75 IRIS is a collection of continuously updated chemical files which contain descriptive and quantitative information with respect to: oral reference doses and inhalation reference concentrations ( RfDs and RfCs, respectively) for chronic noncarcinogenic health effects; and hazard identification, oral slope factors, and oral and inhalation unit risks for carcinogenic 306 as a regulation. Risk assessment   especially multi pathway, indirect exposure assessment   is a highly technical and evolving field. Any regulatory approach EPA might codify in this area is likely to become outdated, or at least artificially constraining, shortly after promulgation in ways that EPA cannot anticipate now. In EPA's view, this is an area that is uniquely fitted for a guidance approach, rather than regulation. In fact, across Agency programs, EPA has generally adopted a guidance approach to risk assessment for exactly this reason. See, e. g., Guidelines for Reproductive Toxicity Risk Assessment, 61 FR 56274 ( October 31, 1996). EPA's Superfund program has not promulgated regulations specifying risk assessment methods. Instead, the program uses site specific approaches for determining risk, employing methods offered in EPA guidance as appropriate. The same is true for the RCRA corrective action program. Although we have attempted to provide our guidance recommendations in a form that responds to or encompasses many of the issues that can arise when conducting an SSRA, we recognize that the flexibility to apply other methodologies, assumptions, or recommendations has been important to both regulators and the regulated community in terms of developing an appropriate site specific protocol. 74 For example, some of EPA's technical recommendations may not be appropriate for the combustion device in question, and risk assessors must have the flexibility to make adjustments for the specific conditions present at the source, and the state of risk assessment science at the time that the SSRA is being performed. As an obvious example, sources that are located in a dry, desert climate with no nearby permanent or temporary water bodies of concern should not be required to include a fisher exposure scenario in an SSRA. In addition, risk assessors should be free to use the most recent air modeling tools and toxicity values available rather than be limited to those that may be out of date because a regulation has not been revised following the development of the new tools or values. Guidance allows for this flexibility. CKRC points out the EPA codified certain parameters for BIF risk assessments, to show that it is possible to do so. While EPA agrees it is possible, the codification in the BIF area is the exception, not the rule. It has been our experience in implementing the BIF regulations that codification of certain risk parameters has proven to be overly constraining because risk science is a continually changing field. For example, by codifying the toxicity values, risk managers were not able to utilize more recent values available through EPA's Integrated Risk Information System ( IRIS) 75 and other resources. Also, shortly after we codified the air modeling guidelines Redline strikeout highlighting changes made during OMB review effects. For more information, see http:// www. epa. gov/ iris/ index. html.

76 USEPA. " Human Health Risk Assessment Protocol for Hazardous Waste Combustion Facilities" EPA 520 D 98 001A, B& C. External Peer Review Draft, 1998. ( http:// www. epa. gov/ epaoswer/ hazwaste/ combust/ risk. htm)

77 We are not responding to the specific comments here, but will respond to them as part of the public process for developing the final guidance documents.

307 in support of the risk parameters and procedures, the Air program revised their air modeling guidelines, rendering some of the BIF air modeling guidelines inconsistent and so, they were removed. Further, it is important to note that at the time of codification, BIF risk assessments were not intended to address indirect routes of exposure, thus making the parameters easier to implement. Today, however, risk assessments are more complex due to the necessary inclusion of multi pathway and indirect exposure routes. Given the complexity of multi pathway and indirect exposure assessments and the fact that risk science is continuously evolving, it would be difficult and again, overly constraining, to codify risk parameters today. We also believe that a guidance approach is consistent with the fact that permit writers must make site specific decisions whether to do risk assessments at all. We expect that permit writers will reach their decisions based on different factors and concerns   in some cases, factors and concerns that we may not have identified at this time. We think that it makes little sense to allow this kind of flexibility regarding whether to do a risk assessment and for what purposes, while prescribing how one must be conducted if one is required. CKRC further contends that the guidance is overly conservative and constitutes " a confusing pattern of drafts over a number of years in a seemingly endless fashion" that has resulted in their members incurring significant costs. Because of the variability in the many factors that influence the risk from hazardous waste combustors, the guidance contains some conservative recommendations and assumptions in order to address this wide range. However, based on input from users of the guidance, we have attempted to correct the recommendations and assumptions that we consider to be overly conservative and, as stated previously, because they are guidance recommendations and not requirements, the risk assessor may choose not to follow them. More recently, we have solicited public and peer review comments on the 1998 guidance76, and are in the process of revising it based on the comments received. This includes comments CKRC submitted related to the components of the guidance they contended were overly conservative. 77 With respect to CKRC's assertion that the guidance is " a confusing pattern of drafts over a number of years", we acknowledge that we have issued a number of guidance documents since 1990. However, we disagree that this has resulted in a confusing pattern of drafts. The development and release of the guidance documents correspond to three specific regulatory time periods in the area of hazardous waste combustion. In addition, the issuance of subsequent versions relates to the fact that the Agency has repeatedly solicited public and peer review Redline strikeout highlighting changes made during OMB review 78 USEPA. " Guidance for Performing Screening Level Risk Analyses at Combustion Facilities Burning Hazardous Wastes" Draft, April 1994. USEPA. " Implementation of Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Facilities" Draft, 1994.

79 We noted earlier that the 1998 guidance is currently being revised in consideration of public and peer review comments received. With respect to the 1999 guidance ( USEPA. " Screening Level Ecological Risk Assessment Protocol for Hazardous Waste Combustion Facilities" EPA 530 D 99 001A, B& C. Peer Review Draft, 1999), we solicited public comment and plan to conduct a peer review. ( http:// www. epa. gov/ epaoswer/ hazwaste/ combust/ ecorisk. htm)

308 comments on its technical guidance, and has built upon the experience of regulators and facilities in using earlier guidance. In 1990, EPA developed its initial guidance document during the same time period as the RCRA BIF emission standards. In 1993, we released an addendum to the 1990 guidance in response to the draft Hazardous Waste Minimization and Combustion Strategy and our increasing concerns about the potential impacts from indirect routes of exposure, and solicited comments from the public and the Science Advisory Board. A revised document taking into account these comments was issued one year later. 78 At the time that we were developing the Phase 1 MACT standards, we again updated our combustion risk assessment guidance by releasing a document specifically addressing human health risk in 1998 and one addressing ecological risk in 1999, again soliciting public input and peer review on these documents. 79 For purposes of clarity, both of these documents refer to all earlier guidance where appropriate and discuss briefly the progression of the guidance. Although the 1998 human health guidance and the 1999 ecological guidance provide our current thinking regarding SSRA methodology for hazardous waste combustors, we noted to our permit writers that we recommended that they should continue to use the 1994 guidance for those SSRAs that were in progress. Although CKRC claims to find these guidance documents confusing, EPA's judgment is that most interested parties   both regulators and the regulated community   have found the guidance to be useful, and that the documents have substantially reduced the uncertainty and confusion that surrounded multi pathway risk assessments a decade ago. As stated above, no one is obligated to follow this guidance, and regulators often depart from it; but EPA believes it has been extremely helpful on the whole, rather than confusing. CKRC has alleged that SSRA's typically cost between $ 200,000 and $ 1,000,000 for an individual facility. We are aware that prior to the release of the 1998 guidance, combustion risk assessments were more costly than we understand them to be today. For an individual facility, we do not know to what extent these costs are attributed to the act of conducting a risk assessment, to recommendations provided in our guidance, to changes that the facility chose to make during the risk assessment, or the facility's desire to develop its own site specific protocol. Not including the collection and analysis of emission risk data, we have been advised that the cost of Redline strikeout highlighting changes made during OMB review 80 The cost ranges for CKRC include both the cost of risk assessments and emission data collection. In its petition, CKRC provided a range of costs ($ 100,000 to $ 500,000 for risk assessments and $ 100,000 to $ 500,000 for emission data collection), but also provided an upper bound cost ($ 728,297 for a risk assessment and $ 588,790 for emission data collection, plus additional permit costs to equate to $ 1.3M).

309 an average SSRA today is approximately $ 84,000. ( See document entitled Hazardous Waste Combustion MACT  Replacement Standards: Proposed Rule. Preliminary Cost Assessment for Site Specific Risk Assessment, October 29November, 2003, as provided in the docket for today's action.) The emission risk data is projected to add on average between $ 57,000 ( if the facility collects its emission risk data at the same time as its emission standards performance data) and $ 285,000 ( if the facility must conduct a separate emission test solely for the purpose of collecting data for the SSRA). Therefore, including emission data collection, the average cost of an SSRA is between $ 141,000 and $ 370,000. This is considerably less than the cost range provided by CKRC of $ 200,000 to $ 1,000,000. Additionally, EPA's upper bound cost of $ 370,000 is significantly less than the upper bound cost of $ 1,300,000, as reported by CKRC in their petition ( and the attached affidavit). 80 We believe that the cost of SSRAs has decreased over time, particularly since the release of the 1998 guidance. This may be in large part because the 1998 guidance is much more comprehensive than previous guidance documents and because private software companies have developed computer programs based on the guidance, which can further decrease costs associated with the risk calculations for each exposure scenario. CKRC also expressed specific concern that it and its members have been denied an opportunity to comment on the combustion risk assessment guidance documents. We strongly disagree with this assertion. We have repeatedly sought public comment on the guidance documents. For the 1998 human health guidance we not only requested public comment, but also submitted the document for an external peer review and held a peer review meeting which was open to the public. Since the peer review meeting, we have been incorporating both the public and peer review comments into the human health guidance. While we have not yet completed this task and released a final document, any member of the public may at any time discuss any concerns that they have with our recommendations. In addition, regardless of whether a risk assessor uses the recommendations provided in our guidance or not, we have encouraged the permit writer and facility representatives to meet prior to any analysis to discuss the appropriate risk methodology and data input needs for an SSRA. Such a meeting allows both the permitting authority and the facility the opportunity to raise questions and objections concerning the appropriateness of different methodologies, assumptions, or default values and their application to the hazardous waste combustor. Facility representatives and any member of the public also may comment on the risk assessment methodology as part of the public comment process associated with the RCRA permit. The third general concern raised by CKRC in its petition was that we had not provided a threshold level for a " yes" or " no" decision to trigger the need for additional risk based permit conditions. EPA agrees that its guidance does not establish a bright line threshold level for Redline strikeout highlighting changes made during OMB review 81 Particulate matter is not a listed HAP pursuant to CAA 112( b).

82 " Enumerated" metals are those HAP metals that are directly controlled with an emission limit, i. e., lead, cadmium, arsenic, beryllium, and chromium. The remaining nonmercury metal HAP are controlled using particulate matter as a surrogate.

310 determining whether to impose additional permit conditions; such a binding requirement would only be appropriately established through rulemaking. However, EPA has provided recommendations about the overall targets for acceptable risk levels. See USEPA. Implementation of Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Facilities, Draft, 1994. Moreover, we do not intend to codify our recommended target levels for some of the same reasons that we are not proposing to codify the risk assessment technical guidance. Our recommended target levels provide risk managers with a starting point from which to determine if a combustor's potential risk may or may not be acceptable. However, we believe that it is important, and indeed essential, that risk managers be afforded sufficient flexibility to apply different target levels as dictated by the circumstances surrounding the combustor. For example, a risk manager may wish to apply a more stringent carcinogenic target level for a combustor that is located in a densely populated area with a high concentration of industrial emission sources. In summary, we have made a tentative decision to deny CKRC's request that we repeal the SSRA policy and guidance and to grant CKRC's request in part by proposing to codify the authority to require SSRAs. We are not proposing to codify the SSRA guidance or our recommended risk methodology for hazardous waste combustors. We are requesting comment on our tentative decision.

XVIII. What Alternatives to the Particulate Matter Standard Is EPA Proposing or Requesting Comment On? As discussed in Part Two, Section IV. C, we are proposing particulate matter standards as surrogates to control metal HAP. 81 We are not proposing numerical metal HAP emission standards that would have accounted for all metal HAP because we generally do not have as much compliance test emissions information in our database for the nonenumerated metal HAP compared to the enumerated metal HAP, 82 and because we believe that a particulate matter standard, in lieu of emission standards that directly regulate all the metals in all feedstreams, simplifies compliance activities. Nonetheless, we are today proposing an alternative to the particulate matter standard for incinerators, liquid fuel fired boilers, and solid fuel fired boilers that is conceptually similar to the alternative metal emission control requirements that were previously promulgated for incinerators. We are also requesting comment on another alternative to the particulate matter standard that would apply to all source categories that would be subject to particulate matter standards ( i. e., all source categories except hydrochloric acid production furnaces). We discuss these two different alternatives below. Redline strikeout highlighting changes made during OMB review 83 Sources electing to comply with these alternative requirements thus remain subject to the RCRA PM standard in their RCRA permit. The RCRA permit must include applicable operating limits that ensure compliance with the RCRA PM limit.

84 Please note that the particulate matter standard is not redundant to the semivolatile and low volatile metal standards. Although controlling particulate matter also controls semivolatile and low volatile metals in combustion gas, these metals can also be controlled by feedrate control. Thus, sources can achieve the emission standard for semivolatile and low volatile metals primarily by feedrate control. In such cases, the particulate matter standard would be controlling nonenumerated metals primarily.

311 A. What Alternative to the Particulate Matter Standard Is EPA Proposing for Incinerators, Liquid Fuel Fired Boilers, and Solid Fuel Fired Boilers? We promulgated an alternative to the particulate matter standard for incinerators feeding low levels of metals in the July 3, 2001 direct final rule. See 66 FR at 35093. Today we propose a simplified alternative to the particulate matter standard for incinerators, and we propose to expand the provision to also apply to liquid and solid fuel fired boilers. Below, we first describe the alternative that was originally promulgated for incinerators, after which we describe the simplified approach and our rationale for proposing it. The July 3, 2001 final rule allows incinerators to operate under alternative metal emission control requirements reflecting MACT in lieu of complying with the 0.015 gr/ dscf particulate emission standard. Under the alternative, no particulate matter emission standard applies to incinerators under Subpart EEE; however, the incinerator remains subject to the RCRA particulate matter standard of 0.08 gr/ dscf pursuant to § 264.343( c). This is because Clean Air Act standards can supplant RCRA standards only when the CAA standard is sufficiently protective of human health and the environment to make the RCRA standard duplicative ( within the meaning of RCRA section 1006 ( b) ( 3)). 83 See Part Two, Section XVII. D. This previously promulgated alternative to the particulate matter standard has three components. The first component is simply to meet metal emission limitations for semivolatile and low volatile metals. The emission limitations apply to both enumerated and non enumerated metal HAP, excluding mercury. Enumerated semivolatile metals are those metals that are directly controlled with the numerical semivolatile emission standard, i. e., cadmium and lead. Enumerated low volatile metals are those metals that are directly controlled with the numerical low volatile metals emission standard, i. e., arsenic, beryllium and chromium. Non enumerated metals are those remaining metal HAP: antimony, cobalt, manganese, nickel, and selenium that are not controlled directly with an emission standard, but are rather controlled through the surrogate particulate matter standard. 84 For purposes of these alternative requirements, the non enumerated metals are classified as either a semivolatile or a low volatile metal, and included in the calculation of compliance with the corresponding emissions limit. The level of the standard is the same as that which applies to other incinerators, but the standard would apply to all metal HAP, not just those enumerated in the present low volatile metal and semivolatile metal standards. Redline strikeout highlighting changes made during OMB review 312 The second component is a requirement for the incinerator to demonstrate that it is using reasonable hazardous waste metal feed control, i. e., a defined metal federatefeedrate that is better than the MACT defining metal feed floor control level. The third component is a requirement for the incinerator to demonstrate that its air pollution control system achieves, at a minimum, a 90 percent system removal efficiency for semivolatile metals. Today we propose a simplified version of the above described alternative in that we propose to require you to comply only with the first component described above, which is to achieve metal emission standards for semivolatile and low volatile metals. As discussed above, the level of the proposed standard is the same as that which applies to other sources, but the standard would apply to all metal HAP, not just those enumerated in the present semivolatile and low volatile metal standards. As with the previously promulgated alternative, no particulate matter emission standard would apply to these sources under Subpart EEE; however, sources would remain subject to the RCRA particulate matter standard of 0.08 gr/ dscf pursuant to § § 264.343( c) or 266.105. We propose to eliminate the requirements for you to demonstrate that: ( 1) you are using reasonable hazardous waste metal feed control, i. e., a defined metal feed control that is better than the MACT defining feed control level; and ( 2) your source is equipped with an air pollution control system that achieves at least a 90 percent system removal efficiency for semivolatile metals. We believe these two requirements are not necessary to ensure you are in fact controlling metals below MACT levels given that all sources electing to comply with this alternative must limit both the enumerated metals and non enumerated metals to levels below the proposed levels that apply only to enumerated metals. Today's proposed approach, in effect, lowers the existing semivolatile and low volatile metal emissions limits because the contribution of nonenumerated metals must be accounted for when achieving the same numerical semivolatile and low volatile emission limits. We believe this is appropriate because this effectively lower emissions limit for enumerated metals compensates for the lower emission levels that would have been achieved if the source used a particulate matter control device capable of achieving the particulate matter standard. Put another way, we regard this emission limitation as an equivalent means of meeting the standard for HAP metals ( except mercury) already established in the rule. As discussed above, the approach we promulgated on July 3, 2001 required you, in practice, to feed low levels of metals on a continuous basis in order to qualify for the alternative. The rule required that the source's feed control level must be equivalent to or lower than 25% of the MACT defining hazardous waste feed control level. We considered whether it would be appropriate to also apply such a qualification requirement to today's proposed alternative. Unfortunately, the methodology used to calculate today's proposed emission standards does not base the standards on a specific MACT defining feed control level. Thus, we do not have a MACT feed control level that we can readily use to define an appropriate low feed control level. We request comment on whether it is appropriate and/ or necessary to establish a minimum feed control level, and if so, how it could be determined. 1. What Emission Limitation Must Incinerators Comply With under this Alternative? For existing incinerators, the emissions limits under this alternative would be: ( 1) a semivolatile metal emission limit of 59 g/ dscm for the combined emissions of lead, cadmium, and Redline strikeout highlighting changes made during OMB review 313 selenium; and ( 2) a low volatile metal emission limit of 84 g/ dscm for combined emissions of arsenic, beryllium, chromium, antimony, cobalt, manganese, and nickel ( all emissions corrected to 7% oxygen). For new sources, the emissions limits would be: ( 1) a semivolatile emission limit of 7 g/ dscm for combined emissions of lead, cadmium, and selenium; and ( 2) a low volatile emission limit of 9 g/ dscm for emissions of arsenic, beryllium, chromium, antimony, cobalt, manganese, and nickel ( all emissions corrected to 7% oxygen). 2. What Emission Limitation Must Liquid Fuel Fired Boilers Comply With under this Alternative? For existing liquid fuel fired boilers, the emissions limits under this alternative would be: ( 1) a semivolatile metal emission limit of 1.1E 5 lb/ MM BTU for the combined emissions of lead, cadmium, and selenium; and ( 2) a low volatile metal emission limit of 7.7E 5 lb/ MM BTU for combined emissions of arsenic, beryllium, chromium, antimony, cobalt, manganese, and nickel ( all emissions corrected to 7% oxygen). For new sources, the emissions limits would be: ( 1) a semivolatile metal emission limit of 4.3E 6 lb/ MM BTU for combined emissions of lead, cadmium, and selenium; and ( 2) a low volatile metal emission limit of 3.6E 5 lb/ MM BTU for emissions of arsenic, beryllium, chromium, antimony, cobalt, manganese, and nickel ( all emissions corrected to 7% oxygen). 3. What Emission Limitation Must Solid Fuel Fired Boilers Comply With under this Alternative? For existing solid fuel fired boilers, the emissions limits under this alternative would be: ( 1) a semivolatile metal emission limit of 170 g/ dscm for the combined emissions of lead, cadmium, and selenium; and ( 2) a low volatile metal emission limit of 210 g/ dscm for combined emissions of arsenic, beryllium, chromium, antimony, cobalt, manganese, and nickel ( all emissions corrected to 7% oxygen). For new sources, the emissions limits would be: ( 1) a semivolatile metal emission limit of 170 g/ dscm for combined emissions of lead, cadmium, and selenium; and ( 2) a low volatile metal emission limit of 190 g/ dscm for emissions of arsenic, beryllium, chromium, antimony, cobalt, manganese, and nickel ( all emissions corrected to 7% oxygen). 4. Why Don't We Offer this Alternative to Lightweight Aggregate Kilns and Cement Kilns? This alternative is intended to apply to sources that feed de minimis levels of metal HAP. We do not believe hazardous waste burning lightweight aggregate kilns and cement kilns feed these metals at de minimis levels primarily because raw materials and coal that is co fired may contain these metal HAP, and because hazardous waste that is combusted by sources that receive off site hazardous waste shipments ( i. e., commercial hazardous waste combustors) typically contain these metal HAP. Thus, we think that allowing this alternative would not be of practical significance because we do not believe these sources could meet the standard. As a result, we are not proposing this alternative for these source categories. B. What Alternative to the Particulate Matter Standard Is EPA Requesting Comment On? As previously discussed, we do not have sufficient metal HAP compliance data to calculate MACT floors that would account for all the nonmercury metal HAP in all feedstreams. Redline strikeout highlighting changes made during OMB review 314 We discuss below, however, an alternative approach to the particulate matter standard that could be implemented if sources monitor and collect nonmercury metal HAP feed concentration data prior to the compliance date. Such an approach, if promulgated, would result in site specific metal HAP emission limits that would be dependent, in part, on each source's average feed concentration levels of metal HAP in their hazardous and nonhazardous waste feedstreams, and, for energy recovery units, each source's hazardous waste firing rate. We discuss this alternative below, and we request comment as to whether this approach is appropriate given the complexities associated with its implementation. Also see USEPA, " Draft Technical Support Document for HWC MACT Replacement Standards, Volume IIIV: Selection ofCompliance With MACT Standards and Technologies",," March 2004, Chapter 23.9, for more discussion. 1. What Are the Components of the Total Metal Emissions Limitations? This total metal emission limitation would regulate all nonmercury metal HAP with separate semivolatile HAP metal and low volatile HAP metal emission limits. Each semivolatile and low volatile metal limit would have separate MACT components that would control and limit enumerated and nonenumerated metal HAP emissions that are attributable to: ( 1) hazardous waste feedstreams; ( 2) nonhazardous waste, non fuel feedstreams ( e. g., cement kiln raw material); and ( 3) nonhazardous waste fuels ( e. g., coal). Some of these components may or may not apply depending on the source category. Each semivolatile and low volatile metal component is converted to a mass emission limitation, and each source's resultant total metal emissions would be limited to the summation of each of the applicable components. We describe these MACT components below. a. Energy Recovery Units: Allowable Enumerated Semivolatile and Low Volatile Metal Emissions Attributable to the Hazardous Waste. This first component limits enumerated metal emissions attributable to hazardous waste feedstreams from energy recovery units, i. e., liquid boilers, cement kilns, and lightweight aggregate kilns, and is equivalent to the enumerated semivolatile and low volatile metal mass emission rate that would be allowed by today's proposed standards. Each source's allowable mass emission rate limit for this component would be equivalent to its associated hazardous waste thermal feed rate ( expressed as million Btu hazardous waste per hour) multiplied by the proposed semivolatile and low volatile metal thermal emission standard. b. Solid Fuel Fired Boilers and Incinerators: Allowable Enumerated Semivolatile and Low Volatile Metal Emissions Attributable to All Feedstreams. This second component applies only to solid fuel fired boilers and incinerators, and limits enumerated metal mass emissions attributable to all feedstreams , i. e., hazardous waste, nonhazardous waste, and nonhazardous waste fuels. This component limit is equivalent to the enumerated semivolatile and low volatile metal mass emission rate that would be allowed by today's proposed standards. Today's proposed standards for incinerators and solid fuel fired boilers limits total emissions from all feedstreams, and are expressed as stack gas concentration limits. Each source's allowable mass emission rate limit for this component would be equivalent to its gas flowrate multiplied by the proposed standard. c. All Source Categories: Allowable Nonenumerated Semivolatile and Low Volatile Metal Emissions Attributable to the Hazardous Waste. This third component limits Redline strikeout highlighting changes made during OMB review 85 We request comment on how such an approach would work for new sources, given that new sources may not have historical feed concentration data at the time they begin operations.

86 Each source would be required to calculate its associated three year average nonenumerated metal hazardous waste concentrations for both semivolatile metals ( lead, cadmium, and selenium) and low volatile metals ( arsenic, beryllium, chromium, antimony, cobalt, manganese, and nickel) expressed in either hazardous waste thermal concentrations, i. e., pounds per million Btus ( for energy recovery units) or maximum theoretical emissions concentrations, i. e., pounds per dry standard cubic feet ( for incinerators and solid fuel fired boilers).

87 Sources would not be required to collect three years of data if the nonhazardous waste fuels such as natural gas do not contain metal HAP.

315 nonenumerated semivolatile and low volatile metal emissions attributable to hazardous waste feedstreams, and is applicable to all source categories. We currently do not have sufficient data to calculate a MACT emission limitation for nonenumerated metals in the hazardous waste. As a result, sources complying with this alternative would be required to collect three years of nonenumerated semivolatile and low volatile metal hazardous waste feed control concentrations. 85 Incinerators and solid fuel fired boilers would be required to collect hazardous waste maximum theoretical emissions concentrations, and energy recovery units would be required to collect three years of hazardous waste thermal feed concentration data for these metal groups. 86 Each incinerator and solid fuel fired boiler's allowable semivolatile and low volatile metal mass emission rate for this component would be equivalent to its associated three year average hazardous waste maximum theoretical emissions concentrations for each metal group multiplied by: ( 1) 1 minus the MACT system removal efficiency; and ( 2) its associated volumetric gas flow rate. Each energy recovery unit's allowable mass emission rate for this component would be equivalent to its associated three year average hazardous waste thermal feed concentration for each metal group multiplied by: 1 minus the MACT system removal efficiency; and ( 2) its associated hazardous waste thermal federatefeedrate ( expressed as million Btu hazardous waste per hour). The MACT system removal efficiency that would be applied separately for semivolatile metals and low volatile metals would be determined as described in Part Two, Section VI. G. 5 for each source category. d. Energy Recovery Units: Enumerated and Nonenumerated Metal HAP Emissions Attributable to Nonhazardous Waste Fuels. The fourth component limits enumerated and nonenumerated semivolatile and low volatile metal mass emissions attributable to nonhazardous waste fuels ( e. g., coal) and is applicable to energy recovery units, i. e., cement kilns, lightweight aggregate kilns, and liquid fuel fired boilers. Energy recovery units complying with this alternative would be required to collect three years of enumerated and nonenumerated semivolatile and low volatile metal nonhazardous waste fuel thermal feed concentration levels. 87 Each source's allowable mass emission rate for this component would be equivalent to its Redline strikeout highlighting changes made during OMB review 88 Each source would be required to calculate its associated three year average metal concentrations in their coal for both semivolatile metals ( lead, cadmium, and selenium) and low volatile metals ( arsenic, beryllium, chromium, antimony, cobalt, manganese, and nickel) expressed in pounds per million Btu of coal.

89 This would be equivalent to a kiln's coal feedrate expressed in million Btus per hour.

90 Each source would be required to calculate its associated three year average nonenumerated metal concentrations in their nonhazardous waste fuel for both semivolatile metals ( selenium) and low volatile metals ( antimony, cobalt, manganese, and nickel) expressed in pounds per million Btu.

316 associated three year average metal nonhazardous waste fuel thermal feed concentration for each metal group88 multiplied by: ( 1) one minus the MACT system removal efficiency for the specified metal group; and ( 2) its associated nonhazardous waste thermal federatefeedrate. 89 As discussed above, the MACT system removal efficiency that would be applied separately for semivolatile metals and low volatile metals would be determined as described in Part Two, Section VI. G. 5 for each source category. e. Incinerators and Solid Fuel Fired Boilers: Nonenumerated Metal HAP Emissions Attributable to Nonhazardous Waste Fuels. The fifth component limits nonenumerated semivolatile and low volatile metal mass emissions attributable to nonhazardous waste fuels ( e. g., coal, fuel oil) and is applicable to incinerators and solid fuel fired boilers. Sources complying with this alternative would be required to collect three years of nonenumerated semivolatile and low volatile metal nonhazardous waste fuel thermal feed concentrations. Each source's allowable mass emission rate for this component would be equivalent to its associated three year average metal nonhazardous waste fuel thermal feed concentration for each metal group90 multiplied by: ( 1) one minus the MACT system removal efficiency for the specified metal group; and ( 2) its associated nonhazardous waste fuel thermal federatefeedrate ( expressed as million btu per hour). As discussed above, the MACT system removal efficiency that would be applied separately for semivolatile metals and low volatile metals would be determined as described in Part Two, Section VI. G. 5 for each source category. f. Incinerators and Solid Fuel Fired Boilers: Nonenumerated Metal HAP Emissions Attributable to Nonfuel Nonhazardous Waste. The sixth component limits nonenumerated metal HAP emissions attributable to nonfuel nonhazardous waste feedstreams from incinerators and solid fuel fired boilers. Sources complying with this alternative would be required to collect three years of nonenumerated semivolatile and low volatile metal nonfuel nonhazardous waste feedstream concentration data, expressed as mass of metal fed in its nonfuel nonhazardous waste feedstream per total thermal input into the combustor. Each source's allowable mass emission rate for this component would be equivalent to its associated three year average metal nonfuel Redline strikeout highlighting changes made during OMB review 91 Each source would be required to calculate its associated three year average nonenumerated metal thermal feed concentrations in their nonfuel nonhazardous waste feedstreams for both semivolatile metals ( selenium) and low volatile metals ( antimony, cobalt, manganese, and nickel) expressed in pounds per million Btu.

92 Total thermal input to kiln would include both hazardous and nonhazardous fuel thermal input.

93 Each source would be required to calculate its associated three year average metal thermal feed concentrations in their raw material for both semivolatile metals ( lead, cadmium, and selenium) and low volatile metals ( arsenic, beryllium, chromium, antimony, cobalt, manganese, and nickel) expressed in pounds per million Btus.

317 nonhazardous waste thermal feed concentration for each metal group91 multiplied by: ( 1) one minus the MACT system removal efficiency for the specified metal group; and ( 2) its associated total thermal feedrate ( expressed as million Btus per hour). As discussed above, the MACT system removal efficiency that would be applied separately for semivolatile metals and low volatile metals would be determined as described in Part Two, Section VI. G. 5 for each source category. g. Cement Kilns and Lightweight Aggregate Kilns: Enumerated and Nonenumerated Metal HAP Emissions Attributable to Raw Materials. The seventh component limits enumerated and nonenumerated metal HAP emissions attributable to raw material from cement kilns and lightweight aggregate kilns. Cement kilns and lightweight aggregate kilns complying with this alternative would be required to collect three years of enumerated and nonenumerated semivolatile and low volatile metal raw material feed concentration data, expressed as mass of metal fed in raw material per total thermal input into the kiln. 92 Each cement kiln and lightweight aggregate kiln's allowable mass emission rate for this component would be equivalent to its associated three year average metal raw material thermal feed concentration for each metal group93 multiplied by: ( 1) one minus the MACT system removal efficiency for the specified metal group; and ( 2) its associated total thermal federatefeedrate. As discussed above, the MACT system removal efficiency that would be applied separately for semivolatile metals and low volatile metals would be determined as described in Part Two, Section VI. G. 5 for each source category. 2. Would Sources Still Be Required to Comply with a Particulate Matter Standard if They Comply with this Alternative? As previously discussed in Part Two, Section VI. F, we conclude that today's proposed floor levels can be no higher than the interim standards because all sources, not just the best performing sources, are achieving the interim standards. It is not clear whether this alternative total metal emission limitation is less stringent than the current interim particulate matter standard Redline strikeout highlighting changes made during OMB review 94 There is not a direct correlation between particulate matter emissions and metal emissions given that metal emission levels are both a function of feed control and particulate matter control.

95 As previously discussed, this is because Clean Air Act standards can supplant RCRA standards only when the CAA standard is sufficiently protective of human health and the environment to make the RCRA standard duplicative ( within the meaning of RCRA section 1006 ( b) ( 3)).

318 for incinerators, cement kilns, and lightweight aggregate kilns. 94 As a result, incinerators, cement kilns, and lightweight aggregate kilns complying with this alternative would also be required to comply with the interim standard for particulate matter. Liquid and solid fuel fired boilers complying with this alternative would remain subject to the RCRA particulate matter standard of 0.08 gr/ dscf pursuant to § 264.343( c). 95 3. How Would Sources Demonstrate Compliance with this Alternative? Sources complying with this alternative would be required to calculate its site specific semivolatile and low volatile metal mass emission rate limitation as described above. Each source's emission limitation would not only be a function of its average three years of metal concentration data collected, but also would be a function of either its gas flowrate ( for incinerators and solid fuel fired boilers), hazardous waste thermal firing rate ( for cement kilns, lightweight aggregate kilns, and liquid fuel fired boilers), and total thermal input rate ( for all sources). As a result each source's mass emission limitation would vary over time as the dependent variables change ( e. g., a cement kiln's allowable mass emission limitation would increase if its hazardous waste thermal firing rate increases). Sources would demonstrate compliance with these site specific metal emission rate limitations during its comprehensive performance test and would establish operating parameter limits on its air pollution control device to ensure that the source achieves the metal system removal efficiency that was demonstrated during the test during normal day to day operations. Sources would then establish total metal federatefeedrate limits that would assure compliance with this site specific metal emission limitation. Given that these metal emission limitations may vary over time, we request comment as to whether these emission limitations ( and associated federatefeedrate operating limits) should be instantaneous limits based on each source's current operating levels ( e. g., hazardous waste thermal input rate for energy recovery units, or gas flowrate for incinerators), or rather 12 hour rolling average limits that would be updated each minute.

XIX. What Are the Proposed RCRA State Authorization and CAA Delegation Requirements? A. What Is the Authority for this Rule? Today's rule amends the promulgated standards located at 40 CFR part 63, subpart EEE. It amends the standards for the Phase I source categories incinerators, cement kilns, and Redline strikeout highlighting changes made during OMB review 96 Accordingly, S/ L/ T agencies are required to reopen existing title V permits that have 3 or more years remaining in the permit term to include the promulgated standards. If there are less than 3 years remaining, S/ L/ T agencies may wait until renewal to incorporate the standards. Provided that a source is not required to reopen its title V permit, it must still fully comply with the promulgated standards ( 40 CFR § 70.7( f)( 1)( i)).

319 lightweight aggregate kilns that burn hazardous waste, and it also amends subpart EEE to establish MACT standards for the Phase II source categories boilers and hydrochloric acid production furnaces that burn hazardous waste. Additionally, this rule amends several RCRA regulations located in 40 CFR part 270 to reflect changes in applicability, addition of a new permit modification procedure and additions related site specific risk assessments and permitting. 1. How Is this Rule Delegated under the CAA? Consistent with the September 1999 rule, we recommend that state, local, and tribal ( S/ L/ T) air pollution control agencies apply for delegation of this subpart ( and all NESHAP) under section 112( l) of the CAA, if they have not done so already, so that they can exercise delegable authorities for the final Phase I Replacement standards and Phase II standards. Delegable authorities are the discretionary activities, such as approving changes to the reporting schedule, that are part of each NESHAP. EPA retains some of those authorities, but allows most to be implemented by those S/ L/ T agencies who accept straight delegation of the NESHAP; in this case, subpart EEE. The delegable authorities, those that can and cannot be delegated, are described in section 63.1214 of this subpart. ( For more information on delegation of part 63 provisions, see 65 FR 55810  55846.) All major sources of air pollutants, such as all sources subject to this subpart, must have a title V operating permit which would contain all applicable requirements, including those for this subpart. ( For more information, please see 40 CFR part 70.) While S/ L/ T agencies can implement and enforce MACT standards through their approved title V programs, approval of title V programs alone do not allow S/ L/ T authorities to be the primary enforcement authority and they cannot exercise delegable provisions' authorities. An approved title V program means that S/ L/ T agencies commit to incorporating all MACT standards into title V permits as permit conditions and to enforcing all the terms and conditions of the permit. 96 Having an approved title V program, for instance, does not automatically allow S/ L/ T agencies to approve test plans, requests for ( minor and intermediate) changes to monitoring, performance test waivers, document notifications, or other Category I Authorities ( see 40 CFR 63.91( g)( 1)( i)). For those S/ L/ T agencies who have been previously delegated authority for the MACT standards under 40 CFR part 63 subpart EEE, we encourage you to request approval of the revisions to emission standards and various other compliance requirements of today's proposal when promulgated. B. Are There Any Changes to the CAA Delegation Requirements for Phase I Sources? With regard to CAA delegation requirements for Phase I sources, we intend to clarify which provisions in 40 CFR part 63 subpart EEE are delegable and those that are not in today's Notice of proposed rulemaking. We recently published a final rule, Clarifications to Existing National Emissions Standards for Hazardous Air Pollutants Delegations' Provisions on June 23, Redline strikeout highlighting changes made during OMB review 97 EPA Regions may choose whether they will or will not delegate authority to S/ L/ T agencies to approve minor and intermediate changes.

320 2003 ( see 68 FR 37334), that clarifies and streamlines delegable provisions for each existing NESHAP. Prior to finalization of this rule, many permitting authorities and sources alike were left to interpret which Category I authorities were delegable according to provisions specific to one NESHAP versus another. In light of this final rule, which outlines the non delegable provisions for subpart EEE, some confusion remains today as to which actions can be taken by a delegated S/ L/ T agency. Therefore, we intend to clarify specific actions in subpart EEE that can or cannot be taken by permitting agencies who have received delegation under 112( l) of the CAA for subpart EEE. 2. What Are the Clarifications and Changes to CAA Delegable Authorities for this Rule? Sections 63.91( g)( 1)( i) and ( g)( 2)( i) list authorities that are generally delegable to S/ L/ T agencies and those that are not, respectively. These apply to all NESHAP. Similar information contained in § 63.1214 explains that some of the discretionary authorities, such as approval of alternative reporting schedules, under subpart EEE, can be implemented and enforced by a delegated authority. It also lists the authorities that are retained by EPA and are not delegable to S/ L/ T agencies even if they have received delegation for subpart EEE. These non delegable authorities are: ( 1) approval of alternatives to requirements in § § 63.1200, 63.1203 through 63.1205, and 63.1206( a); ( 2) approval of major alternatives to test methods under § 63.7( e)( 2)( ii) and ( f); ( 3) approval of major alternatives to monitoring under § 63.8( f) and; ( 4) approval of major alternatives to recordkeeping and reporting under § 63.10( f). It is important to note that if the alternatives mentioned in items ( 2) through ( 4) are determined to be minor or intermediate according to the definitions in § 63.90( a), then they are considered delegable and can be approved by a S/ L/ T agency who has been granted authority for subpart EEE. 97 To aid in the determination of whether a request is major, intermediate, or minor, we recommend that you consult the September 14, 2000 final rule, Hazardous Air Pollutants: Amendments to the Approval of State Programs and Delegation of Federal Authorities ( 65 FR 55810). The preamble to this rule provides examples, as well as the regulatory definitions as they exist today in 40 CFR § 63.90( a). Additionally, you may consult a guidance document entitled, How to Review and Issue Clean Air Act Applicability Determinations and Alternative Monitoring ( EPA 305 B 99 004, February 1999). While § 63.1214( c) and § 63.90( a) provide which authorities are not delegable for subpart EEE sources and define degrees of changes, they may not be clear in certain applications. We will address specific sections in subpart EEE, through the following preamble discussion and through regulatory amendments, where we believe there is a need for clarity based upon our experiences with the implementation of the Phase I standards thus far. Also, there are some alternatives in subpart EEE that were inadvertently left out of § 63.1214( c) which we are adding through this Notice of proposed rulemaking. Beginning with test methods, major alternatives are not delegable. ( See 40 CFR 63.90( a) Redline strikeout highlighting changes made during OMB review 98 Send requests to: Conniesue B. Oldham, Ph. D., Group Leader, Source Measurement Technology Group ( D205 02), Office of Air Quality Planning and Standards, US Environmental Protection Agency, Research Triangle Park, NC 27711 321 for definitions of major, intermediate, and minor changes to test methods.) We noted in § 63.1214( c)( 2) that major alternatives to the test methods as addressed in the general provisions at § 63.7( e)( 2)( ii) and ( f) were not delegable, however, we did not specifically include test methods relevant to subpart EEE. Section 63.1208( b) specifies the test methods sources must use to determine compliance with emission standards in subpart EEE. This section is delegable in its entirety to S/ L/ T agencies who have been delegated authority for subpart EEE, as long as the request is not a major change. Additionally, the CEMS required in § 63.1209( a)( 1), although a monitoring requirement, is considered to be a test method since it serves as the benchmark measurement method for demonstrating compliance with emission standards. The authority to approve changes to the CEMS related requirements is also delegable to S/ L/ T agencies as long as the request is not a major change. To summarize, if a source proposes a major change to a test method specified in § § 63.1208( b) and 63.1209( a)( 1), it must send the request to the appropriate EPA Region and EPA's Office of Air Quality Planning and Standards, 98 since major changes to test methods are not delegable. We are adding § § 63.1208( b) and 63.1209( a)( 1), to the authorities in § 63.1214( c)( 2) that are not delegable for major changes. Consistent with the major alternatives to test methods, major alternatives to monitoring are not delegable. ( See 40 CFR 63.90( a) for definitions of major, intermediate, and minor changes to test methods.) We noted in § 63.1214( c)( 2) that major alternatives to monitoring as addressed in the general provisions in § 63.8( f) were not delegable, but we did not specifically address the relevant monitoring requirements in subpart EEE. Section 63.1209 specifies the monitoring requirements sources must use to determine compliance with emission standards in EEE. Depending upon the pollutant to be monitored, either a CEMS or COMS is required. Before discussing whether changes to monitoring in subpart EEE are delegable, it is important first to review how requests for changes to monitoring are handled under the general provisions of § 63.8( f). In general, requests for alternative monitoring follow the same approach, with respect to delegation authority, as requests for alternative test methods discussed above; requests that are defined as major should be sent to the appropriate EPA Region and requests that are intermediate or minor should be sent to the delegated S/ L/ T agency. A request to use other monitoring in lieu of a CEMS is always considered a major change. However, if a source proposes to use a CEMS in lieu of an operating parameter, the request may be considered an intermediate change, so long as the CEMS to be used is regarded as a " proven technology" and could be submitted to a S/ L/ T agency for approval. The rationale for this is that the use of a CEMS, rather than monitoring via an operating parameter, provides a better measure of compliance and thus, we want encourage the use of CEMS when possible. While we want to encourage the use of CEMS, we recognize that S/ L/ T agencies may not always have the technical resources to review these applications, particularly when there are no federally promulgated performance specifications for the CEMS. In such cases, we expect that the S/ L/ T agency will Redline strikeout highlighting changes made during OMB review 322 rely on EPA Regions for approval. In subpart EEE, § 63.1209, there are two alternative approaches to monitoring that sources may use. One is located at § 63.1209( a)( 5), Petitions to use CEMS for other standards, and the other is at § 63.1209( g)( 1), Alternative monitoring requirements other than continuous emissions monitoring systems. Section 63.1209( a)( 5) allows sources to request to use CEMS to monitor particulate matter, mercury, semivolatile metals, low volatile metals, and/ or hydrochloric acid/ chlorine gas in lieu of compliance with operating parameter limits. In these cases, a source would be monitoring the pollutant of concern and comparing the emissions measurements directly against an emission limitation rather than comparing the measurements to an operating parameter. We consider a request under § 63.1209( a)( 5) to be major change to monitoring and consequently, it is not delegable. We classify § 63.1209( a)( 5) to be a major change ( rather than an intermediate change which can be delegable) mainly because we have not yet promulgated Performance Specifications for the CEMS that may be used. In other words, it could be argued that these CEMS do not yet qualify as fully " proven technology". We understand that it could be argued either way, but for the reasons discussed in the previous paragraph and as an added measure of consistency, requests to use CEMS in lieu of operating parameters should be submitted to the EPA Region for approval. Therefore, we are adding § 63.1209( a)( 5) to the authorities in § 63.1214( c)( 2) that are not delegable for major changes. The other alternative monitoring provision, § 63.1209( g)( 1), allows sources to use alternative monitoring methods, with the exception of the standards that must be monitored with a CEMS, and to request a waiver of an operating parameter limit. Section 63.1209( g)( 1) applies to requests for alternative parameter monitoring that involve the use of a different detector ( i. e., thermocouple, pressure transducer, or flow meter), a different monitoring location, a different method as recommend by the manufacturer, or a different averaging period that is more stringent than the applicable standard. For example, sources equipped with wet scrubbers are required to establish a minimum pressure drop limit to assure adequate contact between the gas and liquid. A source may petition to have this monitoring requirement waived if the manufacturer does not recommend pressure drop as a critical control parameter that affects the unit's operating efficiency. Depending upon the type of wet scrubber, an appropriate minimum limit may be specified for steam injection rate, disk spin rate, or a maximum temperature limit on liquid and flue gas, rather than pressure drop. Also, sources could request more stringent averaging periods in order to " mirror" the averaging periods required under RCRA. This may facilitate an easier transition from RCRA to MACT during the time period sources may need to comply with both sets of requirements. Since we do not consider these changes to be major, requests under § 63.1209( g)( 1) should be sent to the delegated S/ L/ T agency for approval. Accordingly, we are amending the language in § 63.1209( g)( 1) to specify that a source may submit an application to the Administrator or a State with an approved Title V program. Also, we are revising the title under § 63.1209( g)( 1) so that it is more specific regarding its intended use. Lastly, major alternatives to recordkeeping and reporting also are not delegable. ( See 40 CFR 63.90( a) for definitions of major, intermediate, and minor changes to test methods.) We noted in § 63.1214( c)( 2) that major alternatives to the general provisions of § 63.10( f) were not delegable, but we did not specifically address any relevant recordkeeping and reporting Redline strikeout highlighting changes made during OMB review 323 requirements in subpart EEE. Section 63.1211 specifies the recordkeeping and reporting requirements sources must comply with in subpart EEE. This section is delegable in its entirety to S/ L/ T agencies who have been delegated authority to implement and enforce subpart EEE, as long as the request is not a major change. It is worthwhile to note that paragraph ( e), Data compression, may be incorrectly interpreted as a major change itself to the recordkeeping and reporting requirements, because it appears as though there are no criteria to define fluctuation or data compression limits. However, this is not the case. In the preamble to the September 1999 final rule ( see 64 FR 52961 and 52962), we provided guidance for preparing a request to use data compression techniques and recommended fluctuation and data compression limits. This guidance was not affected by the court's vacatur of portions of this rule, so it remains in effect. Consequently, this allows permitting authorities to be consistent in their evaluation of requests. We view paragraph ( e) to be a minor change itself and so a written request to use data compression techniques can be submitted to a delegated S/ L/ T agency. We are adding § 63.1211( a)  ( d) to the authorities in § 63.1214( c)( 2) that are not delegable for major changes. In addition to the clarifications and amendments addressed above, there are two important delegation issues we would like to emphasize. The first is simply to remind sources and permitting authorities alike that, if a provision in this subpart specifies that you may petition or request that the " Administrator or State with an approved Title V program ...," then a state that has not been delegated for that requirement, but has an approved Title V program, does have the authority to approve or disapprove the request. For instance, § 63.6( i)( 1) and § 63.1213( a) both specify that the " Administrator ( or a State with an approved permit program)" can grant a compliance extension request. The second is that EPA Regions can decide whether or not to delegate the authority to approve intermediate changes to state and local agencies. In some cases, a state may have received delegation to approve only minor changes. Where there is uncertainty, we recommend that sources try to determine if a request is major, intermediate, or minor based on the definitions in 40 CFR § 63.90( a), and then consult with their S/ L/ T agency and/ or EPA Region to determine where to submit the request. Or, sources may submit requests to the S/ L/ T agency or EPA Region who will then determine where it should go for approval. C. What Are the Proposed CAA Delegation Requirements for Phase II Sources? With respect to CAA delegation requirements for Phase II sources, they are the same as those for Phase I sources. Since both Phase I and Phase II MACT standards are located in the same subpart, EEE, the same delegation provisions apply to both. Generally speaking, authority to approve alternatives to standards or major changes to test methods, monitoring, and recordkeeping and reporting are not delegated to S/ L/ T agencies. Authority to approve intermediate and minor changes to test methods, monitoring, and recordkeeping and reporting are delegated to S/ L/ T agencies who have been delegated authority to implement subpart EEE. All other subpart EEE implementation requirements may be handled by the delegated S/ L/ T agency. For specific information, please refer to the previous section, A. 1. What are the clarifications and changes to CAA delegable authorities for this rule? How Would States Become Authorized under RCRA for this Rule? Under section 3006 of RCRA, EPA may authorize qualified states to administer their own hazardous waste programs in lieu of the federal program within the state. Following authorization, EPA retains enforcement Redline strikeout highlighting changes made during OMB review 324 authority under sections 3008, 3013, and 7003 of RCRA, although authorized states have primary enforcement responsibility. The standards and requirements for state authorization are found at 40 CFR Part 271. Prior to enactment of the Hazardous and Solid Waste Amendments of 1984 ( HSWA), a State with final RCRA authorization administered its hazardous waste program entirely in lieu of EPA administering the federal program in that state. The federal requirements no longer applied in the authorized state, and EPA could not issue permits for any facilities in that state, since only the state was authorized to issue RCRA permits. When new, more stringent federal requirements were promulgated, the state was obligated to enact equivalent authorities within specified time frames. However, the new federal requirements did not take effect in an authorized state until the state adopted the federal requirements as state law. In contrast, under RCRA section 3006( g) ( 42 U. S. C. 6926( g)), which was added by HSWA, new requirements and prohibitions imposed under HSWA authority take effect in authorized states at the same time that they take effect in unauthorized states. EPA is directed by the statute to implement these requirements and prohibitions in authorized states, including the issuance of permits, until the state is granted authorization to do so. While states must still adopt HSWA related provisions as state law to retain final authorization, EPA implements the HSWA provisions in authorized states until the states do so. Authorized states are required to modify their programs only when EPA enacts federal requirements that are more stringent or broader in scope than existing federal requirements. RCRA section 3009 allows the states to impose standards more stringent than those in the federal program ( see also 40 CFR 271.1). Therefore, authorized states may, but are not required to, adopt federal regulations, both HSWA and non HSWA, that are considered less stringent than previous federal regulations. The amendments to the RCRA regulations proposed today in sections 40 CFR 270.10, 270.22, 270.32, 270.42, 270.66, and 270.235 are considered to be either less stringent or equivalent to the existing Federal program. Thus, states are not required to modify their programs to adopt and seek authorization for these provisions, although we strongly encourage them to do so to facilitate the transition from the RCRA program to the CAA program and to promote national consistency. Additionally, EPA will not implement those provisions promulgated under HSWA authority that are not more stringent than the previous federal regulations in States that have been authorized for those previous federal provisions. The amendments in sections 40 CFR 270.22 and 270.66 in today's notice are proposed under the HSWA amendments to RCRA. Further, today's proposed amendment in 40 CFR 270.235 to apply this provision to solid and liquid fuel fired boilers and HCL production furnaces, is proposed under HSWA statutory authority. The amendments to the RCRA regulations proposed today in sections 40 CFR 270.10 and 270.32 are proposed under both non HSWA and HSWA authority, depending on the type of unit to which these amendments are applied ( under HSWA authority if applied to BIFs or non HSWA authority if applied to incinerators). Refer to Part Two, Section XVII. D. 4 for a more detailed discussion of the implementing authorities for proposed regulations in 40 CFR 270.10 and 270.32. The following RCRA sections, enacted as part of HSWA, apply to today's rule: 3004( o), 3004( q), and 3005 ( c)( 3). As a part of HSWA, Redline strikeout highlighting changes made during OMB review 99 See discussion in Part One, Section I. B. 1.

100 These stakeholders assumed, correctly, that today's proposed replacement emission standards would be substantially more stringent than the current ( September 1999 Final Rule) standards.

101 Please note that this does not affect the compliance date. You must be in compliance with the replacement standards on the compliance date, and certify in the 325 these RCRA provisions are federally enforceable in an authorized State until the necessary changes to a State's authorization are approved by us. See RCRA § 3006, 42 U. S. C. § 6926. The Agency is adding these requirements to Table 1 in 271.1( j), which identifies rulemakings that are promulgated pursuant to HSWA.

Part Three: Proposed Revisions to Compliance Requirements In this section, we discuss proposed revisions to compliance requirements that may affect all hazardous waste combustors. We also request comment on whether we should make revisions to other compliance requirements, and explain why we conclude not to make revisions to other compliance requirements that we proposed ( or requested comment on) previously.

I. Why Is EPA Proposing to Allow Phase I Sources to Conduct the Initial Performance Test to Comply with the Replacement Rules 12 Months After the Compliance Date? We propose to allow owners and operators of incinerators, cement kilns, and lightweight aggregate kilns to commence the initial comprehensive performance test to comply with the replacement standards proposed at § § 63.11203A1219, 63.1204A1220, and 63.1205A1221 within 12 months of the compliance date rather than within six months of the compliance date. See proposed § 63.1207( c)( 3). Owners and operators of solid fuel fired boilers, liquid fuel fired boilers, and hydrochloric acid production furnaces, however, must commence the initial comprehensive performance test within six months of the compliance date. During development of the joint motion by petitioners to the United States Court of Appeals for the District of Columbia Circuit that resulted in the Agency promulgating the Interim Standards Rule on February 13, 2002,99 stakeholders representing owners and operators of incinerators, cement kilns, and lightweight aggregate kilns requested that we propose to allow them 12 months after the compliance date to commence the initial comprehensive performance test. These stakeholders request a 12 month window rather than the six month window currently required under § 63.1207( c) to give them longer to amortize the cost of the comprehensive performance test demonstrating compliance with the Interim Standards before having to retest to demonstrate compliance with the replacement standards proposed today. 100 We believe this request has merit and so are proposing to allow them to commence the initial comprehensive performance test within 12 months after the compliance date. 101 Redline strikeout highlighting changes made during OMB review Documentation of Compliance that you have established operating parameter limits that you believe will ensure compliance with the standards. You must record the Documentation of Compliance in the operating record by the compliance date.

326 II. Why Is EPA Requesting Comment on Requirements Promulgated as Interim Standards or as Final Amendments? As discussed in Part One, Section I. B., EPA promulgated interim standards ( called the Interim Standards Rule) on February 13, 2002 that amended compliance and implementation provisions of the September 1999 Final Rule. The amended provisions were specified in a joint motion by petitioners to the United States Court of Appeals for the District of Columbia Circuit ( the Court). Although petitioners agreed that the amendments should be promulgated ( see 67 FR at 6794), petitioners requested that EPA reopen certain amended provisions for public comment. Also as discussed in Part One, Section I. B, EPA promulgated amendments ( called Final Amendments) to the September 1999 Final Rule on February 14, 2002 that revised certain implementation and compliance requirements. These amendments were also specified in the joint motion to the Court, and petitioners requested that EPA reopen specific amended provisions for public comment. We discuss these provisions in this section, and reopen them for public comment. ( We note, however, that we are not reopening for comment any RCRA rules, and are not soliciting comment on any aspect of those rules, or otherwise reconsidering or reexaming any such rules. Any references to RCRA rules in the discussion which follows is solely as an aid to readers.) Although we are not proposing additional revisions to these provisions, we may determine after review of public comments on the issues we raise that revisions are appropriate. If so, we would promulgate those amendments in the Replacement Rule. Although these provisions currently apply only to incinerators, cement kilns, and lightweight aggregate kilns, we are proposing today to apply them to boilers and hydrochloric acid production furnaces as well. ( See Part Two, Sections XIII XV.) Accordingly, any amendments to these requirements that we may promulgate would also apply to boilers and hydrochloric acid production furnaces. A. Interim Standards Amendments to the Startup, Shutdown, and Malfunction Plan Requirements The September 1999 Final Rule required compliance with the emission standards and operating requirements at all times that hazardous waste is in the combustion system, including during startup, shutdown, and malfunctions. Industry stakeholders noted that requiring compliance with emission standards and operating requirements during startup, shutdown, and malfunctions is inconsistent with the General Provisions of Subpart A, Part 63, that apply to MACT sources ( unless alternative requirements are prescribed for a source category). Stakeholders stated that it is inappropriate to penalize a source for exceeding emission standards and operating requirements during malfunctions because some exceedances are unavoidable and sources are already required to take corrective measures prescribed in the startup, shutdown, and malfunction plan ( SSMP) to minimize emissions. Redline strikeout highlighting changes made during OMB review 102 These requirements are needed to minimize emissions of HAP during startup, shutdown, and malfunctions and, thus, help meet our RCRA mandate to ensure that emissions from hazardous waste combustors do not pose a hazard to human health and the environment. Sources may elect either to remain under RCRA control during these events or to comply under MACT with requirements to develop and implement a comprehensive and proactive startup, shutdown, and malfunction plan that is reviewed and approved by the delegated regulatory authority.

103 We also request comment on whether the startup, shutdown, and malfunction plan should be expanded beyond the scope required under § 63.6( e)( 3) ( requiring appropriate corrective measures in reaction to a malfunction) to address specific, proactive measures that the owner and operator have considered and are taking to minimize the frequency and severity of malfunctions.

327 In response to industry stakeholder concerns, the Interim Standards Rule amended the SSMP requirements to: ( 1) exempt sources from the Subpart EEE emission standards and operating requirements during startup, shutdown, and malfunctions; ( 2) continue to subject sources to RCRA requirements during malfunctions, unless they comply with alternative MACT requirements including expanding the SSMP to minimize the frequency and severity of malfunctions, and submit the plan to the delegated CAA authority for review and approval102; ( 3) continue to subject sources that burn hazardous waste during startup and shutdown to RCRA requirements for startup and shutdown, unless they comply with alternative MACT requirements, and require sources to include waste feed restrictions and operating conditions and limits in the startup, shutdown, and malfunction plan; ( 4) require sources to include in the SSMP a requirement to comply with the automatic hazardous waste feed cutoff system during startup, shutdown, and malfunctions; and ( 5) make conforming revisions to the emergency safety vent opening requirements. See 67 FR at 6798 6802. In response to Sierra Club's request during development of the joint motion to the Court, we specifically request comment on the following issues. Notwithstanding the rationale for revising the September 1999 Final Rule to exempt sources from the Subpart EEE emission standards and operating requirements during malfunctions, would it be appropriate to require compliance with those standards and operating requirements during malfunctions to ensure that owners and operators have an incentive to minimize the frequency and duration of malfunctions that result in exceedances of the standards or operating requirements. Given that most excess emissions would occur during startup, shutdown, and malfunctions, should the SSMP be submitted for review by the delegated regulatory authority and made available for public review under all options for controlling emissions during startup, shutdown, and malfunctions? Providing a mechanism for public review may help ensure that the SSMP is complete, proactive, and provides appropriate corrective measures. 103 And finally, should the final rule clarify the definitions of startup, shutdown, and malfunctions to preclude, for example, an owner or operator incorrectly classifying an exceedance of an operating limit while hazardous waste remains in the Redline strikeout highlighting changes made during OMB review 104 EPA voluntarily vacated operating parameter limits for electrostatic precipitators ( and fabric filters) on May 14, 2001. See 66 FR at 24272. Until new operating parameter limits are promulgated, sources and delegated CAA authorities will use § 63.1209( g) to establish operating parameter limits for electrostatic precipitators ( and fabric filters) on a site specific basis.

328 combustion chamber as a malfunction when, in fact, the exceedance occurred because of a not infrequent event that could have been prevented by proper operation and maintenance of equipment? B. Interim Standards Amendments to the Compliance Requirements for Ionizing Wet Scrubbers The September 1999 Final Rule required sources to establish a limit on minimum total power to an ionizing wet scrubber. The Interim Standards Rule deleted that requirement to conform with the requirements for electrostatic precipitators given that an ionizing wet scrubber is essentially an ESP integrated with a packed bed scrubber. See 67 FR at 6802 03.104 In lieu of establishing a limit on the minimum total power requirement to an ionizing wet scrubber, sources and delegated CAA authorities will use the alternative monitoring provisions of § 63.1209( g) to identify appropriate controls for an ionizing wet scrubber on a site specific basis. This is the same approach that is used for electrostatic precipitators. Please note that we are requesting comment today on compliance requirements for electrostatic precipitators and fabric filters. In that discussion ( see Section III. I below), we explain that we are proposing to apply the same compliance requirements to both electrostatic precipitators and ionizing wet scrubbers. C. Why Is EPA Requesting Comment on the Fugitive Emission Requirements? The September 1999 Final Rule required sources to control combustion system leaks by either: ( 1) keeping the combustion zone sealed; ( 2) maintaining the maximum combustion zone pressure lower than ambient pressure using an instantaneous monitor; or ( 3) using an alternative means to provide control of system leaks equivalent to maintaining the maximum combustion zone pressure lower than ambient. After publication of the September 1999 Final Rule, stakeholders expressed concern that the option to maintain combustion zone pressure lower than ambient pressure ( option 2 above) could result in overly prescriptive requirements. Stakeholders believed that this regulatory language could be interpreted to require sources to monitor and record combustion zone pressure at a frequency of every 50 milliseconds. Stakeholders also requested that we clarify that combustion system leaks refers to fugitive emissions resulting from the combustion of hazardous waste, and not fugitive emissions that originate from nonhazardous process streams. In response to these concerns, we proposed amendments to the combustion system leak provisions on July 3, 2001. See 66 FR at 35132. We promulgated several revisions in the Final Amendments Rule after considering stakeholder comments. See 67 FR at 6973. The amended provisions that we are reopening for public comment today are discussed below. First, we amended the definition of an instantaneous pressure monitor to better clarify that the intent of the combustion system leak requirements is to prevent fugitive emissions from the Redline strikeout highlighting changes made during OMB review 329 combustion of hazardous waste rather than from nonhazardous feedstreams. The revised definition also clarifies that instantaneous pressure monitors must detect and record pressure at a frequency adequate to detect combustion system leak events, as determined on a site specific basis. See § 63.1201( a) and § 63.1209( p). Second, we added a provision that requires sources to specify the method used to control combustion system leaks in the performance test workplan and Notification of Compliance. See § 63.1206( c)( 5)( ii). Finally, in response to numerous comments, we added a provision that will allow sources, upon prior written approval of the Administrator, to use other techniques that can be demonstrated to prevent fugitive emissions without the use of instantaneous pressure limits. See § 63.1206( c)( 5)( i)( D). The provision allowing sources, upon prior written approval, to use other techniques that are demonstrated to prevent fugitive emissions without the use of instantaneous pressure limits was the most controversial. Specifically, some stakeholders believe this revised regulatory language is inappropriate because it suggests sources can sustain a positive pressure event and still prevent fugitive emissions. We believe that all positive pressure events do not necessarily result in fugitive emissions. As discussed in detail in the Final Amendments Rule, there are stateof the art rotary kiln seal designs ( such as shrouded and pressurized seals) which are capable of handling positive pressures without fugitive releases. However, we believe these kilns are highly unusual, and that other conventional rotary kilns used in the hazardous waste combustion industry may not have seals which are designed for such positive pressure operation. In fact, we believe that, for most rotary kilns in use today, positive pressure events can result in fugitive releases. The level of such fugitive releases will be dependent on factors including the magnitude and duration of the pressure excursion and the design and operation of the kiln. Furthermore, one commenter recommends that sources should be allowed to petition the regulatory official to use an alternative approach, i. e. an approach that does not require instantaneous pressure limits, only if they meet specific combustor design criteria. For example, it may be appropriate to apply this provision only to sources that we know are designed in manner that would not necessitate use of instantaneous pressure limits to prevent fugitive emissions ( e. g., kilns with multiple graphite seals with pressurized chambers between the seals to prevent outleakage or overlapping spring plate seals to form an air seal). We request comment on whether this specificity is necessary, or whether it is more appropriate to determine this on a site specific basis ( as is currently required). We also request comment on whether all the previously discussed combustion system leak regulatory revisions are appropriate. D. Why Is EPA Requesting Comment on Bag Leak Detector Sensitivity? The September 1999 Final Rule required sources equipped with fabric filters to install a bag leak detection system where the detector has the capability to detect PM emissions at concentrations of 1.0 milligrams per actual cubic meter, or less. In response to industry stakeholder concerns that a detector need not be able to detect levels as low as 1.0 mg/ acfm to detect subtle changes in baseline, normal emissions of PM, we proposed in the July 3, 2001 proposed rule ( 66 FR at 35134 35) to allow sources to use detectors with less sensitivity provided that the detector could detect subtle increases in normal emissions ( e. g., caused by pinhole leaks in the bags). The stakeholders noted that sources equipped with well designed and operated fabric filters can have normal, baseline emissions well above 1.0 mg/ acfm and be in compliance Redline strikeout highlighting changes made during OMB review 330 with the particulate matter emission standards. Stakeholders recommended that we revise the bag leak detection requirements to explicitly allow detectors with lower sensitivity in lieu of source's having to petition the delegated regulatory authority under the alternative monitoring provisions of § 63.1209( g)( 2) to receive case by case approval. All commenters on the proposed amendment supported the revision, and we finalized the amendment in the February 14, 2002 Final Amendments. See 67 FR at 6981. In response to a petitioner's request during development of the joint motion to the Court, however, we specifically request additional comment on whether allowing detectors that have a level of detection that is higher than 1.0 mg/ acfm will enable the detector to detect subtle increases in normal emissions. The petitioner is concerned that a detector with a level of detection higher than 1.0 mg/ acfm may not have the same sensitivity as a detector that can detect PM at 1.0 mg/ acfm. Thus, petitioner is concerned that the less sensitive detector may not be able to detect subtle increases in PM emissions due to bag degredation as readily as a detector that can detect at 1.0 mg/ acfm. We specifically request comment on this issue. We reopen this issue for comment without prejudice to the existing regulations which allow for less sensitive bag leak detectors. You may use less sensitive bag leak detectors until the compliance date for any change we may make in the final rule. E. Final Amendments Waiving Operating Parameter Limits during Testing without an Approved Test Plan The September 1999 Final Rule waived operating parameter limits during subsequent performance testing under an approved performance test plan. In response to stakeholder concerns, we addressed two issues in the Final Amendments: ( 1) applicability of operating parameter limits, established in the Documentation of Compliance, during an initial performance test conducted without an approved test plan; and ( 2) applicability of operating parameter limits, established in the Notification of Compliance, during subsequent performance tests conducted without an approved test plan. See 67 FR at 6978. Regarding the initial performance test, we explained that a source can revise the operating parameter limits specified in the Documentation of Compliance at any time based on supporting information. This information would also be included in the performance test plan to support deviating from the operating limits established in the previous Documentation of Compliance. Given that sources operate after the compliance date until the Notification of Compliance is submitted under operating limits established in the Documentation of Compliance, and that the technical support for the operating limits established in the Documentation of Compliance is the same as would be included in the test plan, it is appropriate to allow initial performance testing and associated pretesting without an approved test plan. Regarding subsequent performance testing, we amended the rule to waive the operating parameter limits during performance testing and associated pretesting even when testing without an approved test plan. We reasoned that stack emissions data obtained during the testing would document whether the source maintained compliance with the emission standards. ( Please note that during testing, including pretesting, stack emissions must be documented for any emissions standard for which the source waives an operating parameter limit.) Absent approval of the test plan, documentation of potential violation of an emission standard is nonetheless an ample Redline strikeout highlighting changes made during OMB review 105 Hazardous waste research, development, and demonstration sources remain subject to RCRA permit requirements under § 270.65, which direct the Administrator to establish permit terms and conditions that will assure protection of human health and the environment.

331 incentive to operate within the emission standards. In response to a petitioner's request during development of the joint motion to the Court, however, we request comment on whether documentation of stack emissions during subsequent performance testing and associated pretesting is adequate to ensure compliance with the emission standards absent an approved test plan.

III. Why Is EPA Requesting Comment on Issues and Amendments that Were Previously Proposed? In a July 3, 2001 proposed rule, EPA proposed several revisions to implementation and compliance requirements, and discussed other implementation and compliance issues. See 66 FR 35126. We promulgated several of those amendments in the February 14, 2002 Final Amendments Rule, and we stated in that rule that we would address the remaining proposed amendments and other issues in a future rulemaking. See 67 FR at 6970 71. We discuss below those remaining proposed amendments and issues. Although these issues and proposed amendments originally pertained only to incinerators, cement kilns, and lightweight aggregate kilns, any amendments that we may promulgate subsequent to this notice would also apply to boilers and hydrochloric acid production furnaces. A. Definition of Research, Development, and Demonstration Source. In response to industry stakeholder concerns, EPA requested comment in the July 3, 2001 proposed rule on approaches to preclude inappropriate use of the exemption for research, development, and demonstration sources. See 66 FR at 35128. We indicated we were considering two approaches: ( 1) clearly distinguishing between research and development sources, and limiting the exemption for demonstration sources to one year or less; or ( 2) requiring documentation of how a source's demonstration of an innovative or experimental hazardous waste treatment technology or process is different from the waste management services provided by a commercial hazardous waste combustor. Two stakeholders provided comments, and both recommended that EPA not revise the definition of research, development, and demonstration source. One commenter suggested that EPA should be able to determine if a source is inappropriately claiming the exemption for research, development, and demonstration source without amending the regulation. The other commenter suggested that, rather than amend the regulation, EPA should reiterate that RCRA regulations continue to apply to exempt research, development, and demonstration sources. 105 We concur with the commenters and are not proposing to amend the definition of research, development, and demonstration source. B. Identification of an Organics Residence Time that Is Independent of, and Shorter than, the Hazardous Waste Residence Time In response to industry stakeholder recommendations, EPA requested comment in the July Redline strikeout highlighting changes made during OMB review 106 Stakeholders also wanted the hazardous waste residence time ( for organics) to expire as soon as possible to avoid violations associated with exceedances of an organics emission standard or associated operating requirement during malfunctions when hazardous waste remained in the combustion chamber. The rule has been amended, however, to state that an exceedance of an emission standard or operating requirement during a malfuncation is not a violation provided that the source has developed an appropriate startup, shutdown, and malfuncation plan, and follows the corrective measures provided by the plan. See 67 FR at 6798 6801.

107 We questioned whether available information on low oxygen destruction would adequately model destruction under the pyrolytic conditions that occur within solid matrices and whether it is practicable to perform valid engineering calculations for multiple waste streams that are not homogeneous and that contain multiple organic constituents of concern.

332 3, 2001 proposed rule on whether it is practicable to calculate a hazardous waste organics residence time that defines when organic constituents in solid materials have been destroyed. See 66 FR at 35128 30. Under stakeholders' recommendation, after the hazardous waste organics residence time expires, sources could comply with standards the Agency has promulgated under sections 112 or 129 of the Clean Air Act to control organic emissions for source categories that do not burn hazardous waste in lieu of the hazardous waste combustor standards and associated compliance requirements under Subpart EEE, Part 63, for dioxin/ furan, destruction and removal efficiency, and carbon monoxide or hydrocarbon emissions. 106 In the July 3, 2001 proposed rule, we raised several concerns regarding the approach recommended by stakeholders to calculate an organics residence time, and specifically requested comment on how these concerns could be addressed. See 66 FR at 35130. Although several stakeholders provided comment on the discussion we presented in the July 3, 2001 proposed rule, commenters did not address the concerns we raised. Rather, commenters generally note that calculation of an organics residence time for solid waste streams would be difficult to characterize generically. Accordingly, commenters suggest that the rule be amended to specifically allow calculation of an organics residence time on a site specific basis. We are reluctant to encourage site specific petitions to calculate an organics residence time, however, given that the concerns we raised in the July 3, 2001 proposal have not been addressed. 107 Moreover, we believe that stakeholders' primary motive for identifying an organics residence time has been eliminated by the February 13, 2002 amendment to the rule stating that an exceedance of an emission standard or operating requirement during a malfunction when hazardous waste remains in the combustion chamber is not a violation provided that the source follows the corrective measures provided by an appropriate startup, shutdown, and malfunction plan. For these reasons, we are not proposing an organics residence time or explicitly encouraging sources to petition the delegated CAA authority on a site specific basis to identify an organics residence time. Redline strikeout highlighting changes made during OMB review 108 Please note that you are subject to the standards under Subpart EEE at all times, including after the hazardous waste residence time has expired, unless you have established an alternative mode of operation under § 63.1209( q)( 1).

333 C. Why Is EPA Not Proposing to Extend APCD Controls after the Residence Time Has Expired when Sources Operate under Alternative Section 112 or 129 Standards? In the July 3, 2001 proposed rule, we proposed to extend applicability of operating requirements for dry particulate matter emission control devices before you could switch modes of operation and become subject to Section 112 or 129 standards for sources that do not burn hazardous waste. See 66 FR at 35130 32. We proposed to require you to maintain compliance with applicable emission standards for semivolatile metals, low volatile metals, and particulate matter, including the operating parameter limits for dry control systems, after the hazardous waste residence time has expired until the control device undergoes a complete cleaning cycle. We were concerned that dry particulate matter control devices such as electrostatic precipitators and baghouses retain collected particulate matter contaminated with waste derived metals; and dioxin/ furan when activated carbon injection is used. In such cases, we were concerned that waste derived metals and dioxin/ furan may be emitted at levels exceeding the hazardous waste combustor emission standards if you were to switch modes of operation and comply with potentially less stringent alternative MACT standards for sources that do not burn hazardous waste ( e. g., Subpart LLL for cement kilns, Section 129 standards the Agency is developing for commercial and industrial solid waste incinerators, and MACT standards the Agency is developing for boilers). 108 Commenters raised several concerns about the practicability of maintaining compliance with the semivolatile metals, low volatile metals, and particulate matter standards after the hazardous waste residence time has expired until the particulate matter device undergoes a complete cleaning cycle. Commenters explained that it is difficult to determine when a cleaning cycle has been completed for multi field electrostatic precipitators and multi compartment fabric filters because fabric filter cleaning is typically a continuous process, and electrostatic precipitator plate cleaning frequency varies significantly depending on the plate position within the electrostatic precipitator. Commenters also stated that the proposed requirement would encourage more frequent cleaning of electrostatic precipitators and fabric filters than normal, which could increase emissions of HAP and adversely affect bag life. After review of comments and further consideration, we conclude that it is not necessary to revise the standards to extend applicability of the operating requirements for dry particulate matter control devices before you could switch modes of operation and become subject to MACT standards for sources that do not burn hazardous waste. We now believe that it is highly unlikely that entrained particulate matter contaminated with hazardous waste derived metals would be released from the electrostatic precipitator or fabric filter at rates higher than when feeding hazardous waste when the source begins operating under the alternative MACT ( or Section 129) standards for sources that do not burn hazardous waste. In addition, incinerators, cement kilns, and solid fuel fired boilers would be subject to alternative standards and operating limits for Redline strikeout highlighting changes made during OMB review 109 The Agency determined that lightweight aggregate kilns that do not burn hazardous waste are not a significant source of HAP emissions and, thus, that MACT standards are not necessary for that source category.

110 The Agency did not propose PM standards for existing liquid fuel fired industrial, commercial, and institutional boilers and process heaters. See 68 FR 1660.

334 particulate matter. Although lightweight aggregate kilns would not be subject to alternative standards for particulate matter, 109 lightweight aggregate kilns that burn hazardous waste are equipped with fabric filters where their performance is not highly sensitive to operating conditions. And, although liquid fuel fired boilers would not be subject to alternative Section 129 standards for particulate matter, 110 over 80% of liquid fuel fired boilers that burn hazardous waste are not equipped with a control device, and only about one third of those with a control device are equipped with an electrostatic precipitator or fabric filter. Thus, the absence of particulate matter controls under the alternative Section 129 standards is not a significant concern.

For these reasons, we are not proposing to extend applicability of the operating requirements for dry particulate matter control devices before you could switch modes of operation and become subject to MACT standards for sources that do not burn hazardous waste D. Why Is EPA Proposing to Allow Use of Method 23 as an Alternative to Method 0023A for Dioxin/ Furan? The September 1999 Final Rule requires use of Method 23A for stack sampling of dioxin/ furan emissions. In response to industry stakeholder requests, we proposed in the July 3, 2001 proposed rule to allow you to petition the delegated regulatory authority to use Method 23 found in 40 CFR Part 60, Appendix A, instead of Method 0023A. See 66 FR at 35137. We are revising the proposal today to allow you to use Method 23 in lieu of Method 0023A after justifying use of Method 23 as part of your performance test plan that must be reviewed and approved by the delegated regulatory authority. See proposed § 63.1208( b)( 1)( i)( B). This approach would achieve the same objectives as a petition, but would be simpler to implement because it would not require a separate petition/ document. In the July 3, 2001 proposed rule, we explain that Method 0023A is an improved version of Method 23 in that it can improve the quality assurance of the method. By analyzing the sampling train front half catch ( filter and probe rinse) separately from the back half catch ( sorbent and rinses), Method 0023A provides quality assurance of recovery of dioxin/ furan contained in solid phase particulate and collected on the filter and probe. Under Method 23, poor recovery of dioxin/ furan contained in solid phase particulate may go unnoticed because the front half catch and back half catch are combined before analysis. This may be of particular importance for sources that use activated carbon injection or sources that have carbonaceous material in particulate matter. Although Method 0023A can improve quality assurance, it is slightly more expensive than Method 23 and, in many situations, quality assurance may not be improved. For example, Redline strikeout highlighting changes made during OMB review 335 Method 0023A may not be warranted in the future if Method 0023A analyses document that dioxin/ furan are not detected, are detected at low levels in the front half of Method 0023A, or are detected at levels well below the emission standard, and the design and operation of the combustor has not changed in a manner that could increase dioxin/ furan emissions. Environmental stakeholders comment that use of Method 23 would allow sources to emit dioxin/ furan in excess of the standards without being detected. We disagree. Owners and operators seeking to use Method 0023A would be required to document using data or information that Method 23 would provide front half recoveries comparable to Method 0023A. Industry stakeholders comment that we should simply revise the rule to allow use of either method, rather than requiring a petitioning process to use Method 23. As discussed above ( and in the July 3, 2001 proposal), we believe that there are situations where the quality assurance and added cost of Method 0023A may be warranted, and, so, are not proposing to allow use of Method 23 without justification and prior approval. We agree, however, that the formal petitioning process that we proposed is not necessary. Rather, we propose today to require you to justify use of Method 23A as part of the performance test plan that you submit to the delegated regulatory authority for review and approval. See proposed § 63.1207( f)( 1)( xxv). In the interim, you may request to use Method 23 in lieu of Method 0023A under § 63.7( e)( 2)( i) which allows use of a test method with minor changes in methodology. You should submit your request and the supporting justification to the delegated regulatory authority. E. Why Is EPA Not Proposing the " Matching the Profile" Alternative Approach to Establish Operating Parameter Limits? In response to stakeholder concerns about the stringency of calculating most operating parameter limits as the average of the test run averages of the comprehensive performance test, EPA requested comment in the July 3, 2001 proposed rule on an alternative approach to establish operating parameter limits. See 66 FR at 35138 39. The alternative approach, called " matching the profile", was intended to allow sources to identify limits for operating parameters that would allow the operating parameters to have the same average variability as experienced during the comprehensive performance test. The parameter could exceed the average achieved during the performance test for a period of time, provided that it was equivalently lower than the average for the same duration of time. Commenters generally note that the matching the profile approach has a significant disadvantage in that multiple limits would be established for each parameter. Accordingly, commenters recommend that we not include this approach in the regulation, but rather continue to offer it as guidance. Moreover, commenters note that sources can request approval of alternative monitoring approaches under § 63.1209( g)( 1), and they are concerned that codification of only one approach, and particularly an approach with potentially limited utility, could lead the delegated CAA authority to conclude incorrectly that other approaches may not be appropriate. We believe that this matter is best dealt with on a site specific basis, but note that by specifying one approach in the rule, we do not mean to preclude use of a different approach pursuant to § 63.1209( g)( 1). Sources thus may request approval of the profiling approach, or another approach, to establish operating limits on a site specific basis under § 63.1209( g)( 1). Redline strikeout highlighting changes made during OMB review 111 Please note that the rule already allows extrapolation of mercury feedrates ( § 63.1209( l)( 1)( i)) and semivolatile and low volatile metal feedrates ( § 63.1209( n)( 2)( ii)).

336 F. Why Is EPA Not Proposing to Allow Extrapolation of OPLs? In response to industry stakeholder concerns, we requested comment in the July 3, 2001 proposed rule on whether the rule should allow extrapolation of an operating parameter limit to a higher limit using a site specific, empirically derived relationship between the parameter and emissions of the pollutant in question. 111 See 66 FR at 35139 40. We also requested comment on whether the rule should allow use of established engineering principles that define the relationship between operating parameter and emissions to extrapolate operating limits and emissions in lieu of a site specific, empirically derived relationship. Industry stakeholders are concerned that the rule inappropriately penalizes sources that achieve comprehensive performance test emission levels well below the standard by requiring them to establish operating limits based on performance test operations at those low emission levels. They note that operating under conditions to artificially increase emissions during testing ( e. g., by detuning emission control equipment) may not be feasible or desirable from a worker/ public health and cost perspective. Although stakeholders acknowledge that they may request such extrapolation as an alternative monitoring approach under § 63.1209( g)( 2), they note that explicitly defining an extrapolation approach in the rule may better facilitate their efforts to obtain approval from the delegated regulatory authority. Several industry stakeholders agreed with the principle of extrapolation as we discussed it in the July 3, 2001 notice, but disagreed with the requirements for, and limits on, extrapolation that we recommended. Several other stakeholders oppose the use of extrapolation generally because of concern that it is difficult to define completely and accurately the relationship between an operating parameter and emissions. Given the extent of the issues associated with explicitly providing for extrapolation of operating parameter limits, particularly on a categorical rather than a site specific level, and given that you already have the ability to request approval of extrapolation procedures under § 63.1209( g)( 2), we are not proposing to revise the rule to explicitly allow extrapolation. We believe that extrapolation must be justified by a site specific analysis. G. Why Is EPA Proposing to Delete the Limit on Minimum Combustion Chamber Temperature for Dioxin/ Furan for Cement Kilns? In response to stakeholder concerns that it is technically impracticable for cement kilns to establish a minimum combustion chamber temperature based on the average of the test run averages for each run of the comprehensive performance test, EPA requested comment in the July 3, 2001 proposed rule on whether the rule should continue to require cement kilns to establish and comply with a minimum combustion chamber temperature limit. See 66 FR at 35140. We received a total of five comments to the July 3, 2001 proposed rule. Three commenters opposed deleting the requirement for cement kilns to establish and comply with a minimum combustion chamber temperature. Currently, cement kilns are required to establish a Redline strikeout highlighting changes made during OMB review 337 minimum combustion chamber temperature as an operating parameter limit to ensure compliance with the destruction and removal efficiency and dioxin/ furan standards. See § § 63.1209( j)( 1) and ( k)( 2). These commenters generally cited the need for monitoring combustion chamber temperature by noting that combustion chamber temperature is a principal factor in ensuring combustion efficiency and destruction of toxic organic compounds. Two commenters support deleting the minimum combustion chamber temperature requirements. Commenters state that a cement kiln inherently controls the kiln temperature to produce clinker because the required material temperatures must exceed approximately 2,500 ° F with combustion gas temperatures higher still. These commenters note that a cement kiln operates well above minimum temperatures required to destroy the organic compounds in the hazardous waste, and, therefore, a minimum combustion chamber temperature limit is not necessary to control organic hazardous air pollutant emissions. Commenters also state that combustion chamber temperatures cannot be maintained at low enough levels for the duration of the comprehensive performance test to establish workable operating limits that would allow them to burn hazardous waste fuels economically without frequent waste feed cutoffs because of potential exceedences of the limit. Commenters indicate that combustion chamber temperature levels are fairly constant within a narrow range and note that there is a very narrow range of temperatures and feed composition in which a cement kiln must operate in order to produce quality clinker and a marketable product. Moreover, commenters state that cement kiln operators must take extreme actions, including potentially equipment damaging steps, to lower kiln temperatures to establish an economically viable minimum combustion chamber limit. Finally, commenters indicate that these problems are compounded by the requirement in the MACT rule to establish the hourly rolling limit based on the average of the test run averages ( § § 63.1209( j)( 1)( ii) and ( k)( 2)( ii)). We are not proposing to delete the requirement for cement kilns to establish and comply with a minimum combustion chamber temperature to help ensure compliance with the destruction and removal efficiency standard. Even though we remain reluctant to delete this requirement, commenters may, if they choose, provide additional comments on whether the rule should continue to require cement kilns to establish a minimum combustion chamber temperature limit as specified in § 63.1209( j)( 1). We are, however, proposing to delete the requirement to establish a minimum combustion chamber temperature limit for dioxin/ furan under § 63.1209( k)( 2). As mentioned above, sources are currently required to establish a minimum combustion chamber temperature as an operating parameter limit for both the destruction and removal efficiency and dioxin/ furan standards. This proposed amendment would not affect the requirement for cement kilns to establish a minimum combustion chamber temperature under § 63.1209( j)( 1) during the destruction and removal efficiency demonstration. Currently, the destruction and removal efficiency demonstration need be made only once during the operational life of a source provided that the design, operation, and maintenance features do not change in a manner that could reasonably be expected to affect the ability to meet the destruction and removal efficiency standard. See § 63.1206( b)( 7). If a facility wishes to operate under new operating parameter limits that could be expected to affect the ability to meet the destruction and removal efficiency standard, then the source will need to conduct Redline strikeout highlighting changes made during OMB review 338 another destruction and removal efficiency test. In addition, if a source feeds hazardous waste at locations other than the flame zone, the destruction and removal efficiency demonstration must be verified during each comprehensive performance test and new operating parameter limits must be established. Sources that fire hazardous waste only at the flame zone ( i. e., the kiln end where clinker product is normally discharged) are required to make only one destruction and removal efficiency demonstration test during the operational life of the kiln. During this destruction and removal efficiency demonstration test, the source would set a minimum combustion chamber temperature limit under § 63.1209( j)( 1) that would be the limit for the operational life of the kiln. However, as the rule is currently written, such sources would need to establish a minimum combustion chamber temperature limit during subsequent comprehensive performance tests for the dioxin/ furan test under § 63.1209( k)( 2). The source would be required to comply with the more stringent ( higher) of two minimum combustion chamber temperature limits, which could lead to a situation where the controlling minimum combustion chamber temperature limit is based on the dioxin/ furan test rather than the destruction and removal efficiency demonstration. We believe that this may be an inappropriate outcome given that the operating limit for minimum combustion chamber temperature is a more important parameter to ensure compliance with the destruction and removal efficiency standard than to ensure compliance with the dioxin/ furan standard. Our data indicate that limiting the gas temperature at the inlet to the particulate matter control device, an operating parameter limit established during each comprehensive performance test ( § 63.1209( k)( 1)), is a critical dioxin/ furan control parameter. We are, therefore, inviting comment on deleting the requirement to establish a minimum combustion chamber temperature limit when complying with the dioxin/ furans standard. This proposed amendment does not affect the other operating parameter limits under § 63.1209( k) that must be established for dioxin/ furan such as establishing a limit on the gas temperature at the inlet to the particulate matter control device. For cement kilns that fire hazardous wastes at locations other than the flame zone, the current requirements would effectively remain the same. Given that a source conducts the destruction and removal efficiency demonstration and dioxin/ furan test simultaneously and that a source is also required to establish a minimum combustion chamber temperature limit when demonstrating compliance with and establishing operating parameter limits for the destruction and removal efficiency standard, the minimum combustion chamber temperature limits is effectively retained.