<SEC-DOCUMENT>0000911177-24-000045.txt : 20240314
<SEC-HEADER>0000911177-24-000045.hdr.sgml : 20240314
<ACCEPTANCE-DATETIME>20240314161845
ACCESSION NUMBER:		0000911177-24-000045
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20240312
FILED AS OF DATE:		20240314
DATE AS OF CHANGE:		20240314

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			CASELLA DOUGLAS R
		CENTRAL INDEX KEY:			0001055353
		ORGANIZATION NAME:           	

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-23211
		FILM NUMBER:		24750420

	MAIL ADDRESS:	
		STREET 1:		CASELLA WASTE SYSTEMS INC
		STREET 2:		25 GREENS HILL LN
		CITY:			RUTLAND
		STATE:			VT
		ZIP:			05701

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			CASELLA WASTE SYSTEMS INC
		CENTRAL INDEX KEY:			0000911177
		STANDARD INDUSTRIAL CLASSIFICATION:	REFUSE SYSTEMS [4953]
		ORGANIZATION NAME:           	01 Energy & Transportation
		IRS NUMBER:				030338873
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		25 GREENS HILL ROAD
		CITY:			RUTLAND
		STATE:			VT
		ZIP:			05701
		BUSINESS PHONE:		8027750325

	MAIL ADDRESS:	
		STREET 1:		25 GREENS HILL ROAD
		CITY:			RUTLAND
		STATE:			VT
		ZIP:			05701
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wk-form4_1710447513.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2024-03-12</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000911177</issuerCik>
        <issuerName>CASELLA WASTE SYSTEMS INC</issuerName>
        <issuerTradingSymbol>CWST</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001055353</rptOwnerCik>
            <rptOwnerName>CASELLA DOUGLAS R</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O CASELLA WASTE SYSTEMS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>25 GREENS HILL LANE</rptOwnerStreet2>
            <rptOwnerCity>RUTLAND</rptOwnerCity>
            <rptOwnerState>VT</rptOwnerState>
            <rptOwnerZipCode>05702</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>VICE CHAIRMAN, BD OF DIRECTORS</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>1</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2024-03-12</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1758</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>136500</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2024-03-13</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F2"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>674</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>94.06</value>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>135826</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2024-03-14</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F4"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>391</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>94.17</value>
                    <footnoteId id="F5"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>135435</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Class B Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>169000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Class B Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>131000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By SLAT</value>
                    <footnoteId id="F6"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Class B Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>57100</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Spouse</value>
                    <footnoteId id="F7"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Class B Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>137000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By SLAT 2</value>
                    <footnoteId id="F8"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Represents the award of Restricted Stock Units (RSUs) under the Casella Waste Systems, Inc. 2016 Incentive Plan. Each RSU represents a contingent right to receive one share of Casella's Class A Common
Stock. RSUs vest in three equal annual installments beginning on March 12, 2025.</footnote>
        <footnote id="F2">Represents the sale of shares of Class A Common Stock pursuant to a &quot;sell-to-cover&quot; transaction in order to satisfy tax withholding obligations in connection with the vesting of RSUs previously granted to the reporting person. This sale was effected pursuant to an automatic sell-to-cover instruction adopted by the reporting person on May 25, 2022 and August 30, 2023 and does not represent a discretionary sale by the reporting person.</footnote>
        <footnote id="F3">Represents the weighted average sales price for shares sold in multiple transactions, ranging from $94.06 to $94.11. Upon request of the staff of the Securities and Exchange Commission, the issuer or a security holder of the issuer, the reporting person will provide full information regarding the number of shares sold at each separate price.</footnote>
        <footnote id="F4">Represents the sale of shares of Class A Common Stock pursuant to a &quot;sell-to-cover&quot; transaction in order to satisfy tax withholding obligations in connection with the vesting of RSUs previously granted to the reporting person. This sale was effected pursuant to an automatic sell-to-cover instruction adopted by the reporting person on August 23, 2021 and does not represent a discretionary sale by the reporting person.</footnote>
        <footnote id="F5">Represents the weighted average sales price for shares sold in multiple transactions, ranging from $94.05 to $94.33. Upon request of the staff of the Securities and Exchange Commission, the issuer or a security holder of the issuer, the reporting person will provide full information regarding the number of shares sold at each separate price.</footnote>
        <footnote id="F6">Held by the Spousal Lifetime Access Trust for the benefit of Mr. Casella's spouse (&quot;SLAT&quot;). Mr. Casella's spouse is the trustee of the SLAT. Mr. Casella disclaims beneficial ownership of the securities indicated to the extent to which he does not have an actual pecuniary interest in such securities.</footnote>
        <footnote id="F7">Held by Mr. Casella's spouse. Mr. Casella disclaims beneficial ownership of the securities indicated to the extent to which he does not have an actual pecuniary interest in such securities.</footnote>
        <footnote id="F8">Held by the Spousal Lifetime Access Trust for the benefit of Mr. Casella (&quot;SLAT 2&quot;). Mr. Casella is the trustee of the SLAT 2.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Douglas R. Casella</signatureName>
        <signatureDate>2024-03-14</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
