Exhibit A

JOINT FILING AGREEMENT

We, the undersigned, hereby express our agreement that the attached Schedule 13D is, and any further amendments thereto signed by each of the undersigned shall be, filed on behalf of each of us pursuant to and in accordance with the provisions of Rule 13d-1(k) under the Securities Exchange Act of 1934, as amended. This agreement may be terminated with respect to the obligations to jointly file future amendments to such statement on Schedule 13D as to any of the undersigned upon such person giving written notice thereof to each of the other persons signatory hereto, at the principal office thereof.

Date: September 23, 2016	WESTERN REFINING, INC.
	By:	/s/ Karen B. Davis
	Name:	Karen B. Davis
	Title:	Executive Vice President and Chief Financial Officer
	GIANT INDUSTRIES, INC.
	By:	/s/ Karen B. Davis
	Name:	Karen B. Davis
	Title:	Executive Vice President and Chief Financial Officer
	WESTERN ACQUISITION HOLDINGS, LLC
	By:	/s/ Karen B. Davis
	Name:	Karen B. Davis
	Title:	Executive Vice President and Chief Financial Officer
	WESTERN REFINING SOUTHWEST, INC.
	By:	/s/ Karen B. Davis
	Name:	Karen B. Davis
	Title:	Executive Vice President and Chief Financial Officer