Exhibit 10.1

SEPARATION BENEFITS PLAN AND EMPLOYMENT AGREEMENT

(AND SUMMARY PLAN DESCRIPTION)

EFFECTIVE FEBRUARY 13, 2012

THIS SEPARATION BENEFITS PLAN AND EMPLOYMENT AGREEMENT (this “Plan”) is made and effective as of February 13, 2012 (the “Effective Date”), by and between Ronald J. Mittelstaedt (the “Executive”) and Waste Connections, Inc., a Delaware corporation (the “Company”), and amends and restates in its entirety that certain Employment Agreement, dated as of October 1, 1997, by and among the Executive, the Company, J. Bradford Bishop, Frank W. Cutler and James N. Cutler, Jr., as amended as of June 1, 2000 by and between the Executive and the Company, and as further amended as of March 1, 2004 by and between the Executive and the Company. One of the purposes of this Plan is to provide for severance and change of control benefits to the Executive in the event that employment with the Company is involuntarily terminated.

This Plan is intended to be an unfunded “top hat” welfare plan subject to the Employee Retirement Income Security Act of 1974, as amended (“ERISA”). This Plan document is also the summary plan description of this Plan.

Immediately on termination of employment pursuant to this Section 7(a), the Company shall pay to the Executive in a lump sum his then current Base Salary under Section 4(a) on a prorated basis to the Date of Termination (as defined in Section 9(b)). For the avoidance of doubt, upon termination of employment for Cause, the Executive shall be subject to the non-competition and non-solicitation provisions of Section 12. On the Executive’s termination of employment pursuant to this Section 7(a), the Executive shall not be entitled to any additional benefits or compensation above accrued but unpaid amounts, to the extent required by applicable law. On termination of employment pursuant to this Section 7(a), the Executive shall forfeit his Bonus under Section 4(b) for the year in which such termination occurs. In addition, on termination pursuant to this Section 7(a), the Executive shall forfeit all outstanding but unvested stock options, unvested restricted stock, unvested restricted stock units (“RSUs”) and any other unvested equity awards related to the capital stock of the Company (such stock options, restricted stock, RSUs and other equity awards together, the “equity awards”).

For purposes of this Plan, “Cause” shall mean:

In the event that the Executive’s employment is terminated pursuant to this Section 7(a), on or prior to the 90^th day following the Date of Termination, the Board shall elect whether the Restricted Period (as defined in Section 12 hereof), during which the Executive shall be subject to the non-competition and non-solicitation provisions of Section 12 hereof, shall be extended to the end of the 24th full month following the Date of Termination (the “Optional Restricted Period”). If the Board elects to apply the Optional Restricted Period, then in addition to the payments and benefits described in the preceding paragraphs of this Section 7(a), the Company shall pay to the Executive Seven Million Dollars ($7,000,000) in a lump sum on the first anniversary of the Date of Termination.

In the event that the Executive’s employment is terminated pursuant to this Section 7(b), on or prior to the 90^th day following the Date of Termination, the Board shall elect whether to apply the Optional Restricted Period. If the Board elects to apply the Optional Restricted Period, then in addition to the payments and benefits described in the preceding paragraph of this Section 7(b), Company shall pay to the Executive the amounts as set forth in the last paragraph of Section 7(a) hereof relating to the election of the Optional Restricted Period at the times and subject to the conditions set forth therein.

In the event that the Executive’s employment is terminated pursuant to this Section 7(c), on or prior to the 90^th day following the Date of Termination, the Board shall elect whether to apply the Optional Restricted Period. If the Board elects to apply the Optional Restricted Period, then in addition to the payments and benefits described in the preceding paragraph of this Section 7(c), the Company shall pay to the Executive the amounts as set forth in the last paragraph of Section 7(a) hereof relating to the election of the Optional Restricted Period at the times and subject to the conditions set forth therein.

For purposes of this Agreement, “Good Reason” shall mean:

No termination of employment shall constitute Good Reason unless (i) the Executive’s Notice of Termination is provided to the Company within 30 days of the initial occurrence of the action giving rise to Good Reason and (ii) the Company fails to remedy the basis for Good Reason prior to 30 days following the date of the Notice of Termination.

In the event that the Executive’s employment is terminated pursuant to this Section 8(a), on or prior to the 90^th day following the Date of Termination, the Board shall elect whether to apply the Optional Restricted Period. If the Board elects to apply the Optional Restricted Period, then in addition to the payments and benefits described in the preceding paragraphs of this Section 8(a), the Company shall pay to the Executive the amounts as set forth in the last paragraph of Section 7(a) hereof relating to the election of the Optional Restricted Period at the times and subject to the conditions set forth therein.

In the event that the Executive’s employment is terminated pursuant to this Section 8(b), on or prior to the 90^th day following the Date of Termination, the Board shall elect whether to apply the Optional Restricted Period. If the Board elects to apply the Optional Restricted Period, then in addition to the payments and benefits described in the preceding paragraph of this Section 8(a), the Company shall pay to the Executive the amounts as set forth in the last paragraph of Section 7(a) hereof relating to the election of the Optional Restricted Period at the times and subject to the conditions set forth therein.

The term “Parent” means a corporation, partnership, trust, limited liability company or other entity that is the ultimate “beneficial owner” (as defined above) of fifty percent (50%) or more of the Company’s outstanding voting securities.

No benefits deemed non-qualified deferred compensation subject to Section 409A shall be payable upon a Change in Control pursuant to this Plan unless such Change in Control constitutes a “change in control event” with respect to the Company within the meaning of Section 409A.

[Signatures appear on the following page]

IN WITNESS WHEREOF, the parties have executed and delivered this Separation Benefits Plan and Employment Agreement as of the day and year set forth above.

Address: ####

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APPENDIX A

Detailed Claims And Arbitration Procedures

Initial Claims

All claims shall be presented to the Plan Administrator in writing. Within ninety (90) days after receiving a claim, a claims official appointed by the Plan Administrator shall consider the claim and issue his or her determination thereon in writing. If the Plan Administrator or claims official determines that an extension of time is necessary, the claims official may extend the determination period for up to an additional ninety (90) days by giving the Claimant written notice indicating the special circumstances requiring the extension of time prior to the termination of the initial ninety (90) day period. Any claims that the Claimant does not pursue in good faith through the initial claims stage shall be treated as having been irrevocably waived.

Claims Decisions

If the claim is granted, the benefits or relief the Claimant seeks shall be provided. If the claim is wholly or partially denied, the claims official shall, within ninety (90) days (or a longer period, as described above), provide the Claimant with written notice of the denial, setting forth, in a manner calculated to be understood by the Claimant: (1) the specific reason or reasons for the denial; (2) specific references to the provisions on which the denial is based; (3) a description of any additional material or information necessary for the Claimant to perfect the claim, together with an explanation of why the material or information is necessary; and (4) an explanation of the procedures for appealing denied claims. If the Claimant can establish that the claims official has failed to respond to the claim in a timely manner, the Claimant may treat the claim as having been denied by the claims official.

Appeals of Denied Claims

Each Claimant shall have the opportunity to appeal the claims official’s denial of a claim in writing to an appeals official appointed by the Plan Administrator (which may be a person, committee, or other entity). A Claimant must appeal a denied claim within sixty (60) days after receipt of written notice of denial of the claim, or within sixty (60) days after it was due if the Claimant did not receive it by its due date. The Claimant shall have the opportunity to submit written comments, documents, records and other information relating to the Claimant’s claim. The Claimant (or the Claimant’s duly authorized representative) shall be provided upon request and free of charge, reasonable access to, and copies of, all documents, records and other information relevant to the Claimant’s claim. The appeals official shall take into account during its review all comments, documents, records and other information submitted by the Claimant relating to the claim, without regard to whether such information was submitted or considered in the initial benefits review. Any claims that the Claimant does not pursue in good faith through the appeals stage, such as by failing to file a timely appeal request, shall be treated as having been irrevocably waived.

Appeals Decisions

The decision by the appeals official shall be made not later than sixty (60) days after the written appeal is received by the Plan Administrator, however, if the appeals official determines that an extension of time is necessary, the appeals official may extend the determination period for up to an additional sixty (60) days by giving the Claimant written notice indicating the special circumstances requiring the

Appendix A-

extension of time prior to the termination of the initial sixty (60) day period. The appeal decision shall be in writing, shall be set forth in a manner calculated to be understood by the Claimant and shall include the following: (1) the specific reason or reasons for the denial; (2) specific references to the provisions on which the denial is based; (3) a statement that the Claimant is entitled to receive, upon request and free of charge, reasonable access to, and copies of, all documents, records and other information relevant to the Claimant’s claim. If a Claimant does not receive the appeal decision by the date it is due, the Claimant may deem the appeal to have been denied.

Procedures

The Plan Administrator shall adopt procedures by which initial claims shall be considered and appeals shall be resolved; different procedures may be established for different claims. All procedures shall be designed to afford a Claimant full and fair consideration of his or her claim.

Arbitration of Rejected Appeals

If a Claimant has pursued a claim through the appeal stage of these claims procedures, the Claimant may contest the actual or deemed denial of that claim through arbitration, as described below. In no event shall any denied claim be subject to resolution by any means (such as in a court of law) other than arbitration in accordance with the following provisions.

Request for Arbitration

A Claimant must submit a request for arbitration to the Plan Administrator within 60 days after receipt of the written denial of an appeal (or within sixty (60) days after he or she should have received the determination). The Claimant or the Plan Administrator may bring an action in any court of appropriate jurisdiction to compel arbitration in accordance with these procedures.

Applicable Arbitration Rules

If the Claimant has entered into a valid arbitration agreement with the Company, the arbitration shall be conducted in accordance with that agreement. If not, the rules set forth in the balance of this Appendix shall apply: The arbitration shall be held under the auspices of the Judicial Arbitration and Mediation Service (“JAMS”), whichever is chosen by the party who did not initiate the arbitration. Except as provided below, the arbitration shall be in accordance with JAMS’ then-current employment dispute resolution rules. The Arbitrator shall apply the Federal Rules of Evidence and shall have the authority to entertain a motion to dismiss or a motion for summary judgment by any party and shall apply the standards governing such motions under the Federal Rules of Civil Procedure. The Federal Arbitration Act shall govern all arbitrations that take place under these Detailed Claims and Arbitration Procedures (or that are required to take place under them), and shall govern the interpretation or enforcement of these Procedures or any arbitration award. To the extent that the Federal Arbitration Act is inapplicable, Texas law pertaining to arbitration agreements shall apply.

Arbitrator

The arbitrator (the “Arbitrator”) shall be an attorney familiar with employee benefit matters who is licensed to practice law in the state in which the arbitration is convened. The Arbitrator shall be selected in the following manner from a list of eleven arbitrators drawn by the sponsoring organization under whose auspices the arbitration is being conducted and taken from its panel of labor and

Appendix A-

employment arbitrators. Each party shall designate all arbitrators on the list whom they find acceptable; the parties shall then alternately strike arbitrators from the list of arbitrators acceptable to both parties, with the party who did not initiate the arbitration striking first. If only one arbitrator is acceptable to both parties, he or she will be the Arbitrator. If none of the arbitrators is acceptable to both parties, a new panel of arbitrators shall be obtained from the sponsoring organization and the selection process shall be repeated.

Location

The arbitration will take place in or near the city in which the Claimant is or was last employed by the Company or in which the Plan is principally administered, whichever is specified by the Plan Administrator, or in such other location as may be acceptable to both the Claimant and the Plan Administrator.

Authority of Arbitrator

The Arbitrator shall have the authority to resolve any factual or legal claim relating to the Plan or relating to the interpretation, applicability, or enforceability of these arbitration procedures, including, but not limited to, any claim that these procedures are void or voidable. The Arbitrator may grant a Claimant’s claim only if the Arbitrator determines that it is justified because: (1) the appeals official erred on an issue of law; or (2) the appeals official’s findings of fact, if applicable, were not supported by substantial evidence. The arbitration shall be final and binding on all parties.

Limitation on Scope of Arbitration

The Claimant may not present any evidence, facts, arguments, or theories at the arbitration that the Claimant did not pursue in his or her appeal, except in response to new evidence, facts, arguments, or theories presented on behalf of the other parties to the arbitration. However, an arbitrator may permit a Claimant to present additional evidence or theories if the Arbitrator determines that the Claimant was precluded from presenting them during the claim and appeal procedures due to procedural errors of the Plan Administrator or its delegates.

Administrative Record

The Plan Administrator shall submit to the Arbitrator a certified copy of the record on which the appeals official’s decision was made.

Experts, Depositions, and Discovery

Except as otherwise permitted by the Arbitrator on a showing of substantial need, either party may: (1) designate one expert witness; (2) take the deposition of one individual and the other party’s expert witness; (3) propound requests for production of documents; and (4) subpoena witnesses and documents relating to the discovery permitted in this paragraph.

Pre-Hearing Procedures

At least thirty (30) days before the arbitration hearing, the parties must exchange lists of witnesses, including any expert witnesses, and copies of all exhibits intended to be used at the hearing. The Arbitrator shall have jurisdiction to hear and rule on pre-hearing disputes and is authorized to hold pre-hearing conferences by telephone or in person, as the Arbitrator deems necessary.

Appendix A-

Transcripts

Either party may arrange for a court reporter to provide a stenographic record of the proceedings at the party’s own cost.

Post-Hearing Procedures

Either party, on request at the close of the hearing, may be given leave to file a post-hearing brief within the time limits established by the Arbitrator.

Costs and Attorneys’ Fees

The prevailing party shall be entitled to reasonable attorneys’ fees, costs and necessary disbursements in addition to any other relief to which such party may be entitled, except as required by applicable law.

Procedure for Collecting Costs From Claimant

Before the arbitration commences, the Claimant must deposit with the Plan Administrator his or her share of the anticipated fees and costs of the Arbitrator, as reasonably determined by the Plan Administrator. At least two weeks before delivering his or her decision, the Arbitrator shall send his or her final bill for fees and costs to the Plan Administrator for payment. The Plan Administrator shall apply the amount deposited by the Claimant to pay the Claimant’s share of the Arbitrator’s fees and costs and return any surplus deposit. If the Claimant’s deposit is insufficient, the Claimant will be billed for any remaining amount due. Failure to pay any amount within 10 days after it is billed shall constitute the Claimant’s irrevocable election to withdraw his or her arbitration request and abandon his or her claim.

Arbitration Award

The Arbitrator shall render an award and opinion in the form typically rendered in labor arbitrations. Within twenty (20) days after issuance of the Arbitrator’s award and opinion, either party may file with the Arbitrator a motion to reconsider, which shall be accompanied by a supporting brief. If such a motion is filed, the other party shall have twenty (20) days from the date of the motion to respond, after which the Arbitrator shall reconsider the issues raised by the motion and either promptly confirm or promptly change his or her decision. The decision shall then be final and conclusive on the parties. Arbitrator fees and other costs of a motion for reconsideration shall be borne by the losing party, unless the Arbitrator orders otherwise. Either party may bring an action in any court of appropriate jurisdiction to enforce an arbitration award. A party opposing enforcement of an arbitration award may not do so in an enforcement proceeding, but must bring a separate action in a court of competent jurisdiction to set aside the award. In any such action, the standard of review shall be the same as that applied by an appellate court reviewing the decision of a trial court in a nonjury trial.

Severability

The invalidity or unenforceability of any part of these arbitration procedures shall not affect the validity of the rest of the procedures.

Appendix A-

APPENDIX B

ADDITIONAL INFORMATION

RIGHTS UNDER ERISA

As a participant in the Plan, you are entitled to certain rights and protections under ERISA. ERISA provides that all Plan participants will be entitled to:

Receive Information About Your Plan and Benefits

1. Examine, without charge, at the Company’s headquarters, all documents governing the Plan including collective bargaining agreements, if any, and annual reports and Plan descriptions.

2. Obtain, upon written request to the Plan administrator, copies of documents governing the operation of the Plan, including collective bargaining agreements, if any, and copies of the latest annual report (Form 5500 Series) and summary plan description. The Plan Administrator may make a reasonable charge for the copies.

3. Receive a summary of the Plan’s annual financial report, if any. The Plan administrator is required by law to furnish each participant with a copy of this summary annual report.

Prudent Actions by Plan Fiduciaries

In addition to creating rights for Plan participants, ERISA imposes duties upon the people who are responsible for the operation of the employee benefit plan. The people who operate your Plan, called “fiduciaries” of the Plan, have a duty to do so prudently and in the interest of you and other Plan participants and beneficiaries. No one, including the Company, your union, or any other person, may fire you or otherwise discriminate against you in any way to prevent you from obtaining a welfare benefit or exercising your right under ERISA.

Enforce Your Rights

If your claim for a welfare benefit is denied or ignored, in whole or in part, you have a right to know why this was done, to obtain copies of documents relating to the decision without charge, and to appeal any denial, all within certain time schedules. Under ERISA, there are steps you can take to enforce the above rights. For instance, if you request a copy of plan documents or the latest annual report from the Plan and do not receive them within thirty (30) days, you may file suit in a Federal court. In such a case, the court may require the Plan Administrator to provide the materials and pay you up to $110 a day until you receive the materials, unless the materials were not sent because of reasons beyond the control of the Plan administrator. If you have a claim for benefits, which is denied or ignored, in whole or in part, you may file suit in a state or Federal court. In addition, if you disagree with the Plan’s decision or lack thereof concerning the qualified status of a domestic relations order or a medical child support order, you may file suit in Federal court. If it should happen that Plan fiduciaries misuse the Plan’s money, or if you are discriminated against for asserting your rights, you may seek assistance from the U.S. Department of Labor, or you may file suit in a federal court. The court will decide who should pay court costs and legal fees. If you are successful, the court may order the person you have sued to pay these costs and fees. If you lose, the court may order you to pay these costs and fees, for example, if it finds your claim is frivolous.

Appendix B-

Assistance with Your Questions

If you have any questions about your Plan, you should contact the Plan Administrator. If you should have any questions about this statement or about your rights under ERISA, or if you need assistance in obtaining documents from the Plan Administrator, you should contact the nearest office of the Employee Benefits Security Administration, U.S. Department of Labor, listed in your telephone directory or the Division of Technical Assistance and Inquiries, Employee Benefits Security Administration, U.S. Department of Labor, 200 Constitution Avenue N. W., Washington, D. C. 20210. You may also obtain certain publications about your rights and responsibilities under ERISA by calling the publications hotline of the Employee Benefits Security Administration.

ADMINISTRATIVE INFORMATION

Appendix B-