ECOL US Ecology Inc

NOTICE OF SPECIAL MEETING OF STOCKHOLDERS TO BE HELD ON OCTOBER 23, 2019

Dear US Ecology stockholders:

        We are pleased to invite you to attend the special meeting of the US Ecology stockholders, which will be held at 101 S. Capitol Blvd., Suite 1000, Boise, Idaho 83702, on October 23, 2019, at 10:00 a.m., local time (the "US Ecology Special Meeting"), to vote:

•

on a proposal to adopt the Agreement and Plan of Merger, dated as of June 23, 2019 (as it may be amended from time to time, the "Merger Agreement"), by and among US Ecology, Inc., a Delaware corporation ("US Ecology"), US Ecology Parent, Inc., a Delaware corporation and wholly-owned subsidiary of US Ecology ("Holdco"), Rooster Merger Sub, Inc., a Delaware corporation and a wholly-owned subsidiary of Holdco, ECOL Merger Sub, Inc., a Delaware corporation and a wholly-owned subsidiary of Holdco, and NRC Group Holdings Corp. (such transactions contemplated therein, the "Mergers"), which is attached as Annex A to the accompanying joint proxy statement/prospectus (the "US Ecology Merger Agreement Proposal");



•

on a proposal to approve the issuance of Holdco Common Stock as merger consideration pursuant to the terms and conditions set forth in the Merger Agreement (the "Holdco Stock Issuance Proposal");



•

on a proposal to amend the Holdco charter as further described in the accompanying joint proxy statement/prospectus (the "Holdco Charter Amendment Proposal"); and



•

on a proposal to approve adjournments of the US Ecology Special Meeting to solicit additional proxies if there are not sufficient votes at the time of the US Ecology Special Meeting to approve the US Ecology Merger Agreement Proposal, the Holdco Stock Issuance Proposal or the Holdco Charter Amendment Proposal or to ensure that any supplement or amendment to the accompanying joint proxy statement/prospectus is timely provided to US Ecology stockholders (the "US Ecology Adjournment Proposal").

        Completion of the Mergers is conditioned on, among other things, approval by the US Ecology stockholders of each of the US Ecology Merger Agreement Proposal, the Holdco Stock Issuance Proposal and the Holdco Charter Amendment Proposal.

        US Ecology will transact no other business at the special meeting except such business as may properly be brought before the special meeting or any adjournment or postponement thereof. Please refer to the attached joint proxy statement/prospectus for further information with respect to the business to be transacted at the US Ecology Special Meeting.

        At a meeting of the board of directors of US Ecology (the "US Ecology Board") held on June 23, 2019, the US Ecology Board determined that the Merger Agreement and the transactions contemplated thereby, including the Mergers, the issuance of Holdco Common Stock as consideration in the Mergers and the amendment of the Holdco charter as described in the accompanying joint proxy statement/prospectus, are advisable and in the best interests of US Ecology and its stockholders, and approved the Merger Agreement and the Mergers, the execution of the Merger Agreement and the consummation of the transactions contemplated thereby and declared advisable and recommended that US Ecology's stockholders adopt the Merger Agreement, approve the issuance of Holdco Common

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Stock as merger consideration and approve the amendment of the Holdco charter as further described in the accompanying joint proxy statement/prospectus.

        The US Ecology Board recommends that US Ecology stockholders vote "FOR" the US Ecology Merger Agreement Proposal, "FOR" the Holdco Stock Issuance Proposal, "FOR" the Holdco Charter Amendment Proposal and, if necessary, "FOR" the US Ecology Adjournment Proposal.

        Holders of record of shares of ECOL Common Stock, at the close of business on September 11, 2019, are entitled to notice of, and may vote at, the US Ecology Special Meeting and any adjournment of the US Ecology Special Meeting. A list of US Ecology stockholders entitled to vote at the US Ecology Special Meeting will be available for inspection at US Ecology's principal executive offices, located at 101 S. Capitol Blvd., Suite 1000, Boise, ID 83702, at least ten days prior to the date of the US Ecology Special Meeting and continuing through the date thereof for any purpose germane to the US Ecology Special Meeting, between the hours of 9:00 a.m. and 4:30 p.m., local time. The list will also be available at the US Ecology Special Meeting for inspection by any US Ecology stockholder present at the US Ecology Special Meeting.

        The US Ecology Merger Agreement Proposal and the Holdco Charter Amendment Proposal each requires the affirmative vote of holders of a majority of the issued and outstanding shares of ECOL Common Stock entitled to vote on the proposal. The Holdco Stock Issuance Proposal and the US Ecology Adjournment Proposal each requires the affirmative vote of the majority of all votes cast at the US Ecology Special meeting and entitled to vote thereon.

        Your vote is very important, regardless of the number of shares of ECOL Common Stock you own.    Whether or not you plan to attend the US Ecology Special Meeting, we urge you to vote and submit your proxy by Internet, telephone or mail, pursuant to the instructions on your proxy card. If your shares are held in the name of a brokerage firm, bank or other nominee of record, follow the voting instructions you receive from such holder of record to vote your shares.

        US Ecology will transact no other business at the US Ecology Special Meeting except such business as may properly be brought before the US Ecology Special Meeting or any adjournment or postponement thereof. The enclosed joint proxy statement/prospectus provides further information with respect to these matters. We urge you to read the accompanying joint proxy statement/prospectus, including any documents incorporated by reference, and the annexes carefully and in their entirety.

        If you have any questions about the Mergers, please contact US Ecology at (208) 331-8400 or write to US Ecology, Attn: Corporate Secretary, 101 S. Capitol Blvd., Suite 1000, Boise, Idaho 83702.

		By Order of the Board of Directors,
		Jeffrey R. Feeler President and Chief Executive Officer
		September 19, 2019

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NRC Group Holdings Corp.
952 Echo Lane, Suite 460
Houston, Texas 77024
(832) 767-4749

NOTICE OF SPECIAL MEETING OF COMMON STOCKHOLDERS TO BE HELD ON OCTOBER 22, 2019

Dear NRC Group Holdings Corp. common stockholders:

        We are pleased to invite you to attend the special meeting of NRCG common stockholders, which will be held at 717 Texas, Suite 3300, Houston, Texas 77002, on October 22, 2019, at 9:00 a.m., local time (the "NRCG Special Meeting"), to vote:

•

on a proposal to adopt the Agreement and Plan of Merger, dated as of June 23, 2019 (as it may be amended from time to time, the "Merger Agreement"), by and among US Ecology, Inc., a Delaware corporation ("US Ecology"), US Ecology Parent, Inc., a Delaware corporation and wholly-owned subsidiary of US Ecology ("Holdco"), Rooster Merger Sub, Inc., a Delaware corporation and a wholly-owned subsidiary of Holdco, ECOL Merger Sub, Inc., a Delaware corporation and a wholly-owned subsidiary of Holdco, and NRCG, which is attached as Annex A to the accompanying joint proxy statement/prospectus (the "NRCG Merger Agreement Proposal"); and



•

on a proposal to approve adjournments of the NRCG Special Meeting to solicit additional proxies if there are not sufficient votes at the time of the NRCG Special Meeting to approve the NRCG Merger Agreement Proposal or to ensure that any supplement or amendment to the accompanying joint proxy statement/prospectus is timely provided to NRCG common stockholders (the "NRCG Adjournment Proposal").

        Completion of the Mergers is conditioned on, among other things, approval by the NRCG common stockholders of the NRCG Merger Agreement Proposal.

        NRCG will transact no other business at the NRCG Special Meeting except such business as may properly be brought before the NRCG Special Meeting or any adjournment or postponement thereof. Please refer to the attached joint proxy statement/prospectus for further information with respect to the business to be transacted at the NRCG Special Meeting.

        At a meeting of the board of directors of NRCG (the "NRCG Board") held on June 23, 2019, the NRCG Board determined that the Merger Agreement and the transactions contemplated thereby, including the Mergers as described in the accompanying joint proxy statement/prospectus, are advisable and in the best interests of NRCG and its common stockholders, and approved the Merger Agreement and the Mergers, the execution of the Merger Agreement and the consummation of the transactions contemplated thereby and declared advisable and recommended that NRCG common stockholders adopt the Merger Agreement.

        The NRCG Board recommends that NRCG common stockholders vote "FOR" the NRCG Merger Agreement Proposal and "FOR" the NRCG Adjournment Proposal.

        Holders of record of shares of NRCG Common Stock, at the close of business on August 29, 2019, are entitled to notice of, and may vote at, the NRCG Special Meeting and any adjournment of the NRCG Special Meeting. A list of NRCG common stockholders entitled to vote at the NRCG Special Meeting will be available for inspection at NRCG's principal executive offices, located at 952 Echo Lane, Suite 460, Houston, TX 77024, at least ten days prior to the date of the NRCG Special Meeting

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and continuing through the date thereof for any purpose germane to the NRCG Special Meeting, between the hours of 9:00 a.m. and 4:30 p.m., local time. The list will also be available at the NRCG Special Meeting for inspection by any NRCG common stockholder present at the NRCG Special Meeting.

        The NRCG Merger Agreement Proposal requires the affirmative vote of holders of a majority of the issued and outstanding shares of NRCG Common Stock entitled to vote as of the record date for the NRCG Special Meeting. The NRCG Adjournment Proposal requires the affirmative vote of the majority of all votes cast at the NRCG Special meeting and entitled to vote thereon.

        Your vote is very important, regardless of the number of shares of NRCG Common Stock you own.    Whether or not you plan to attend the NRCG Special Meeting, we urge you to vote and submit your proxy by Internet, telephone or mail, pursuant to the instructions on your proxy card. If your shares are held in the name of a brokerage firm, bank or other nominee of record, follow the voting instructions you receive from such holder of record to vote your shares.

        NRCG will transact no other business at the NRCG Special Meeting except such business as may properly be brought before the NRCG Special Meeting or any adjournment or postponement thereof. The enclosed joint proxy statement/prospectus provides further information with respect to these matters. We urge you to read this joint proxy statement/prospectus, including any documents incorporated by reference, and the annexes carefully and in their entirety.

        If you have any questions about the Mergers, please contact NRCG at (832) 767-4749 or write to NRC Group Holdings Corp., Attn: Corporate Secretary, 952 Echo Lane, Suite 460, Houston, Texas 77024.

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ADDITIONAL INFORMATION

        This joint proxy statement/prospectus of US Ecology Parent, Inc. ("Holdco") incorporates important business and financial information about US Ecology, Inc. ("US Ecology") and NRC Group Holdings Corp. ("NRCG") from other documents that are not included in or delivered with this joint proxy statement/prospectus. For a listing of documents incorporated by reference into this joint proxy statement/prospectus, please see the section entitled "Where You Can Find More Information" of this joint proxy statement/prospectus. This information is available to you without charge upon your request.

        You can obtain the documents incorporated by reference into this joint proxy statement/prospectus by requesting them in writing or by telephone from the appropriate company at the following addresses and telephone numbers:

        Investors may also consult US Ecology's or NRCG's website for more information concerning the Mergers described in this joint proxy statement/prospectus. US Ecology's website is www.usecology.com. NRCG's website is www.nrcg.com. Information included on these websites is not incorporated by reference into this joint proxy statement/prospectus.

        In addition, if you have questions about the Mergers or the accompanying joint proxy statement/prospectus, would like additional copies of the joint proxy statement/prospectus, or need to obtain proxy cards (holders of common stock only) or other information related to the proxy solicitation, please call Morrow Sodali, LLC, US Ecology's proxy solicitor, by telephone toll-free at (800) 662-5200 (banks and brokers call collect at (203) 658-9400), or contact NRCG's General Counsel at 952 Echo Lane, Suite 460, Houston, Texas 77024 or by telephone at (832) 767-4749. You will not be charged for any of these documents that you request.

        If you would like to request any documents, please do so no later than five business days before the date of the relevant special meeting in order to receive timely delivery of such documents before such special meeting. Therefore, if you would like to request documents from US Ecology or NRCG, please do so by October 15, 2019 or October 16, 2019 in order to receive such documents before the NRCG Special Meeting or US Ecology Special Meeting, respectively.

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ABOUT THIS DOCUMENT

        This joint proxy statement/prospectus, which forms part of a registration statement on Form S-4 filed with the Securities and Exchange Commission (the "SEC") by Holdco (File No. 333-232930), constitutes a prospectus of Holdco under Section 5 of the Securities Act with respect to the shares of Holdco Common Stock proposed to be issued to US Ecology stockholders, NRCG stockholders and NRCG warrant holders pursuant to the Merger Agreement. This document also constitutes a joint proxy statement under Section 14(a) of the Securities Exchange Act of 1934, as amended (the "Exchange Act") of US Ecology and NRCG. It also includes (1) a notice of meeting with respect to the special meeting of US Ecology stockholders, at which US Ecology stockholders will be asked to vote upon the US Ecology Merger Agreement Proposal, the Holdco Stock Issuance Proposal, the Holdco Charter Amendment Proposal and the US Ecology Adjournment Proposal, (2) a notice of meeting with respect to the special meeting of NRCG common stockholders, at which NRCG common stockholders will be asked to vote upon the NRCG Merger Agreement Proposal and the NRCG Adjournment Proposal (as each of the foregoing proposals is defined herein) and (3) the required notice to holders of NRCG Series A Preferred Stock under Section 262 of the Delaware General Corporation Law (the "DGCL").

        US Ecology has supplied all information contained in this joint proxy statement/prospectus relating to US Ecology, Holdco, Rooster Merger Sub and ECOL Merger Sub. NRCG has supplied all information contained in or incorporated by reference into this joint proxy statement/prospectus relating to NRCG. US Ecology and NRCG have both contributed information relating to the proposed transactions.

        Before casting your vote, you should carefully review all the information contained or incorporated by reference into this joint proxy statement/prospectus. Neither US Ecology nor NRCG has authorized anyone to provide you with information that is different from that contained in, or incorporated by reference into, this joint proxy statement/prospectus. This joint proxy statement/prospectus is dated September 19, 2019. You should not assume that the information contained in, or incorporated by reference into, this joint proxy statement/prospectus is accurate as of any date other than the date on the front cover of those documents. Neither the mailing of this joint proxy statement/prospectus to US Ecology stockholders or NRCG stockholders nor the issuance by Holdco of Holdco Common Stock in connection with the Mergers will create any implication to the contrary.

        In deciding how to vote with respect to any of the proposals discussed herein, you must make your own independent examination of the merits and risks of the proposal. You should not construe anything included in this joint proxy statement/prospectus as investment, legal, business or tax advice, and should consult with your own advisors if you have questions concerning any of the matters described herein.

        This joint proxy statement/prospectus does not constitute an offer to sell, or a solicitation of an offer to buy, any securities, or the solicitation of a proxy, in any jurisdiction in which or from any person to whom it is unlawful to make any such offer or solicitation in such jurisdiction. Statements contained in this document or in any document incorporated into this document by reference as to the contents of any contract or other document referred to in this document or in other documents that are incorporated by reference into this document are not necessarily complete and, in each instance, reference is made to the copy of the applicable contract or other document filed as an exhibit to the registration statement or otherwise filed with the SEC. Each statement contained in this document is qualified in its entirety by reference to the underlying documents. You are encouraged to read the entire registration statement. You may obtain copies of the Form S-4, including documents incorporated by reference into the Form S-4 (and any amendments to those documents), by following the instructions in the section entitled "Where You Can Find More Information."

        All references in this joint proxy statement/prospectus to "NRCG" refer to NRC Group Holdings Corp, a Delaware corporation (except that in connection with the description of its operations or business in the sections entitled "Cautionary Statement Regarding Forward-Looking Statements" and "Risk Factors," such term refers to the consolidated operations of NRCG and its subsidiaries); all

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references in this joint proxy statement/prospectus to "US Ecology" refer to US Ecology, Inc., a Delaware corporation (except that in connection with the description of its operations or business in the sections entitled "Cautionary Statement Regarding Forward-Looking Statements" and "Risk Factors," such term refers to the consolidated operations of US Ecology and its subsidiaries); all references to "Holdco" refer to US Ecology Parent, Inc., a Delaware corporation and a direct wholly-owned subsidiary of US Ecology, formed for the purpose of effecting the Mergers; all references to "ECOL Merger Sub" refer to ECOL Merger Sub, Inc., a Delaware corporation and a direct wholly-owned subsidiary of US Ecology, formed for the purpose of effecting the Mergers; all references to "Rooster Merger Sub" refer to Rooster Merger Sub, Inc., a Delaware corporation and a direct wholly-owned subsidiary of US Ecology, formed for the purpose of effecting the Mergers; all references to the "ECOL Merger" refer to the merger of ECOL Merger Sub with and into US Ecology, with US Ecology continuing as the surviving corporation and as a wholly-owned subsidiary of Holdco; all references to "NRCG Merger" refer to the merger of Rooster Merger Sub with and into NRCG, with NRCG continuing as the surviving corporation and a wholly-owned subsidiary of Holdco; and the "Mergers" refers to the ECOL Merger and the NRCG Merger. Unless otherwise indicated or as the context requires, all references to the "Merger Agreement" refer to the Agreement and Plan of Merger, dated as of June 23, 2019, among US Ecology, NRCG, Holdco, Rooster Merger Sub and ECOL Merger Sub, a copy of which is included as Annex A to this joint proxy statement/prospectus.

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QUESTIONS AND ANSWERS ABOUT THE MERGERS AND THE SPECIAL MEETINGS

        The following are brief answers to certain questions that US Ecology stockholders and NRCG stockholders may have regarding the Mergers (as defined above), the Merger Agreement (as defined above), the issuance of shares of Holdco Common Stock (as defined below) in connection with the Mergers, the special meeting of US Ecology stockholders (the "US Ecology Special Meeting"), the special meeting of NRCG common stockholders (the "NRCG Special Meeting"), and other matters to be considered at the US Ecology Special Meeting and at the NRCG Special Meeting. US Ecology and NRCG urge you to read carefully the remainder of this joint proxy statement/prospectus and additional important information contained in the annexes and exhibits to, and the documents incorporated by reference into, this joint proxy statement/prospectus because the information in this section may not provide all of the information that might be important to you in determining how to vote. See the section entitled "Where You Can Find More Information" in this joint proxy statement/prospectus.

Q:

What is the proposed transaction?

A:

As previously disclosed, on June 23, 2019, US Ecology, Holdco, ECOL Merger Sub, Rooster Merger Sub and NRCG entered into the Merger Agreement. A copy of the Merger Agreement is attached to this joint proxy statement/prospectus as Annex A.

Under the terms of the Merger Agreement, ECOL Merger Sub will merge with and into US Ecology, with US Ecology as the surviving entity and continuing as a wholly-owned subsidiary of Holdco and, simultaneously therewith, Rooster Merger Sub will merge with and into NRCG, with NRCG as the surviving entity and continuing as a wholly-owned subsidiary of Holdco.

In the ECOL Merger, each share of common stock, par value $0.01 per share, of US Ecology ("ECOL Common Stock") issued and outstanding immediately prior to the effective time of the Mergers (the "Effective Time") (other than cancelled shares) will be converted into the right to receive (1) one share of common stock, par value $0.01 per share, of Holdco ("Holdco Common Stock") and (2) any dividends or other distributions to which the holder thereof becomes entitled to upon the surrender of shares of ECOL Common Stock in accordance with the Merger Agreement. Outstanding equity awards of US Ecology will be assumed by Holdco and converted into equity awards at Holdco on a one-for-one basis as set forth in the Merger Agreement and described herein under the section entitled "The Merger Agreement—Treatment of US Ecology Stock Options, Restricted Stock Units, Performance Stock Units and Restricted Shares." Each share of ECOL Common Stock that is held by US Ecology as treasury stock or that is owned by Holdco, ECOL Merger Sub, US Ecology or any of their respective direct or indirect wholly-owned subsidiaries as of immediately prior to the Effective Time will automatically be cancelled and will cease to exist, without any conversion thereof, and no consideration will be delivered in exchange therefor.

In the NRCG Merger, each share of common stock, par value $0.0001 per share, of NRCG ("NRCG Common Stock") issued and outstanding immediately prior to the Effective Time (other than cancelled shares) will be converted into the right to receive, and become exchangeable for (1) 0.196 (the "NRCG Exchange Ratio") of a share of Holdco Common Stock for each share of NRCG Common Stock, (2) any cash in lieu of fractional shares of Holdco Common Stock payable pursuant to the Merger Agreement and (3) any dividends or other distributions to which the holder thereof becomes entitled to upon the surrender of such shares of NRCG Common Stock in accordance with the Merger Agreement. Each share of 7.00% Series A Convertible Cumulative Preferred Stock, par value $0.0001 per share, of NRCG (the "NRCG Series A Preferred Stock") issued and outstanding immediately prior to the Effective Time will be converted into the right to receive, and become exchangeable for (1) a whole number of shares of Holdco Common Stock equal to the product of (a) the number of shares of NRCG Common Stock that such share of

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NRCG Series A Preferred Stock could be converted into at the Effective Time (including Fundamental Change Additional Shares and Accumulated Dividends (each as defined in the Certificate of Designations, Preferences, Rights and Limitations of NRCG Series A Preferred Stock, dated as of October 17, 2018 and corrected on October 23, 2018 (the "NRCG Series A Certificate of Designations"))) multiplied by (b) the NRCG Exchange Ratio, (2) any cash in lieu of fractional shares of Holdco Common Stock payable pursuant to the Merger Agreement and (3) any dividends or other distributions to which the holder thereof becomes entitled to upon the surrender of such shares of NRCG Series A Preferred Stock in accordance with the Merger Agreement. In the NRCG Merger, each share of NRCG Common Stock or NRCG Series A Preferred Stock that is owned by NRCG, Rooster Merger Sub or any of their respective direct or indirect wholly-owned subsidiaries immediately prior to the Effective Time will automatically be cancelled and will cease to exist, without any conversion thereof, and no consideration will be delivered in exchange therefor.

Also at the Effective Time, US Ecology shall cause all shares of Holdco Common Stock that are issued and outstanding immediately prior to the Effective Time to be surrendered and cancelled and cease to exist, with no consideration delivered in exchange therefor.

At the Effective Time, in respect of each outstanding warrant to purchase NRCG Common Stock (each, a "NRCG Warrant") issued pursuant to that certain Warrant Agreement, dated as of June 22, 2017 (the "NRCG Warrant Agreement"), between Continental Stock Transfer & Trust Company and NRCG, unless otherwise elected by the holder of any such NRCG Warrant, Holdco will issue a replacement warrant (each, a "Replacement Warrant") that complies with and satisfies the applicable terms and conditions under the NRCG Warrant Agreement to each holder of an NRCG Warrant providing that such Replacement Warrant will be exercisable for a number of shares of Holdco Common Stock equal to the product (rounded to the nearest whole number) of (1) the number of shares of NRCG Common Stock that would have been issuable upon the exercise of the NRCG Warrant immediately prior to the Effective Time and (2) the NRCG Exchange Ratio, at an exercise price equal to the quotient obtained by dividing (a) the pre-NRCG Merger exercise price ($11.50 per share) by (b) the NRCG Exchange Ratio. Following the closing of the Mergers, Holdco will comply with all terms and conditions set forth in each such Replacement Warrant.

Outstanding shares of NRCG equity awards will be converted into equity awards of Holdco pursuant to the mechanics set forth in the Merger Agreement and described herein under the section entitled "The Merger Agreement—Treatment of NRCG Stock Options and Restricted Stock Units."

Q:

What is the value of the merger consideration?

A:

US Ecology stockholders will be entitled to receive one share of Holdco Common Stock for each share of ECOL Common Stock they own at the closing of the ECOL Merger, and NRCG stockholders will be entitled to receive a fixed number of shares of Holdco Common Stock for each share of NRCG Common Stock or NRCG Series A Preferred Stock (based on the number of shares of NRCG Common Stock that such share of NRCG Series A Preferred Stock could be converted into at the Effective Time (including Fundamental Change Additional Shares and Accumulated Dividends (each, as defined in the NRCG Series A Certificate of Designation))) as applicable, they own at the closing of the NRCG Merger based on the NRCG Exchange Ratio of 0.196 shares of Holdco Common Stock per share of NRCG Common Stock, rather than a number of shares of Holdco Common Stock with a particular fixed market value. Because the NRCG Exchange Ratio and the conversion mechanics are fixed and will not be adjusted to reflect any changes in the market prices of ECOL Common Stock or NRCG Common Stock, the market value of the Holdco Common Stock issued in the ECOL Merger or the NRCG Merger, as

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applicable, and the ECOL Common Stock, NRCG Common Stock and NRCG Series A Preferred Stock surrendered in the ECOL Merger and the NRCG Merger, as applicable, may be higher or lower than the anticipated values of these shares on dates earlier than the Effective Time. We urge you to obtain current market quotations of ECOL Common Stock and NRCG Common Stock. See also the section entitled "Comparative Stock Price Data and Dividends" of this joint proxy statement/prospectus.

Q:

What percentage of Holdco will US Ecology stockholders and NRCG stockholders, respectively, own following the Mergers?

A:

Upon completion of the Mergers, US Ecology stockholders (including holders of securities convertible, exchangeable or exercisable for shares of NRCG Common Stock) immediately prior to the Effective Time are expected to beneficially own approximately 70% of Holdco Common Stock and NRCG stockholders (including holders of securities convertible, exchangeable or exercisable for shares of NRCG Common Stock) immediately prior to the Effective Time are expected to beneficially own approximately 30% of Holdco Common Stock, in each case, calculated on a fully diluted basis.

Q:

When and where will the special meetings be held?

A:

US Ecology Stockholders:    The US Ecology Special Meeting will be held at the offices of US Ecology located at 101 S. Capitol Blvd., Suite 1000, Boise, Idaho 83702, on October 23, 2019, at 10:00 a.m., local time.

NRCG Common Stockholders:    The NRCG Special Meeting will be held at 717 Texas, Suite 3300, Houston, Texas 77002, on October 22, 2019, at 9:00 a.m., local time.

If you wish to attend your respective company's special meeting, you must bring photo identification. If you hold your shares through a broker, bank or other nominee, including an employee benefit plan trustee, you must also bring proof of ownership such as the voting instruction form from your broker, bank or other nominee or an account statement.

Q:

Who is entitled to vote at the special meetings?

A:

US Ecology Stockholders:    The US Ecology record date for the US Ecology Special Meeting is September 11, 2019 (the "US Ecology Record Date"). Only holders of record of issued and outstanding shares of ECOL Common Stock as of the close of business on the US Ecology Record Date are entitled to notice of, and to vote at, the US Ecology Special Meeting or any adjournments or postponements of the US Ecology Special Meeting.

NRCG Common Stockholders:    The NRCG record date for the NRCG Special Meeting is August 29, 2019 (the "NRCG Record Date"). Only holders of record of issued and outstanding shares of NRCG Common Stock as of the close of business on the NRCG Record Date are entitled to vote at the NRCG Special Meeting or any adjournments or postponements of the NRCG Special Meeting.

Q:

Who is being asked to vote, and what are they being asked to vote on and why is this approval necessary?

A:

US Ecology stockholders are being asked to vote on the following proposals:

(1)

to adopt the Merger Agreement, a copy of which is attached as Annex A to this joint proxy statement/prospectus (the "US Ecology Merger Agreement Proposal");

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(2)

to approve the issuance of Holdco Common Stock as merger consideration pursuant to the terms and conditions set forth in the Merger Agreement (the "Holdco Stock Issuance Proposal");



(3)

to approve the amendment of the Holdco charter as further described in this joint proxy statement/prospectus (the "Holdco Charter Amendment Proposal"); and



(4)

to approve adjournments of the US Ecology Special Meeting to solicit additional proxies if there are not sufficient votes at the time of the US Ecology Special Meeting to approve the US Ecology Merger Agreement Proposal, the Holdco Stock Issuance Proposal or the Holdco Charter Amendment Proposal or to ensure that any supplement or amendment to the accompanying joint proxy statement/prospectus is timely provided to US Ecology stockholders (the "US Ecology Adjournment Proposal").

Completion of the Mergers is conditioned on, among other things, approval by the US Ecology stockholders of each of the US Ecology Merger Agreement Proposal, the Holdco Stock Issuance Proposal and the Holdco Charter Amendment Proposal.

NRCG common stockholders are being asked to vote on the following proposals:

(1)

to adopt the Merger Agreement, a copy of which is attached as Annex A to this joint proxy statement/prospectus (the "NRCG Merger Agreement Proposal"); and



(2)

to approve the adjournment of the NRCG Special Meeting to solicit additional proxies if there are not sufficient votes at the time of the NRCG Special Meeting to approve the NRCG Merger Agreement Proposal or to ensure that any supplement or amendment to the accompanying joint proxy statement/prospectus is timely provided to NRCG common stockholders (the "NRCG Adjournment Proposal").

Completion of the Mergers is conditioned on, among other things, approval by the NRCG common stockholders of the NRCG Merger Agreement Proposal.

Q:

Why is US Ecology seeking stockholder approval to amend the Holdco charter?

US Ecology stockholders are being asked to consider and vote upon a proposal to add certain provisions to the charter of Holdco that will be in effect after completion of the Mergers and that are not in the current charter of US Ecology. These provisions are proposed to be added to the proposed Holdco Amended Charter to facilitate Holdco's compliance with the U.S. citizen ownership requirements of the U.S. coastwise trade laws, which are principally contained in 46 U.S.C. Chapters 121, 505 and 551 and the related regulations and are commonly referred to collectively as the "Jones Act," following the closing of the Mergers.

Q:

What vote is required to approve each proposal at the US Ecology Special Meeting?

A:

The US Ecology Merger Agreement Proposal and the Holdco Charter Amendment Proposal each requires the affirmative vote of holders of a majority of the issued and outstanding shares of ECOL Common Stock entitled to vote on the proposal. Failures to vote, abstentions and broker non-votes will have the effect of a vote against the US Ecology Merger Agreement Proposal and the Holdco Charter Amendment Proposal.

The Holdco Stock Issuance Proposal and the US Ecology Adjournment Proposal each requires the affirmative vote of the majority of all votes cast at the US Ecology Special Meeting and entitled to vote thereon. Failures to vote, abstentions and broker non-votes will have no effect on the outcome of the Holdco Stock Issuance Proposal or the US Ecology Adjournment Proposal, assuming a quorum is present.

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US Ecology stockholder approval of each of the US Ecology Merger Agreement Proposal, the Holdco Charter Amendment Proposal and the Holdco Stock Issuance Proposal is a condition precedent to the closing of the Mergers.

At the close of business on the US Ecology Record Date, less than 1% of the issued and outstanding shares of ECOL Common Stock were held by US Ecology's directors and executive officers. For additional information regarding the ownership of US Ecology's directors, executive officers and certain stockholders, see the section entitled "Security Ownership of Certain Beneficial Owners and Management of US Ecology."

Q:

What vote is required to approve each proposal at the NRCG Special Meeting?

A:

The NRCG Merger Agreement Proposal requires the affirmative vote of holders of a majority of the issued and outstanding shares of NRCG Common Stock entitled to vote on the proposal. Failures to vote, abstentions and broker non-votes will have the effect of a vote against the NRCG Merger Agreement Proposal. NRCG common stockholder approval of the NRCG Merger Agreement Proposal is a condition precedent to the consummation of the Mergers.

The NRCG Adjournment Proposal requires the affirmative vote of the majority of all votes cast at the NRCG Special Meeting and entitled to vote thereon. Failures to vote, abstentions and broker non-votes will have no effect on the outcome of the NRCG Adjournment Proposal.

JFL-NRC-SES Partners, LLC ("JFL Partners"), JFL-NRCG Holdings III, LLC ("JFL Holdings III") and JFL-NRCG Holdings IV, LLC ("JFL Holdings IV" and collectively, the "JFL Entities"), are the registered holders of approximately 66% of the issued and outstanding NRCG Common Stock as of the NRCG Record Date, and have agreed, among other things, to vote their shares of NRCG Common Stock in favor of the adoption of the Merger Agreement at the NRCG Special Meeting, with certain exceptions described in this joint proxy statement/prospectus. As a result, and subject to the terms of the Support Agreement (as defined below), the approval of the NRCG Merger Agreement Proposal is effectively assured. Furthermore, at the close of business on the NRCG Record Date, approximately 70% of the issued and outstanding shares of NRCG Common Stock were directly held by NRCG's directors and executive officers and the JFL Entities. For additional information regarding the ownership of NRCG's directors, executive officers and certain stockholders, see the section entitled "Security Ownership of Certain Beneficial Owners and Management of NRCG."

Q:

What constitutes a quorum at the special meetings?

A:

US Ecology Special Meeting:    Stockholders who hold shares representing at least a majority of the issued and outstanding shares of ECOL Common Stock entitled to vote at the US Ecology Special Meeting must be present in person or represented by proxy to constitute a quorum for the transaction of business at the US Ecology Special Meeting. If a quorum is not present, the US Ecology Special Meeting may be adjourned by the chairman of the US Ecology Special Meeting or the holders of a majority of shares of the ECOL Common Stock entitled to vote who are present, in person or by proxy, to another place, date, or time without notice other than announcement at the meeting, until a quorum shall be present or represented. Abstentions and broker non-votes are not included in the determination of the number of votes cast at the US Ecology Special Meeting, but abstentions and broker non-votes, if any, will be counted for purposes of determining whether a quorum is present.

NRCG Special Meeting:    Stockholders who hold shares representing at least a majority of the issued and outstanding shares of NRCG Common Stock entitled to vote at the NRCG Special Meeting must be present in person or represented by proxy to constitute a quorum for the transaction of business at the NRCG Special Meeting. If a quorum is not present, the NRCG

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Special Meeting may be adjourned by the chairman of the NRCG Special Meeting to allow additional time for obtaining additional proxies until a quorum is present or represented, to reconvene at the same or another place, and notice need not be given of any such adjourned meeting if the time and place thereof are announced at the meeting at which the adjournment is taken. Abstentions and broker non-votes, if any, will be counted for purposes of determining whether a quorum is present at the NRCG Special Meeting.

Q:

How does the US Ecology board of directors (the "US Ecology Board") recommend that US Ecology stockholders vote?

A:

The US Ecology Board has unanimously approved the Merger Agreement and determined that the Merger Agreement and the transactions contemplated thereby, including the Mergers, are fair, advisable and in the best interests of US Ecology and its stockholders. The US Ecology Board unanimously recommends that the US Ecology stockholders vote "FOR" each of the US Ecology Merger Agreement Proposal, the Holdco Stock Issuance Proposal, the Holdco Charter Amendment Proposal and, if necessary, the US Ecology Adjournment Proposal.

Q:

How does the NRCG board of directors (the "NRCG Board") recommend that NRCG common stockholders vote?

A:

The NRCG Board has determined that the Merger Agreement and the transactions contemplated thereby, including the Mergers, are fair, advisable and in the best interests of NRCG and its common stockholders. The NRCG Board recommends that NRCG common stockholders vote "FOR" the NRCG Merger Agreement Proposal and the NRCG Adjournment Proposal.

Q:

How do I vote if I am a stockholder of record?

A:

If you are a stockholder of record of US Ecology as of September 11, 2019 or a common stockholder of record of NRCG as of August 29, 2019, you may submit your proxy before your respective company's special meeting in one of the following ways:

•

use the toll-free number shown on your proxy card;

•

visit the website shown on your proxy card to submit a proxy via the Internet; or

•

complete, sign, date and return the enclosed proxy card in the enclosed postage-paid envelope.

If you are a stockholder of record of US Ecology or a common stockholder of record of NRCG, you may also cast your vote in person at your respective company's special meeting.

If your shares are held in "street name," through a broker, bank or other nominee, that institution will send you separate instructions describing the procedure for causing your shares to be voted. "Street name" common stockholders who wish to vote at the special meetings will need to obtain a "legal proxy" form from their broker, trustee or other nominee.

Q:

How many votes do I have?

A:

Holders of ECOL Common Stock and NRCG Common Stock are entitled to one vote for each share owned as of the close of business on such company's record date. Holders of NRCG Series A Preferred Stock or NRCG warrants do not have the right to vote. As of the close of business on the US Ecology Record Date, there were 22,080,545 shares of ECOL Common Stock issued and outstanding and entitled to vote at the US Ecology Special Meeting. As of the close of business on the NRCG Record Date, there were 38,050,385 shares of NRCG Common Stock issued and outstanding and entitled to vote at the NRCG Special Meeting.

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Q:

My shares are held in "street name" by my broker, bank or other nominee. Will my broker, bank or other nominee automatically vote my shares for me?

A:

No. If your shares are held in the name of a broker, bank or other nominee, you are considered the "beneficial holder" of the shares held for you in what is known as "street name." You are not the record holder of such shares. If this is the case, this joint proxy statement/prospectus has been forwarded to you by your broker, bank or other nominee. As the beneficial holder, unless your broker, bank or other nominee has discretionary authority over your shares, you generally have the right to direct your broker, bank or other nominee as to how to vote your shares. If you do not provide voting instructions, your shares will not be voted on any proposal, as your broker, bank or other nominee will not have discretionary voting authority with respect to any of the proposals described in this joint proxy statement/prospectus. This is often called a broker non-vote.

In connection with the US Ecology Special Meeting:

•

broker non-votes, if any, will have the same effect as a vote "AGAINST" the US Ecology Merger Agreement Proposal;

•

broker non-votes, if any, will have no effect on the outcome of the Holdco Stock Issuance Proposal;

•

broker non-votes, if any, will have the effect of a vote "AGAINST" the Holdco Charter Amendment Proposal; and

•

broker non-votes, if any, will have no effect on the US Ecology Adjournment Proposal.

In connection with the NRCG Special Meeting:

•

broker non-votes, if any, will have the same effect as a vote "AGAINST" the NRCG Merger Agreement Proposal; and



•

broker non-votes, if any, will have no effect on the NRCG Adjournment Proposal.

You should therefore provide your broker, bank or other nominee with instructions as to how to vote your shares of ECOL Common Stock or NRCG Common Stock.

Please follow the voting instructions provided by your broker, bank or other nominee so that it may vote your shares on your behalf. Please note that you may not vote shares held in street name by returning a proxy card directly to US Ecology or NRCG or by voting in person at your special meeting unless you first obtain a proxy from your broker, bank or other nominee.

Q:

What will happen if I fail to vote or I abstain from voting?

A:

For purposes of each of the US Ecology Special Meeting and the NRCG Special Meeting, an abstention occurs when a respective US Ecology stockholder or NRCG common stockholder either (1) attends the applicable special meeting in person and does not vote or (2) returns a proxy with an "abstain" vote.

An abstention will have the same effect as a vote "AGAINST" each of the US Ecology Merger Agreement Proposal, the Holdco Charter Amendment Proposal and the NRCG Merger Agreement Proposal, but will have no effect on the outcome of the Holdco Stock Issuance Proposal, the US Ecology Adjournment Proposal or the NRCG Adjournment Proposal.

In addition, a failure to vote altogether will have the same effect as a vote "AGAINST" each of the US Ecology Merger Agreement Proposal, the Holdco Charter Amendment Proposal and the NRCG Merger Agreement Proposal, but will have no effect on the outcome of the Holdco Stock Issuance Proposal, US Ecology Adjournment Proposal or the NRCG Adjournment Proposal.

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Q:

What will happen if I return my proxy card without indicating how to vote?

A:

US Ecology Stockholders:    If you properly complete and sign your proxy card but do not indicate how your shares of ECOL Common Stock should be voted on a matter, the shares of ECOL Common Stock represented by your proxy will be voted as the US Ecology Board recommends and, therefore, "FOR" the US Ecology Merger Agreement Proposal, "FOR" the Holdco Stock Issuance Proposal, "FOR" the Holdco Charter Amendment Proposal and, if necessary, "FOR" the US Ecology Adjournment Proposal.

NRCG Common Stockholders:    If you properly complete and sign your proxy card but do not indicate how your shares of NRCG Common Stock should be voted on a matter, the shares of NRCG Common Stock represented by your proxy will be voted as the NRCG Board recommends and, therefore, "FOR" the NRCG Merger Agreement Proposal and "FOR" the NRCG Adjournment Proposal.

Q:

Can I change my vote or revoke my proxy after I have returned a proxy or voting instruction card?

A:

Yes.

If you are a holder of record of either ECOL Common Stock or NRCG Common Stock:    If you are a holder of record of either ECOL Common Stock or NRCG Common Stock, as applicable, you can change your vote or revoke your proxy at any time before your proxy is voted at your respective special meeting. You can do this in one of three ways:

•

timely delivering a signed written notice of revocation to the respective Secretary of US Ecology or NRCG, as applicable;

•

timely delivering a new, valid proxy for US Ecology or NRCG, as applicable, bearing a later date than your original proxy by submitting instructions through the Internet, by telephone or by mail as described on the applicable proxy card; or

•

attending your special meeting and voting in person, which will automatically cancel any proxy previously given, or you can revoke your proxy in person. Simply attending the US Ecology Special Meeting or the NRCG Special Meeting without voting will not revoke any proxy that you have previously given or change your vote.

If you choose either of the first two methods, your notice of revocation or your new proxy must be received by US Ecology or NRCG, as applicable, no later than the beginning of the applicable special meeting. If you have submitted a proxy for your shares by telephone or via the Internet, you may revoke your prior telephone or Internet proxy by any manner described above.

If you hold shares of either ECOL Common Stock or NRCG Common Stock in "street name":    If your shares are held in street name, you must contact your broker, bank or other nominee to change your vote.

Q:

What are the U.S. federal income tax consequences of the Mergers to U.S. holders of ECOL Common Stock, NRCG Common Stock, NRCG Warrants and NRCG Series A Preferred Stock?

A:

Consequences to U.S. holders of ECOL Common Stock, NRCG Common Stock and NRCG Series A Preferred Stock:    It is a condition to US Ecology's and NRCG's obligations to complete the Mergers that each of US Ecology and NRCG receive an opinion from Dechert LLP ("Dechert") or Jones Day to the effect that, in the case of US Ecology, the Mergers will each qualify as a "reorganization" within the meaning of Section 368(a) of the U.S. Internal Revenue Code of 1986, as amended (the "Code") or, alternatively, the Mergers together will be treated as an "exchange" described in Section 351 of the Code and, in the case of NRCG, the NRCG Merger will qualify as

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a "reorganization" within the meaning of Section 368(a) of the Code or, alternatively, the NRCG Merger, together with the ECOL Merger, will be treated as an "exchange" described in Section 351 of the Code. Assuming the Mergers are treated for U.S. federal income tax purposes as described above, a "U.S. holder" (as defined in the section entitled "Material U.S. Federal Income Tax Consequences of the Mergers") of ECOL Common Stock, NRCG Common Stock, or NRCG Series A Preferred Stock generally will not recognize any gain or loss for U.S. federal income tax purposes upon the exchange of shares of ECOL Common Stock, NRCG Common Stock or NRCG Series A Preferred Stock for shares of Holdco Common Stock in the ECOL Merger or the NRCG Merger, respectively, except with respect to cash received by NRCG stockholders in lieu of fractional shares of Holdco Common Stock.

Consequences to U.S. holders of NRCG Warrants.    Assuming the NRCG Merger qualifies as a "reorganization" within the meaning of Section 368(a) of the Code, a U.S. holder of NRCG Warrants will not recognize gain or loss for U.S. federal income tax purposes upon the exchange of NRCG Warrants for Replacement Warrants. If the NRCG Merger does not qualify as a "reorganization" within the meaning of Section 368(a) of the Code, and, assuming the NRCG Merger, together with the ECOL Merger, will be treated as an "exchange" described in Section 351 of the Code, (1) a U.S. holder that exchanges solely NRCG Warrants for Replacement Warrants will recognize gain or loss equal to the difference between the fair market value of such Replacement Warrants and the U.S holder's tax basis in the NRCG Warrants surrendered therefor and (2) a U.S. holder that exchanges NRCG Warrants in addition to shares of NRCG Common Stock and/or NRCG Series A Preferred Stock will recognize gain (but not loss) equal to the lesser of (a) the sum of the fair market value of the Replacement Warrants and Holdco Common Stock received by such holder minus such U.S. holder's aggregate adjusted tax basis in the NRCG Warrants, NRCG Common Stock and/or NRCG Series A Preferred Stock surrendered therefor and (b) the fair market value of the Replacement Warrants received by such U.S. holder.

Please carefully review the information set forth in the section entitled "Material U.S. Federal Income Tax Consequences of the Mergers" for a discussion of the U.S. federal income tax consequences of the Mergers. Please consult your own tax advisors as to the specific tax consequences to you of the Mergers.

Q:

Are there any voting or stockholder rights agreements with existing stockholders that were entered into in connection with the proposed Mergers?

A:

Yes. Simultaneously with the execution of the Merger Agreement, US Ecology entered into a Support Agreement, dated June 23, 2019 (the "Support Agreement"), with Holdco, Rooster Merger Sub and the JFL Entities. As of each of the date of the Merger Agreement and the NRCG Record Date, the JFL Entities were the registered holders of approximately 66% of the currently issued and outstanding NRCG Common Stock. Pursuant to the Support Agreement, the JFL Entities agreed, among other things, to vote all of their shares of NRCG Common Stock in favor of the adoption of the Merger Agreement. The Support Agreement is attached hereto as Annex B. As a result of the Support Agreement, and subject to the terms thereof, the holders of a majority of the outstanding shares of NRCG Common Stock have agreed to vote their shares in favor of the adoption of the Merger Agreement, resulting in the approval of the NRCG Merger Agreement Proposal being effectively assured.

Also in connection with the execution of the Merger Agreement, US Ecology entered into an Investor Agreement, dated June 23, 2019 (the "Investor Agreement"), with Holdco, the JFL Entities and, solely with respect to Section 4 thereof, NRCG, pursuant to which each of the JFL Entities agreed, among other things, to (1) a standstill for a period lasting until the earlier of (a) 120 days after the closing date of the Mergers and (b) the date that each such JFL Entity ceases to own any Holdco Common Stock and (2) lock-up restrictions for a period of 60 days from

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the closing of the Mergers with respect to 1/3 of the shares held by the JFL Entities at closing of the Mergers, 90 days from the closing of the Mergers with respect to 1/3 of the shares held by the JFL Entities at closing of the Mergers and 120 days from the closing of the Mergers with respect to 1/3 of the shares held by the JFL Entities immediately following closing of the Mergers. The Investor Agreement is attached hereto as Annex C.

In addition, in connection with the execution of the Merger Agreement, US Ecology entered into a Registration Rights Agreement, dated June 23, 2019 (the "Registration Rights Agreement"), with Holdco and the JFL Entities, pursuant to which US Ecology granted the JFL Entities certain demand and piggyback registration rights with respect to the Registrable Securities (as defined in the Registration Rights Agreement). The Registration Rights Agreement is attached hereto as Annex D.

For additional information regarding the Support Agreement, Investor Agreement and Registration Rights Agreement, see the section entitled "The Mergers—Support Agreement, Investor Agreement and Registration Rights Agreement."

Q:

What will happen to my US Ecology stock options, restricted stock units ("RSUs"), performance stock units ("PSUs") and/or restricted shares and NRCG stock options and/or RSUs at the time of the Mergers?

A:

US Ecology stock options, RSUs, PSUs and restricted shares and NRCG stock options and RSUs will be converted into replacement equity awards of Holdco on substantially the same terms that were applicable to the corresponding US Ecology or NRCG equity awards immediately prior to the closing of the Mergers, subject to adjustment as described below. See the section entitled "The Merger Agreement—Treatment of US Ecology Stock Options, Restricted Stock Units, Performance Stock Units and Restricted Shares" and "The Merger Agreement—Treatment of NRCG Stock Options and Restricted Stock Units."

Q:

How will the rights of NRCG stockholders and US Ecology stockholders change after the Mergers?

A:

NRCG stockholders and US Ecology stockholders will be entitled to receive shares of Holdco Common Stock in connection with the NRCG Merger and ECOL Merger, respectively, and will no longer be stockholders of NRCG or US Ecology, respectively, following the Mergers. Their rights as holders of Holdco Common Stock will be governed by the amended and restated certificate of incorporation of Holdco (the "Holdco Amended Charter") and Holdco's amended and restated bylaws (the "Holdco Amended Bylaws"). For additional information on stockholder rights, see the section entitled "Comparison of Rights of US Ecology Stockholders, NRCG Stockholders and Holdco Stockholders" of this joint proxy statement/prospectus.

Q:

Are there any risks that I should consider in deciding how to vote?

A:

Yes. US Ecology stockholders and NRCG common stockholders should read and carefully consider the risk factors set forth in the section entitled "Risk Factors." US Ecology stockholders and NRCG common stockholders also should read and carefully consider the risk factors of US Ecology and NRCG contained in the documents that are incorporated by reference into this joint proxy statement/prospectus.

Q:

What happens if the Mergers are not completed?

A:

If the Mergers are not completed for any reason, US Ecology and NRCG stockholders will not receive the merger consideration payable or issuable under the Merger Agreement. Instead, US Ecology and NRCG will remain separate public companies. NRCG expects that NRCG Common

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Stock would continue to be registered under the Exchange Act and traded on the NYSE American. US Ecology expects that ECOL Common Stock would continue to be registered under the Exchange Act and traded on Nasdaq. In specified circumstances, either US Ecology or NRCG may be required to pay to the other party a termination fee or reimburse the other party's transaction expenses, as described below.

Q:

Does NRCG have to pay anything to US Ecology if the NRCG Merger Agreement Proposal is not approved by the NRCG common stockholders or if the Merger Agreement is otherwise terminated?

A:

In certain circumstances, depending on the reasons for termination of the Merger Agreement, NRCG may be required to pay US Ecology a termination fee of $35 million. For a discussion of the circumstances under which a termination fee is payable by NRCG, see the section entitled "The Merger Agreement—Expenses and Termination Fees; Liability for Breach."

Q:

Does US Ecology have to pay anything to NRCG if the US Ecology Merger Agreement Proposal is not approved by the US Ecology stockholders or if the Merger Agreement is otherwise terminated?

A:

If the US Ecology stockholders do not approve the US Ecology Merger Agreement Proposal, the Holdco Charter Amendment Proposal or the Holdco Stock Issuance Proposal at the US Ecology Special Meeting and the Merger Agreement is terminated by NRCG or US Ecology as a result of such failure to approve, US Ecology must reimburse NRCG's reasonable and documented out-of-pocket expenses up to $10 million.

In other circumstances, depending on the reasons for termination of the Merger Agreement, US Ecology may be required to pay NRCG a termination fee of $60 million. For a discussion of the circumstances under which a termination fee is payable by US Ecology or US Ecology is required to reimburse NRCG for certain transaction expenses, see the section entitled "The Merger Agreement—Expenses and Termination Fees; Liability for Breach."

Q:

When do you expect the Mergers to be completed?

A:

NRCG and US Ecology intend to complete the Mergers as soon as reasonably practicable and currently anticipate the closing of the Mergers to occur in the fourth quarter of 2019, following the satisfaction of all the conditions to completion of the Mergers. However, the Mergers are subject to the satisfaction or waiver of certain conditions, and it is possible that factors outside the control of Holdco, NRCG and US Ecology could result in the Mergers being completed at a later time or not at all. On July 16, 2019, each of US Ecology and JFL-AIV Investors III-JA, L.P. (as the controlling stockholder of NRCG) received early termination of the waiting period under the Hart-Scott Rodino Antitrust Improvement Act of 1976, as amended, and the rules and regulations promulgated thereunder (the "HSR Act"). Accordingly, the condition to the Mergers related to obtaining that clearance has been satisfied. There can be no assurances as to when or if the Mergers will close. See the section entitled "The Merger Agreement—Conditions to Completion of the Mergers."

Q:

What do I need to do now?

A:

You should carefully read and consider the information contained in and incorporated by reference into this joint proxy statement/prospectus, including its annexes. Even if US Ecology stockholders and NRCG common stockholders plan to attend the US Ecology Special Meeting or the NRCG Special Meeting in person, after carefully reading and considering the information contained in this joint proxy statement/prospectus, please submit your proxy promptly to ensure that your shares

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are represented and voted at the US Ecology Special Meeting or the NRCG Special Meeting, as applicable.

Q:

Do I need to do anything with my stock certificates now?

A:

NRCG Stockholders:    No. NRCG stockholders should keep any physical stock certificates they hold at this time. After the Mergers are completed, NRCG stockholders holding NRCG stock certificates will receive from the exchange agent a letter of transmittal and instructions on how to obtain the merger consideration to which they are entitled. The shares of Holdco Common Stock to be received by any current holder of a physical stock certificate representing NRCG Common Stock in connection with the NRCG Merger will be issued in book-entry form.

US Ecology Stockholders:    No. US Ecology stockholders should keep any physical stock certificates they hold at this time. After the Mergers are completed, US Ecology stockholders holding US Ecology stock certificates will receive from the exchange agent a letter of transmittal and instructions on how to obtain the merger consideration to which they are entitled. The shares of Holdco Common Stock to be received by any current holder of a physical stock certificate representing US Ecology Common Stock in connection with the ECOL Merger will be issued in book-entry form.

Q:

Do I need to do anything with my shares of stock held in book-entry form now?

A:

No. After the Mergers are completed, if you held shares of NRCG Common Stock, NRCG Series A Preferred Stock or ECOL Common Stock, as applicable, in book-entry form prior to the Mergers, the exchange agent will send you a letter of transmittal and instructions for exchanging your shares of NRCG Common Stock, NRCG Series A Preferred Stock or ECOL Common Stock, as applicable, for the merger consideration. Upon receipt of an agent's message in customary form (or such other evidence, if any, as the exchange agent may reasonably request), along with the executed letter of transmittal and other required documents described in the instructions, a stockholder will receive the applicable merger consideration. The shares of Holdco Common Stock you receive in connection with the Mergers will be issued in book-entry form.

Q:

Do I need identification to attend the US Ecology Special Meeting or NRCG Special Meeting in person?

A:

Yes. Please bring proper identification, together with proof that you are a record owner of ECOL Common Stock or NRCG Common Stock, as applicable. If your shares are held in street name, please bring acceptable proof of ownership, such as a letter from your broker or an account statement stating or showing that you beneficially owned shares of ECOL Common Stock or NRCG Common Stock, as applicable, on the record date for the applicable special meeting.

Q:

Are stockholders entitled to appraisal rights?

A:

Under Delaware law, holders of NRCG Common Stock and ECOL Common Stock will not be entitled to appraisal rights in connection with the Mergers or the other transactions contemplated by the Merger Agreement. Holders of NRCG Series A Preferred Stock will be entitled to appraisal rights in connection with the NRCG Merger. See the section entitled "Appraisal Rights" for more information regarding appraisal rights to which holders of NRCG Series A Preferred Stock will be entitled.

Q:

How can I contact US Ecology's or NRCG's transfer agent?

A:

You may contact US Ecology's transfer agent by writing to American Stock Transfer and Trust Co., 6201 15^th Avenue, Brooklyn, NY 11219 or by telephoning (800) 937-5449.

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You may contact NRCG's transfer agent by writing to Continental Stock Transfer & Trust Company, 1 State Street, 30^th Floor, New York, NY 10004, Attn: Henry Farrell, hfarrell@continentalstock.com.

Q:

Who should I contact if I have any questions about the proxy materials or about voting?

A:

If you have any questions about the proxy materials or if you need assistance submitting your proxy or voting your shares or need additional copies of this joint proxy statement/prospectus or the enclosed proxy card (common stockholders only), you should, if you are a US Ecology stockholder, contact US Ecology's proxy solicitor, Morrow Sodali, LLC by telephone toll-free at (800) 662-5200 (banks and brokers call collect at (203) 658-9400), and, if you are a NRCG stockholder, contact NRCG's General Counsel at 952 Echo Lane, Suite 460, Houston, Texas 77024 or by telephone at (832) 767-4749.

Q:

Who is the exchange agent in the Mergers?

A:

American Stock Transfer, US Ecology's transfer agent, is expected to be the exchange agent for the Mergers.

Q:

Where can I find more information about US Ecology and NRCG?

A:

You can find more information about US Ecology and NRCG from the various sources described under the section entitled "Where You Can Find More Information" of this joint proxy statement/prospectus.

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RISK FACTORS

        In addition to the other information included and incorporated by reference in this joint proxy statement/prospectus, including the matters addressed in the section entitled "Cautionary Statement Regarding Forward-Looking Statements," you should carefully consider the following risks before deciding how to vote. In addition, you should read and consider the risks associated with each of the businesses of NRCG and US Ecology because these risks will also affect the combined company. These risks can be found in the Annual Report on Form 10-K for the fiscal year ended December 31, 2018 filed on March 25, 2019, in the case of NRCG, and in the Annual Report on Form 10-K for the fiscal year ended December 31, 2018 filed on February 28, 2019, and any amendments thereto, in the case of US Ecology, as such risks may be updated or supplemented in each company's subsequently filed Quarterly Reports on Form 10-Q or Current Reports on Form 8-K, which are incorporated by reference into this joint proxy statement/prospectus. You should also read and consider the other information in this joint proxy statement/prospectus and the other documents incorporated by reference in this joint proxy statement/prospectus. See the section entitled "Where You Can Find More Information" of this joint proxy statement/prospectus.

Risk Factors Relating to the Mergers

US Ecology stockholders and NRCG stockholders cannot be sure of the value of the merger consideration they will receive.

        US Ecology stockholders and NRCG stockholders will be entitled to receive a fixed number of shares of Holdco Common Stock in the ECOL Merger and the NRCG Merger, respectively, rather than a number of shares of Holdco Common Stock with a particular fixed market value. The market values of ECOL Common Stock and NRCG Common Stock at the Effective Time may vary significantly from their prices on the date prior to the date the Merger Agreement was executed, the date of this joint proxy statement/prospectus or the date on which US Ecology stockholders and NRCG common stockholders vote on the proposal to adopt the Merger Agreement. Because the exchange ratios are fixed and will not be adjusted to reflect any changes in the market prices of ECOL Common Stock or NRCG Common Stock, the market value of the Holdco Common Stock issued in the ECOL Merger or the NRCG Merger, as applicable, and the ECOL Common Stock and NRCG Common Stock surrendered in the ECOL Merger and the NRCG Merger, respectively, may be higher or lower than the values of these shares on earlier dates. All of the merger consideration to be received by US Ecology stockholders and NRCG stockholders will be Holdco Common Stock (other than any cash in lieu of fractional shares received by NRCG stockholders). At the time of the special meetings, US Ecology stockholders and NRCG stockholders will not know or be able to determine the value of the Holdco Common Stock they may receive upon completion of the Mergers. Changes in the market prices of ECOL Common Stock and NRCG Common Stock may result from a variety of factors that are beyond the control of US Ecology or NRCG, including changes in their respective businesses, operations and prospects, regulatory considerations, governmental actions, and legal proceedings and other developments. Market assessments of the benefits of the Mergers, the likelihood that the Mergers will be completed and general and industry-specific market and economic conditions may also have an effect on the market price of ECOL Common Stock and NRCG Common Stock. Changes in market prices of ECOL Common Stock and NRCG Common Stock may also be caused by fluctuations and developments affecting industry-specific and general economic and market conditions and may have an adverse effect on ECOL Common Stock and NRCG Common Stock prior to the consummation of the Mergers.

        Neither US Ecology nor NRCG is permitted to terminate the Merger Agreement solely because of changes in the market prices of either party's common stock. In addition, the market values of ECOL Common Stock and NRCG Common Stock may vary significantly from the date of the special meetings to the date of the completion of the Mergers. You are urged to obtain up-to-date prices for ECOL Common Stock and NRCG Common Stock. There is no assurance that the Mergers will be completed,

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that there will not be a delay in the completion of the Mergers or that all or any of the anticipated benefits of the Mergers will be obtained.

        US Ecology and NRCG are working to complete the transactions as promptly as practicable. The parties currently expect that the Mergers will be completed during the fourth quarter of 2019, subject to the satisfaction or waiver of the conditions to the closing of the Mergers. Moreover, during the period between the special meetings and the closing of the Mergers, events, conditions or circumstances could arise that could have a material impact or effect on US Ecology, NRCG or the industries in which they operate.

The market price for Holdco Common Stock may be affected by factors different from those that historically have affected ECOL Common Stock and NRCG Common Stock.

        Upon completion of the Mergers, holders of shares of ECOL Common Stock (other than any shares held in treasury), holders of shares of NRCG Common Stock (other than any shares held in treasury) and holders of NRCG Series A Preferred Stock will become holders of shares of Holdco Common Stock. US Ecology and NRCG each have businesses that differ from each other. Accordingly, the results of operations of Holdco will be affected by some factors that are different from those currently affecting the results of operations of each of US Ecology and NRCG. For a discussion of the businesses of US Ecology and NRCG and of some important factors to consider in connection with those businesses, see the documents incorporated by reference in this joint proxy statement/prospectus and referred to under "Where You Can Find More Information" of this joint proxy statement/prospectus.

Any delay in completing the Mergers may reduce or eliminate the benefits expected to be achieved thereunder.

        The Mergers are subject to a number of conditions beyond US Ecology's and NRCG's control that may prevent, delay or otherwise materially adversely affect their completion. We cannot predict whether and when these other conditions will be satisfied. Any delay in completing the Mergers could cause the combined company not to realize, or to be delayed in realizing, some or all of the synergies and other benefits that the parties expect to achieve if the Mergers are successfully completed within their expected time frame. See the section entitled "The Merger Agreement—Conditions to Completion of the Mergers" in this joint proxy statement/prospectus.

US Ecology and NRCG will be subject to business uncertainties while the Mergers are pending, which may cause a loss of customers, suppliers, management personnel and other key employees that could adversely affect the future business and operations of the combined company.

        Uncertainty about the completion or effect of the Mergers may affect the relationship between US Ecology and NRCG and their respective customers and suppliers and may have an adverse effect on US Ecology and/or NRCG, and consequently on the combined company. These uncertainties may cause customers, suppliers and others that deal with the parties to seek to change existing business relationships with them and to delay or defer decisions concerning US Ecology or NRCG. Changes to existing business relationships, including termination or modification, could negatively affect each of US Ecology's and NRCG's revenues, earnings and cash flow, as well as the market price of its common stock.

        US Ecology and NRCG are dependent on the experience and industry knowledge of their respective officers and other key employees to execute their business plans. The combined company's success after the Mergers will depend in part upon the ability of US Ecology and NRCG to retain management personnel and other key employees. Current and prospective employees of US Ecology and NRCG may experience uncertainty about their roles within the combined company following the Mergers, which may have an adverse effect on the ability of each of US Ecology and NRCG to attract

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or retain management personnel and other key employees. If key employees depart because of issues related to the uncertainty and difficulty of integration or a desire not to remain with the businesses, the combined company's business following the consummation of the Mergers could be negatively impacted. Accordingly, no assurance can be given that the combined company will be able to attract or retain management personnel and other key employees of US Ecology and NRCG to the same extent that US Ecology and NRCG have previously been able to attract or retain their own employees. A failure by US Ecology, NRCG or, following the completion of the Mergers, the combined company to attract and retain management personnel and other key employees during the period prior to or after the completion of the Mergers could have a negative impact on their respective businesses.

US Ecology and NRCG will be subject to certain contractual restrictions while the Mergers are pending.

        The Merger Agreement restricts each of US Ecology and NRCG from making certain acquisitions and divestitures, issuing or selling securities other than pursuant to certain specified exceptions, and taking other specified actions, if outside the ordinary course of business consistent with past practice, until the earlier of the completion of the Mergers or the termination of the Merger Agreement without the consent of the other party. These restrictions may prevent US Ecology and/or NRCG from pursuing attractive business opportunities that may arise prior to the completion of the Mergers and could have the effect of delaying or preventing other strategic transactions. Adverse effects arising from the pendency of the Mergers could be exacerbated by any delays in consummation of the Mergers or the termination of the Merger Agreement. See the section entitled "The Merger Agreement—Conduct of Business Pending the Effective Time" of this joint proxy statement/prospectus.