[6] U.S. Environmental Protection Agency, “Control of Emissions of Air Pollution From Nonroad Diesel Engines and Fuel: Final Rule,” 40 CFR Parts 9, 69, et al. (May 11, 2004).

[7] Tier 4 refers to the fourth set of emissions standards applying to nonroad diesel emissions. The standards do not apply to locomotive and marine applications, which are covered by separate EPA regulations.

[8] U.S. Environmental Protection Agency, “Control of Emissions of Air Pollution From New Locomotive Engines and New Marine Compression Ignition Engines Less Than 30 Liters per Cylinder: Proposed Rule,” 40 CFR Parts 92 and 94 (June 29, 2004).

[9] U.S. Environmental Protection Agency, Clean Air Nonroad Diesel Summary, EPA-420-F-04-029 (Washington, DC, May 2004), web site www. epa.gov/otaq/regs/ nonroad/equip-hd/2004fr/420f04029.htm.

[10] The EPA has designated seven regional Credit Trading Areas (CTAs) in the United States, organized along State lines. See web site www.npradc.org/issues/fuels/pdf/ diesel_summary.pdf.

[11] Transmix is the mixture in a pipeline at the interface between adjoining batches of petroleum product with dissimilar physical characteristics, which cannot be absorbed into adjoining batches.

[12] U.S. Environmental Protection Agency, Clean Air Nonroad Diesel Rule Facts and Figures, EPA-420-F-04-037 (Washington, DC, May 2004), web site www.epa.gov/ nonroad-diesel/2004fr/420f04037.htm.