May 8, 1991 MEMORANDUM SUBJECT: PM-10 State Implementation Plan Attainment Demonstration Policy for Initial Moderate Nonattainment Areas FROM: Joseph A. Tikvart, Chief Source Receptor Analysis Branch (MD-14) TO: Regional Modeling Contact, Regions I-X For your information, attached is a March 4, 1991 memorandum from Office of Air Quality Planning and Standards to the Regional Offices outlining the current policy regarding SIP demonstrations for initial PM-10 nonattainment areas, which are due on November 15, 1991. This policy may be useful to you in reviewing the State submittals and in preparing the necessary documentation for forwarding the SIP's to Headquarters. It should be noted that this attached memorandum was transmitted to the Regions by Air Quality Management Division as a part of a larger package dated April 2, 1991 labeled "Final Staff Work Product." It should also be noted that the cover memorandum on the package (also attached here) contains certain cautions with respect to the legal interpretation of the material. If you have any questions, please contact me at 629-5562. Attachments cc: G. Blais W. Laxton F. Renner D. Wilson Attachment MEMORANDUM SUBJECT: PM-10 SIP Attainment Demonstration Policy for Initial Moderate Nonattainment Areas FROM: John Calcagni, Director Air Quality Management Division (MD-15) William G. Laxton, Director Technical Support Division (MD-14) TO: Director, Air, Pesticides, and Toxics Management Division, Regions I, IV, VI Director, Air and Waste Management Division Region II Director, Air Management Division Regions III and IX Director, Air and Radiation Division Region V Director, Air and Toxics Division Regions VII, VIII, X Overview The purpose of this memorandum is to document EPA's attainment demonstration policy for initial moderate PM-10 nonattainment areas, i.e., those designated nonattainment upon enactment of the Clean Air Act Amendments of 1990 and, by operation of law, classified as moderate upon enactment. This policy supplements the attainment demonstration guidance set forth in the PM-10 SIP Development Guideline (June 1987), the Guideline on Air Quality Models (Revised), and the memorandum from Joseph Tikvart and Robert Bauman dated July 5, 1990. It is limited in application to those moderate PM-10 nonattainment areas designated nonattainment at enactment, all of which have a November 15, 1991 deadline for submitting attainment demonstrations and other State implementation plan (SIP) requirements. The short period in which the statute mandates the demonstration submittal for these areas has been an important factor in EPA's decision to supplement its attainment demonstration policy. Policy Generally, all SIP submittals for the initial moderate PM-10 nonattainment areas should follow the existing guidance on PM-10 modeling as noted above. In the situation where an area has completed or can complete its demonstration by November 15, 1991 consistent with existing guidance, an attainment demonstration based on the existing guidance should be submitted. However, in those situations where time constraints, inadequate resources, inadequate data bases, lack of a model for some unique situations, and other unavoidable circumstances would leave an area unable to submit an attainment demonstration within the short timeframe provided by the newly revised law, then a modified demonstration based on this policy statement may be submitted. Section 189(a)(1)(B) of the recently revised Clean Air Act requires that all modified demonstrations be based on some form of "air quality modeling." In addition, 40 CFR Section 51.112 requires that a demonstration be shown to be "adequate and appropriate." This supplemental policy is issued in accordance with these statutory and regulatory requirements. All such modified demonstrations should be accompanied by the following: 1. Documentation of Modified Modeling Method. Documentation of the procedures or analyses used in lieu of those set forth in the previously issued guidance. 2. Rationale for Modified Demonstration. An explanation of why the alternative modeling techniques set forth in the guidance were not used. 3. Justification of Modified Demonstration. A description of how and why the SIP provides an adequate and appropriate demonstration of areawide attainment. If the design value contained in the demonstration is based on monitoring data, the justification should also: (a) Show that the SIP is based on at least one full year of data from an approved network that meets EPA's quality assurance requirements. Also, the justification should contain a review of the monitoring data (e.g., data completeness, prescribed sampling frequency) in accordance with EPA's SIP development guidance. The justification should also include a review of the network's ability to identify the point of maximum concentration and the impact of the most significant sources. (b) Based on the network and data review in (a) above, the SIP should include appropriate provisions to conduct followup monitoring (e.g., daily monitoring, saturation monitoring, expansion or modification of the monitoring network and meteorological data collection) to address those issues raised during that review. The purpose of the followup monitoring is to ensure that the monitoring network in place as of January 1, 1994 will be appropriate to evaluate attainment. Demonstrations based on this policy will be considered on a case-by-case basis. The policy applies only to those initial moderate PM-10 nonattainment areas which have completed the technical analysis for their SIP submittal and have made a good- faith effort to submit a final SIP by their November 15, 1991 due date. Technical analyses that are being developed on a schedule which goes beyond November 15, 1991 will be expected to follow all previously established guidance for modeling and demon- strations. The SIP's for all other PM-10 nonattainment areas will be reviewed in accordance with the previously issued attainment demonstration guidance cited above. If you have any questions regarding this guidance, please contact Fred Renner at FTS 629-5556 or Joe Tikvart at 629-5562. cc: Chief, Air Branch, Regions I-X PM-10 Contacts, Regions I-X Jim Dicke Tom Pace Fred Renner Dave Stonefield Joe Tikvart Dean Wilson