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Billings/Laurel Sulfur Dioxide Air Quality Plan

Release Date: 3/27/2002
Contact Information:
EPA 303-312-6005,

Release Date: 3/27/2002
Contact Information:
EPA 303-312-6004,

Release Date: 3/27/2002
Contact Information:
EPA 303-312-6437,

Release Date: 3/27/2002
Contact Information:
EPA 303-312-6603,

Release Date: 3/27/2002
Contact Information:
EPA 800-227-8917
EPA’s Action:

Approval: EPA will approve much of the Billings/Laurel State Implementation Plan (SIP) for sulfur dioxide (SO2). The Agency is addressing other portions of the plan, as discussed below. The Agency originally proposed action on the Billings/Laurel SO2 SIP in July 1999.

Rejection: EPA is disapproving the following provisions of the SIP:

! The escape clause - a clause which allows sources to back out of the plan.
! The Montana Sulphur & Chemical Company’s (MSCC’s) stack height credit and emission limitations on the 100-meter stack because of improper stack-height credit given by the State.
! The emission limitation on MSCC’s auxiliary vent stacks.
! The attainment demonstration, because:
W improper stack height credit and emission limits at MSCC;
W the lack of flare emission limits at Cenex, Conoco, ExxonMobil, and MSCC; and
W the disapproval of the emission limit for MSCC’s auxiliary vent stacks.
! Other provisions of the SIP affected by above disapprovals.

Limitedly approving/disapproving: EPA is “limitedly approving/disapproving” the following provision of the SIP:
The emission limitation for the 30-meter stack at MSCC

Proposed action: Additionally, EPA is proposing to approve, “limitedly approve” and “limitedly disapprove” other provisions of the Billings/Laurel SO2 SIP (most pertain to compliance monitoring methods) submitted to EPA after our July 1999 proposed action:

EPA is proposing to approve the following provisions of the SO2 SIP:
T Yellowstone Energy Limited Partnership’s (YELP’s) emission limits and reporting requirements.
T Provisions related to the burning of SWS overheads in the F-1 Crude Furnace (and exhausted through the F-2 Crude/Vacuum Heater stack) at ExxonMobil.
T Other minor changes in ExxonMobil’s exhibit A.

      EPA is proposing to “limitedly approve” and “limitedly disapprove” the following provisions:
Provisions related to the fuel gas combustion emission limits at ExxonMobil.
Provisions related to ExxonMobil’s coker CO-boiler emission limits.
Provisions related to the burning of SWS overheads at Cenex.

Future Federal Implementation Plan: In a future notice, EPA plans to propose instituting a Federal Implementation Plan (FIP) to cover the parts of the State’s plan considered unacceptable.

Health/Environmental Effects: Sulfur dioxide (SO2) results from burning fossil fuels. Asthmatics exposed to short peaks of SO2 when exercising may have temporary breathing difficulty, such as shortness of breath. The current standards help prevent asthma attacks and other acute lung illnesses, such as respiratory infections. Asthmatics, the elderly, children and people with existing lung disease are the most at risk to health problems caused by the pollutant. Environmental problems resulting from SO2 emissions traveling downwind can include reduced visibility in national parks and acid rain/snow.

History: In March 1993, EPA determined the existing SO2 SIP for the Billings/Laurel area would not meet national SO2 air quality standards based on computer modeled SO2 violations. EPA directed the State to revise its SIP by September 1994. In September 1995, August 1996, April 1997, July 1998 and May 2000 the State submitted revisions of the SIP for the area, along with control strategies for the seven affected industrial facilities (Cenex, Conoco, ExxonMobil, Montana Power, Montana Sulphur & Chemical Company, Western Sugar and Yellowstone Energy Limited Partnership).