From: Keith Barnett/RTP/USEPA/US

To: Cortney_Higgins@omb.eop.gov

Cc: Charlotte Bertrand/DC/USEPA/US@EPA, Steven Silverman/DC/USEPA/US@EPA

Date: 07/29/2010 10:38 AM Subject: Information on Pollutant by Po l lutant approach

I have attached excerpts from federal register notices dealing with the legal

aspects of the pollutant by pollutant approach.

(See attached file: Polutant

‐ by

‐ pollutant.docx)

Note that the statement that the different controls requited for the various pollutants can operate independently is also applicable here.

For example:

Five kilns have PM controls followed by wet scrubbers

One of those five has a PM control followed by the wet scrubber

followed by a regenerative thermal oxidizer.

One kiln has a PM control followed by carbon injection followed by a

second fabric filter.

There are no technical reasons that the controls required cannot work in

sequence.

However, as I have previously noted, some of the controls can remove multiple pollutants. ACI can remove both mercury and THC. If you also add some types of

alkaline reagent (such as lime), a single control system (sorbet injection

followed by a second fabric filter) could conceivably remove mercury, THC, HCl,

and PM. So you get all four pollutants with one control system.

For a high sulfur applications a wet scrubber could remove HCl, SO2, and mercury.

You can also use additives to improve scrubber performance by oxidizing the

mercury.

Keith W. Barnett USEPA/OAQPS/SPPD/MMG

Mail Code D243

‐ 02

Research Triangle Park, NC 27711

919

‐ 541

‐ 5605 barnett.keith@epa.govForm 51382 Federal Register / Vol. 74, No. 192 / Tuesday, October 6, 2009 / Rules and RegulationsThis is a section 129 regulation, byt the legal isue re relevant to a section112 rule. 2.

2. Pollutant-by-Pollutant Approach

Comment: Numerous commenters objected to our continued use of the EPA’s longstanding pollutant-bypollutant approach to choosing the best performing HMIWI. The commenters argued that this approach essent ially created a hypothetical ‘‘s uper unit’’ and resulted in the

selection of a set of new and existing MACT floors (and standard s) that no one existing source has completely achieved and that cannot be simultaneously achieved by any of the best performing sources. The commenters stated that the ‘‘best performing’’ sources must be real

sources, not theoretical or hypothetical, based on the st atute and legislative history. S. Rep. No. 228, 101st Cong., 1st Sess. 169 (1989). According to the commenters, the proposed standards do not reflect the performance of actual sources, and as such, these pr oposed standards are not legal under Section 129.

One commenter argued that Section 129(a)(2) (and the similar Sect ion 112(d)(3)) does not speak in terms of the best performing sour ce for each listed pollutant but the best existing source for all pollutants and what these sources ca n achieve on an overall basis. The commenter claimed that Congress abandoned Section 112’s pr evious focus on individual pollutant standards in the 1990 CAA Amendments and also adopted the technology-based multi pollutant approach to regulating toxics in use unde r the Clean Water Act (CWA). See S. Rep. No. 228, 101st Cong., 1st Sess. 133–34 (1989). The commenter c oncluded that if one source can achieve a tight degree of control for one pollutant but not for another, there may be no justification for including it in the set of sources fr om which the floor is calculated. See, e.g., Tanners’ Council of America v. Train, 540 F.2d 1188, 1193 (4th Cir. 1976) (CWA effluent limitations guidelines were deemed not achievable where plants in EP A’s data base were ‘‘capable of meeting the limitations for some, but not all, of the pollutant parameters’’).

Two commenters stated that under CAA Sections 129(a)(2) and 112(d)(2) consideration of a higher level of control than the average aggregate levels achieved by the best sources ( i.e., using the pollutant-by-pollutant approach instead of basing floors on levels of the full set of pollutants achieved by particular units) must be done only as a ‘‘beyond-the-floor’’ assessment, required to weigh economics and other factors, a nd not be ‘‘hidden’’ in the floor evaluation, in which costs may not be considered.

Multiple commenters also questioned the technical feasibility of EPA’s pollutant-bypollutant approach. According to the comment ers, establishing MACT standards based on the

best achievable emissions limits for each type of pollution cont rol equipment assumes that the equipment can be combined in the same system and that the emissions limits of each system are additive. The commenters stated that, in practic e, this outcome is likely not achievable due to the challenge of finding po llution control equipment ( e.g., fabric filters for PM removal and wet scrubbers for HCl removal) that can work in con cert with each other. The commenters said that

EPA should consider how the different emissions controls may interfere with each other if employed simultaneously. As an example, one commenter noted that employing a wet scrubber to control HCl would saturate the gas stream, whic h would bind the bags in the fabric filter used to control PM, thereby compromisi ng the filter’s effectiveness. Some of the commenters alsonoted that the interrelationships between pollutants mu st be considered in order to ensure that the emissions control is operating effectively for control of all of the related po llutants, and not just a single pollutant. For example, commenters note d that improving combustion to control CO may

affect NOX.

Multiple commenters suggested EPA should revisit the MACT floors for HMIWI and choose the best performing sources on an overall basi s, so that at least one source can meet all of the new source standards and a certain portion of the existing sources can meet the existing source standards. One commenter suggested that EPA combine the indivi dual pollutants into a single analysis to determine which control pr ovides the best overall control or otherwise determine that the MACT floor resulting from th e analysis is actually achieved by those sources

identified as the ‘‘best contro lled.’’ According to various co mmenters, one possible way for doing this would be to establish rankings for how a HMIWI performs fo r each of the regulated pollutants and then sum the individual pollutant rankings to determine the overall ranking for the

HMIWI.

Response: We disagree with the commenters who object to setting MACT floors on a pollutantby-pollutant basis. We continue to interpret Section 129 as su pporting the pollutant-bypollutant approach. Section 129(a)(4) says that the sta ndards promulgated under Section 129 shall specify

numerical emissions limitations fo r each pollutant enumerated in that provision. Section 129(a)(2) requires EPA to establish standards requiring ‘‘maximum de gree of reduction of emissions.’’ ‘‘Maximum degree of reduction of emissions,’’ in turn is defined in Section 129(a)(2) as including a minimum le vel of control (the so-called MA CT floor). EPA, therefore, believes—and has long believed—that the combinati on of Section 129(a)(4), requiring numerical standards for each enumerated pollutant, and Secti on 129(a)(2), requiring that each such standard be at least as stringen t as the MACT floor, supports, if not re quires, that floors be derived for each pollutant based on the emissions le vels achieved for each pollutant.

We also disagree with the commenters who co mplain that there may not be any operating unit that currently employs the complete suite of MACT technologies and meets the revised

limits. The suite of MACT floor controls identifi ed by the final rule approach (specifically, the combination of dry and wet control systems) is already used by four existing HMIWI that meet most of the MACT floor standards. For exampl e, one HMIWI, equipped with a high efficiency particulate air (HEPA) filtering system, carbon bed adsorber, and rotary atomizing wet scrubber, is estimated to meet all nine revised emissions limits in the final rule; another HMIWI, equipped with a lime injection system, powdered activat ed carbon injection system , baghouse, and vertical upflow two-stage multimicroventuri scrubber system, is estimated to meet eight of the nine

revised limits. Also, an estimat ed 42 of the 57 HMIWI are estim ated to meet both the CO and NOX revised limits simultaneously with existing combustion controls. ( See 2009 memorandum entitled ‘‘Revised Compliance Costs and Econom ic Inputs for Existing HMIWI,’’ which is included in the docket for today’s rulemaking.) The MACT control techniques for the various pollutants are fully integratable and compatible. There do not appear to be any conflicts where meeting the standard for one pollutant may je opardize the achievability of meeting another pollutant’s limit. This conclusion is supporte d in part by a review of available data and information. As discussed above, there are currently four units that are achi eving most, if not all, of the floor standards (based on ac tual data for each pollutant) us ing the complete suite of MACTfloor controls. Thus, we concl ude that our approach results in compatible MACT controls.

Further, an evaluation of the emissions data from units that have measured data for all pollutants supports our conclusion. Our analysis shows that 12 percent (7 of 57 units) simultaneously meet all of the MACT floor emissions levels. (For further information, see 2009 memorandum entitled ‘‘Revised Compliance Costs and Econom ic Inputs for Existing HMIWI,’’ which is included in the docket for today’s rulemaking.)

We also disagree with commenters claiming that it is inappropriate to consider a suite of floor control techniques that may not be curr ently in use by the source category. There is no

reason not to consider emissions data and controls in use at sources that may be the best performers from some pollutants but not for ot her pollutants. The MACT floor controls applicable for one pollutant do not preclude th e use of MACT floor controls for another pollutant. Therefore, it is appropriate to cons ider controls at sources employing MACT controls for some pollutants, but not all. For example, floor controls for existing large HMIWI include wet scrubbers for HCl control, dry scrubbers or combination dry/wet systems for PM and metals control, activated carbon injection for CDD/CDF control, and wet scrubbers or dry scrubbers for SO2 control. As noted previously, wet and dry systems are demonstrated to be compatible, and it would be inappropriate to exclude from the MA CT floor pool those units equipped with wet or dry systems because some of the control systems do better with some pollutants ( e.g., wet scrubbers with HCl) than others ( see previous memorandum).

EPA disagrees strongly with commenters ar guing that Congress has directly addressed

the issue of whether the MACT fl oor can be established on a polluta nt-by-pollutant basis. With respect to the MACT floor mandate of Section 112, there appears, rather, to be a substantial ambiguity in the statutory language about whet her the MACT floor is to be based on the performance of an entire source or on the pe rformance achieved in c ontrolling particular hazardous air pollutants. The language regarding best performing ‘‘sources’’ (or, for new sources, ‘‘source’’) could apply either to the sour ces’ (or source’s) performance as a whole, or performance as to a particular po llutant or pollutants. The same is true of the definition of ‘‘emission limitation’’ in Section 302(k), which refe rs to ‘‘air pollutants,’’ but does not address whether the limitation must apply to every pollutant emitted by a source, or just some of them. (The same is true of the referen ce to ‘‘air pollutants’’ (in the plur al) in Section 112(d)(2).) In this regard, we note that commenters in other MA CT rulemakings have assumed that Section 129, which governs today’s rule and which uses langu age essentially identical to Section 112 in mandating MACT, requires a pollutant-by-pollutant approach to establishing floors, because EPA is commanded to establish standards for enumerated pollutants under Section 129(a)(4).

We further note that the DC Circuit, when re viewing the floor determinations we made in

1997 for HMIWI under Section 129 in Sierra Club v. EPA, noted that they were set pollutantby-pollutant and found no erro r in this approach ( see 167 F.3d at 660) (although this aspect of the rule was not challenged specifically). Indeed, the commenters who object so vehemently to the pollutant-bypollutant approach in this rule raised no such obj ection when the opportunity to litigate the same approach in establishing the 1997 HMIWI standards was first presented. EPA

also believes that the commenters’ reference to basing MACT floors on the performance of a hypothetical or theoretical unit, so that the limits are not based on those achi eved in practice, is not only wrong factually ( see above), but just re-b egs the question of what the language inSections 112(d)(3) and 129(a )(2) is referring to. We did not base the controls or emissions levels on theoretical sources, but on the performance of actual units in the HMIW I source category. All

of the MACT floors are achieved in practice (since they are based on actual performance data). Moreover, the DC Circuit has emphasized that EP A may use any reasonable means to determine what levels of performance are achieved in practice. Sierra Club v. EPA, 167 F.3d at 663, 665. The commenters’ reliance on cases that they claim preclude EPA’s use of a pollutant-bypollutant approach does not compel a unit-based a pproach, and the issue is not critical to EPA’s position in any event, since the r ecord shows that some units are meeting all of the floor limits and many are meeting several of them. At the very least, the CMA v. EPA decision under the CWA supports the proposition that a technology-bas ed standard can be considered achievable even if all limits are not yet met by a single un it. Since the floor sta ndards are demonstrably being achieved in practice by some sources, this i ssue is largely academic. In short, EPA is not persuaded that the floors must be established on the basis of a unit’s performance for all pollutants overall.

We continue to believe, as we explained in the 1997 final rule, that such a reading would

lead to results that are at odds with evident congressiona l intent (and with the Court’s rulings in NLA II, CKRC and Brick MACT). To argue that Congress compelled this type of result is at odds with both the language of Sections 112 and 129 and common sense. Indeed, it would necessarily suggest that EPA could continue to adopt floor s that reflect ‘‘no emissions

reduction,’’ even after the DC Circuit so emphatically forbade that approach in the Brick MACT ruling ( Sierra Club v. EPA, 479 F.3d 875 (DC Cir. 2007). As we stated in the preamble to the 1997 regulation (62 FR 48363), we recognize that the pollutant-by-pollutant approach for determining the MACT floor can, as it does in th is case, cause the overall cost of the regulation to increase compared to what would result under a unit-based methodology. For example, the pollutant-by-pollutant approach for the HMIWI re gulation results in a stringent MACT floor for HCl based on control using a wet scrubber, and st ringent MACT floors for PM and metals based on control using a dry scrubber. We interpret Se ction 129 of the CAA to require that the MACT

floor be determined in this manner, and we belie ve that Congress did in fact intend that sources subject to regulations develope d under Section 129 meet emissi ons limits that are achieved by the best controlled unit for each pollutant, as lo ng as the control systems are compatible with each other. To our knowledge, there is no tech nical reason why these two air pollution control systems cannot be combined. (62 FR 48363–4) Combined dry/wet scrubber systems are currently in operation on severa l HMIWI. In response to commenters’ concerns regarding the technical feasibility of combined dry/wet sy stems, available data on the performance of combined dry/wet scrubber systems indicate that the MACT floor emissions levels are achievable and technically feasib le. The performance of dry scrubbers with activated carbon injection and the performance of wet scrubbers are well document ed. The available data for combination dry/wet systems provide no indication of operational or emissions problems that occur as a result of combining dr y and wet control systems. Re garding the inverse relationship between CO and NOX with regard to combus tion control, it is incumbent upon the HMIWI facility to determine whether combustion conditions can be adjusted to meet both standards and, if not, install add-on NOX controls as necessary, e.g., SNCR systems.

The MACT floor reflects the least stringent emissions standards that EPA may adopt in accordance with Section 129(a)(2) rega rdless of costs. Other stat utory provisions are relevant,although they also do not decisi vely address this issue. Section 129(a)(4) requires MACT standards for, at a minimum, PM, opacity, SO2, HCl, NOX, CO, P b, Cd, Hg, and CDD/CDF emitted by HMIWI. This provision certainly ap pears to direct maximum reduction of each specified pollutant. Moreover, although the prov isions do not state whether there is to be a separate floor for each pollutant, the fact that Congress singled out these pollutants suggests that the floor level of control need not be limited by the performance of devices that only control some of these pollutants well. (62 FR 48364)

Regarding the commenter’s suggestion that EPA choose the best performing sources on

an overall basis, so that at leas t one source can meet all of the new source standards and a certain portion of the existing sources can meet the existing source standards, we reviewed this approach and found that the suggested approach does not consis tently result in emissions limits that are at least as stringent as would have resulted in 1997 if we had actual emissions data and used the correct methodology. We estimate that four em issions limits for large and small non-rural HMIWI and five emissions limits for medium and small rural HMIWI calculated using the suggested overall unit-based approach would be higher than the 1997 emissions limits. Further, because not all pollutants ar e required to be tested ( e.g., NOX and SO2), a substantial fraction of

available emissions data would ha ve to be discarded in order to rank only those HMIWI with a complete set of data for all nine pollutant s (PM, SO2, HCl, NOX, CO, Pb, Cd, Hg, and CDD/CDF). Specifically, we would have to discar d emissions data for 30 percent of large, 40 percent of medium, 100 percent of small non-rural, and 50 percent of small rural HMIWI in

order to calculate MACT floors us ing the suggested approach. ( See 2009 memorandum entitled ‘‘Revised MACT Floors, Data Variability Anal ysis, and Emission Limits for Existing and New

HMIWI,’’ which is included in the docket for today’s rulemaking.)

A unit-based approach would tend to result in least common denominator floors where, as here, multiple pollutants are emitted, wh ereby floors would no longer be reflecting performance by the best performing sources for those pollutants. For ex ample, if the best performing 12 percent of units for HAP metals did not control acid gases as well as a different 12 percent of units, the floors for acid gases and meta ls would not reflect best performance. Having separate floors for metals and acid gases in this example certainly promotes the stated purpose of the floor to provide a minimum level of contro l reflecting what best performing units have demonstrated the ability to do.

Similarly, a unit-based approach that em ploys ranking of a weighted average of pollutants would require EPA to assume priority for certain pollutants (one unit may have lower NOX emissions but higher CDD/CDF, for example) . This approach would similarly tend to require EPA to disregard the factual levels reflecting the best performers for individual performers, but based on value judgments regard ing the risks presented by various pollutants.

Such considerations are antithetic al to strictly performance-based analyses such as MACT floor determinations. Indeed, reviewing EPA’s prim ary copper smelters MACT standard, the DC Circuit rejected the argument that risk-based co nsiderations have any place in the MACT context

( see Sierra Club v. EPA,From the HCW rule October 12, 2005

c. Comment: The commenter disputes EPA’s conclusions that failure of sources to meet all of the standards based on a straight emissions me thodology at once shows that the methodology is flawed. The standards are not mutually depende nt, so the fact that they are not achieved simultaneously is irrelevant. There is no reason a best performer for one HAP should be a best performer for other HAP.

Response: EPA agrees with this comment. On reflection, EPA believes that because all

our standards are not te chnically interdependent (i.e., impl ementation of one emission control technology does not prevent the source from implem enting another control technology), the fact that sources are not achieving al l the standards simultaneously does not indicate a flaw in a straight emissions approach. See Chemical Manufacturers Ass’n , 870 F. 2d at 239 (best performing sources can be determined on a pollutant -by-pollutant basis so that different plants can be best performers fo r different pollutants).

d. Comment: Several commenters took the opposite position that EPA must assure that all existing source standards must be achievable by at least 6 percent of the s ources, and that all new source standards must be achievable by at least one existing source.

Response: As discussed above, we are not obligated to establish a suite of floors that are simultaneously achievable by at least six percent of the sources because the standards are not technically interdependent. None theless, the SRE/Feed methodology does result in existing floor levels (when combined with the other floor leve ls for sources in the source category) that are simultaneously achievable by at least six percent of the sources (or, fo r source categories that have fewer than 30 sources, by at least two or three sources). 90 However, for the new source

standards, three of the source categories do not include any so urces that are simultaneously achieving all the standards (incin erators, cement kilns, and light weight aggregate kilns). Again, similar to existing sources, EPA is not obligated to establish a su ite of new source floors that are simultaneously achievable by at least one exis ting source because thes e standards are not technically interdependent. We conclude that a new source can be designed (from a back-end control perspective) to achieve all the new sour ce standards.