Diesel fuel subject to the 15 ppm sulfur standard must meet that standard on a per-gallon basis and not on average. The pipeline or terminal must handle the interface in a manner that ensures that product distributed as subject to the 15 ppm cap is in compliance with that cap. If any portion of a tank that is offered for sale or supply as fuel subject to the 15 ppm sulfur cap is out of compliance with the 15 ppm cap, then that volume of fuel would be in violation. However, if a pipeline or terminal accidentally cuts part of an interface having a sulfur content greater than 15 ppm into a tank containing fuel subject to the 15 ppm sulfur standard, it may be possible to remedy the violation. We would not pursue an enforcement action where a terminal determines that product exceeding the 15 ppm standard has been added to a tank if the terminal: discovers the commingling of higher sulfur product with 15 ppm product through its quality assurance program and not by an EPA inspection; immediately locks down the tank before any of the product is released; transfers product exceeding the 15 ppm standard to some appropriate high sulfur product distribution; retests the 15 ppm product tank to assure that the entire remaining volume of the tank meets the 15 ppm standard before releasing the product as 15 ppm product; and maintains records demonstrating the occurrence, the actions taken to remedy the violation, sampling and test results, and actions to prevent future violations.

Such situations may also be remedied by blending the contaminated product with low sulfur product in order to bring the sulfur level of all the product in the tank to the 15 ppm sulfur standard. Again, before releasing product the sulfur level should be retested, and records of the occurrence, remedial actions, sampling and test results, and of actions to prevent future violations should be maintained.

Finally, such situations could be remedied by downgrading the entire volume of product affected by the commingling with the higher sulfur interface. When 15 ppm product is downgraded, the party should document the circumstances that gave rise to the downgrading. The diesel fuel in question should be segregated from diesel fuel subject to the 15 ppm standard, the product transfer documents must reflect the downgraded classification, and the diesel fuel must not be sold, dispensed or transported in a manner that is inconsistent with the downgraded classification.

Question and Answer was originally posted at Questions and Answers on the Clean Diesel Fuel Rules (PDF)(135 pp, 888 K, EPA420-B-06-010, July 2006, About PDF)