State of Utah 

Department of 

Environmental Quality 

Dianne R. Nielson, Ph.D. 

Executive Director 

DIVISION OF AIR QUALITY 

Richard W. Sprott 

Director 

April 12, 2006 

Richard Long 

US EPA REGION 8 

JON M. HUNTSMAN, JR. 

Governor 

GARY HERBERT 

Lieutenant Governor 

999 18th Street Suite 300 

Mail Code: 8P-AR 

Denver, CO 80202-2466 

Dear Mr. Long: 

RE: Utah Diesel liM State Implementation Plan (SIP) 

DAQP-017-06 

On February 6, 1996, Governor Leavitt submitted the Utah Diesel liM SIP to Region VIII for 

approval. In its review, Region VIII staff recently identified the following deficiencies in our 

initial submittal: 

1. The 20% program credit in the SIP attributable to the diesel inspection and 

maintenance (I/M) program is not defensible and no scientific basis has been provided 

either in the SIP or its technical appendices. 

2. There are no set opacity limits indicated in the SIP. 

3. EPA cannot approve locomotive requirements or idling ordinances. 

4. The SIP appendices are incomplete and marked DRAFT. 

5. Opacity limits, equipment and test specifications, inspection procedures and cutpoints 

are not defined. 

When the SIP was submitted, Utah led the nation in establishing an effective diesel liM 

program for heavy-duty and light-duty diesel vehicles. Other liM jurisdictions have benefited 

from Utah 's diesel I/M program experience in establishing their programs. Since 1996, 

Utah's liM counties have finalized their respective regulations and ordinances. The Society 

of Automotive Engineers (SAE) has finalized its J-1667 Snap Acceleration Smoke Test 

Procedure for Heavy -Duty Powered Vehicles. J-1667 is used by many states and other 

jurisdictions and is available from the California Air Resources Board at 

http://www.arb.ca.gov/msprog/hdvip/saej1667.pdf. To facilitate your staffs review, the 

150 North 1950 West • PO Box 144820 • Salt Lake City, UT 84114-4820 • phone (801) 536-4000 • fax (801) 536-4099 

T.D.D. (801 ) 536-44 14 • www.deq.utah.gov 
DAQP-017-06 

April}1, 2006 

finalized test procedures and specifications are attached. These specifications include the 

opacity limits for each vehicle type. 

Over the past several years, UDAQ staff have endeavored to work with EPA staff to establish 

a reasonable credit for our light and heavy duty diesel liM programs. While the 20% credit 

initially requested may have been ambitious, we believe the attached study clearly justifies 

granting a minimum of a 2% SIP credit for reducing on-road diesel PM10 exhaust emissions. 

This request is also consistent with EPA's emphasis on the public health benefits gained from 

reducing diesel exhaust emissions. Denying Utah SIP credit eliminates any incentive to 

integrate future diesel On-board Diagnostics (OBD) testing into our liM programs and 

conflicts with EPA's substantial investment in diesel retrofit and idling reduction technology 

throughout the nation. The anticipated promulgation of a more stringent fine particulate 

standard will require program areas to evaluate the effectiveness of a variety of control 

measures, including further controls on diesel vehicles. Diesel liM programs were effective 

in identifying modified and tampered vehicles, which is a growing issue due to the increased 

availability of aftermarket 'performance' devices. Not granting any SIP credit for a diesel 

liM program seems counter to the EPA's priorities and sends an inconsistent message to the 

public and program administrators. As a consequence of not being granted any program 

credit, Utah County suspended its diesel liM program. 

UDAQ requests that EPA review the attached data and finalize its rulemaking on the subject 

submittal. If you have any questions, feel free to call Joe Thomas at (801) 536-4175. 

Sin eM 

~dW.S rott 

cc: Margo Oge 

RWS/BC/kd 

Attach: 

1. Davis County Diesel liM program regulation, equipment specification and test 

procedure 

2. Salt Lake County Diesel liM program regulation, equipment specification and test 

procedure 

3. Utah County Diesel liM program regulation, equipment specification and test 

procedure 

4. Diesel liM program effectiveness study 

2