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As filed with the Securities and Exchange Commission on July 20, 2011

Registration No. 333-175621

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549

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AMENDMENT NO. 1
TO
FORM S-4
REGISTRATION STATEMENT
UNDER
THE SECURITIES ACT OF 1933

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CLEAN HARBORS, INC.
(Exact name of Registrant as specified in its charter)
(See table of additional Guarantor Registrants on next page)

42 Longwater Drive
Norwell, Massachusetts 02161-9149
(781) 792-5000
(Address, including zip code, and telephone number, including
area code, of Registrant's principal executive offices)
(See inside front cover for information regarding Guarantor Registrants.)

C. Michael Malm, Esq.
Davis, Malm & D'Agostine, P.C.
One Boston Place
Boston, Massachusetts 02108
Telephone: (617) 367-2500
Telecopy: (617) 523-6215
(Address, including zip code, and telephone number, including area code, of agent for service of process)

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Approximate date of commencement of proposed sale to the public:
As soon as practicable after this Registration Statement becomes effective.

          If the securities being registered on this Form are being offered in connection with the formation of a holding company and there is compliance with General Instruction G, check the following box.    o

          If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.    o

          If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.    o

          Indicate by check mark whether the Registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definitions of "large accelerated filer," accelerated filer" and "smaller reporting company" in Rule 12b-2 of the Exchange Act.

          If applicable, place an X in the box to designate the appropriate rule provisions relied upon in conducting this transaction:

          Exchange Act Rule 13e-4(i) (Cross-Border Issuer Tender Offer)    o

          Exchange Act Rule 14d(d) (Cross-Border Third Party Tender Offer)    o

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          The Registrant hereby amends this registration statement on such date or dates as may be necessary to delay its effective date until the Registrant shall file a further amendment which specifically states that this registration statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933 or until this registration statement shall become effective on such date as the Securities and Exchange Commission, acting pursuant to said Section 8(a), may determine.

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Guarantor Registrants

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        The address, including zip code, and telephone number, including area code, of the principal executive office of each guarantor registrant listed above is the same as those of the Registrant, Clean Harbors, Inc.

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EXPLANATORY NOTE

        In connection with the obligation of Clean Harbors, Inc. (the "Company"), to file a registration statement with respect to an exchange offer for $250,000,000 in aggregate principal amount of the Company's 7.625% Senior Subordinated Notes due 2016, the Company and the Company's wholly-owned domestic subsidiaries named therein as Gurantor Registrants filed with the Securities and Exchange Commission on July 15, 2011 a Registration Statement on Form S-4 (File No. 333-175621) (the "Registration Statement"). Exhibit 23.1 to the Registration Statement is a consent of Deloitte & Touche LLP as the independent registered public accounting firm for the Company and the Guarantor Registrants.

        The Company has determined that an incorrect form of the consent of Deloitte & Touche LLP was inadvertently filed as Exhibit 23.1 to the Registration Statement. The sole purpose of this Amendment No. 1 to the Registration Statement is to file as Exhibit 23.1 the correct form of such consent. This Amendment makes no other changes to the Registration Statement or the Exhibits thereto.

Item 21.    Exhibits and Financial Statement Schedules

PART II
INFORMATION NOT REQUIRED IN THE PROSPECTUS

(a)

Exhibits.

II-1

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REGISTRANT SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, as amended, the Registrant has duly caused this Amendment to Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the Town of Norwell, Commonwealth of Massachusetts on July 20, 2011.

        Pursuant to the requirements of the Securities Act of 1933, as amended, this Registration Statement has been signed by the following persons in the capacities and on the dates indicated.

II-2

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II-3

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GUARANTOR REGISTRANTS SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, as amended, the undersigned Guarantor Registrants have duly caused this Amendment to Registration Statement to be signed on their behalf by the undersigned, thereunto duly authorized, in the Town of Norwell, Commonwealth of Massachusetts, on July 20, 2011.

II-4

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        Pursuant to the requirements of the Securities Act of 1933, as amended, this Amendment to Registration Statement has been signed by the following persons in the capacities and on the dates indicated.

II-5

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GUARANTOR REGISTRANTS SIGNATURE

        Pursuant to the requirements of the Securities Act of 1933, as amended, the undersigned Guarantor Registrants have duly caused this Amendment to Registration Statement to be signed on their behalf by the undersigned, thereunto duly authorized, in the Town of Norwell, Commonwealth of Massachusetts, on July 20, 2011.

        Pursuant to the requirements of the Securities Act of 1933, as amended, this Amendment to Registration Statement has been signed by the following persons in the capacities and on the dates indicated.

II-6

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GUARANTOR REGISTRANT SIGNATURE

        Pursuant to the requirements of the Securities Act of 1933, as amended, the undersigned Guarantor Registrant has duly caused this Amendment to Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the Town of Norwell, Commonwealth of Massachusetts, on July 20, 2011.

        Pursuant to the requirements of the Securities Act of 1933, as amended, this Amendment to Registration Statement has been signed by the following persons in the capacities and on the dates indicated.

II-7

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GUARANTOR REGISTRANT SIGNATURE

        Pursuant to the requirements of the Securities Act of 1933, as amended, the undersigned Guarantor Registrant has duly caused this Amendment to Registration Statement to be signed on their behalf by the undersigned, thereunto duly authorized, in the Town of Norwell, Commonwealth of Massachusetts, on July 20, 2011.

        Pursuant to the requirements of the Securities Act of 1933, as amended, this Amendment to Registration Statement has been signed by the following persons in the capacities and on the dates indicated.

II-8

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GUARANTOR REGISTRANTS SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, as amended, the undersigned Guarantor Registrants have duly caused this Amendment to Registration Statement to be signed on their behalf by the undersigned, thereunto duly authorized, in the Town of Norwell, Commonwealth of Massachusetts, on July 20, 2011.

        Pursuant to the requirements of the Securities Act of 1933, as amended, this Amendment to Registration Statement has been signed by the following persons in the capacities and on the dates indicated.

II-9

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GUARANTOR REGISTRANT SIGNATURE

        Pursuant to the requirements of the Securities Act of 1933, as amended, the undersigned Guarantor Registrant has duly caused this Amendment to Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the Town of Norwell, Commonwealth of Massachusetts, on July 20, 2011.

        Pursuant to the requirements of the Securities Act of 1933, as amended, this Amendment to Registration Statement has been signed by the following persons in the capacities and on the dates indicated.

II-10

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GUARANTOR REGISTRANT SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, as amended, the undersigned Guarantor Registrant has duly caused this Amendment to Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the Town of Norwell, Commonwealth of Massachusetts, on July 20, 2011.

        Pursuant to the requirements of the Securities Act of 1933, as amended, this Registration Amendment to Statement has been signed by the following persons in the capacities and on the dates indicated.

II-11

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GUARANTOR REGISTRANT SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, as amended, the undersigned Guarantor Registrant has duly caused this Amendment to Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the Town of Norwell, Commonwealth of Massachusetts, on July 20, 2011.

        Pursuant to the requirements of the Securities Act of 1933, as amended, this Amendment to Registration Statement has been signed by the following persons in the capacities and on the dates indicated.

 

II-12

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GUARANTOR REGISTRANTS SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, as amended, the undersigned Guarantor Registrants have duly caused this Amendment to Registration Statement to be signed on their behalf by the undersigned, thereunto duly authorized, in the Town of Norwell, Commonwealth of Massachusetts, on July 20, 2011.

        Pursuant to the requirements of the Securities Act of 1933, as amended, this Amendment to Registration Statement has been signed by the following persons in the capacities and on the dates indicated.

II-13

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GUARANTOR REGISTRANT SIGNATURE

        Pursuant to the requirements of the Securities Act of 1933, as amended, the undersigned Guarantor Registrant has duly caused this Amendment to Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the Town of Norwell, Commonwealth of Massachusetts, on July 20, 2011.

        Pursuant to the requirements of the Securities Act of 1933, as amended, this Amendment to Registration Statement has been signed by the following persons in the capacities and on the dates indicated.

II-14

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GUARANTOR REGISTRANT SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, as amended, the undersigned Guarantor Registrants has duly caused this Amendment to Registration Statement to be signed on their behalf by the undersigned, thereunto duly authorized, in the Town of Norwell, Commonwealth of Massachusetts, on July 20, 2011.

        Pursuant to the requirements of the Securities Act of 1933, as amended, this Amendment to Registration Statement has been signed by the following persons in the capacities and on the dates indicated.

II-15

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GUARANTOR REGISTRANT SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, as amended, the undersigned Guarantor Registrant has duly caused this Amendment to Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the Town of Norwell, Commonwealth of Massachusetts, on July 20, 2011.

        Pursuant to the requirements of the Securities Act of 1933, as amended, this Amendment to Registration Statement has been signed by the following person in the capacities and on the dates indicated.

II-16

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QuickLinks

Guarantor Registrants
EXPLANATORY NOTE

Item 21. Exhibits and Financial Statement Schedules

PART II INFORMATION NOT REQUIRED IN THE PROSPECTUS
REGISTRANT SIGNATURES
GUARANTOR REGISTRANTS SIGNATURES
GUARANTOR REGISTRANTS SIGNATURE
GUARANTOR REGISTRANT SIGNATURE
GUARANTOR REGISTRANT SIGNATURE
GUARANTOR REGISTRANTS SIGNATURES
GUARANTOR REGISTRANT SIGNATURE
GUARANTOR REGISTRANT SIGNATURES