### RESPONSE TOCOMMENTS

MassDEPissued for public reviewand comment the proposed Massachusetts State Implementation Plan (SIP) to DemonstrateAttainment of the NationalAmbientAir Quality Standardfor Ozone (Ozone SIP) . The substantive comments received, and MassDEP's responses thereto, are discussed below . In addition to substantive comments, the U .S. EPA noted typographical errors or suggested points of clarification. Minor corrections and clarifications are addressed in the final Ozone SIP submitted to EPA, but are not discussed below . Commenters: 1 . U.S. Environmental Protection Agency, Region 1 comments dated: December 27, 2007; January 17, 2008; January 28, 2008 2. Associated Industries of Massachusetts 3. General Electric 4. St. Gobain Abrasives, Inc. 5. Bob Machaver Summary of Comments Received and MassDEP Responses EPAcomments regarding Reasonable Further Progress (Comments #2, 3 - 12/27/07) MassDEP should include the source of the growth factors for commercial marine and locomotive emission projections. The last step shown in Table RFP3 (line #8) should be revised or eliminated. Since the baselines from

which the combined reductions were calculated are different, combining the percentages gives a somewhat inaccurate result . Response: The growth factor for commercial marine and locomotive sources has been added in Section 4.5. The last calculation in Table RFP 3 has been deleted . EPA comments regarding control measures (Comments # 1, #17, #18 - 1/17/08) MassDEP should include a commitment to submit the regulations listed in Table CM 1 (Section 3, Control Measures) to EPAas a State Implementation Plan (SIP) revision by a date certain. When MassDEP submits the SIPrevision for the revised enhanced inspection and maintenance (I/M) program, it should demonstrate that its revised I/M programeffectively replaces the emission reductions required by the existing program, as well as meets the requirements ofEPA's I/M rule. MassDEPshould also provide a date for submittal of its power plant regulation, 310 CMR7.29, (discussed in Section 6, Reasonably Available Control Technology (RACT)) as a SIPrevision. Response: In the final SIP, MassDEPhas added a column to Table CM 1 of Section 3 to include the date by which it intends to submit the listed regulations to EPAas SIP amendments. The separate I/M SIP amendment that MassDEPwill submit forthe revised I/M program will demonstrate that the revised programeffectively replaces the emission reductions achieved by the existing program, and will meet the requirements of EPA's I&M rule. The NOx provisions of Massachusetts power plan regulation, 310 CMR7.29, will be submitted to EPAas a SIPrevision by March 1, 2008; this is noted in Section 6, RACT (page 10) . EPA comment regarding emission reductions (Comment #3 - 1/17/08) Footnote #7 to Table CM 3, which provides emission reduction estimates for new post -2002 area source control measures, states that the estimates for the area source measures are based on the combined analysis of MassDEPand MACTEC (Appendix 5K, Identification andEvaluation ofCandidate Control Measures: Final Technical Support Document, MACTEC, February 28, 2007), as part ofthe OTCregional ozone attainment planning process. The estimates in Table CM 3 appear to differ fromthe estimates in Appendix K . MassDEP should explain how these estimates were developed, or reference a specific location in the appendices where this is discussed. Response: MassDEPhas revised Table CM 3 to make the estimated emission benefits consistent with the estimates in Appendix 5K, Identification andEvaluation ofCandidate Control Measures: Final Technical Support Document; that document was developed by MACTEC for the OTC, with input fromthe OTCstates. The benefits estimated for 2009 in the earlier version ofTable CM 3 in the proposed Ozone SIPwere calculated using the 2002 base year emissions. The revised Table CM3, consistent with Appendix 5K, estimates the reductions benefits ofthe control measures listed by comparing base 2009emissions with 2009 controlled emissions for each post2002 control measure. Also, Appendix Kdoes not discuss the two area source categories of solvent cleaning and architectural and industrial maintenance (AIM) coatings. These are post-2002 measures for Massachusetts and are, therefore, listed in Table CM3 . These were not measures recommended for adoption by the OTCin 2006, so are not included in Appendix 5K. EPAcomments regarding anti-back-sliding (Comment #4 - 1/17/08) The discussion ofthe 1-hour ozone standard control measures (Appendix 3A) concerning New Source Review

should be revised to reflect the Phase I court ruling on anti-backsliding, whichrequires Massachusetts to maintain the 50 ton per year threshold for VOCand NOx and a 1 .2- to1 offset ratio based on its "serious" classification under the one-hour ozone standard. Response: MassDEPhas revised this discussion to reflect that the court set aside the provisions of EPA's Phase I Rule that would have permitted backsliding. (MassDEP decided to retain the 50tons per year threshold for VOCand NOx 1 .2- to-1 offset ratio even prior to the court decision.) EPA comment regarding 1-hour ozone standard (Comment # 6- 1/17/08) The statement (Section 1 .3, Page 3) that both EMAand WMAhad monitored readings that met the 1-hour ozone standard for 2004-2006 is incorrect. The Chicopee monitor in WMAexceeded the 1-hour ozone standard during the 2004-2006period. Response: MassDEP has deleted this statement, which it agrees was inaccurate for WMA . Only EMAmet the now-revoked 1-hour standard for the 2004-2006period. EPAcomment regarding extension of attainment date (Comments #5, #7 - 1/17/08) EPA suggests revisions to the discussion in Section 1 .1 that relates to the criteria for Massachusetts to seek an extension of the 2009attainment year if either EMAor WMAfail to attain the standard by the 2009attainment year. Response; MassDEP has revised the discussion to clarify the criteria under which Massachusetts may seek a 1-year extension of the 2009attainment date. EPAcomment regarding trends data (comment #9, 1-17-08) The "Air Quality Trends" section (Section 5.19.1, page 33) presents graphs of design value trends for EMAand WMAand states that the trends suggest that EMAand WMAare on trackto meet the ozone standard by 2009. EPAdoes not agree that the trend line forthe WMAdesign values shows it to be on track to meet 84 parts per billion (ppb) by 2009. The discussion in the introduction (Section 1 .5, Page 5) seems to present a more realistic interpretation of the status of the WMA

. Response: MassDEPagrees that while the trend data for EMAclearly shows it to be on track to attain in 2009, there is no clear trend for WMAdata. MassDEPhas revised the discussion to state that based upon ozone modeling results, ozone air quality trends and ozone precursor trends,MassDEP expects that EMAwill attain the 8-hour ozone NAAQS by 2009, and that, while

WMAmay attain by 2009, if it does not, it will be eligible for a 1-year extension of the 2009 attainment date. EPA comments regarding 2007 ozone episodes (comment #10 - 1/17/08) The discussion of high ozone concentrations in WMAon August 3 and August 30, 2007 (Section 5.19.5) never comes to a conclusion as to the significance ofthese two days. Ifthe smoke did interfere with the measurement of ozone or caused enhanced ozone production on these days, then absent the smoke, what would the resulting 4th high ozone concentration be for the key sites of Chicopee and Ware? How would this effect design values and ozone trends? Is the smoke a regular occurrence, or is it a unique circumstance that might rise to the level ofan "exceptional event" following EPAguidance? How do these two days impact the conclusions presented at the end of Section 5 (specifically, Section 5.20, page 48-49)? Response: These high monitored ozone readings in Chicopee 2007 (August 3 - 3rd highest of 103 ppb) and (August 30 - 4th highest of 98 ppb) were discussed to illustrate the unusual nature of these concentrations and to identify factors that likely contributed to these high concentrations, specifically, meteorological conditions and smoke. These contributing factors support MassDEP's view

that the readings in 2007 were unusually high and that MassDEPcan reasonably anticipate that the Chicopee monitor will have a 4a' high reading of 84 ppb or less in 2009. This would satisfy the eligibility requirements for a 1-year extension of attainment year in 2009 for WMA

. EPAComment Regarding Regional Ozone Attainment Modeling (1-28-08) MassDEPshould provide detailed daily emission files by state, source sector and time ofyear for 2002 ozone episodes. EPARegion I analysis indicates that actual hourly emission files forthe electric generating sector in 2002 are higher than some CMAQhourly emission files, and that implies that future year emissions and ozone levels may be underestimated. Response: The 2002 and 2009ozone precursor emission inputs (pre-SMOKE and post-SMOKE processed files) used forthe CMAQSIPmodeling runs are available in electronic format upon request to NYS DEC

. MassDEP does not presently have the resources to construct the daily 2002 and 2009emission files requested, and recommends that EPAcontact the NYS DEC, which served as the lead OTC Modeling Center, to see if detailed daily emission files by state, source sector and time ofyear can be extracted fromCMAQinput files. It is not clear that inspection ofthese daily emission files is needed to determine ifthe EGU control program is being accurately quantified in the CMAQSIP-quality modeling runs. Future year EGU emission inventory documentation is contained in Appendix 5M to Section 5, Attainment Demonstration.The CMAQSIP-quality modeling runs performed on behalf ofthe OTC (and used by MassDEP)

did not incorporate daily variations in EGU emissions associated with weather-induced electricity demand. The OTCapproach was to use the SMOKE model to apportion annual emissions (based on annual CEM data) provided by the states in orderto prepare consistent emission files using month-of-year, day-of-week, and hour-of-day temporal profiles. No adjustments for ozone or non-ozone episodes were attempted; none ofthe control strategies are day-specific or aimed specifically at high ozone episodes. MassDEPrecognizes that on some days actual hourly emissions may be higher than CMAQ model run emissions and that on other days actual hourly emissions may be lower than CMAQ model run emissions. However, using the CMAQmodel in a relative way (as recommended by EPA guidance) helps minimize the effects of any under-estimated or over-estimated emissions in the base case (2002) that are grown out to and controlled in the future case (2009) . Future case emissions projections for the energy sector were estimated using the IPM model which was considered to be the best available tool at the time the OTCCMAQSIP-quality modeling runs were performed (2006) . The IPM model produced summer season and annual emissions, reflecting the CAIR program, the national control strategy for this sector . For consistency, the same month-of-year, day-of-week, and hour-of-day temporal profiles used to prepare 2002 hourly emission files were also used to prepare 2009 hourly emission files. To apply temporal files based upon actual 2002 hourly emission rates was considered to be guesswork since IPM

does not assume that the same sources in 2002 would be operating in the same way in future-case years. In summary, MassDEP believes that the use of consistent temporal files for 2002 and 2009and using the CMAQmodel in a relative way (calculating the percent reduction in ozone levels instead of using the actual predicted 2009 ozone levels) is the most appropriate way of assessing the effectiveness of ozone control strategies in the OTCat this time. The 2002 and 2009ozone precursor emission inputs (pre-SMOKE and post-SMOKE processed files) used forthe CMAQ SIP modeling runs are available in electronic formupon request to NYS DEC (contact Gopal Sistla at gsistla@dec.state.ny.us) .

Comments regarding Reasonably Available Control Technology (RACT) EPA Comment on Municipal Waste Combustors (MWCs) RACT (Comment #15 - 1/17/08) The NOx RACT section does not contain an analysis ofwhether the current limits in Massachusetts represent RACT in light of more stringent limits adopted by other states. For example, the NOx emission limits found within Connecticut's MWCregulation are more stringent than the Massachusetts limits. EPArecommends that Massachusetts consider adopting limits similar to those adopted by Connecticut.Response:

MassDEP will re-examine whether its current MACT regulations for MWC, 310 CMR7.08 (2), still constitute RACT for MWCs in light of this comment. By April 1, 2008, it commits to do an additional analysis on whether it is cost effective to further reduce NOx emissions fromexisting MWCs. MassDEPwill include stakeholders (i .e. the MWCs, municipalities, and environmental organizations) as part ofthis process. MassDEP expects to propose revisions to its MWCregulations by December 31, 2008 to comply with the U

.S. EPA's Standards of Performance for New Stationary Sources and Emission Guidelines for Existing Stationary Sources: Large Municipal Waste Combustors, 40 CFR60 subpart Cb. Based on the findings of the additional RACT analysis, MassDEPwill consider whether to include a proposal for more stringent NOx limits whenit proposes the revisions to the Massachusetts Municipal Waste Combustor Regulations. EPA Comment on Glass Manufacturing RACT (Comment # 19 -1/17/08) Table RACT-1 indicates that Massachusetts believes its existing NOx RACT rule is sufficient to meet RACT for the glass-manufacturing category. Glass manufacturing is one of the 2006 OTC recommended categories for additional control . MassDEP should document that the one large glass manufacturing facility Massachusetts, Saint Gobain Containers (located in Milford), is currently subject to emission limits that are as stringent as those found in the OTC2006 recommended control measure for this sector . Response: Since 2001, St. Gobain Containers' average NOx emissions have been 3.38 pounds/ton of glass pulled, based on stack testing. These annual stack testing data demonstrate that St . Gobain Containers' actual NOx emission rates fromits glass manufacturing process are below the recommended OTCNOx limit for this category. Documentation is available for review . Comments on Industrial, Commercial and Institutional Boiler RACT: EPA(Comments # 14, #15, #19 - 1-17-08) : EPArecommends that MassDEPconsider adopting more stringent regulations for industrial, commercial, and institutional (ICI) boilers as part of meeting Massachusetts NOx RACT obligation. Furtherregulation of this sector is one of the control options that the Ozone Transport Commission (OTC) states agreed to explore, as discussed in Appendix 5K, which includes recommended emission limits. The Mass DEP NOx RACT analysis in Section 6 .5 does not include any discussion of consideration ofthis measure.Industry Comments:

Associated Industries of Massachusetts (AIM) Comment: AIM supports MassDEP's conclusion with respect to the adequacy of RACT for ICI boilers, noting that the sources that would be covered by any tighter RACT restrictions for this category represent some of the most vulnerable and cost-sensitive companies in the state. St . Gobain Abrasives, Inc . Comment : The commenter is concerned about the impact of added compliance costs and resubmitted its May 31, 2006 letter to MassDEP . That letter estimated the high costs of installing Selective Catalytic or Selective Non-Catalytic Reductionto its existing boiler and the estimated range of costs per ton of NOx reductions. General Electric Comment: The commenter supports MassDEP's conclusion that current RACT satisfied 8-hour ozone standard RACT requirements for ICI boilers. It resubmitted its 8-page May 2006 preliminary assessment of the technological feasibility and estimated costs of additional NOx controls at its Lynn facility. Bob Machaver Comment : The commenter agrees that current NOx RACT levels are technically and regulatorilyjustified, and that an additional reason why it is not appropriate to enhance the stringency of NOx RACT, is that two major stationary source programs will begin in 2009: the Clean Air Interstate Rule (CAIR) and the Regional Greenhouse Gas Initiative (RGGI) . Until the impact ofthese programs on ozone can be evaluated, new stationary source RACT requirements are premature. Response to all comments regarding ICI boiler RACT: MassDEPhas re-examined this issue in light of the comments it received, but maintains that the position presented in the RACT analysis in its proposed Ozone SIP (Section 6, RACT) is appropriate. MassDEP agrees with the commenters who stated that imposition oftighter RACT restrictions for the ICI boiler category would not be reasonable. With respect to EPA's comments, MassDEP agrees that the OTCanalysis ofpotential control measures summarized in Appendix 5K, Identification andEvaluation ofPotential Control Measures, includes arecommendation that OTC member states pursue, as necessary and appropriate, controls on ICI boilers located at major sources consistent with guidelines shown in Table 4 .2 ofAppendix K

. (As noted in Appendix K, Section 4, ICI boilers located at minor sources generally are not subject to emission limits.)Consistent with the OTCreview, MassDEPanalyzed the potential fortighter controls on ICI

boilers within Massachusetts. It convened a stakeholder meeting inApril 2006 to advise facilities with ICI boilers _>I 00mmBtu/hour that tighter RACT measures were being considered under the OTCregional ozone attainment planning process. Subsequent to the meeting, MassDEP asked facilities to submit information concerning the existing NOx and S02 control technologies for each boiler and the technological feasibility and estimated costs of additional controls. MassDEPreceived comments from six facilities in 2006, all ofwhich cited technical or economic constraints on the adoption of tighter RACT controls on boilers at their respective facilities. (As noted above, some of these comments were resubmitted as official comments on the proposed Ozone SIP.)' With the adoption, in May 2007, of the Massachusetts Clean Air Interstate Rule, 310 CMR7.32 (MassCAIR), all large electric generating units (EGUs) and facilities with boiler >250 mmBtulhr became subject to the Mass CAIR NOx cap-and-trade program, which constitutes RACT for these facilities. With respect to boilers of >_100 - 250mmBtu/hour, MassDEPreviewed the comments submitted by facilities following its 2006 stakeholder meeting . The comments indicated that anumber of facilities were subject to constraints that made additional control measures infeasible froman engineering perspective. They also indicated that the likely costs of additional controls for many of the facilities made theminfeasible froman economic perspective. Based on these comments, MassDEP determined that it is not appropriate and necessary to adopt additional controls for ICI boilers of 100- 250mmBtu/hr and that current emission limits imposed pursuant to 310 CMR 7.19represents RACT. In making this determination, MassDEP considered that many of the affected facilities are part ofthe remaining industrial base in the state, and that to the extent that EPAhas not issued updated RACT requirements that would be applied to comparable sized sources on a national basis (especially in upwind states outside of the OTCregion), tighter requirements on Massachusetts' sources imposes a unreasonable economic hardship on these facilities. MassDEP continues to maintain that the NOx controls required by 310 CMR7.19, Reasonably Available Control Technology (R .4CT)for Sources ofOxides ofNitrogen (NOx), constitute NOx RACT underthe 8-hour ozone standard for the ICI boiler category2 as well as for major sources of NOx with ICI boilders for which single-source RACT determinations were made pursuant to 310 CMR7.19(12) . With respect to the comment of Bob Machaver, MassDEP agrees that the Massachusetts CAIR program, 310 CMR7.32, which includes a cap on NOx emissions fromlarge electric generating units and large boilers will have an impact on NOx emissions. Also, the reductionof electrical demand, whether it takes place in the context of RGGI or otherwise, mayreduce NOx emissions. However, RACT requirements are not based on whether an area, once it has been designated nonattainment, needs additional reductions for the purposes of attaining the standard. Rather, 1 Industry responses submitted in 2006 and in response to the proposed Ozone SIP are available for EPAand public review . Z The source categories covered in this regulation are: large, mediumand small boilers; stationary combustion turbines; stationary reciprocating internal combustion engines; glass melting furnaces; and miscellaneous sources.RACT is a technology-based requirement for nonattaimnent areas. So while, MassDEPagrees

with the commenter with respect to his support for MassDEP's conclusions regarding RACT for ICI boilers, its RACT analysis for this category was independent ofthe anticipated impact of either CAIRor RGGI on ozone concentrations in Massachusetts. (As discussed in the Ozone SIP, however, sources covered by CAIRare deemed to meet RACT.) EPA comment regarding Transportation Conformity (# 20) The date or version of the Statewide/Regional Travel Demand Models used in preparing the reasonable further progress plan, the attainment demonstration, and the motorvehicle emissions budgets (transportation conformity budgets) should be identified. Response: The Massachusetts Office ofTransportation Planning (EOT) used the latest version of the Massachusetts Statewide Travel Demand Model, with the latest planning assumptions, for the Reasonable Further Progress analysis, the 2009 attainment demonstration, and the conformity budget . While the Statewide Travel Demand Model is often updated, there are no specific dates or version numbers attached to the updates. The version used forthe 2008 and 2009 conformity budgets was the latest update as of 10/17/07.