### State of Utah Department of Environmental Quality Dianne R. Ni e lso n , Ph.D. Executive Director D IV IS ION OF A IR QUA LIT Y Richard W . Spro tt Director

April 12, 2006 Rich a rd Long US EPA REGION 8JON M . HU NT SMAN, JR . Governor GARY HERB ERT Lie ute nan t Gove rn o r

999 18th Street Suite 300 Mail Code: 8P-AR Denver , CO 80202-2466 D ear 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 attributab le 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 H eav y -Duty Powered Vehicles. J-1667 is used by many states and other juri sdictions 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 Wes t • PO B ox 144 820 • S alt Lake C ity, UT 84114 -4820 • ph one (80 1 ) 536 -4 00 0 • fax (80 1 ) 5 36 -4 099 T . D.D . (8 01 ) 536 -44 14 • www .de q.utah.govDAQP-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. 

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# 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

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