MEMORANDUM

TO: Toni Jones, U.S. Environmental Protection Agency (EPA)

FROM: Eastern Research Group, Inc.

DATE: December 20, 2012

SUBJECT: Final Reconsideration Beyond-the-Floor Analysis for CISWI Units

1.0 P URPOSE

This memorandum presents the data, methodology and assumpt ions used to conduct a beyond-the-floor (BTF) analysis for the emission lim its that the Agency is finalizing in the

reconsideration of certain new source standards establi shed in the March 2011 final Standards of Performance for New Stationary Sources an d Emission Guidelines for Existing

Sources: Commercial and Industrial Solid Waste Incinerat ion (CISWI) Units. 1 Sections 2 and 3 of this memorandum present the EPA’s analysis of BTF options for existing and new sources respectively. Spreadsheets associated with this a nalysis accompany this memorandum in the CISWI docket (EPA-HQ-OAR-2003-0119) and are na med for the CISWI unit subcategory evaluated. Emission reductions est imates are in the “BTF Emission Reductions” spreadsheet.

Clean Air Act (CAA) sections 129 and 111 require the EPA to regulate emissions of nine pollutants from CISWI units: hydrogen chloride (HCl), car bon monoxide (CO), lead (Pb), cadmium (Cd), mercury (Hg), particulate matter (PM ), dioxins/furans (PCDD/PCDF), nitrogen oxides (NO

x ), and sulfur dioxide (SO 2 ). Under CAA section 129(a)(2), the EPA

first must determine the minimum level of control for e ach regulated pollutant, commonly known as the maximum achievable control technology (MACT) floor. The MACT floor is established based on the level of emissions achieved by th e best performing 12 percent of sources in the category or subcategory for existing sources and on the best performing similar source for new sources. A separate memorandum discusses development of the MACT floors in more detail (see Reference 1). Clean Air Ac t section 129(a)(2) then requires the EPA to determine whether a more stringent level of cont rol – the BTF level of control – is achievable for the different regulated pollutants after cons idering associated costs, non-air quality health and environmental impacts, and energy requirem ents.

1 On March 21, 2011, the EPA promulgated New Source Perform ance Standards (NSPS) and Emission Guidelines (EGs) (2011 CISWI rule) for six subcategories of CISWI units: three subcategories of energy recovery units (ERUs) (biomass-fired, coal-fired ERUs, and liquid/gas-fired); waste burning kilns; incinerators ; and small, remote incinerators. Following promulgati on of the 2011 CISWI rule, the Administrator received petitions for reconsideration and identified certain issues that warranted further opportunity for public comment. On December 23, 2011, the EPA published in the Federal Registe r a reconsideration proposal that incorporated changes to the 2011 CISWI rule based on new information an d data. The proposed rule included the CISWI subcategories above and further subcategorized waste burn ing kilns into long kilns and kilns that have a preheater for CO emissions only.2.0 E XISTING U NITS

Table 1 compares the March 2011 CISWI rule emission limits and the final emission limits after reconsideration. As explained in the prea mble to the 2011 CISWI rule rule, the EPA did not establish any emissions limits based on a BT F level of control in that rule. (76 FR 15279). We are not reconsidering these prior determinatio ns to the extent the analyses remain the same, either because the limit remains th e same or became more stringent pursuant to the incorporation of new data in the reconsi deration action. However, we evaluated BTF options for emission limits in today’s f inal rule that are less stringent than the limits in the 2011 CISWI rule to determine whether the prio r analyses remain valid, notwithstanding the reduction in stringency based on the revised MACT floor calculations. The following sections summarize the existing unit limit s that became less stringent and our analysis of BTF levels of control.

2.1 Incinerators

For the incinerator subcategory, the final emission lim it for Pb is less stringent than

the limit in the 2011 CISWI rule. The limit in that fina l rule was calculated using data that included data below the detection level, but EPA did not at t hat time have sufficient information to establish a representative detection le vel (RDL) for Pb. For this reason, the Agency was unable to compare the calculated limit to the level equal to three times the RDL, as we do for all limits that are based in part on non-de tect data. Since finalization of the 2011 CISWI rule, the data set for determining the method detec tion level (MDL) for various test methods and pollutants was improved, including for Pb, and th e Agency established an RDL

for Pb. The new emission limit for Pb is based on t he level equal to three times the RDL determined for Method 29 metals. The development and use of the revised detection limits are described further in Appendix G of the MACT floor me morandum (see Reference 1).

Existing units in this subcategory are equipped with FFs for c ontrol of Pb emissions. We estimate that some incinerator units in this category will require retrofitting of existing FFs or installation of additional FFs to comply with the MACT floor limits for Pb. This would result in annual costs of approximately $8.6 million, with an associated reduction of about 0.7 tons of Pb per year. Considering Pb emission reductions alone, the cost

effectiveness of the MACT floor emission limit is a pproximately $12 million per ton. If cocontrol of Cd and PM are also considered, the cost effe ctiveness is approximately $154,000 per ton to achieve the MACT floor emission levels using FF technology. Based on these cost estimates, we do not believe it would be reasonable from a cost perspective to impose a BTF level of control on these sources, which would involve a very high efficiency FF, such as membrane filter technology. We note that we expect that the high costs of controls necessary to meet the MACT standard, when compared to the costs of alternative waste disposal methods (e.g., landfilling), will lead some source owners to shut down existing incinerators rather than comply with the MACT floor limits when pr omulgated, as discussed in the current costs analysis and in our earlier analyses.

Additionally, demonstrating compliance with a BTF limi t for Pb is problematic. Since the Pb limit is established at the level equal to three t imes the RDL, sources would be unableto demonstrate compliance with a reasonable level of cer tainty with emission limits lower

than the MACT floor level of control based on current sampling and laboratory practices. Therefore, any potential further emission reduction would b e difficult for sources and implementing agencies to quantify.

We conclude that BTF controls for Pb emissions are not reasonable because of the high control costs that would likely be associated with any BTF control given the already high cost for meeting the MACT floor emission limit a nd the limited amount of additional reductions that would be achieved with a more stringent st andard. We are also declining to

establish a BTF level of control because of the uncerta inty in quantifying emissions at levels more stringent than the MACT floor.

2.2 Small Remote Incinerators

For the small remote incinerator (SRI) subcategory, th e final emissions limits for HCl, CO, Cd, PM, and PCDD/PCDF are less stringent than the March 2011 limits, though the EPA employed the same MACT floor methodology. Thi s change occurred because the Agency revised the SRI inventory by removing two units (one of which had emissions data but was reassigned to the incinerator subcategory) and addi ng 16 units (see Reference 2). Further, we adjusted available CO emissions data to reflec t limitations of instrumental methods used in measuring emissions. Appendix F of the MACT floor memorandum discusses the adjustments in more detail (see Referen ce 1).

Regarding HCl, SRI units control HCl by waste segregation practices – removal of as many chlorine and sulfur-containing compounds as possible prior to incineration – to meet

the MACT floor limits. We have determined based on infor mation in the record (see Reference 4) that wet or semi-dry acid gas control syst ems are not technically feasible for year-round use by SRI units. Any completely dry control te chnology, such as duct sorbent injection, would require sorbent transport, installatio n of a FF, and transport of collected spent sorbent to landfill, driving up the costs of the cont rol device considerably. Fabric filter costs alone would $1.3 for existing sources, as discussed belo w. This does not account for additional cost of sorbent transport and disposal or DS I system costs. Assuming that the control captures 10 tons per year of the estimated baseline emission of HCl, and transport costs are $20,000 per ton, this would result in a cost effec tiveness of at least $150,000 per year. Thus, any limitation beyond waste segregation is not feasible based on climate for wet

controls and cost for HCl control from SRIs. We thus have determined that no add-on control as a BTF option for HCl for SRIs is reasonable.

Regarding CO, existing SRI units often employ an afterburn er to reduce CO emissions. To achieve the MACT floor limits for CO, w e estimate that more than half of SRI units would require afterburner retrofits. A more stringen t BTF limit would require SRIs that

can meet the MACT floor limit without an afterburner retrofit to have one and would require

SRIs that would need an afterburner to meet the MACT floo r to purchase a more robust afterburner design and additional gas to fuel the larger unit . We estimate that a BTF limit for CO would reduce CO emissions by approximately 6.5 tons per yea r, yielding a costeffectiveness of approximately $24,000 per ton. We do not beli eve this cost is reasonable.In addition, only a small amount of CO emissions would r emain after meeting the

MACT floor, and other than an afterburner, no demonstrat ed control technologies exist for reducing these emissions from SRIs. We also understand t hat some units that would

otherwise close due to cost

- related issues will be forced to operate at a loss, because closure

may not be an option due to other, non-air-related environment al regulations. For example, SRIs are typically operated in remote locations where alternative disposal options (e.g., landfilling) are not available. Considering all these c oncerns, we conclude that no reasonable

BTF alternatives exist for CO emissions from the SRI subcategory.

Regarding Cd, PM and PCDD/PCDF, existing SRI units often em ploy good combustion practices and waste segregation to reduce emis sions of these pollutants. As a BTF option to capture additional amounts of these pollut ants, we estimated costs to install activated carbon injection with a fabric filter (ACI/ FF) to SRI units. Our analysis estimated an annual cost of approximately $1.3 million to reduce addition al 5.6 tons of combined PM, Cd, and PCDD/PCDF, yielding a cost-effectiveness of approxi mately $237,000 per ton. A fabric filter (FF) alone, considered as a BTF option t o further reduce emissions of just PM and Cd, has a cost-effectiveness of approximately $209,000 per t on. As mentioned, we also

believe that some units that would otherwise close due to c ost-related issues may be forced to operate at a loss because closure may not be an option due to other non-air quality environmental regulations aimed at protecting human health and wildlife, so any additional costs imposed on these units is arguably unreasonable. Con sidering all these concerns, we

conclude that no reasonable BTF alternatives exist for Cd, PM, or PCDD/PCDF emissions from the SRI subcategory.

2.3 Energy Recovery Units

The following emission limits in the final standards f or energy recovery units (ERUs) are less stringent than the March 2011 final rule emissio n limits:

• CO, Cd, Pb, Hg, HCl and PCDD/PCDF from coal-fired ERUs

,

• Cd, Pb, Hg, and PCDD/PCDF from biomass-fired ERUs, and

• Hg from liquid/gas waste-fired ERUs.

2.3.1 Solid Waste ERUs

2.3.1.1 Coal-Fired ERUs

Existing units in this subcategory employ a variety of part iculate and acid gas controls, including wet scrubbers and electrostatic precip itators, to comply with the MACT

floor emissions limits for HCl and SO 2 . To meet lower, BTF HCl and SO 2 limits, these units would likely install a semi-dry scrubber system, with a f abric filter and a polishing caustic scrubber, which would enable these units to reduce both HCl an d SO 2 and meet stricter limits. Space availability and facility layout affect c osts of these installations, which industry estimates to be approximately $44 million annually to reduce 711 tons of HCl and SO 2 beyond reductions achieved by the MACT limit. The resulting cost-effectiveness forreduction of HCl and SO 2 is approximately $62,000 per ton. We do not believe these costs to

be reasonable.

Units in this subcategory currently employ either a wet sc rubber or electrostatic precipitator to meet the MACT floor emission limits fo r Cd, Pb, and PM. To meet a BTF limit, these units would require upgrading the existing control s or the addition of a FF

control device in series. We estimate costs of these additional controls to be approximately $9 million per year, with annual combined reductions of approxi mately 121 tons of PM, Cd,

and Pb. 2 The resulting cost-effectiveness is approximately $74,000 doll ars per ton. We do

not consider these costs to be reasonable.

Regarding control of Hg and PCDD/PCDF, existing ERU current ly employ either a wet scrubber or electrostatic precipitator to meet th e MACT floor limits. Meeting BTF limits for these pollutants would require these units to install A CI/FF. We note that for PCDD/PCDF, the MACT standard is established at the detect ion limit. Thus, quantifying further PCDD/PCDF reductions would involve high degrees of un certainty. We hence conclude that imposition of a BTF limit is not reasonabl e. Regarding Hg, we anticipate that ACI/FF would further reduce only a small amount of emissi ons (0.016 tons), at a cost of $11.9 million annually. We estimated a cost-effectiveness o f about $743 million per ton ($371,000 per lb) of Hg removal. We do not consider these costs to be reasonable.

Regarding CO, the revised MACT limit is based upon an expa nded data set that encompasses a year’s worth of data from the best perf orming source and accounts for continuous monitoring data available from this source. We anticipate that existing sources will require a tune-up to improve combustion efficiency t o comply with the MACT floor emission level. To further reduce CO emissions, sources woul d likely need to install a linkageless boiler management system (LBMS) or an oxidati on catalyst. The LBMS system is fairly low-cost, but considering the long term data a vailable from one unit in this subcategory, we are uncertain of actual reductions this cont rol option would achieve compared to non-waste combusting boilers of similar desi gn, and thus do not consider it feasible to set a numeric limit based on reductions by t his control system. For this reason, catalyst device would be more feasible to set a BTF lim it and assess compliance. Installation of oxidation catalyst controls would likely cost approxim ately an additional $3 million per year and reduce approximately 340 tons of CO. The resulting c ost-effectiveness is approximately $9,000 per ton of CO. We do not believe these co sts to be reasonable.

2.3.1.2 Biomass-fired ERUs

For biomass-fired ERUs the final emissions limits for Pb and Cd are less stringent

than the limits in the 2011 CISWI rule. Those limits we re calculated using data that included data below the detection level, but EPA did not at that t ime have sufficient information to establish a RDL for Cd and Pb. For this reason, the Age ncy was unable to compare the calculated limits to the level equal to three times the RDL, as we do for all limits that are based in part on non-detect data. Since finalization of the 2011 CISWI rule, the data set for determining the MDL for various test methods and pollutan ts was improved, including for

2 PM reductions alone constitute 120.6 tons of this total

.Cd and Pb, and the Agency established RDLs for Cd and Pb. Th e new emission limits for Cd

and Pb are based on the level equal to three times the R DL determined for Method 29 metals. The development and use of the revised detection limits ar e described further in Appendix G

of the MACT floor memorandum.

An FF system is considered the best control available for Cd and Pb emissions for this subcategory. To meet the final limit, more than half of existing units will need to reduce their Cd and Pb emissions -- by more than 80 percent in m ost cases. These units will likely require highly-efficient FF systems, with an annual cost of approximately $9.1 million and associated annual reductions of approximately 1.7 tons of Cd an d Pb combined. Considering these two pollutants alone, the cost effectiveness of the MACT floor emission limit is approximately $5.2 million per ton. However, the controls needed for these pollutants also result in significant coincidental reductions in PM em issions. If co-control of PM is also considered, the cost-effectiveness of Cd, Pb, and PM re ductions is approximately $10,000 per ton. Any BTF limits for Cd and Pb would likely necessi tate a second FF in series, essentially doubling the cost, but achieving small additional emissions reductions because of the low concentration entering the second FF. For thi s reason, we do not think the cost of establishing a BTF level of control is reasonable.

Additionally, demonstrating compliance with a BTF limi t for Cd or Pb is problematic. Since the limits are established at the level equal to t hree times the RDL, sources would be unable to demonstrate compliance with a reasonable level of certainty with emission limits

lower than the MACT floor level of control. Theref ore, any potential further emission reduction would be difficult for sources and implementing agencies to quantify.

For these reasons, we are not establishing a MACT standa rd based on a BTF level of control for Cd and Pb emissions for this subcategory.

For Hg emissions, achieving the MACT floor emission limi ts is typically achieved via ACI/FF controls. Nearly half of existing biomass-bur ning ERUs will likely require installation of ACI/FFs to meet the MACT floor Hg lim it. If a BTF emission limit were imposed, these units would need to increase their ACI sorb ent injection rate, and units that currently can meet the MACT limit without ACI/FF cont rols would need to install them. We estimate that a BTF limit based on this technology would result in annual costs of around $6 million, with a reduction of 0.0022 tons of Hg per year. Th e resulting cost-effectiveness for this option is about $1.4 million/lb. We do not believe t hese costs to be reasonable.

The PCDD/PCDF limit in the 2011 CISWI rule was calculate d using data that included data below the detection level, but EPA did not at t hat time have sufficient

information to establish a RDL for PCDD/PCDF. For thi s reason, the Agency was unable to compare the calculated limit to the level equal to thre e times the RDL, as we do for all limits that are based in part on non-detect data. Since finali zation of the 2011 CISWI rule, the data set for determining the MDL for various test methods and pol lutants was improved, including for PCDD/PCDF, and the Agency established a RDL for PC DD/PCDF. The new emission limit for PCDD/PCDF is based on the level equal to three times the RDL determined forMethod 29 metals. The development and use of the revised dete ction limits are described

further in Appendix G of the MACT floor memorandum (see Reference 1).

As discussed above, almost half of the biomass-burning ERU s will likely require ACI/FF to meet the Hg limit, which also controls PCDD/ PCDF. Also noted above, if a BTF emission limit were imposed, these units would need to incr ease their ACI sorbent injection rate, and units that currently can meet the MACT limit without ACI/FF controls would need

to install them. We estimate that a BTF limit based o n this technology would result in annual costs of around $23 million, with a reduction of 0.00005 tons of PCDD/PCDF per year. The resulting cost-effectiveness for this option is about $ 212 million/lb. We do not believe these

costs to be reasonable.

Additionally, demonstrating compliance with a BTF limi t for PCDD/PCDF is problematic. Since the limit is established at the level equal to three times the RDL, sources would be unable to demonstrate compliance with a reasonable level of certainty with an

emission limit lower than the MACT floor level of co ntrol. Therefore, any potential further

emission reductions would be difficult for sources and im plementing agencies to quantify.

3.3.2 Liquid/Gas-Fired Waste ERUs

For Hg reductions, sources in this subcategory currently em ploy particulate matter

control devices to meet the MACT floor emission limit s. For BTF Hg reductions, we analyzed use of ACI/FF controls to achieve a level based on the 3XRDL. Baseline emissions and the MACT floor emission limit are already reason ably low; hence, a BTF limit achieves little reductions (0.002 tons/yr) at a fairly significant cost of about $3 million per year. The resulting cost-effectiveness estimate of this option is about $1.6 billion per ton. We do not

believe these costs to be reasonable.

3.4 Waste-Burning Kilns

The emission limits in the final CISWI rule for wast e-burning kilns are less stringent than

the March 2011 CISWI rule emission limits for the follo wing pollutants: Cd, Pb, Hg, PCDD/PCDF, CO, NOx, and SO 2

.

3.4.1 Cd and Pb Emissions

The March 2011 CISWI rule limits were calculated using data that included data below the detection level, but EPA did not at that time have sufficient information to establish a RDL for Cd and Pb. For this reason, the Age ncy was unable to compare the calculated limits to the level equal to three times the RDL, as we do for all limits that are based in part on non-detect data. Since finalization of the 2011 CISWI rule, the data set for determining the MDL for various test methods and pollutan ts was improved, including for Cd and Pb, and the Agency established RDLs for Cd and Pb. Th e new emission limits for Cd and Pb are based on the level equal to three times the R DL determined for Method 29 metals. The development and use of the revised detection limits ar e described further in Appendix G

of the MACT floor memorandum.A FF is considered the best control available for Cd an d Pb emissions for this

subcategory. We estimate that every waste-burning kiln will either need to improve an existing FF or install a FF to meet the MACT floor em ission limits for both pollutants. This results in annual costs of approximately $110 million, with an associated reduction of about 917 tons of Cd, Pb and PM (co-controlled) per year. Consi dering these three pollutants, the

cost effectiveness of the MACT floor emission limit is approximately $120,000 per ton of Cd, Pb and PM reduced. If Cd and Pb are considered solely, t he cost-effectiveness is around $355 million per ton. To achieve a BTF level of control f or Cd and Pb, sources would likely have to install a more robust FF system or perhaps a sec ond FF in series.We do not believe

these costs to be reasonable.

Additionally, demonstrating compliance with a BTF limi t for Cd or Pb is problematic. Since the limits are established at the level equal to t hree times the RDL, sources would be unable to demonstrate compliance with a reasonable level of certainty with emission limits

lower than the MACT floor level of control. Theref ore, any potential further emission reduction would be difficult for sources and implementing agencies to quantify based on current sampling and laboratory practices.

3.4.2 Hg Emissions

The less-stringent Hg limit for waste-burning kilns resul ts from the expanded inventory for this subcategory. EPA analyzed the materia ls being combusted in the inventory of Portland cement kilns in light of the final NHSM rul e 3 and as a result added 11 kilns to our inventory of waste-burning kilns. We identified test records associated with these units, extracted data, added it to the CISWI database, and re-calcu lated the MACT floor emission limits. The December 2011 proposed rule reflected the updated inv entory and additional data. Following proposal, we learned of one additional waste-b urning kiln and another kiln that was not burning waste. Adjusting for these additional ki lns brings the total waste-burning kiln inventory to 23 kilns. We recalculated the standards i n this final rule to include all 23 waste burning kilns.

To meet even the less-stringent MACT floor emission limit for Hg, all but one of the units in this subcategory will need to install ACI and either improve existing FFs or install FFs to capture the additional spent sorbent load. In our BTF analysis, we considered a limit that would require all units to install the ACI/FF combina tion. This option resulted in costeffectiveness for Hg reductions of approximately $351 millio n/ton. We do not believe these

costs to be reasonable.

3.4.3 CO Emissions

During reconsideration, waste-burning kilns were further s ubcategorized for CO,

based on the demonstrated difference in combustion and CO formation characteristics of long kilns and preheater or preheater/precalciner kilns. The fi nal limit for long kilns is more stringent than the March 2011 CO limit for waste-burning kil ns, and the rationale for notrequiring BTF measures for these units still holds. Prehe ater and preheater/precalciner kilns

have much higher CO emission rates, and this fact has l ed to a less stringent MACT floor.

Of the 10 precalciner/preheater kilns, 6 are estimated to r equire additional control. The only effective CO control for significant CO reduct ions we identified for waste-burning kilns is a regenerative thermal oxidizer (RTO), and we expect over half of the units will need

to install an RTO to meet the MACT floor limit. As a BTF option, we considered setting a CO limit at a level that would require most of the rem aining waste-burning kilns to install an RTO. This level also would require some of the units requi ring an RTO to meet the MACT

floor emission limit for CO to install a more robust RTO system to meet a more stringent limit, increasing both capital costs of the RTO and the amount of fuel used to heat the control device. Based on these considerations, we estimated cos t-effectiveness of CO reductions achieved by a BTF limit to be $26,000 per ton. We do not belie ve these costs to be

reasonable.

3.4.4 NO

x Emissions

The less-stringent NO

x limit for waste-burning kilns is a result of the expan ded inventory for this subcategory, as discussed earlier. Exi sting units in this subcategory are currently using selective non-catalytic reduction (SNCR) t o meet the MACT floor emission limit. We do not have data showing reductions achieved by th ese controls on existing kilns in our inventory, so we are unable to evaluate whether thi s control technology will provide additional reductions for these units as a BTF option.

Test data for two kilns equipped with SNCR show NOx emiss ions of about 470 ppm, and one kiln will likely require SNCR to meet the MACT floor emission limit. This kiln has NOx emission levels around 2,000 ppm. SNCR will enable this ki ln to achieve the MACT floor emission level of 630 ppm. These other two kilns a lready equipped with SNCR will likely have to evaluate whether their current SNCR cont rol system and operation will ensure an adequate margin of compliance with the MACT floor e mission limit.

An option of setting a BTF limit would require, at lea st for three kilns, two SNCR controls in series, or perhaps the addition of selectiv e catalytic reduction (SCR). Neither of these options appears reasonable based on cost, energy i mpacts or environmental effects (e.g., increased solid waste and wastewater discharge). S NCR controls require a certain temperature range and degree of mixing to be effective. An SNCR is usually integrated into the combustion chamber process in a region where optim al reaction conditions exist. If too much reagent is added, then ammonia slip becomes an issue, where the control generates ammonia emissions due to unreacted reagent. Therefore, a s eries of SNCR systems would be more practical to reduce NOx emissions than simply injec ting more reagent into one SNCR system. For such a system to work, the second SNCR w ould likely require reheating the flue gas to optimal temperature and providing turbulence for the r eaction. As the first SNCR is installed in a portion of the combustion device that is i ntegral to the combustion or heat recovery process, this second chamber would not be a nece ssary component but simply be an extra combustion chamber or reaction vessel requiring additional combustion to achieve reaction temperatures. Due to increased footprint and fue l consumption for the reheatchamber, this would result in control costs more than double what an SNCR system alone

would cost.

Selective catalytic reduction (SCR) is another technol ogy that some combustion sources use to reduce NOx emissions; however, SCR is a c atalyst technology that has not been demonstrated to work effectively on waste-burning kil ns (or cement kilns) in the United

States. We believe that SCR is not effective on waste -burning kilns due to difficulties operating SCR in applications where significant PM or s ulfur loading in the gas stream exists. These two gas stream constituents can reduce cata lyst activity and lower the resulting effectiveness of the SCR, through catalyst poisoning and blinding/plugging of active sites by ammonia sulfur salts (formed from sulfur in the flue gas with the ammonia reagent) and PM (Air Pollution Control Technology Fact Sheet, SCR, EP A–452/ F–03–032).

We could not identify any other controls beyond SCR and SNCR, alone or in tandem, that reduce NOx emissions from waste-burning kilns. As di scussed above, we believe that SNCR in series is unreasonable in cost and energy impa cts and appears to be unproven in practice. We also believe that SCR is not currently demonstrated to successfully achieve reductions for kilns and may not be technically feasible. F or these reasons, we do not believe a viable BTF option exists for reducing NOx emissions for the waste-burning kiln subcategory.

3.4.5 SO 2 Emissions

The less-stringent SO 2 limit for waste-burning kilns is a result of the expan ded inventory for this subcategory as discussed above.

We expect that existing waste-burning kilns will install sc rubbers to meet the MACT

floor emission limits for HCl and SO 2 . The only other option for further HCl and SO 2 control is addition of a dry sorbent injection system, possibly in series with a wet scrubber. Our estimates for use of this control for existing waste -burning kilns yield a costeffectiveness for annual HCl and SO 2 reductions of around $5,000 per ton, based on 95% control efficiency applied to SO2 control. Some uncertai nty exists regarding the appropriate control system that some existing kilns would need to em ploy to meet a BTF limit, especially kilns that use ingredients with a high sulfur content. A lso, our analysis is unable to account for potential costs at existing sources for additional scr ubber water and spent sorbent. Therefore, we do not consider a BTF SO 2 limit for existing waste-burning kilns to be

reasonable.

4.0 New Units

We do not expect any new CISWI units in the waste-burning ki ln or ERU subcategories to come online in the near future. We anticipa te that facilities installing new

kilns or boilers will choose to combust materials that will prevent them from being subject to CISWI standards. However, regarding new kilns, we examined the analysis performed forthe Portland cement NSPS (75 FR 54970), as those kilns are a similar source to the subject waste-burning kilns. In the Portland cement NSPS, the new source SO 2 limit is 0.4 lb/ton clinker, which translates to 28 ppmvd @ 7% oxygen. For new so urces, the estimated costeffectiveness of this emission limit ranges from $470 to $1430 per ton SO 2 . In that rulemaking, EPA determined that the 0.4 lb/ton clinker lim it had reasonable costs, and limits beyond that level provided little environmental benefit (75 FR 54995). For new sources, adequate time and resources can be devoted to ensure control device equipment selection and sizing, as well as ancillary processes, such as waste w ater treatment and waste disposal, may be accounted for prior to commencing construction. We hav e therefore concluded that adopting the Portland cement NSPS limit is an acceptable BTF option for new waste-burning kilns (should any waste-burning kilns ever be constructed) a nd have established the 28 ppmvd @ 7% oxygen limit as the SO 2 limit for new waste-burning kilns.

The incinerator and the small remote incinerator subcat egories may see new units within the immediate future, primarily due to the replace ment of old units. While facilities may find alternative disposal options are available, we are cognizant of the fact that, for these subcategories, there may be instances where alternative disposal options are unavailable, and a new incineration unit may be required.

For incinerators, we estimate new units will require a combination of the ACI system/FF, SNCR, and wet scrubbers to achieve the new so urce MACT floor limits. See Tables 9A and 9B of the CISWI cost memorandum (Referenc e 4) for a comparison of assumed baseline (without controls) concentrations and n ew source MACT floor limits for each pollutant. As discussed above for existing incinera tors, no control technologies are demonstrated or reasonably cost-effective that we could co nsider at this time that would perform better or be more cost-effective than those b eing used to meet the new source MACT floor limits. Therefore, we have concluded that no BTF emission limits should be

selected for new incinerators.

For small remote incinerators, we anticipate new sour ces will install an afterburner to

achieve the CO limit and that the afterburner will also be equipped with low NOx burners, will require waste segregation for ferrous and non-ferro us metals and chlorinated plastics, and likely will require an ACI/FF system to meet the new source MACT floor limits. See Table 9C of the CISWI cost memorandum (Reference 4) for a comparison of assumed baseline (without controls) concentrations and new sour ce MACT floor limits for each pollutant. Because many existing small remote incinerators are operated in cold climates were freezing temperatures are common, control technolog ies that require water for operation for this subcategory of unit are not feasible. As a re sult, no additional or better control technologies are available other than those being used to meet the new source MACT floor limits for the small remote incinerator subcategory. The refore, we have concluded that no

BTF emission limits should be selected for new small remote incinerators.

R EFERENCES1. “ CISWI Emission Limit Calculations for Existing and New S ources for the Reconsideration Final

Rule ” Memorandum from Eastern Research Group, Inc. to Toni Jones, U.S. Environmental Protection Agency. November 16, 2012.

2. “CISWI Data Revisions since Reconsideration Proposal” Memorandum from Eastern Research Group, Inc. to Toni Jones, U.S. Environmental P rotection Agency. November 16,

2012.

3. “Revised Floors without Kilns that Would have been CI SWI Kilns Had the Solid Waste Definition Applied” Memorandum from Keith Barnett, U.S . Environmental Protection Agency, to Portland Cement Project Team. April 25, 2011.

4. “Final Reconsideration Compliance Cost Analyses for C ISWI Units” Memorandum from Eastern Research Group, Inc. to Toni Jones, U.S. Environm ental Protection Agency. November 26, 2012.