag	false
Class A Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		50,692,053
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, 2022	Dec. 31, 2021
CURRENT ASSETS:
Cash and cash equivalents	$ 47,934	$ 33,809
Accounts receivable, net of allowance for credit losses of $4,265 and $3,276, respectively	108,010	86,979
Prepaid expenses	14,998	12,766
Inventory	13,432	9,729
Other current assets	7,109	3,196
Total current assets	191,483	146,479
Property, plant and equipment, net of accumulated depreciation and amortization of $1,038,576 and $973,094, respectively	685,348	644,604
Operating lease right-of-use assets	93,066	93,799
Goodwill	272,442	232,860
Intangible assets, net	94,792	93,723
Restricted assets	1,705	2,122
Cost method investments	10,967	11,264
Deferred income taxes	25,549	43,957
Other non-current assets	23,995	14,772
Total assets	1,399,347	1,283,580
CURRENT LIABILITIES:
Current maturities of debt	8,337	9,901
Current operating lease liabilities	6,898	7,307
Accounts payable	71,074	63,086
Accrued payroll and related expenses	20,056	22,210
Accrued interest	2,956	2,042
Contract liabilities	3,891	3,404
Current accrued final capping, closure and post-closure costs	10,880	7,915
Other accrued liabilities	38,740	36,328
Total current liabilities	162,832	152,193
Debt, less current portion	578,462	542,503
Operating lease liabilities, less current portion	58,528	56,375
Accrued final capping, closure and post-closure costs, less current portion	83,727	78,999
Deferred income taxes	522	868
Other long-term liabilities	28,717	30,185
COMMITMENTS AND CONTINGENCIES
STOCKHOLDERS' EQUITY:
Additional paid-in capital	658,453	652,045
Accumulated deficit	(180,341)	(224,999)
Accumulated other comprehensive income (loss), net of tax	7,930	(5,103)
Total stockholders' equity	486,559	422,457
Total liabilities and stockholders' equity	1,399,347	1,283,580
Class A Common Stock
STOCKHOLDERS' EQUITY:
Common stock	507	504
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
CONSOLIDATED BALANCE SHEETS (Parenthetical) $ in Thousands	Sep. 30, 2022 USD ($) vote $ / shares shares	Dec. 31, 2021 USD ($) vote $ / shares shares
Accounts receivable - trade, allowance for credit losses \| $	$ 4,265	$ 3,276
Accumulated depreciation and amortization \| $	$ 1,038,576	$ 973,094
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)	50,692,000	50,423,000
Common stock, shares outstanding (in shares)	50,692,000	50,423,000
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, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Income Statement [Abstract]
Revenues	$ 295,268	$ 241,969	$ 812,962	$ 647,375
Operating expenses:
Cost of operations	190,285	153,892	538,779	419,583
General and administration	34,348	30,993	97,702	87,336
Depreciation and amortization	32,527	27,491	93,106	74,510
Expense from acquisition activities	816	1,904	3,878	3,950
Environmental remediation charge	759	0	759	0
Southbridge Landfill closure charge	245	302	563	653
Total operating expenses	258,980	214,582	734,787	586,032
Operating income	36,288	27,387	78,175	61,343
Other expense (income):
Interest income	(178)	(61)	(260)	(191)
Interest expense	6,177	5,164	17,078	15,928
Other income	(1,523)	(178)	(1,978)	(825)
Other expense, net	4,476	4,925	14,840	14,912
Income before income taxes	31,812	22,462	63,335	46,431
Provision for income taxes	9,140	6,601	18,677	14,476
Net income	$ 22,672	$ 15,861	$ 44,658	$ 31,955
Basic earnings per share attributable to common stockholders:
Weighted average common shares outstanding, basic (in shares)	51,677	51,389	51,604	51,312
Basic earnings per common share (in dollars per share)	$ 0.44	$ 0.31	$ 0.87	$ 0.62
Diluted earnings per share attributable to common stockholders:
Weighted average common shares outstanding, diluted (in shares)	51,806	51,586	51,749	51,506
Diluted earnings per common share (in dollars per share)	$ 0.44	$ 0.31	$ 0.86	$ 0.62

UNAUDITED CONSOLIDATED STATEM_2

UNAUDITED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Statement of Comprehensive Income [Abstract]
Net income	$ 22,672	$ 15,861	$ 44,658	$ 31,955
Hedging activity:
Interest rate swap settlements	(129)	(1,205)	(2,224)	(3,551)
Interest rate swap amounts reclassified into interest expense	14	1,204	2,136	3,551
Unrealized gain resulting from changes in fair value of derivative instruments	5,493	1,215	17,362	5,866
Other comprehensive income, before tax	5,378	1,214	17,274	5,866
Income tax provision related to items of other comprehensive income	1,468	322	4,241	1,379
Other comprehensive income, net of tax	3,910	892	13,033	4,487
Comprehensive income	$ 26,582	$ 16,753	$ 57,691	$ 36,442

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), net of tax	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, 2020	$ 362,142	$ 639,247	$ (266,099)	$ (11,517)		$ 501		$ 10
Beginning balance (in shares) at Dec. 31, 2020						50,101,000		988,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances of Class A common stock	112	109				$ 3
Issuance of Class A common stock (in shares)						273,000
Stock-based compensation	2,941	2,941
Net income (loss)	4,311		4,311
Hedging activity	3,830			3,830
Ending balance at Mar. 31, 2021	373,336	642,297	(261,788)	(7,687)		$ 504		$ 10
Ending balance (in shares) at Mar. 31, 2021						50,374,000		988,000
Beginning balance at Dec. 31, 2020	362,142	639,247	(266,099)	(11,517)		$ 501		$ 10
Beginning balance (in shares) at Dec. 31, 2020						50,101,000		988,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	31,955
Hedging activity	4,487
Ending balance at Sep. 30, 2021	407,951	648,611	(234,144)	(7,030)		$ 504		$ 10
Ending balance (in shares) at Sep. 30, 2021					50,410,000	50,410,000	988,000	988,000
Beginning balance at Mar. 31, 2021	373,336	642,297	(261,788)	(7,687)		$ 504		$ 10
Beginning balance (in shares) at Mar. 31, 2021						50,374,000		988,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances of Class A common stock	492	492
Issuance of Class A common stock (in shares)						24,000
Stock-based compensation	3,116	3,116
Net income (loss)	11,783		11,783
Hedging activity	(235)			(235)
Ending balance at Jun. 30, 2021	388,492	645,905	(250,005)	(7,922)		$ 504		$ 10
Ending balance (in shares) at Jun. 30, 2021						50,398,000		988,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances of Class A common stock	51	51
Issuance of Class A common stock (in shares)						12,000
Stock-based compensation	2,655	2,655
Net income (loss)	15,861		15,861
Hedging activity	892			892
Ending balance at Sep. 30, 2021	407,951	648,611	(234,144)	(7,030)		$ 504		$ 10
Ending balance (in shares) at Sep. 30, 2021					50,410,000	50,410,000	988,000	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	50,423,000	988,000	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 (loss)	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	50,423,000	988,000	988,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	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 (loss)	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]
Issuances of Class A common stock	0
Issuance of Class A common stock (in shares)						2,000
Stock-based compensation	2,411	2,411
Net income (loss)	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

UNAUDITED CONSOLIDATED STATEM_4

UNAUDITED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Cash Flows from Operating Activities:
Net income	$ 44,658	$ 31,955
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	93,106	74,510
Interest accretion on landfill and environmental remediation liabilities	6,018	5,915
Amortization of debt issuance costs	1,414	1,716
Stock-based compensation	5,589	8,712
Operating lease right-of-use assets expense	10,405	9,981
Gain on sale of property and equipment	(580)	0
Non-cash expense from acquisition activities	298	532
Deferred income taxes	13,819	12,974
Changes in assets and liabilities, net of effects of acquisitions and divestitures:
Accounts receivable	(14,230)	(10,943)
Landfill operating lease contract expenditures	(3,336)	(3,646)
Accounts payable	7,946	20,318
Prepaid expenses, inventories and other assets	(5,799)	(14,391)
Accrued expenses, contract liabilities and other liabilities	(6,877)	(3,544)
Net cash provided by operating activities	152,431	134,089
Cash Flows from Investing Activities:
Acquisitions, net of cash acquired	(73,963)	(153,112)
Additions to property, plant and equipment	(87,667)	(81,577)
Proceeds from sale of property and equipment	571	593
Net cash used in investing activities	(161,059)	(234,096)
Cash Flows from Financing Activities:
Proceeds from debt borrowings	82,200	500
Principal payments on debt	(57,407)	(8,517)
Payments of debt issuance costs	(1,232)	0
Payments of contingent consideration	(1,000)	0
Proceeds from the exercise of share based awards	192	163
Net cash provided by (used in) financing activities	22,753	(7,854)
Net increase (decrease) in cash and cash equivalents	14,125	(107,861)
Cash and cash equivalents, beginning of period	33,809	154,342
Cash and cash equivalents, end of period	47,934	46,481
Supplemental Disclosure of Cash Flow Information:
Cash interest payments	14,750	14,378
Cash income tax payments	2,875	597
Right-of-use assets obtained in exchange for new finance lease liabilities	9,420	18,153
Right-of-use assets obtained in exchange for operating lease obligations	$ 7,672	$ 3,566

BASIS OF PRESENTATION

BASIS OF PRESENTATION	9 Months Ended
BASIS OF PRESENTATION	Sep. 30, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
BASIS OF PRESENTATION	BASIS OF PRESENTATION Casella Waste Systems, Inc. (“Parent”), and its 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 seven states: Vermont, New Hampshire, New York, Massachusetts, Connecticut, Maine and Pennsylvania, with our headquarters located in Rutland, Vermont. We manage our solid waste operations on a geographic basis through two regional operating segments, the Eastern and Western regions, each of which provides a full 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, 2021 ("fiscal year 2021"), which was filed with the SEC on February 18, 2022. 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, which include normal recurring and nonrecurring adjustments, 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, 2022 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 Annual Report on Form 10-K for fiscal year 2021. Subsequent Events We have evaluated subsequent events or transactions that have occurred after the consolidated balance sheet date of September 30, 2022 through the date of filing of the consolidated financial statements with the SEC on this Quarterly Report on Form 10-Q. We have determined that there are no subsequent events that require disclosure in this Quarterly Report on Form 10-Q.

ACCOUNTING CHANGES

ACCOUNTING CHANGES	9 Months Ended
ACCOUNTING CHANGES	Sep. 30, 2022
Accounting Changes and Error Corrections [Abstract]
ACCOUNTING CHANGES	ACCOUNTING CHANGES A table providing a brief description of recent Accounting Standards Updates ("ASUs") to the Accounting Standards Codification ("ASC") issued by the Financial Accounting Standards Board (“FASB”) that are pending adoption and deemed to have a possible material impact on our consolidated financial statements based on current account balances and activity follows: Standard Description Effect on the Financial Statements or Other Accounting standards issued pending adoption ASU No. 2020-04: Reference Rate Reform (Topic 848), as amended through January 2021 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. We currently have interest rate derivative agreements with hedging relationships that reference LIBOR. 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. We are currently reviewing and updating our existing contracts, as applicable, for transition or fallback language that specifies how a replacement rate for LIBOR will be identified. We are also no longer using LIBOR as a reference rate for any new contracts. We do not expect that the adoption of this guidance will have a material impact on our consolidated financial statements and related disclosures. This guidance will be in effect from March 12, 2020 through December 31, 2022. See Note 7, Debt for further disclosure over our interest rate derivative agreements and debt instruments that reference LIBOR. ASU No. 2021-08: Accounting for Contract Assets and Contract Liabilities from Contracts with Customers (Topic 805) Requires entities to apply ASC 606 to recognize and measure contract assets and contract liabilities in a business combination. This guidance improves comparability after the business combination by providing consistent recognition and measurement guidance for revenue contracts with customers acquired in a business combination and revenue contracts with customers not acquired in a business combination. We have made in the past, and we may make in the future, acquisitions to densify existing operations, expand service areas, and grow services for our customers, and these acquisitions may include contract assets or contract liabilities. We do not expect that the adoption of this guidance will have a material impact on our consolidated financial statements and related disclosures. This guidance is effective January 1, 2023 with early adoption permitted.

REVENUE RECOGNITION

REVENUE RECOGNITION	9 Months Ended
REVENUE RECOGNITION	Sep. 30, 2022
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 services are derived from processing and non-processing services. 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, 2022 and 2021: Three Months Ended September 30, 2022 Eastern Western 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 Non-processing — — 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 Three Months Ended September 30, 2021 Eastern Western Resource Solutions Total Revenues Collection $ 48,951 $ 69,921 $ — $ 118,872 Landfill 6,622 18,201 — 24,823 Transfer station 16,948 10,375 — 27,323 Transportation 54 3,393 — 3,447 Landfill gas-to-energy 269 984 — 1,253 Processing 2,310 649 27,418 30,377 Non-processing — — 35,874 35,874 Total revenues $ 75,154 $ 103,523 $ 63,292 $ 241,969 Transferred at a point-in-time $ 43 $ 296 $ 19,927 $ 20,266 Transferred over time 75,111 103,227 43,365 221,703 Total revenues $ 75,154 $ 103,523 $ 63,292 $ 241,969 Nine Months Ended September 30, 2022 Eastern Western Resource Solutions Total Revenues Collection $ 172,671 $ 228,239 $ — $ 400,910 Landfill 19,819 53,028 — 72,847 Transfer station 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 Non-processing — — 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 Nine Months Ended September 30, 2021 Eastern Western Resource Solutions Total Revenues Collection $ 124,389 $ 199,278 $ — $ 323,667 Landfill 18,143 48,336 — 66,479 Transfer station 39,847 27,498 — 67,345 Transportation 148 8,646 — 8,794 Landfill gas-to-energy 784 2,873 — 3,657 Processing 5,246 1,508 65,721 72,475 Non-processing — — 104,958 104,958 Total revenues $ 188,557 $ 288,139 $ 170,679 $ 647,375 Transferred at a point-in-time $ 125 $ 1,284 $ 44,964 $ 46,373 Transferred over time 188,432 286,855 125,715 601,002 Total revenues $ 188,557 $ 288,139 $ 170,679 $ 647,375 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 $5,460 and $15,162 in the three and nine months ended September 30, 2022, respectively, and $4,341 and $8,440 in the three and nine months ended September 30, 2021, 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 any revenues in the three and nine months ended September 30, 2022 or September 30, 2021 from performance obligations satisfied in previous periods. Contract receivables, which are included in Accounts receivable, net 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 $111,256 and $89,232 as of September 30, 2022 and December 31, 2021, respectively. Certain customers are billed in advance and, accordingly, recognition of the related revenues is deferred as a contract liability until the services are provided and control transferred to the customer. We recognized contract liabilities of $3,891 and $3,404 as of September 30, 2022 and December 31, 2021, 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, 2021 and December 31, 2020 was recognized as revenue during the nine months ended September 30, 2022 and September 30, 2021, respectively, when the services were performed.

BUSINESS COMBINATIONS

BUSINESS COMBINATIONS	9 Months Ended
BUSINESS COMBINATIONS	Sep. 30, 2022
Business Combination and Asset Acquisition [Abstract]
BUSINESS COMBINATIONS	BUSINESS COMBINATIONS In the nine months ended September 30, 2022, we acquired twelve businesses, including: an organic materials management business and a full service solid waste collection, recycling and transportation business in our Resource Solutions operating segment; a closed waste-to-energy facility that is being decommissioned and rebuilt as a transfer station, a transfer station, and six tuck-in solid waste collection businesses in our Western region; a portable toilets business in our Eastern region; and a scrap metal collection business whose assets are allocated between our Eastern region and Resource Solutions operating segments. In the nine months ended September 30, 2021, we acquired eight businesses, including: a residential, commercial and roll-off collection business in eastern Connecticut that operates a rail-served construction and demolition processing and waste transfer facility, a waste transfer station, a single-stream recycling facility, and several other recycling operations whose assets and liabilities are allocated between our Eastern region and Resource Solutions operating segments; a septic and portable toilet business, a tuck-in solid waste collection business and a solid waste collection business that operates a waste transfer station in our Eastern region; and a waste composting and food-scrap hauling business, a solid waste collection business that operates a waste transfer station, and two tuck-in solid waste collection businesses in our Western region. The operating results of these businesses are 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, including contingent consideration. Acquired intangible assets other than goodwill that are subject to amortization 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. 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 2022 2021 Purchase Price: Cash used in acquisitions, net of cash acquired $ 72,731 $ 150,364 Other non-cash consideration 1,220 — Holdbacks to sellers and contingent consideration 4,112 4,865 Total consideration $ 78,063 $ 155,229 Allocated as follows: Current assets $ 7,599 $ 7,260 Property, plant and equipment: Land 3,141 803 Finance lease right-of-use-assets — 31,467 Buildings and improvements 8,566 8,468 Machinery and equipment 10,296 42,458 Operating lease right-of-use assets 405 6,500 Intangible assets: Trade names — 8,350 Covenants not-to-compete 2,034 3,069 Customer relationships 11,417 30,340 Other non-current assets 40 — Current liabilities (3,721) (5,952) Other long-term liabilities (123) — Financing lease liabilities, less current portion — (10,535) Operating lease liabilities, less current portion (282) — Fair value of assets acquired and liabilities assumed 39,372 122,228 Excess purchase price allocated to goodwill $ 38,691 $ 33,001 Certain purchase price allocations 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, 2021 is as follows: Three Months Ended Nine Months Ended 2022 2021 2022 2021 Revenues $ 295,512 $ 262,000 $ 825,020 $ 733,819 Operating income $ 36,247 $ 28,516 $ 79,473 $ 64,360 Net income $ 22,635 $ 15,308 $ 44,888 $ 27,993 Basic earnings per share attributable to common stockholders: Weighted average common shares outstanding 51,677 51,389 51,604 51,312 Basic earnings per common share $ 0.44 $ 0.30 $ 0.87 $ 0.55 Diluted earnings per share attributable to common stockholders: Weighted average common shares outstanding 51,806 51,586 51,749 51,506 Diluted earnings per common share $ 0.44 $ 0.30 $ 0.87 $ 0.54

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS	9 Months Ended
GOODWILL AND INTANGIBLE ASSETS	Sep. 30, 2022
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 Adjustments to Acquisitions September 30, Eastern $ 52,072 $ 93 $ 241 $ 52,406 Western 163,728 16,892 650 181,270 Resource Solutions 17,060 21,706 — 38,766 $ 232,860 $ 38,691 $ 891 $ 272,442 Summaries of intangible assets by type follows: Covenants Customer Relationships Trade Names Total Balance, September 30, 2022 Intangible assets $ 30,812 $ 126,372 $ 8,350 $ 165,534 Less accumulated amortization (23,609) (43,254) (3,879) (70,742) $ 7,203 $ 83,118 $ 4,471 $ 94,792 Covenants Customer Relationships Trade Names Total Balance, December 31, 2021 Intangible assets $ 28,777 $ 115,005 $ 8,350 $ 152,132 Less accumulated amortization (22,148) (34,809) (1,452) (58,409) $ 6,629 $ 80,196 $ 6,898 $ 93,723 Intangible amortization expense was $4,281 and $12,333 during the three and nine months ended September 30, 2022, respectively, and $3,133 and $7,175 during the three and nine months ended September 30, 2021, respectively. A summary of intangible amortization expense estimated for the five fiscal years following fiscal year 2021 and thereafter follows: Estimated Future Amortization Expense as of September 30, 2022 Fiscal year ending December 31, 2022 $ 4,194 Fiscal year ending December 31, 2023 $ 15,918 Fiscal year ending December 31, 2024 $ 15,278 Fiscal year ending December 31, 2025 $ 14,244 Fiscal year ending December 31, 2026 $ 12,579 Thereafter $ 32,579

ACCRUED FINAL CAPPING, CLOSURE

ACCRUED FINAL CAPPING, CLOSURE AND POST CLOSURE	9 Months Ended
ACCRUED FINAL CAPPING, CLOSURE AND POST CLOSURE	Sep. 30, 2022
Asset Retirement Obligation Disclosure [Abstract]
ACCRUED FINAL CAPPING, CLOSURE AND POST CLOSURE	ACCRUED FINAL CAPPING, CLOSURE AND POST CLOSUREAccrued 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 2022 2021 Beginning balance $ 86,914 $ 82,533 Obligations incurred 3,592 3,638 Revision in estimates (1) 1,443 — Accretion expense 5,685 5,496 Obligations settled (2) (3,027) (5,394) Ending balance $ 94,607 $ 86,273 (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
DEBT	Sep. 30, 2022
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 LIBOR plus 1.375% $ 350,000 $ 350,000 Revolving credit facility ("Revolving Credit Facility") due December 2026; bearing interest at LIBOR plus 1.375% — — 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 through 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 through 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 through 2025; bearing interest at 2.750% 40,000 40,000 Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2005R-3 ("FAME Bonds 2005R-3") due January 2025 - fixed rate interest period through 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 through 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 through 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 through 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 through 2027; bearing interest at 5.00% 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 through 2029; bearing interest at 2.95% 11,000 11,000 Other: Finance leases 49,070 45,724 Notes payable maturing through August 2024; bearing interest at a weighted average of 1.6% 712 4,846 Principal amount of debt 596,782 562,570 Less—unamortized debt issuance costs (1) 9,983 10,166 Debt less unamortized debt issuance costs 586,799 552,404 Less—current maturities of debt 8,337 9,901 $ 578,462 $ 542,503 (1) A summary of unamortized debt issuance costs by debt instrument follows: September 30, December 31, Revolving Credit Facility and Term Loan Facility (collectively, the "Credit Facility") $ 5,011 $ 5,884 New York Bonds 2014R-1 882 933 New York Bonds 2014R-2 223 268 New York Bonds 2020 1,150 1,283 FAME Bonds 2005R-3 198 262 FAME Bonds 2015R-1 361 413 FAME Bonds 2015R-2 212 268 Vermont Bonds 2013 392 433 Vermont Bonds 2022A-1 1,176 — New Hampshire Bonds 378 422 $ 9,983 $ 10,166 Financing Activities In the nine months ended September 30, 2022, we completed the issuance of $35,000 aggregate principal amount of Vermont Bonds 2022A-1. The Vermont Bonds 2022A-1, which are unsecured and guaranteed jointly and severally, fully and unconditionally by all of our significant wholly-owned subsidiaries, accrue interest at 5.00% per annum from June 1, 2022 through May 31, 2027, at which time they may be converted to a variable interest rate period or to a new term interest rate period. The Vermont Bonds 2022A-1 mature on June 1, 2052. We borrowed and used the proceeds from the Vermont Bonds 2022A-1 to finance or reimburse certain noncurrent asset costs associated with capital projects in the State of Vermont. Credit Facility We are party to an amended and restated credit agreement ("Credit Agreement"), which provides for a $350,000 aggregate principal amount Term Loan Facility and a $300,000 Revolving Credit Facility, with a $75,000 sublimit for letters of credit. 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 the terms and conditions set forth in the Credit Agreement. The Credit Facility has a 5-year term that matures in December 2026 and bears interest at a rate of LIBOR plus 1.375% per annum, which will be reduced to a rate of LIBOR plus as low as 1.125% upon us reaching a consolidated net leverage ratio of less than 2.25x. The Credit Agreement contains customary benchmark replacement provisions pursuant to which, upon certain triggering events, the LIBOR benchmark used to calculate the LIBOR rate will be replaced with a secured overnight financing rate, as adjusted, on the terms and conditions in the Credit Agreement. 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, 2022, further advances were available under the Revolving Credit Facility in the amount of $271,805. The available amount is net of outstanding irrevocable letters of credit totaling $28,195, and as of September 30, 2022 no amount had been drawn. 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 (loss), 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. As of September 30, 2022 and December 31, 2021, our active interest rate derivative agreements had total notional amounts of $190,000 and $195,000, respectively. According to the terms of the agreements, we receive interest based on the 1-month LIBOR index, in some instances restricted by a 0.0% floor, and pay interest at a weighted average rate of approximately 2.20%. The agreements mature between May 2023 and June 2027. As of December 31, 2021, we had forward starting interest rate derivative agreements with a total notional amount of $85,000 outstanding. As of September 30, 2022, we have a forward starting interest rate derivative agreement with a total notional amount of $20,000 after considering any forward starting interest rate derivative agreements that became effective in the current period. According to the terms of this agreement, we will receive interest based on the 1-month LIBOR index, restricted by a 0.0% floor, and will pay interest at a rate of 1.29%. The agreement matures in May 2028. A summary of the effect of cash flow hedges related to derivative instruments on the consolidated balance sheet follows: Fair Value Balance Sheet Location September 30, December 31, Interest rate swaps Other current assets $ 3,526 $ — Interest rate swaps Other non-current assets 8,814 424 $ 12,340 $ 424 Interest rate swaps Other accrued liabilities $ — $ 3,796 Interest rate swaps Other long-term liabilities — 1,380 $ — $ 5,176 Interest rate swaps Accumulated other comprehensive income (loss), net of tax $ 12,340 $ (4,935) Interest rate swaps - tax effect Accumulated other comprehensive income (loss), net of tax (4,410) (168) $ 7,930 $ (5,103)

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	9 Months Ended
COMMITMENTS AND CONTINGENCIES	Sep. 30, 2022
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Legal Proceedings In the ordinary course of our business and as a 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 $1,071 relating to our outstanding legal proceedings as of September 30, 2022. 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. North Country Environmental Services Expansion Permit On October 9, 2020, our subsidiary, North Country Environmental Services, Inc. ("NCES"), received a Type I-A Permit Modification ("Permit") for Expansion in the Stage VI area of the NCES landfill located in Bethlehem, New Hampshire. On November 9, 2020, the Conservation Law Foundation ("CLF") filed an appeal of the Permit to the New Hampshire Waste Management Council (“Council”) on the grounds it failed to meet the public benefit criteria. Throughout 2021 and early 2022 a number of motions were filed by both NCES and CLF with the Council and in February 2022 the Council held a hearing on the CLF appeal. The Council ruled in favor of NCES on all motions concerning questions of fact, and indicating that a written decision incorporating the Hearing Officer’s decision as to questions of law would follow. On May 11, 2022, an Order was issued denying all of CLF’s arguments on appeal, with the exception of one; the Hearing Officer held that based on his interpretation of the relevant statute, the public benefit determination made by the New Hampshire Department of Environmental Services (“DES”), in issuing the Permit to NCES, was unlawful, and remanded the Permit to the DES with regard to this determination. DES filed a Motion for Reconsideration with the Council on May 31, 2022 (“DES Reconsideration Motion”) and NCES filed a Motion for Rehearing on June 10, 2022 (“NCES Rehearing Motion”). The Hearing Officer suspended his May 11, 2022 decision by Order dated June 20, 2022, pending consideration of the DES Reconsideration Motion and NCES Rehearing Motion. On September 20, 2022, NCES and our subsidiary, Granite State Landfill, LLC (“GSL”), filed a Petition for Declaratory Judgment ("Petition") in Merrimack Superior Court seeking a determination of the meaning and constitutionality of New Hampshire’s public benefit requirement. On September 21, 2022, NCES filed a Motion to Stay the Council proceedings pending resolution of the Petition action. DES assented to the relief sought by that motion, and CLF filed an Objection to the Motion to Stay on September 26, 2022. On October 3, 2022, NCES filed a Motion for Leave to File Reply together with its Reply to CLF’s Objection to Motion to Stay. The aforesaid Motions remain pending before the Council as does the Petition before the Merrimack Superior Court. NCES will continue to vigorously defend the litigation before the Council and together with GSL will continue to pursue Declaratory Judgment before the Merrimack Superior Court. 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 a 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, 2022 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, 2022 and 2021 follows: Nine Months Ended 2022 2021 Beginning balance $ 5,887 $ 5,200 Accretion expense 79 82 Obligations incurred (1) 759 — Obligations settled (2) (353) (281) Ending balance 6,372 5,001 Less: current portion 646 375 Long-term portion $ 5,726 $ 4,626 (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 paid and amounts that are being processed through accounts payable as a part of our disbursement cycle.

STOCKHOLDERS' EQUITY

STOCKHOLDERS' EQUITY	9 Months Ended
STOCKHOLDERS' EQUITY	Sep. 30, 2022
Equity [Abstract]
STOCKHOLDERS' EQUITY	STOCKHOLDERS' EQUITY 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, 2022, there were 793 Class A common stock equivalents available for future grant under the 2016 Plan. 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, 2021 77 $ 15.68 Granted 75 $ 82.47 Exercised (23) $ 8.56 Forfeited — $ — Outstanding, September 30, 2022 129 $ 55.60 7.4 $ 3,148 Exercisable, September 30, 2022 49 $ 12.88 3.5 $ 3,105 Stock-based compensation expense related to stock options was $89 and $122 during the three and nine months ended September 30, 2022, respectively, as compared to $11 during both the three and nine months ended September 30, 2021. As of September 30, 2022, we had $2,225 of unrecognized stock-based compensation expense related to outstanding stock options to be recognized over a weighted average period of 4.7 years. During the three and nine months ended September 30, 2022, the aggregate intrinsic value of stock options exercised was zero dollars and $1,467, 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 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 years, beginning on the grant date based on continued employment. Performance stock units granted to employees, including market-based performance stock units, vest at a future date following the grant date and are based on the attainment of performance targets and market achievements, as applicable. 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, 2021 249 $ 55.40 Granted 82 $ 94.23 Class A Common Stock Vested (65) $ 49.85 Forfeited (34) $ 67.92 Outstanding, September 30, 2022 232 $ 68.83 1.7 $ 17,692 Unvested, September 30, 2022 416 $ 68.95 1.4 $ 31,751 (1) Market-based performance stock unit grants are included at the 100% attainment level. Attainment of the maximum performance targets and market achievements would result in the issuance of an additional 184 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 $2,225 and $5,204 during the three and nine months ended September 30, 2022, respectively, as compared to $2,576 and $8,505 during the three and nine months ended September 30, 2021, respectively. During the three and nine months ended September 30, 2022, the total fair value of other stock awards vested was $218 and $5,577, respectively. As of September 30, 2022, total unrecognized stock-based compensation expense related to outstanding restricted stock awards was $46, which will be recognized over a weighted average period of 1.3 years. As of September 30, 2022, total unrecognized stock-based compensation expense related to outstanding restricted stock units was $4,611, which will be recognized over a weighted average period of 1.8 years. As of September 30, 2022, total expected unrecognized stock-based compensation expense related to outstanding performance stock units was $5,592 to be recognized over a weighted average period of 1.6 years. We also recorded $97 and $262 of stock-based compensation expense related to our Amended and Restated 1997 Employee Stock Purchase Plan during the three and nine months ended September 30, 2022, respectively, as compared to $67 and $196 during the three and nine months ended September 30, 2021, respectively. Accumulated Other Comprehensive Income (Loss), Net of Tax A summary of the changes in the balances of each component of accumulated other comprehensive income (loss), net of tax follows: Interest Rate Swaps Balance, December 31, 2021 $ (5,103) Other comprehensive income before reclassifications 15,138 Amounts reclassified from accumulated other comprehensive income (loss) 2,136 Income tax provision related to items of other comprehensive income (4,241) Net current-period other comprehensive income 13,033 Balance, September 30, 2022 $ 7,930 A summary of reclassifications out of accumulated other comprehensive income (loss), net of tax into earnings follows: Three Months Ended Nine Months Ended 2022 2021 2022 2021 Details About Accumulated Other Comprehensive Income (Loss), Net of Tax Components Amounts Reclassified Out of Accumulated Other Comprehensive Income (Loss), Net of Tax Affected Line Item in the Consolidated Interest rate swaps $ 14 $ 1,204 $ 2,136 $ 3,551 Interest expense (14) (1,204) (2,136) (3,551) Income before income taxes — (496) (190) (765) Provision for income taxes $ (14) $ (708) $ (1,946) $ (2,786) Net income

EARNINGS PER SHARE

EARNINGS PER SHARE	9 Months Ended
EARNINGS PER SHARE	Sep. 30, 2022
Earnings Per Share [Abstract]
EARNINGS PER SHARE	EARNINGS PER SHAREBasic 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 2022 2021 2022 2021 Numerator: Net income $ 22,672 $ 15,861 $ 44,658 $ 31,955 Denominators: Number of shares outstanding, end of period: Class A common stock 50,692 50,410 50,692 50,410 Class B common stock 988 988 988 988 Unvested restricted stock (1) (2) (1) (2) Effect of weighted average shares outstanding (2) (7) (75) (84) Basic weighted average common shares outstanding 51,677 51,389 51,604 51,312 Impact of potentially dilutive securities: Dilutive effect of stock options and other stock awards 129 197 145 194 Diluted weighted average common shares outstanding 51,806 51,586 51,749 51,506 Anti-dilutive potentially issuable shares 84 12 115 12

OTHER ITEMS AND CHARGES

OTHER ITEMS AND CHARGES	9 Months Ended
OTHER ITEMS AND CHARGES	Sep. 30, 2022
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, 2022, we recorded charges of $816 and $3,878, respectively, and in the three and nine months ended September 30, 2021, we recorded charges of $1,904 and $3,950, respectively, comprised primarily of legal, consulting and other similar costs associated with due diligence and the acquisition and integration of acquired businesses or select development projects. 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
FAIR VALUE OF FINANCIAL INSTRUMENTS	Sep. 30, 2022
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, 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 the one-month LIBOR yield curves that are observable at commonly quoted intervals for the full term of the swaps. 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, 2022 Using: Quoted Prices in Significant Other Significant Assets: Restricted investment securities - landfill closure $ 1,705 $ — $ — Interest rate swaps — 12,340 — $ 1,705 $ 12,340 $ — Fair Value Measurement at December 31, 2021 Using: Quoted Prices in Significant Other Significant Assets: Restricted investment securities - landfill closure $ 2,122 $ — $ — Interest rate swaps — 424 — $ 2,122 $ 424 $ — Liabilities: Interest rate swaps $ — $ 5,176 $ — Fair Value of Debt As of September 30, 2022, 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 and New Hampshire Bonds (collectively, the "Industrial Revenue Bonds") was approximately $185,533 and the carrying value was $197,000. 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, 2022, the carrying value of our Term Loan Facility was $350,000 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
SEGMENT REPORTING	Sep. 30, 2022
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 and Western regions. 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 northeastern 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 derived from two lines-of-service: processing and non-processing. Revenues from processing services are derived from customers in the form of processing fees, tipping fees, commodity sales, and organic material sales. Revenues from non-processing services 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, 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 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 Three Months Ended September 30, 2021 Segment Outside Inter-company Depreciation and Operating Total Eastern $ 75,154 $ 18,768 $ 9,407 $ 5,374 $ 352,067 Western 103,523 35,523 15,710 15,805 673,608 Resource Solutions 63,292 156 1,903 6,679 126,529 Corporate Entities — — 471 (471) 128,193 Eliminations — (54,447) — — — $ 241,969 $ — $ 27,491 $ 27,387 $ 1,280,397 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 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 Nine Months Ended September 30, 2021 Segment Outside Inter-company Depreciation and Operating Total Eastern $ 188,557 $ 47,322 $ 23,342 $ 11,401 $ 352,067 Western 288,139 97,771 44,838 38,462 673,608 Resource Solutions 170,679 3,337 5,020 12,792 126,529 Corporate Entities — — 1,310 (1,312) 128,193 Eliminations — (148,430) — — — $ 647,375 $ — $ 74,510 $ 61,343 $ 1,280,397 A summary of our revenues attributable to services provided follows: Three Months Ended Nine Months Ended 2022 2021 2022 2021 Collection $ 144,117 $ 118,872 $ 400,910 $ 323,667 Disposal 66,147 55,593 169,503 142,618 Power generation 1,643 1,253 6,050 3,657 Processing 3,133 2,959 7,883 6,754 Solid waste operations 215,040 178,677 584,346 476,696 Processing 32,159 27,418 93,421 65,721 Non-processing 48,069 35,874 135,195 104,958 Resource Solutions operations 80,228 63,292 228,616 170,679 Total revenues $ 295,268 $ 241,969 $ 812,962 $ 647,375

ACCOUNTING CHANGES (Policies)

ACCOUNTING CHANGES (Policies)	9 Months Ended
ACCOUNTING CHANGES (Policies)	Sep. 30, 2022
Accounting Changes and Error Corrections [Abstract]
Basis of Accounting	Casella Waste Systems, Inc. (“Parent”), and its 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 seven states: Vermont, New Hampshire, New York, Massachusetts, Connecticut, Maine and Pennsylvania, with our headquarters located in Rutland, Vermont. We manage our solid waste operations on a geographic basis through two regional operating segments, the Eastern and Western regions, each of which provides a full 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, 2021 ("fiscal year 2021"), which was filed with the SEC on February 18, 2022.
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, which include normal recurring and nonrecurring adjustments, 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, 2022 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, 2022 through the date of filing of the consolidated financial statements with the SEC on this Quarterly Report on Form 10-Q. We have determined that there are no subsequent events that require disclosure in this Quarterly Report on Form 10-Q.
Accounting Standards Adopted and Pending Adoption	A table providing a brief description of recent Accounting Standards Updates ("ASUs") to the Accounting Standards Codification ("ASC") issued by the Financial Accounting Standards Board (“FASB”) that are pending adoption and deemed to have a possible material impact on our consolidated financial statements based on current account balances and activity follows: Standard Description Effect on the Financial Statements or Other Accounting standards issued pending adoption ASU No. 2020-04: Reference Rate Reform (Topic 848), as amended through January 2021 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. We currently have interest rate derivative agreements with hedging relationships that reference LIBOR. 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. We are currently reviewing and updating our existing contracts, as applicable, for transition or fallback language that specifies how a replacement rate for LIBOR will be identified. We are also no longer using LIBOR as a reference rate for any new contracts. We do not expect that the adoption of this guidance will have a material impact on our consolidated financial statements and related disclosures. This guidance will be in effect from March 12, 2020 through December 31, 2022. See Note 7, Debt for further disclosure over our interest rate derivative agreements and debt instruments that reference LIBOR. ASU No. 2021-08: Accounting for Contract Assets and Contract Liabilities from Contracts with Customers (Topic 805) Requires entities to apply ASC 606 to recognize and measure contract assets and contract liabilities in a business combination. This guidance improves comparability after the business combination by providing consistent recognition and measurement guidance for revenue contracts with customers acquired in a business combination and revenue contracts with customers not acquired in a business combination. We have made in the past, and we may make in the future, acquisitions to densify existing operations, expand service areas, and grow services for our customers, and these acquisitions may include contract assets or contract liabilities. We do not expect that the adoption of this guidance will have a material impact on our consolidated financial statements and related disclosures. This guidance is effective January 1, 2023 with early adoption permitted.
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
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 and Western regions. 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 northeastern 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 derived from two lines-of-service: processing and non-processing. Revenues from processing services are derived from customers in the form of processing fees, tipping fees, commodity sales, and organic material sales. Revenues from non-processing services 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
ACCOUNTING CHANGES (Tables)	Sep. 30, 2022
Accounting Changes and Error Corrections [Abstract]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles	A table providing a brief description of recent Accounting Standards Updates ("ASUs") to the Accounting Standards Codification ("ASC") issued by the Financial Accounting Standards Board (“FASB”) that are pending adoption and deemed to have a possible material impact on our consolidated financial statements based on current account balances and activity follows: Standard Description Effect on the Financial Statements or Other Accounting standards issued pending adoption ASU No. 2020-04: Reference Rate Reform (Topic 848), as amended through January 2021 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. We currently have interest rate derivative agreements with hedging relationships that reference LIBOR. 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. We are currently reviewing and updating our existing contracts, as applicable, for transition or fallback language that specifies how a replacement rate for LIBOR will be identified. We are also no longer using LIBOR as a reference rate for any new contracts. We do not expect that the adoption of this guidance will have a material impact on our consolidated financial statements and related disclosures. This guidance will be in effect from March 12, 2020 through December 31, 2022. See Note 7, Debt for further disclosure over our interest rate derivative agreements and debt instruments that reference LIBOR. ASU No. 2021-08: Accounting for Contract Assets and Contract Liabilities from Contracts with Customers (Topic 805) Requires entities to apply ASC 606 to recognize and measure contract assets and contract liabilities in a business combination. This guidance improves comparability after the business combination by providing consistent recognition and measurement guidance for revenue contracts with customers acquired in a business combination and revenue contracts with customers not acquired in a business combination. We have made in the past, and we may make in the future, acquisitions to densify existing operations, expand service areas, and grow services for our customers, and these acquisitions may include contract assets or contract liabilities. We do not expect that the adoption of this guidance will have a material impact on our consolidated financial statements and related disclosures. This guidance is effective January 1, 2023 with early adoption permitted.

REVENUE RECOGNITION (Tables)

REVENUE RECOGNITION (Tables)	9 Months Ended
REVENUE RECOGNITION (Tables)	Sep. 30, 2022
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, 2022 and 2021: Three Months Ended September 30, 2022 Eastern Western 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 Non-processing — — 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 Three Months Ended September 30, 2021 Eastern Western Resource Solutions Total Revenues Collection $ 48,951 $ 69,921 $ — $ 118,872 Landfill 6,622 18,201 — 24,823 Transfer station 16,948 10,375 — 27,323 Transportation 54 3,393 — 3,447 Landfill gas-to-energy 269 984 — 1,253 Processing 2,310 649 27,418 30,377 Non-processing — — 35,874 35,874 Total revenues $ 75,154 $ 103,523 $ 63,292 $ 241,969 Transferred at a point-in-time $ 43 $ 296 $ 19,927 $ 20,266 Transferred over time 75,111 103,227 43,365 221,703 Total revenues $ 75,154 $ 103,523 $ 63,292 $ 241,969 Nine Months Ended September 30, 2022 Eastern Western Resource Solutions Total Revenues Collection $ 172,671 $ 228,239 $ — $ 400,910 Landfill 19,819 53,028 — 72,847 Transfer station 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 Non-processing — — 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 Nine Months Ended September 30, 2021 Eastern Western Resource Solutions Total Revenues Collection $ 124,389 $ 199,278 $ — $ 323,667 Landfill 18,143 48,336 — 66,479 Transfer station 39,847 27,498 — 67,345 Transportation 148 8,646 — 8,794 Landfill gas-to-energy 784 2,873 — 3,657 Processing 5,246 1,508 65,721 72,475 Non-processing — — 104,958 104,958 Total revenues $ 188,557 $ 288,139 $ 170,679 $ 647,375 Transferred at a point-in-time $ 125 $ 1,284 $ 44,964 $ 46,373 Transferred over time 188,432 286,855 125,715 601,002 Total revenues $ 188,557 $ 288,139 $ 170,679 $ 647,375

BUSINESS COMBINATIONS (Tables)

BUSINESS COMBINATIONS (Tables)	9 Months Ended
BUSINESS COMBINATIONS (Tables)	Sep. 30, 2022
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 2022 2021 Purchase Price: Cash used in acquisitions, net of cash acquired $ 72,731 $ 150,364 Other non-cash consideration 1,220 — Holdbacks to sellers and contingent consideration 4,112 4,865 Total consideration $ 78,063 $ 155,229 Allocated as follows: Current assets $ 7,599 $ 7,260 Property, plant and equipment: Land 3,141 803 Finance lease right-of-use-assets — 31,467 Buildings and improvements 8,566 8,468 Machinery and equipment 10,296 42,458 Operating lease right-of-use assets 405 6,500 Intangible assets: Trade names — 8,350 Covenants not-to-compete 2,034 3,069 Customer relationships 11,417 30,340 Other non-current assets 40 — Current liabilities (3,721) (5,952) Other long-term liabilities (123) — Financing lease liabilities, less current portion — (10,535) Operating lease liabilities, less current portion (282) — Fair value of assets acquired and liabilities assumed 39,372 122,228 Excess purchase price allocated to goodwill $ 38,691 $ 33,001
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, 2021 is as follows: Three Months Ended Nine Months Ended 2022 2021 2022 2021 Revenues $ 295,512 $ 262,000 $ 825,020 $ 733,819 Operating income $ 36,247 $ 28,516 $ 79,473 $ 64,360 Net income $ 22,635 $ 15,308 $ 44,888 $ 27,993 Basic earnings per share attributable to common stockholders: Weighted average common shares outstanding 51,677 51,389 51,604 51,312 Basic earnings per common share $ 0.44 $ 0.30 $ 0.87 $ 0.55 Diluted earnings per share attributable to common stockholders: Weighted average common shares outstanding 51,806 51,586 51,749 51,506 Diluted earnings per common share $ 0.44 $ 0.30 $ 0.87 $ 0.54

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS (Tables)	9 Months Ended
GOODWILL AND INTANGIBLE ASSETS (Tables)	Sep. 30, 2022
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 Adjustments to Acquisitions September 30, Eastern $ 52,072 $ 93 $ 241 $ 52,406 Western 163,728 16,892 650 181,270 Resource Solutions 17,060 21,706 — 38,766 $ 232,860 $ 38,691 $ 891 $ 272,442
Summary of Intangible Assets by Type	Summaries of intangible assets by type follows: Covenants Customer Relationships Trade Names Total Balance, September 30, 2022 Intangible assets $ 30,812 $ 126,372 $ 8,350 $ 165,534 Less accumulated amortization (23,609) (43,254) (3,879) (70,742) $ 7,203 $ 83,118 $ 4,471 $ 94,792 Covenants Customer Relationships Trade Names Total Balance, December 31, 2021 Intangible assets $ 28,777 $ 115,005 $ 8,350 $ 152,132 Less accumulated amortization (22,148) (34,809) (1,452) (58,409) $ 6,629 $ 80,196 $ 6,898 $ 93,723
Summary of Intangible Amortization Expense Estimated	A summary of intangible amortization expense estimated for the five fiscal years following fiscal year 2021 and thereafter follows: Estimated Future Amortization Expense as of September 30, 2022 Fiscal year ending December 31, 2022 $ 4,194 Fiscal year ending December 31, 2023 $ 15,918 Fiscal year ending December 31, 2024 $ 15,278 Fiscal year ending December 31, 2025 $ 14,244 Fiscal year ending December 31, 2026 $ 12,579 Thereafter $ 32,579

ACCRUED FINAL CAPPING, CLOSUR_2

ACCRUED FINAL CAPPING, CLOSURE AND POST CLOSURE (Tables)	9 Months Ended
ACCRUED FINAL CAPPING, CLOSURE AND POST CLOSURE (Tables)	Sep. 30, 2022
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 2022 2021 Beginning balance $ 86,914 $ 82,533 Obligations incurred 3,592 3,638 Revision in estimates (1) 1,443 — Accretion expense 5,685 5,496 Obligations settled (2) (3,027) (5,394) Ending balance $ 94,607 $ 86,273 (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
DEBT (Tables)	Sep. 30, 2022
Debt And Derivatives Disclosure [Abstract]
Summary 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 LIBOR plus 1.375% $ 350,000 $ 350,000 Revolving credit facility ("Revolving Credit Facility") due December 2026; bearing interest at LIBOR plus 1.375% — — 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 through 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 through 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 through 2025; bearing interest at 2.750% 40,000 40,000 Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2005R-3 ("FAME Bonds 2005R-3") due January 2025 - fixed rate interest period through 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 through 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 through 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 through 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 through 2027; bearing interest at 5.00% 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 through 2029; bearing interest at 2.95% 11,000 11,000 Other: Finance leases 49,070 45,724 Notes payable maturing through August 2024; bearing interest at a weighted average of 1.6% 712 4,846 Principal amount of debt 596,782 562,570 Less—unamortized debt issuance costs (1) 9,983 10,166 Debt less unamortized debt issuance costs 586,799 552,404 Less—current maturities of debt 8,337 9,901 $ 578,462 $ 542,503 (1) A summary of unamortized debt issuance costs by debt instrument follows: September 30, December 31, Revolving Credit Facility and Term Loan Facility (collectively, the "Credit Facility") $ 5,011 $ 5,884 New York Bonds 2014R-1 882 933 New York Bonds 2014R-2 223 268 New York Bonds 2020 1,150 1,283 FAME Bonds 2005R-3 198 262 FAME Bonds 2015R-1 361 413 FAME Bonds 2015R-2 212 268 Vermont Bonds 2013 392 433 Vermont Bonds 2022A-1 1,176 — New Hampshire Bonds 378 422 $ 9,983 $ 10,166
Summary of Cash Flow Hedges	A summary of the effect of cash flow hedges related to derivative instruments on the consolidated balance sheet follows: Fair Value Balance Sheet Location September 30, December 31, Interest rate swaps Other current assets $ 3,526 $ — Interest rate swaps Other non-current assets 8,814 424 $ 12,340 $ 424 Interest rate swaps Other accrued liabilities $ — $ 3,796 Interest rate swaps Other long-term liabilities — 1,380 $ — $ 5,176 Interest rate swaps Accumulated other comprehensive income (loss), net of tax $ 12,340 $ (4,935) Interest rate swaps - tax effect Accumulated other comprehensive income (loss), net of tax (4,410) (168) $ 7,930 $ (5,103)

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	9 Months Ended
COMMITMENTS AND CONTINGENCIES (Tables)	Sep. 30, 2022
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, 2022 and 2021 follows: Nine Months Ended 2022 2021 Beginning balance $ 5,887 $ 5,200 Accretion expense 79 82 Obligations incurred (1) 759 — Obligations settled (2) (353) (281) Ending balance 6,372 5,001 Less: current portion 646 375 Long-term portion $ 5,726 $ 4,626 (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 paid and amounts that are being processed through accounts payable as a part of our disbursement cycle.

STOCKHOLDERS' EQUITY (Tables)

STOCKHOLDERS' EQUITY (Tables)	9 Months Ended
STOCKHOLDERS' EQUITY (Tables)	Sep. 30, 2022
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, 2021 77 $ 15.68 Granted 75 $ 82.47 Exercised (23) $ 8.56 Forfeited — $ — Outstanding, September 30, 2022 129 $ 55.60 7.4 $ 3,148 Exercisable, September 30, 2022 49 $ 12.88 3.5 $ 3,105
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, 2021 249 $ 55.40 Granted 82 $ 94.23 Class A Common Stock Vested (65) $ 49.85 Forfeited (34) $ 67.92 Outstanding, September 30, 2022 232 $ 68.83 1.7 $ 17,692 Unvested, September 30, 2022 416 $ 68.95 1.4 $ 31,751 (1) Market-based performance stock unit grants are included at the 100% attainment level. Attainment of the maximum performance targets and market achievements would result in the issuance of an additional 184 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 (loss), net of tax follows: Interest Rate Swaps Balance, December 31, 2021 $ (5,103) Other comprehensive income before reclassifications 15,138 Amounts reclassified from accumulated other comprehensive income (loss) 2,136 Income tax provision related to items of other comprehensive income (4,241) Net current-period other comprehensive income 13,033 Balance, September 30, 2022 $ 7,930
Summary of Reclassifications Out of Accumulated Other Comprehensive Loss	A summary of reclassifications out of accumulated other comprehensive income (loss), net of tax into earnings follows: Three Months Ended Nine Months Ended 2022 2021 2022 2021 Details About Accumulated Other Comprehensive Income (Loss), Net of Tax Components Amounts Reclassified Out of Accumulated Other Comprehensive Income (Loss), Net of Tax Affected Line Item in the Consolidated Interest rate swaps $ 14 $ 1,204 $ 2,136 $ 3,551 Interest expense (14) (1,204) (2,136) (3,551) Income before income taxes — (496) (190) (765) Provision for income taxes $ (14) $ (708) $ (1,946) $ (2,786) Net income

EARNINGS PER SHARE (Tables)

EARNINGS PER SHARE (Tables)	9 Months Ended
EARNINGS PER SHARE (Tables)	Sep. 30, 2022
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 2022 2021 2022 2021 Numerator: Net income $ 22,672 $ 15,861 $ 44,658 $ 31,955 Denominators: Number of shares outstanding, end of period: Class A common stock 50,692 50,410 50,692 50,410 Class B common stock 988 988 988 988 Unvested restricted stock (1) (2) (1) (2) Effect of weighted average shares outstanding (2) (7) (75) (84) Basic weighted average common shares outstanding 51,677 51,389 51,604 51,312 Impact of potentially dilutive securities: Dilutive effect of stock options and other stock awards 129 197 145 194 Diluted weighted average common shares outstanding 51,806 51,586 51,749 51,506 Anti-dilutive potentially issuable shares 84 12 115 12

FAIR VALUE OF FINANCIAL INSTR_2

FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)	9 Months Ended
FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)	Sep. 30, 2022
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, 2022 Using: Quoted Prices in Significant Other Significant Assets: Restricted investment securities - landfill closure $ 1,705 $ — $ — Interest rate swaps — 12,340 — $ 1,705 $ 12,340 $ — Fair Value Measurement at December 31, 2021 Using: Quoted Prices in Significant Other Significant Assets: Restricted investment securities - landfill closure $ 2,122 $ — $ — Interest rate swaps — 424 — $ 2,122 $ 424 $ — Liabilities: Interest rate swaps $ — $ 5,176 $ —

SEGMENT REPORTING (Tables)

SEGMENT REPORTING (Tables)	9 Months Ended
SEGMENT REPORTING (Tables)	Sep. 30, 2022
Segment Reporting [Abstract]
Summary of Segment Reporting Information by Segment	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 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 Three Months Ended September 30, 2021 Segment Outside Inter-company Depreciation and Operating Total Eastern $ 75,154 $ 18,768 $ 9,407 $ 5,374 $ 352,067 Western 103,523 35,523 15,710 15,805 673,608 Resource Solutions 63,292 156 1,903 6,679 126,529 Corporate Entities — — 471 (471) 128,193 Eliminations — (54,447) — — — $ 241,969 $ — $ 27,491 $ 27,387 $ 1,280,397 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 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 Nine Months Ended September 30, 2021 Segment Outside Inter-company Depreciation and Operating Total Eastern $ 188,557 $ 47,322 $ 23,342 $ 11,401 $ 352,067 Western 288,139 97,771 44,838 38,462 673,608 Resource Solutions 170,679 3,337 5,020 12,792 126,529 Corporate Entities — — 1,310 (1,312) 128,193 Eliminations — (148,430) — — — $ 647,375 $ — $ 74,510 $ 61,343 $ 1,280,397
Summary of Revenue Attributable to Services	A summary of our revenues attributable to services provided follows: Three Months Ended Nine Months Ended 2022 2021 2022 2021 Collection $ 144,117 $ 118,872 $ 400,910 $ 323,667 Disposal 66,147 55,593 169,503 142,618 Power generation 1,643 1,253 6,050 3,657 Processing 3,133 2,959 7,883 6,754 Solid waste operations 215,040 178,677 584,346 476,696 Processing 32,159 27,418 93,421 65,721 Non-processing 48,069 35,874 135,195 104,958 Resource Solutions operations 80,228 63,292 228,616 170,679 Total revenues $ 295,268 $ 241,969 $ 812,962 $ 647,375

BASIS OF PRESENTATION (Details)

BASIS OF PRESENTATION (Details)	9 Months Ended
BASIS OF PRESENTATION (Details)	Sep. 30, 2022 regionalOperatingSegment
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of regional operating segments	2

REVENUE RECOGNITION - Disaggreg

REVENUE RECOGNITION - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Disaggregation of Revenue [Line Items]
Total revenues	$ 295,268	$ 241,969	$ 812,962	$ 647,375
Collection
Disaggregation of Revenue [Line Items]
Total revenues	144,117	118,872	400,910	323,667
Landfill
Disaggregation of Revenue [Line Items]
Total revenues	28,140	24,823	72,847	66,479
Transfer station
Disaggregation of Revenue [Line Items]
Total revenues	32,755	27,323	81,486	67,345
Transportation
Disaggregation of Revenue [Line Items]
Total revenues	5,252	3,447	15,170	8,794
Landfill gas-to-energy
Disaggregation of Revenue [Line Items]
Total revenues	1,643	1,253	6,050	3,657
Processing
Disaggregation of Revenue [Line Items]
Total revenues	35,292	30,377	101,304	72,475
Non-processing
Disaggregation of Revenue [Line Items]
Total revenues	48,069	35,874	135,195	104,958
Transferred at a point-in-time
Disaggregation of Revenue [Line Items]
Total revenues	12,934	20,266	48,098	46,373
Transferred over time
Disaggregation of Revenue [Line Items]
Total revenues	282,334	221,703	764,864	601,002
Eastern
Disaggregation of Revenue [Line Items]
Total revenues	93,137	75,154	251,720	188,557
Eastern \| Collection
Disaggregation of Revenue [Line Items]
Total revenues	61,875	48,951	172,671	124,389
Eastern \| Landfill
Disaggregation of Revenue [Line Items]
Total revenues	7,900	6,622	19,819	18,143
Eastern \| Transfer station
Disaggregation of Revenue [Line Items]
Total revenues	19,525	16,948	48,431	39,847
Eastern \| Transportation
Disaggregation of Revenue [Line Items]
Total revenues	1,233	54	4,470	148
Eastern \| Landfill gas-to-energy
Disaggregation of Revenue [Line Items]
Total revenues	205	269	727	784
Eastern \| Processing
Disaggregation of Revenue [Line Items]
Total revenues	2,399	2,310	5,602	5,246
Eastern \| Non-processing
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Eastern \| Transferred at a point-in-time
Disaggregation of Revenue [Line Items]
Total revenues	115	43	352	125
Eastern \| Transferred over time
Disaggregation of Revenue [Line Items]
Total revenues	93,022	75,111	251,368	188,432
Western
Disaggregation of Revenue [Line Items]
Total revenues	121,903	103,523	332,626	288,139
Western \| Collection
Disaggregation of Revenue [Line Items]
Total revenues	82,242	69,921	228,239	199,278
Western \| Landfill
Disaggregation of Revenue [Line Items]
Total revenues	20,240	18,201	53,028	48,336
Western \| Transfer station
Disaggregation of Revenue [Line Items]
Total revenues	13,230	10,375	33,055	27,498
Western \| Transportation
Disaggregation of Revenue [Line Items]
Total revenues	4,019	3,393	10,700	8,646
Western \| Landfill gas-to-energy
Disaggregation of Revenue [Line Items]
Total revenues	1,438	984	5,323	2,873
Western \| Processing
Disaggregation of Revenue [Line Items]
Total revenues	734	649	2,281	1,508
Western \| Non-processing
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Western \| Transferred at a point-in-time
Disaggregation of Revenue [Line Items]
Total revenues	439	296	1,467	1,284
Western \| Transferred over time
Disaggregation of Revenue [Line Items]
Total revenues	121,464	103,227	331,159	286,855
Resource Solutions
Disaggregation of Revenue [Line Items]
Total revenues	80,228	63,292	228,616	170,679
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	32,159	27,418	93,421	65,721
Resource Solutions \| Non-processing
Disaggregation of Revenue [Line Items]
Total revenues	48,069	35,874	135,195	104,958
Resource Solutions \| Transferred at a point-in-time
Disaggregation of Revenue [Line Items]
Total revenues	12,380	19,927	46,279	44,964
Resource Solutions \| Transferred over time
Disaggregation of Revenue [Line Items]
Total revenues	$ 67,848	$ 43,365	$ 182,337	$ 125,715

REVENUE RECOGNITION - Narrative

REVENUE RECOGNITION - Narrative (Details) - USD ($)	3 Months Ended		9 Months Ended
REVENUE RECOGNITION - Narrative (Details) - USD ($)	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Disaggregation of Revenue [Line Items]
Rebates	$ (295,268,000)	$ (241,969,000)	$ (812,962,000)	$ (647,375,000)
Revenue recognized fro performance obligation satisfied in previous period	0	0	0	0
Gross receivables from contracts	111,256,000		111,256,000		$ 89,232,000
Contract liabilities	3,891,000		3,891,000		$ 3,404,000
Rebate for Recycled or Returned Organic Materials
Disaggregation of Revenue [Line Items]
Rebates	$ 5,460,000	$ 4,341,000	$ 15,162,000	$ 8,440,000

BUSINESS COMBINATIONS - Narrati

BUSINESS COMBINATIONS - Narrative (Details) - business	9 Months Ended
BUSINESS COMBINATIONS - Narrative (Details) - business	Sep. 30, 2022	Sep. 30, 2021
Business Acquisition [Line Items]
Number of businesses acquired	12	8
Minimum
Business Acquisition [Line Items]
Useful life of finite lived intangible assets (in years)	2 years
Maximum
Business Acquisition [Line Items]
Useful life of finite lived intangible assets (in years)	10 years
Western \| Tuck-in Solid Waste Collection Business
Business Acquisition [Line Items]
Number of businesses acquired	6	2

BUSINESS COMBINATIONS - Summary

BUSINESS COMBINATIONS - Summary of Purchase Price Paid for Acquisitions (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Purchase Price:
Cash used in acquisitions, net of cash acquired	$ 73,963	$ 153,112
Allocated as follows:
Excess purchase price allocated to goodwill	272,442		$ 232,860
Waste Collection Acquisitions
Purchase Price:
Cash used in acquisitions, net of cash acquired	72,731	150,364
Other non-cash consideration	1,220	0
Holdbacks to sellers and contingent consideration	4,112	4,865
Total consideration	78,063	155,229
Allocated as follows:
Current assets	7,599	7,260
Land	3,141	803
Finance lease right-of-use-assets	0	31,467
Buildings and improvements	8,566	8,468
Machinery and equipment	10,296	42,458
Operating lease right-of-use assets	405	6,500
Other non-current assets	40	0
Current liabilities	(3,721)	(5,952)
Other long-term liabilities	(123)	0
Financing lease liabilities, less current portion	0	(10,535)
Operating lease liabilities, less current portion	(282)	0
Fair value of assets acquired and liabilities assumed	39,372	122,228
Excess purchase price allocated to goodwill	38,691	33,001
Waste Collection Acquisitions \| Trade Names
Allocated as follows:
Intangible assets:	0	8,350
Waste Collection Acquisitions \| Covenants not-to-compete
Allocated as follows:
Intangible assets:	2,034	3,069
Waste Collection Acquisitions \| Customer Relationships
Allocated as follows:
Intangible assets:	$ 11,417	$ 30,340

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, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Business Combination and Asset Acquisition [Abstract]
Revenues	$ 295,512	$ 262,000	$ 825,020	$ 733,819
Operating income	36,247	28,516	79,473	64,360
Net income	$ 22,635	$ 15,308	$ 44,888	$ 27,993
Weighted average common shares outstanding, basic (in shares)	51,677	51,389	51,604	51,312
Basic earnings per common share (in dollars per share)	$ 0.44	$ 0.30	$ 0.87	$ 0.55
Weighted average common shares outstanding, diluted (in shares)	51,806	51,586	51,749	51,506
Diluted earnings per common share (in dollars per share)	$ 0.44	$ 0.30	$ 0.87	$ 0.54

GOODWILL AND INTANGIBLE ASSET_2

GOODWILL AND INTANGIBLE ASSETS - Summary of Goodwill Activity (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2022 USD ($)
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 232,860
Acquisitions	38,691
Adjustments to Acquisitions	891
Goodwill, ending balance	272,442
Eastern
Goodwill [Roll Forward]
Goodwill, beginning balance	52,072
Acquisitions	93
Adjustments to Acquisitions	241
Goodwill, ending balance	52,406
Western
Goodwill [Roll Forward]
Goodwill, beginning balance	163,728
Acquisitions	16,892
Adjustments to Acquisitions	650
Goodwill, ending balance	181,270
Resource Solutions
Goodwill [Roll Forward]
Goodwill, beginning balance	17,060
Acquisitions	21,706
Adjustments to Acquisitions	0
Goodwill, ending balance	$ 38,766

GOODWILL AND INTANGIBLE ASSET_3

GOODWILL AND INTANGIBLE ASSETS - Summary of Intangible Assets by Type (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Finite-Lived Intangible Assets [Line Items]
Intangible assets	$ 165,534	$ 152,132
Less accumulated amortization	(70,742)	(58,409)
Intangible assets, net	94,792	93,723
Covenants not-to-compete
Finite-Lived Intangible Assets [Line Items]
Intangible assets	30,812	28,777
Less accumulated amortization	(23,609)	(22,148)
Intangible assets, net	7,203	6,629
Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Intangible assets	126,372	115,005
Less accumulated amortization	(43,254)	(34,809)
Intangible assets, net	83,118	80,196
Trade Names
Finite-Lived Intangible Assets [Line Items]
Intangible assets	8,350	8,350
Less accumulated amortization	(3,879)	(1,452)
Intangible assets, net	$ 4,471	$ 6,898

GOODWILL AND INTANGIBLE ASSET_4

GOODWILL AND INTANGIBLE ASSETS - Narrative (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible amortization expense	$ 4,281	$ 3,133	$ 12,333	$ 7,175

GOODWILL AND INTANGIBLE ASSET_5

GOODWILL AND INTANGIBLE ASSETS - Summary of Intangible Amortization Expense Estimated (Detail) $ in Thousands	Sep. 30, 2022 USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
Fiscal year ending December 31, 2022	$ 4,194
Fiscal year ending December 31, 2023	15,918
Fiscal year ending December 31, 2024	15,278
Fiscal year ending December 31, 2025	14,244
Fiscal year ending December 31, 2026	12,579
Thereafter	$ 32,579

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, 2022	Sep. 30, 2021
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance	$ 86,914	$ 82,533
Obligations incurred	3,592	3,638
Revision in estimates	1,443	0
Accretion expense	5,685	5,496
Obligations settled	(3,027)	(5,394)
Ending balance	$ 94,607	$ 86,273

DEBT - Summary of Debt (Details

DEBT - Summary of Debt (Details) - USD ($) $ in Thousands	9 Months Ended
DEBT - Summary of Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Weighted-average discount rate - finance leases	3.60%
Finance leases maturing through December 2107; bearing interest at a weighted average of 3.6%	$ 49,070	$ 45,724
Principal amount of debt	596,782	562,570
Less - unamortized debt issuance costs	9,983	10,166
Debt less unamortized debt issuance costs	586,799	552,404
Less—current maturities of debt	8,337	9,901
Debt, less current portion	$ 578,462	$ 542,503
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 LIBOR plus 1.375%
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 LIBOR plus 1.375% \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	1.375%
Line of Credit \| Revolving credit facility ("Revolving Credit Facility") due December 2026; bearing interest at LIBOR plus 1.375%
Debt Instrument [Line Items]
Principal amount of debt	$ 0	0
Line of Credit \| Revolving credit facility ("Revolving Credit Facility") due December 2026; bearing interest at LIBOR plus 1.375% \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	1.375%
Credit Facility \| Revolving Credit Facility and Term Loan Facility (collectively, the "Credit Facility")
Debt Instrument [Line Items]
Less - unamortized debt issuance costs	$ 5,011	5,884
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 through 2029; bearing interest at 2.875%
Debt Instrument [Line Items]
Stated interest rate	2.875%
Principal amount of debt	$ 25,000	25,000
Less - unamortized debt issuance costs	$ 882	933
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 through 2026; bearing interest at 3.125%
Debt Instrument [Line Items]
Stated interest rate	3.125%
Principal amount of debt	$ 15,000	15,000
Less - unamortized debt issuance costs	$ 223	268
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 through 2025; bearing interest at 2.750%
Debt Instrument [Line Items]
Stated interest rate	2.75%
Principal amount of debt	$ 40,000	40,000
Less - unamortized debt issuance costs	$ 1,150	1,283
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 through 2025; bearing interest at 5.25%
Debt Instrument [Line Items]
Stated interest rate	5.25%
Principal amount of debt	$ 25,000	25,000
Less - unamortized debt issuance costs	$ 198	262
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 through 2025; bearing interest at 5.125%
Debt Instrument [Line Items]
Stated interest rate	5.125%
Principal amount of debt	$ 15,000	15,000
Less - unamortized debt issuance costs	$ 361	413
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 through 2025; bearing interest at 4.375%
Debt Instrument [Line Items]
Stated interest rate	4.375%
Principal amount of debt	$ 15,000	15,000
Less - unamortized debt issuance costs	$ 212	268
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 through 2028; bearing interest at 4.625%
Debt Instrument [Line Items]
Stated interest rate	4.625%
Principal amount of debt	$ 16,000	16,000
Less - unamortized debt issuance costs	$ 392	433
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 through 2027; bearing interest at 5.00%
Debt Instrument [Line Items]
Stated interest rate	5%
Principal amount of debt	$ 35,000	0
Less - unamortized debt issuance costs	$ 1,176	0
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 through 2029; bearing interest at 2.95%
Debt Instrument [Line Items]
Stated interest rate	2.95%
Principal amount of debt	$ 11,000	11,000
Less - unamortized debt issuance costs	$ 378	422
Notes payable maturing through August 2024; bearing interest at a weighted average of 1.6%
Debt Instrument [Line Items]
Weighted average interest rate	1.60%
Principal amount of debt	$ 712	$ 4,846

DEBT - Financing Activities and

DEBT - Financing Activities and Credit Facility Narrative (Details)	9 Months Ended
	Sep. 30, 2022 USD ($)
Debt Instrument [Line Items]
Additional borrowing capacity	$ 125,000,000
Line of Credit
Debt Instrument [Line Items]
Debt instrument, term (in years)	5 years
Net leverage ratio	2.25
Line of credit facility, remaining borrowing capacity	$ 271,805,000
Line of credit, amount drawn	$ 0
Line of Credit \| LIBOR \| Maximum
Debt Instrument [Line Items]
Floor interest rate received (as a percent)	1.375%
Line of Credit \| LIBOR \| Minimum
Debt Instrument [Line Items]
Floor interest rate received (as a percent)	1.125%
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 through 2027; bearing interest at 5.00% \| Unsecured Debt
Debt Instrument [Line Items]
Aggregate principal amount	$ 35,000,000
Stated interest rate	5%
Term loan A facility ("Term Loan Facility") due December 2026; bearing interest at LIBOR plus 1.375% \| Secured Debt
Debt Instrument [Line Items]
Aggregate principal amount	$ 350,000,000
Revolving credit facility ("Revolving Credit Facility") due December 2026; bearing interest at LIBOR plus 1.375% \| Revolving Credit Facility \| Line of Credit
Debt Instrument [Line Items]
Credit facility maximum	300,000,000
Letters of credit outstanding	28,195,000
Revolving credit facility ("Revolving Credit Facility") due December 2026; bearing interest at LIBOR plus 1.375% \| Revolving Credit Facility \| Letter of Credit
Debt Instrument [Line Items]
Letters of credit sublimit	$ 75,000,000

DEBT - Cash Flow Hedges Narrati

DEBT - Cash Flow Hedges Narrative (Details) - Cash Flow Hedging - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Interest Rate Derivative
Debt Instrument [Line Items]
Notional amount	$ 190,000	$ 195,000
Floor interest rate (as a percent)	0%
Weighted average percentage rate paid (as a percent)	2.20%
Forward Starting Interest Rate Derivative
Debt Instrument [Line Items]
Notional amount	$ 20,000	$ 85,000
Floor interest rate (as a percent)	0%
Weighted average percentage rate paid (as a percent)	1.29%

DEBT - Summary of Cash Flow Hed

DEBT - Summary of Cash Flow Hedges (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Derivatives, Fair Value [Line Items]
Accumulated other comprehensive income (loss), net of tax	$ 7,930	$ (5,103)
Designated as Hedging Instrument \| Interest rate swaps
Derivatives, Fair Value [Line Items]
Cash flow hedge derivatives, gross asset	12,340	424
Cash flow hedge derivatives, gross liability	0	5,176
Designated as Hedging Instrument \| Interest rate swaps \| Accumulated gain (loss), cash flow hedge
Derivatives, Fair Value [Line Items]
Accumulated other comprehensive income (loss), before tax	12,340	(4,935)
Accumulated other comprehensive income (loss), tax	(4,410)	(168)
Accumulated other comprehensive income (loss), net of tax	7,930	(5,103)
Other current assets \| Designated as Hedging Instrument \| Interest rate swaps
Derivatives, Fair Value [Line Items]
Cash flow hedge derivatives, gross asset	3,526	0
Other non-current assets \| Designated as Hedging Instrument \| Interest rate swaps
Derivatives, Fair Value [Line Items]
Cash flow hedge derivatives, gross asset	8,814	424
Other accrued liabilities \| Designated as Hedging Instrument \| Interest rate swaps
Derivatives, Fair Value [Line Items]
Cash flow hedge derivatives, gross liability	0	3,796
Other long-term liabilities \| Designated as Hedging Instrument \| Interest rate swaps
Derivatives, Fair Value [Line Items]
Cash flow hedge derivatives, gross liability	$ 0	$ 1,380

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - Narrative (Detail) $ in Thousands	Sep. 30, 2022 USD ($)
Loss Contingencies [Line Items]
Loss contingency accrual	$ 1,071
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 - Environmental Remediation Liability (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	$ 5,887	$ 5,200
Obligations settled	(353)	(281)
Ending balance	6,372	5,001
Less: current portion	646	375
Long-term portion	5,726	4,626
Other environmental remediation sites
Accrual for Environmental Loss Contingencies [Roll Forward]
Accretion expense	79	82
Inactive waste disposal site
Accrual for Environmental Loss Contingencies [Roll Forward]
Accretion expense	$ 759	$ 0

STOCKHOLDERS' EQUITY - Narrativ

STOCKHOLDERS' EQUITY - Narrative (Detail) - USD ($)	3 Months Ended		9 Months Ended
STOCKHOLDERS' EQUITY - Narrative (Detail) - USD ($)	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Limited Partners' Capital Account [Line Items]
Unrecognized stock-based compensation, weighted average period			4 years 8 months 12 days
Fair value of stock awards vested	$ 218,000		$ 5,577,000
Stock Options
Limited Partners' Capital Account [Line Items]
Stock-based compensation expense	89,000	$ 11,000	122,000	$ 11,000
Unrecognized stock-based compensation expense, stock options	2,225,000		2,225,000
Aggregate intrinsic value of options exercised	0		1,467,000
Restricted Stock Awards, Restricted Stock Units And Performance Stock Units
Limited Partners' Capital Account [Line Items]
Stock-based compensation expense	2,225,000	2,576,000	5,204,000	8,505,000
Restricted Stock
Limited Partners' Capital Account [Line Items]
Unrecognized stock-based compensation expense	46,000		$ 46,000
Restricted Stock \| Non Employee Director
Limited Partners' Capital Account [Line Items]
Award vesting period			3 years
Restricted Stock Unit
Limited Partners' Capital Account [Line Items]
Unrecognized stock-based compensation expense	4,611,000		$ 4,611,000
Restricted Stock Unit \| Non Employee Director
Limited Partners' Capital Account [Line Items]
Award service period			3 years
Performance Stock Unit
Limited Partners' Capital Account [Line Items]
Unrecognized stock-based compensation expense	5,592,000		$ 5,592,000
Weighted average \| Restricted Stock
Limited Partners' Capital Account [Line Items]
Unrecognized stock-based compensation, weighted average period			1 year 3 months 18 days
Weighted average \| Restricted Stock Unit
Limited Partners' Capital Account [Line Items]
Unrecognized stock-based compensation, weighted average period			1 year 9 months 18 days
Weighted average \| Performance Stock Unit
Limited Partners' Capital Account [Line Items]
Unrecognized stock-based compensation, weighted average period			1 year 7 months 6 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	$ 97,000	$ 67,000	$ 262,000	$ 196,000
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)	793,000		793,000
Class A Common Stock \| 2006 Incentive Plan
Limited Partners' Capital Account [Line Items]
Common stock, additional authorized shares (in shares)			2,723,000

STOCKHOLDERS' EQUITY - Summary

STOCKHOLDERS' EQUITY - Summary of Stock Option Activity (Detail) $ / shares in Units, shares in Thousands, $ in Thousands	9 Months Ended
	Sep. 30, 2022 USD ($) $ / shares shares
Stock Options
Beginning balance, outstanding (in shares) \| shares	77
Granted (in shares) \| shares	75
Exercised (in shares) \| shares	(23)
Forfeited (in shares) \| shares	0
Ending balance, outstanding (in shares) \| shares	129
Exercisable at end of period (in shares) \| shares	49
Weighted Average Exercise Price
Beginning balance, outstanding (in dollars per share) \| $ / shares	$ 15.68
Granted (in dollars per share) \| $ / shares	82.47
Exercised (in dollars per share) \| $ / shares	8.56
Forfeited (in dollars per share) \| $ / shares	0
Ending balance, outstanding (in dollars per share) \| $ / shares	55.60
Exercisable at end of period (in dollars per share) \| $ / shares	$ 12.88
Weighted Average Remaining Contractual Term (years) and Aggregate Intrinsic Value
Outstanding contractual term	7 years 4 months 24 days
Exercisable contractual term	3 years 6 months
Outstanding aggregate intrinsic value \| $	$ 3,148
Exercisable aggregate intrinsic value \| $	$ 3,105

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, 2022 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)	184
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)	249
Granted (in shares)	82
Forfeited (in shares)	(34)
Outstanding, end of period (in shares)	232
Weighted Average Grant Date Fair Value
Outstanding at beginning of period (in dollars per share) \| $ / shares	$ 55.40
Granted (in dollars per share) \| $ / shares	94.23
Forfeited (in dollars per share) \| $ / shares	67.92
Outstanding at end of period (in dollars per share) \| $ / shares	$ 68.83
Weighted Average Remaining Contractual Term (years) and Aggregate Intrinsic Value
Contractual term (in years)	1 year 8 months 12 days
Aggregate intrinsic value \| $	$ 17,692
Restricted Stock Awards, Restricted Stock Units And Performance Stock Units \| Class A Common Stock
Restricted Stock, Restricted Stock Units, and Performance Stock Units
Vested (in shares)	(65)
Weighted Average Grant Date Fair Value
Class A Common Stock Vested (in dollars per share) \| $ / shares	$ 49.85
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)	416
Weighted Average Grant Date Fair Value
Outstanding at end of period (in dollars per share) \| $ / shares	$ 68.95
Weighted Average Remaining Contractual Term (years) and Aggregate Intrinsic Value
Contractual term (in years)	1 year 4 months 24 days
Aggregate intrinsic value \| $	$ 31,751

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, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2022	Sep. 30, 2021
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 457,566	$ 435,050	$ 422,457	$ 388,492	$ 373,336	$ 362,142	$ 422,457	$ 362,142
Other comprehensive income, net of tax	3,910	2,980	6,143	892	(235)	3,830	13,033	4,487
Ending balance	486,559	$ 457,566	435,050	$ 407,951	$ 388,492	$ 373,336	486,559	$ 407,951
Accumulated Gain (Loss), Cash Flow Hedge
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance			$ (5,103)				(5,103)
Other comprehensive income							15,138
Amounts reclassified from accumulated other comprehensive income (loss)							2,136
Income tax provision related to items of other comprehensive income							(4,241)
Other comprehensive income, net of tax							13,033
Ending balance	$ 7,930						$ 7,930

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, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2022	Sep. 30, 2021
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	$ 6,177			$ 5,164			$ 17,078	$ 15,928
Income before income taxes	31,812			22,462			63,335	46,431
Provision for income taxes	9,140			6,601			18,677	14,476
Net income	22,672	$ 17,796	$ 4,190	15,861	$ 11,783	$ 4,311	44,658	31,955
Accumulated Gain (Loss), Cash Flow Hedge \| Amounts Reclassified Out of Accumulated Other Comprehensive Income (Loss), Net of Tax
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	(14)			(1,204)			(2,136)	(3,551)
Provision for income taxes	0			(496)			(190)	(765)
Net income	(14)			(708)			(1,946)	(2,786)
Interest rate swaps \| Accumulated Gain (Loss), Cash Flow Hedge \| Amounts Reclassified Out of Accumulated Other Comprehensive Income (Loss), Net of Tax
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	$ 14			$ 1,204			$ 2,136	$ 3,551

EARNINGS PER SHARE (Details)

EARNINGS PER SHARE (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
EARNINGS PER SHARE (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Numerator:
Net income	$ 22,672	$ 15,861	$ 44,658	$ 31,955
Denominators:
Unvested restricted stock (in shares)	(1,000)	(2,000)	(1,000)	(2,000)
Effect of weighted average shares outstanding (in shares)	(2,000)	(7,000)	(75,000)	(84,000)
Weighted average common shares outstanding, basic (in shares)	51,677,000	51,389,000	51,604,000	51,312,000
Impact of potentially dilutive securities:
Dilutive effect of stock options and other stock awards (in shares)	129,000	197,000	145,000	194,000
Weighted average common shares outstanding, diluted	51,806,000	51,586,000	51,749,000	51,506,000
Anti-dilutive potentially issuable shares (in shares)	84,000	12,000	115,000	12,000
Class A Common Stock
Denominators:
Common stock, shares outstanding (in shares)	50,692,000	50,410,000	50,692,000	50,410,000	50,423,000
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
OTHER ITEMS AND CHARGES (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Unusual or Infrequent Items, or Both [Abstract]
Expense from acquisition activities	$ 816	$ 1,904	$ 3,878	$ 3,950
Environmental remediation charge	$ 759	$ 0	$ 759	$ 0

FAIR VALUE OF FINANCIAL INSTR_3

FAIR VALUE OF FINANCIAL INSTRUMENTS - Recurring Fair Value Measurements (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Assets:
Restricted investment securities - landfill closure	$ 1,705	$ 2,122
Recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Interest rate swaps	0	0
Total assets	1,705	2,122
Liabilities:
Interest rate swaps		0
Recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Landfill
Assets:
Restricted investment securities - landfill closure	1,705	2,122
Recurring \| Significant Other Observable Inputs (Level 2)
Assets:
Interest rate swaps	12,340	424
Total assets	12,340	424
Liabilities:
Interest rate swaps		5,176
Recurring \| Significant Other Observable Inputs (Level 2) \| Landfill
Assets:
Restricted investment securities - landfill closure	0	0
Recurring \| Significant Unobservable Inputs (Level 3)
Assets:
Interest rate swaps	0	0
Total assets	0	0
Liabilities:
Interest rate swaps		0
Recurring \| Significant Unobservable Inputs (Level 3) \| Landfill
Assets:
Restricted investment securities - landfill closure	$ 0	$ 0

FAIR VALUE OF FINANCIAL INSTR_4

FAIR VALUE OF FINANCIAL INSTRUMENTS - Additional Information (Detail) - USD ($)	Sep. 30, 2022	Dec. 31, 2021
Term loan A facility ("Term Loan Facility") due December 2026; bearing interest at LIBOR plus 1.375% \| Secured Debt
Debt Instrument [Line Items]
Principal amount of debt	$ 350,000,000	$ 350,000,000
Fair Value \| Fixed Rate Bonds
Debt Instrument [Line Items]
Fixed rate debt	185,533,000
Carrying Value
Debt Instrument [Line Items]
Revolving credit facility	0
Carrying Value \| Fixed Rate Bonds
Debt Instrument [Line Items]
Fixed rate debt	$ 197,000,000

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, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Segment Reporting Information [Line Items]
Revenues	$ 295,268	$ 241,969	$ 812,962	$ 647,375
Depreciation and amortization	32,527	27,491	93,106	74,510
Operating income (loss)	36,288	27,387	78,175	61,343
Total assets	1,399,347	1,280,397	1,399,347	1,280,397	$ 1,283,580
Operating \| Eastern
Segment Reporting Information [Line Items]
Revenues	93,137	75,154	251,720	188,557
Depreciation and amortization	11,907	9,407	34,895	23,342
Operating income (loss)	10,061	5,374	13,981	11,401
Total assets	361,950	352,067	361,950	352,067
Operating \| Western
Segment Reporting Information [Line Items]
Revenues	121,903	103,523	332,626	288,139
Depreciation and amortization	16,778	15,710	47,376	44,838
Operating income (loss)	22,405	15,805	51,565	38,462
Total assets	725,232	673,608	725,232	673,608
Operating \| Resource Solutions
Segment Reporting Information [Line Items]
Revenues	80,228	63,292	228,616	170,679
Depreciation and amortization	3,138	1,903	9,011	5,020
Operating income (loss)	4,526	6,679	14,453	12,792
Total assets	189,854	126,529	189,854	126,529
Corporate Entities
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Depreciation and amortization	704	471	1,824	1,310
Operating income (loss)	(704)	(471)	(1,824)	(1,312)
Total assets	122,311	128,193	122,311	128,193
Inter-company revenues
Segment Reporting Information [Line Items]
Revenues	(65,309)	(54,447)	(177,202)	(148,430)
Inter-company revenues \| Eastern
Segment Reporting Information [Line Items]
Revenues	(23,027)	(18,768)	(61,842)	(47,322)
Inter-company revenues \| Western
Segment Reporting Information [Line Items]
Revenues	(40,703)	(35,523)	(112,687)	(97,771)
Inter-company revenues \| Resource Solutions
Segment Reporting Information [Line Items]
Revenues	$ (1,579)	$ (156)	$ (2,673)	$ (3,337)

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, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Revenue from External Customer [Line Items]
Revenues	$ 295,268	$ 241,969	$ 812,962	$ 647,375
Solid waste operations
Revenue from External Customer [Line Items]
Revenues	215,040	178,677	584,346	476,696
Collection
Revenue from External Customer [Line Items]
Revenues	144,117	118,872	400,910	323,667
Disposal
Revenue from External Customer [Line Items]
Revenues	66,147	55,593	169,503	142,618
Power generation
Revenue from External Customer [Line Items]
Revenues	1,643	1,253	6,050	3,657
Processing
Revenue from External Customer [Line Items]
Revenues	3,133	2,959	7,883	6,754
Resource Solutions operations
Revenue from External Customer [Line Items]
Revenues	80,228	63,292	228,616	170,679
Processing
Revenue from External Customer [Line Items]
Revenues	32,159	27,418	93,421	65,721
Non-processing
Revenue from External Customer [Line Items]
Revenues	$ 48,069	$ 35,874	$ 135,195	$ 104,958