p.1 

OAR Box 1132 

Prepped by Candice Davis 

Document Number: 

4) ll-C-1 

Docket Number: 

A-86-03 

Printed 4/18/2008 2:24:46 PM Sheet 4 of 122 
P.2 

s UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

rj WASHINGTON, D.C. 20460 

/ fi ri 

Mr. Henry B. Schach t 

Chairma n of th e Boar d an d OFFICEOF 

Chie f Executiv e Office r AIR AND RADIATION 

Cummins Engine Co., Inc. 

P.O. Box 3005 

Columbus, Indiana 47202-3005 

Dear Mr. Schacht: 

Thank you for your letter describing your concerns with 

meeting the 1991 and 1994 diesel particulate standards and the 

effect of fuel sulfur content on such compliance. Briefly 

recapping our efforts in this area to date, in June of 1986 we 

distributed for comment a preliminary report on the effects of 

diesel fuel quality on emissions and performance. We have been 

analyzing the comments received on this report, and in addition 

have been preparing more detailed analyses of some of the key 

issues such as the effect of sulfur on engine wear, the 

conversion of sulfur dioxide to sulfate in the atmosphere and 

the effect of sulfur content on required engine control 

technology and cost. These analyses will be compiled into a 

study to be completed near the end of this year. A decision to 

proceed with a formal rulemaking aimed at regulating diesel 

fuel qualif will be made upon completion of this study. 

One of the more difficult aspects of this study is our 

evaluation of the types of technologies that would be used to 

meet the 1991 and 1994 heavy-duty diesel particulate standards 

on current fuel versus a low-sulfur

 vfuel and- any resultant cost 

differential. We have requested detailed projections on this 

issue from all of tlie heavy-duty engine manufacturers in our 

meetings on trap development efforts. To date, a number of 

manufacturers have submitted general statements concerning the 

effect of low sulfur fuel on potential compliance. However, 

little detailed information supported by complete test data has 

been received. Such information is critical if EPA is to 

accurately quantify the effect of diesel fuel sulfur control on 

the heavy-duty diesel industry, and determine the industry's 

ability to meet the 1991 and 1994 standards with and without 

sulfur control. Thus, any additional information that Cummins 

could supply on this issue would be very helpful. (Cummins' 

staff agreed during a meeting in Ann Arbor on April 23rd, to 

try to supply this information to EPA by May 14.) 
P.3 

We acknowledge the receipt of comments and analyses by 

Cummins' showing sulfur control to be more cost effective than 

exhaust aftertreatment devices. However, we are not sure what 

you mean by these conclusions being "confirmed by the EPA staff 

in Ann Arbor". if Cummins means the conclusions arrived at by 

the authors of the preliminary study (Energy and Resource 

Consultants, Inc.), it should be recognized that EPA views that 

study as preliminary, and EPA has not > yet made a determination 

engine compliance-related data will play an important part 

In summary, we are pushing ahead with our study, on the 

basis of our own analyses and the information we have received 

to date. Thank you again for providing your perspective on the 

importance of reducing sulfur levels in diesel fuel. I assure 

you your comments will receive careful consideration in our 

deliberation on this issue. 

Sincerely, 

J. Craig Potter 

Assistant Administrator 

for Air and Radiation