Exhibit 10.19

FIRST AMENDING AGREEMENT

THIS
AGREEMENT is made as of March 1, 2005

BETWEEN:



OF
THE FIRST PART,

and



OF
THE SECOND PART,

and



OF
THE THIRD PART.

WHEREAS
the parties hereto have agreed to amend and supplement certain provisions of the Credit Agreement as hereinafter set forth;

NOW
THEREFORE THIS AGREEMENT WITNESSES that in consideration of the covenants and agreements herein contained and other good and valuable consideration, the receipt and sufficiency of
which are hereby conclusively acknowledged by each of the parties hereto, the parties hereto covenant and agree as follows:

1.     Interpretation

1.1.  In
this Agreement and the recitals hereto, unless something in the subject matter or context is inconsistent therewith:

"Agreement" means this agreement, as amended, modified, supplemented or restated from time to time.

"Credit Agreement" means the credit agreement made as of May 11, 2004 between the Borrower (by its predecessor, RPC Acquisition
Company), the Lenders and the Agent.

1.2.  Capitalized
terms used herein without express definition shall have the same meanings herein as are ascribed thereto in the Credit Agreement.

1.3.  The
division of this Agreement into Sections and the insertion of headings are for convenience of reference only and shall not affect the construction or
interpretation of this Agreement. The terms "this Agreement", "hereof", "hereunder" and similar expressions refer to this Agreement and not to any particular Section or other portion hereof and
include any agreements supplemental hereto.

1.4.  This
Agreement shall be governed by and construed in accordance with the laws of the Province of Alberta and the federal laws of Canada applicable therein.

2.     Amendments and Supplements

2.1.Definition of "Change of Control".The existing definition of "Change of Control" contained in
Section 1.1(1) of the Credit Agreement is hereby amended to delete the references to "The Anschutz Corporation" in the third line of subparagraph (b) thereof, in the fourth and
fifth lines of subparagraph (c) thereof, in the fifth line of subparagraph (d) thereof and in the fifth line of subparagraph (e) thereof and to substitute therefor, in all cases,
"LB Pacific, LP". The parties hereto hereby confirm and agree that all references to the term "The Anschutz Corporation" in the definition of "Change of Control" shall hereinafter be references to "LB
Pacific, LP".

3.     Representations and Warranties

The Borrower hereby represents and warrants as follows to each Lender and the Agent and acknowledges and confirms that each Lender and the Agent is relying upon
such representations and warranties:

(a)Capacity, Power and Authority



(b)Authorization; Enforceability



(c)Compliance with Other Instruments



(d)No Default



The
representations and warranties set out in this Agreement shall survive the execution and delivery of this Agreement and the making of each Drawdown, notwithstanding any
investigations or


examinations which may be made by or on behalf of the Agent, the Lenders or Lenders' Counsel. Such representations and warranties shall survive until the Credit Agreement has been terminated.

4.     Condition Precedent

The amendments and supplements to the Credit Agreement contained herein shall be effective upon each Guarantor executing and delivering to the Agent and the
Lenders a Confirmation of Guarantee in the form attached hereto.

5.     Confirmation of Credit Agreement and other Documents

The Credit Agreement and the other Documents to which the Borrower is a party and all covenants, terms and provisions thereof, except as expressly amended and
supplemented by this Agreement, shall be and continue to be in full force and effect and the Credit Agreement as amended and supplemented by this Agreement and each of the other Documents to which the
Borrower is a party are hereby ratified and confirmed and shall, from and after the date hereof, continue in full force and effect as herein amended and supplemented, with such amendments and
supplements being effective from and as of the date hereof upon satisfaction of the condition precedent set forth in Section 4 hereof.

6.     Further Assurances

The parties hereto shall from time to time do all such further acts and things and execute and deliver all such documents as are required in order to effect the
full intent of and fully perform and carry out the terms of this Agreement.

7.     Enurement

This Agreement shall enure to the benefit of and shall be binding upon the parties hereto and their respective successors and permitted assigns in accordance with
the Credit Agreement.

8.     Counterparts

This Agreement may be executed in any number of counterparts, each of which shall be deemed to be an original and all of which taken together shall be deemed to
constitute one and the same instrument, and it shall not be necessary in making proof of this Agreement to produce or account for more than one such counterpart. Such executed counterparts may be
delivered by facsimile transmission and, when so delivered, shall constitute a binding agreement of the parties hereto.

IN
WITNESS WHEREOF the parties hereto have executed this Agreement.

| |  | RANGELAND PIPELINE COMPANY
| |  | --------------------------
| |  | By:                       
| |  | By:                       

| |  | LENDERS:                            
| |  | ------------------------------------
| |  | ROYAL BANK OF CANADA                
| |  | By:                                 
| |  | By:                                 
| |  | BANK OF AMERICA, N.A., CANADA BRANCH
| |  | By:                                 
| |  | By:                                 
| |  | BANK OF MONTREAL                    
| |  | By:                                 
| |  | By:                                 
| |  | THE BANK OF NOVA SCOTIA             
| |  | By:                                 
| |  | By:                                 

| |  | BNP PARIBAS (CANADA)                         
| |  | ---------------------------------------------
| |  | By:                                          
| |  | By:                                          
| |  | CONGRESS FINANCIAL CORPORATION (CANADA)      
| |  | By:                                          
| |  | By:                                          
| |  | UNION BANK OF CALIFORNIA, N.A., CANADA BRANCH
| |  | By:                                          
| |  | By:                                          
| |  | AGENT:                                       
| |  | ROYAL BANK OF CANADA,in its capacity as Agent
| |  | By:                                          



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