EPA, Navistar formally end litigation

EPA, CARB move ahead with further SCR reviews

The legal battle Navistar waged against the U.S. Environmental Protection Agency since March 2009 formally came to an end Aug. 16 when the two parties jointly filed to withdraw the lawsuit and a federal appeals court agreed. The dismissal of the case followed a settlement agreement executed in June whereby EPA agreed to hold a workshop or hearing to consider questions surrounding the use of selective catalytic reduction (SCR) to achieve the maximum levels of oxides of nitrogen that EPA mandated for heavy-duty diesel engines beginning in January of this year.

Meanwhile, the California Air Resources Board already held a workshop in late July to make good on its own settlement with Navistar. Navistar, which relies on advanced exhaust gas recirculation (EGR) to comply with EPA’s 2010 regulations, had sued both EPA and CARB, alleging, among other things, that the guidance given SCR-reliant engine makers would allow trucks using SCR to operate effectively for long periods of time without emissions controls if the SCR system were inoperable or if there was no diesel exhaust fluid (DEF) being injected into the system.

One of the questions Navistar has raised is whether new commercial vehicles using selective catalytic reduction to meet federal NOx emissions standards continue to operate effectively even when there is no diesel exhaust fluid being injected into the system.

At an air resources workshop in El Monte, Calif., Navistar representatives contended that independent test findings show new commercial vehicles that must contain DEF to meet federal NOx emissions standards continue to operate effectively when DEF is not present. At such times, Navistar said, the vehicles throw off levels of NOx as much as 10 times higher or more than when DEF is present.

The research cited by Navistar was conducted by EnSight, an independent environmental consulting firm, using two long-haul vehicles and one heavy-duty pickup, all of which used SCR. According to Navistar, EnSight’s research showed that when DEF was not present, there was little or no effect on the vehicles’ operations; this included long periods of time when the vehicles’ DEF tanks were empty or were refilled with water instead. Navistar said one truck tested appeared to operate indefinitely with water and as a result without any functioning SCR NOx control, and that the truck had accumulated more than 13,000 miles with its SCR NOx emissions control turned off.

“What we are doing is looking at tightening up SCR certification requirements and clarifying the guidelines so that manufacturers know exactly how to meet them,” says Annette Hebert, chief of CARB’s mobile source operations division. Hebert said CARB’s initial focus is on the time, speeds and mileage SCR trucks can operate once the DEF tank is empty. “We also want to make certain the trucks cannot operate when they are out of spec – if water has been placed in the DEF tank or the SCR system has been tampered with in any way,” she says. “Our goal is to minimize the time and speed a truck can operate and create driver inducements that are stringent enough to encourage them to keep DEF in the system and avoid any performance penalties.”

Strong rebuttal