From the refiners to the truckstops, adequate supply of ultra low sulfur diesel (ULSD) persist a full day after the Environmental Protection Agency’s (EPA) mandate it must make up 80% of the highway diesel imported and produced by U.S. refiners went into effect.

June 1 also marked the first day retail outlets must label its on-highway diesel pumps as either ULSD or low sulfur, with the ULSD label stating that ULSD is required for 2007 and later highway vehicles and engines but is recommended for all diesel engines. The low sulfur diesel label, by contrast, warns that it’s prohibited for use in 2007 or later engines.

According to Charlie Dresna, director of technical advocacy activities for the National Petrochemical & Refiners Assn. (NPRA), the June 1 deadline marks an important milestone for refiners – one the industry has prepared for since EPA completed its ULSD program in early 2001. In a 2005 pre-compliance report, refiners indicated that by June 1 this year, it expected 90% of its highway diesel it imports or produces to be ULSD— exceeding the EPA’s requirement.

“[The June 1 deadline] is not a time to say that the sky is falling, but to learn and see where the problems are that we didn’t anticipate,” Dresna told FleetOwner. “Given the fact that a real [ULSD spec] doesn’t have to be at market until mid-fall, everyone should be and is using this time to work out the kinks and see where the pitfalls might be and work so when the final compliance date arrives (Oct. 15), the [ULSD] will come out of the nozzle.”

In spite of all the preparation of refiners, plenty of potential remains for ULSD to be contaminated as it travels from refinery to terminals and on to retail pumps at truck stops and other locations. ULSD’s sulfur content is supposed to be limited to 15 parts per million (ppm) or less, versus today’s low sulfur spec of 500 ppm. Yet ULSD remains vulnerable to losing its status if it picks up enough residual sulfur to exceed the 15 ppm limit during shipment to the pump, before the driver fills up.

“NPRA continues to have concerns that this rule would have an impact on supply on a going-forward basis,” Dresna said.

The National Assn. of Truck Stop Operators (NATSO) is also watching for distribution and contamination problems. “We remain concerned that there will be challenges, including supply disruptions, during the transition period and following the retail implementation deadline,” stated NATSO president & CEO Lisa Mullings.

By Oct. 15 all retailers that choose to carry ULSD must meet its specs. This means ensuring that its fuel storage tanks must be flushed of excess sulfur accumulated from low sulfur diesel so that ULSD-spec diesel leaves the nozzle. Consequently, retailers probably won’t start marketing ULSD until mid-October to ensure that the terminals distribute an adequate supply, NATSO said.

“Once a truckstop has invested the time and expense to transition a tank to ULSD, it cannot easily switch back and forth between the products,” Mullings said.