1 December 2 8 , 2010 February 4, 2011

MEMORANDUM

TO: Docket No.: EPA-HQ-OAR-2004-0305

FROM: Sharon Nizi ch, Project Lead Risk and Technology Review - National Emission Standards for Hazardous Air Pollutants (NESHAP) for Primary Lead Smelting

SUBJECT: Technology Review: Developments in Practices , Processes, and Control Technologies

The purpose of this memorandum is to present the results of an analysis to identify developments in practices, processes, and c ontrol technologies for h azardous air pollutants (HAP) emission sources for the Prim ary Lead Smelting source category. This analysis is part of EPA’s review efforts in accordance with sec tion 112(d)(6) of the Cl ean Air Act (CAA).

1.0 BACKGROUND

1.1 Requirements of Section 112(d)(6) of the CAA

Section 112 of the CAA requires EPA to es tablish technology-based standards for sources of HAP. These technolog y-based standards are often refe rred to as maximum achievable control technology, or MA CT, standards. Section 112 also cont ains provisions requiring EPA to revisit these standards. Specifically , paragraph 112(d)(6) section states:

(6) REVIEW AND REVISION. – The Administrator shall review, and revise as necessary (taking into account developmen ts in practices, processes, and control technologies), emission standards promul gated under this section no less often than every 8 years.

1.2 Description of Primary Lead Sm elting Source Category and NESHAP Requirements

The Primary Lead Smelting sour ce category includes all facili ties that smelt lead-bearing ore concentrates to produce lead metal using py rometallugical techniques. The source category does not include secondary lead smelters, lead remelte rs, or lead refiners th at are not located at a primary lead smelting facility. Lead is used to make various constructi on and consumer products such as batteries, paint, glass, piping, and filler. Lead sulfide (P bS) ore concentrates are the main feed material to primar y lead smelters. The primary lead smelting process consists of PbS concentrate storage and handling, sintering of ore concentrates , sinter crushing and handling,2 smelting of sinter to lead meta l, drossing (i.e., removing the so lid oxide deposits), refining and alloying of lead metal, and smelting of the drosses.

HAP is emitted from primar y lead smelting as process emissions, process fugitive emissions, and fugitive dust emissions. Process e missions are associated with the exhaust gases from sinter machines and blast and dross furnace s. HAP expected in process emissions are metals (mostly lead, but also some arsenic, cadmium, and other metals) and also may include organic compounds that re sult from incomplete combustion of coke and natural gas combustion. Process fugitive emissions occur at various poi nts during the smelting pr ocess (such as during charging and tapping of furnaces) and generally include metal HAP. F ugitive dust emissions result from the entrainment of dust due to material handling, ve hicle traffic, and wind erosion from storage piles. All fugiti ve dust emissions contain metal HAP. The majority of these fugitive emissions are related to concentrate handli ng, sinter transfer, and si ntering operations.

The NESHAP for Primary Lead Smelting were promul gated on June 4, 1999 (64 FR 30194) and codified at 40 CFR part 63, subpa rt TTT. The Primary Lead Smelting MACT standard applies to affected sources of HAP at pr imary lead smelters. Pr imary lead smelters are defined as “...any facility engaged in the produc tion of lead metal from lead sulfide ore concentrates through the use of py rometallurgical techni ques.” At the time of promulgation of the Primary Lead Smelting MACT ru le, there were three operating l ead smelters. Today there is one operating facility, The Doe Run Resources Corporation (Doe Run) in Herculaneum, Missouri, that is subject to the MACT standard.

The Primary Lead Smelting MACT standard a pplies to sinter machines, blast furnaces, dross furnaces, process fugitive sources, and f ugitive dust sources. Process and process fugitive emissions of lead compounds from sinter machines , blast furnaces, and dross furnaces are limited to 500 grams (g) of lead emissions per mega gram (M g) of lead produced (i.e., 500 g/Mg of lead produced, or 1.0 lb/ton of lead produced). Process fugitive sources that are subject to the MACT standard are dross furnace charging, bl ast furnace and dross furnace tapping, and the sinter machine (charging, discha rge end, crushing, and sizing). Pr ocess fugitive emissions must be captured by a hood and ventilated to a baghouse or equivalent control device. In addition, the sinter machine area must be enclosed in a building that is vent ilated to a baghouse at a rate that maintains a positive in-draft through any doorway openi ng. The MACT standa rd also requires the use of bag leak detection systems for conti nuous monitoring of baghouses. For fugitive dust sources, the MACT standard requires that the owne r or operator prepare and operate at all times according to a standard operating pr ocedures (SOP) manual that describes in detail the measures used to control fugitive dust em issions from plant roadways, mate rial storage and handling areas, sinter machine areas, fu rnace areas, and refining and casting ar eas. The work practices outlined in the SOP manual developed for compliance with a state implementation plan is considered to be compliant with the MACT sta ndard with regard to fugitive e missions work practice controls.

Other metal HAP emitted from the primary lead smelting processes (arsenic, cadmium, cobalt and nickel) are covered by the MACT standard by the re gulation of lead, which is a surrogate for all other nonvolatile metal HAP. Lead is not a surrogate for mercury. However, mercury emissions are not a concern for this so urce category because the mercury content of the lead sulfide ore and other materials that could introduce mercury into the process is below the3 detection limit. Organic HAP are emitted in very small qua ntities from the incomplete combustion of small amounts of coke in the bl ast furnace and natural gas combustion sources such as space heating and generators. Although th ey were considered in the development of the 1999 MACT rule, they were not regul ated because they are emitted at a rate so low as to be infeasible to reduce

. unreliable to measure and in feasible to reduce. A more detailed discussion of EPA’s consideration of VOC and organic HAP e missions in this review is presented in Attachment 1. Acid gas HAP were not identified and, therefore, were not regulated in the original MACT rule. More recen t emissions data indicate that acid gas HAP are not emitted by the lead smelting process.

2.0 DEVELOPMENTS IN PRACTICES, PROCESSES, AND CONTROL TECHNOLOGIES

For the purposes of this t echnology review, a “developme nt” was considered to be any of the following:

 Add-on control technology or other equipment that was not identified and considered during the development of the NESHAP for the source category;

 Improvement in add-on control technology or other equipment that was identified and considered during NESHAP developm ent for the source category that could result in significant additi onal HAP emissions reductions;

 Work practice or operational procedure th at was not identified and considered during NESHAP development fo r the source category; and

 Process change or pollution prevention alte rnative that could be broadly applied that was not identified and considered during the development of the NESHAP for the source category.

To identify developments in practices, processes, and cont rol technologies, we conducted searches of EPA’ s RACT/BACT/LAER clearing house and the internet for information on primary lead smelting. We also reviewed the state permit, state implementation plan (SIP) and the Section 114 information collect ion request (ICR) response from the one remaining primary lead smelting facility. Th e search results are summarized below.

At the time of the MACT rule promulga tion, HAP emissions from the primary lead smelting source category were primarily lead but also included small amounts of arsenic, cadmium, cobalt, and nickel, and low levels of combustion related organics. Emissions data from a 2010 ICR response from the only remaining primary lead smelter (1) confirmed that, with the exception of the leve l of emissions, the emi ssions profile for the facility has not changed, with lead accounting for about 99 pe rcent of the HAP emissions. Therefore, this technology re view focused on developments in practices, processes, and control technologies applicable to lead emission sources.

2.1 Clearinghouse and Internet Searches

RACT/BACT/LAER Clearinghouse4 The terms “RACT”, “BACT”, and “LAER” are acronyms for different program requirements under EPA’s New Source Revi ew (NSR) program. Under EPA’s New Source Review (NSR) program, if a company is planning to build a new plant or modify an existing plant such that air pollution e missions will increase, th e company must obtain an NSR permit. The NSR permit is a construction permit which requires the company to minimize air pollution emissions by changing the process to prevent air pollution and/or installing air pollution contro l equipment. RACT, or Reas onable Available Control Technology, is required on sources in areas that are not meeting national ambient air quality standards (i.e. non-attainment areas ). BACT, or Best Available Control Technology, is required on major new or modified sources in attainment areas. LAER, or Lowest Achievable Emission Rate, is require d on major new or mo dified sources in nonattainment areas. BACT a nd LAER (and sometimes RACT ) are determined on a caseby-case basis, usually by State or local permitting agencies. EPA established the RACT/BACT/LAER Clearinghouse, or RBLC, to provided a central database of air pollution technology informati on (including past BACT and LAER decisions contained in NSR permits) to promote th e sharing of information amo ng permitting agencies and to aid in future case-by-case determinations. Ho wever, data in the RBLC are not limited to sources subject to RACT, BACT, and LAER requirements. Noteworthy prevention and control technology decisi ons and information are included even if they are not related to past RACT, BACT, or LAER decisions.

The RBLC contains over 5,000 air pollution control permit determinations that can help indentify appropriate technologies to mitigate most ai r pollutant emission streams. It was designed to help permit applicants a nd reviewers to make pollution prevention and control technol ogy decisions for stationary air pollution sources, and includes data submitted by se veral U.S. territories and a ll 50 States on over 200 different air pollutants and 1,000 i ndustrial processes.

The RBLC was searched fo r facilities that conduct prim ary lead smelting as well as for facilities in other nonferrous manuf acturing industries. No facilities were identified during the search and no new control technologies or developments in existing control technologies were id entified to further reduce emissions from primary lead smelting facilities.

Internet Search A general search of the internet was conducted for information on new processes and control technologies for primary lead sm elting. The search identified one new technology : , a hydrometallurgical process, which could potentially be used in lieu of pyrometallurgical smelting to produce lead metal from lead sulfide ore. The hydrometallurgical lead processing technology is unde r development and uses electrolysis and electrowinning to produce lead from lead ore. This technology, however, is currently only in demonstration project status and not commercially available. Therefore, it is not a proven technology a nd currently cannot be considered a replacement technology for primary lead smelting operations.5 2.2 State SIP and ICR

Based on our review of The Doe Run Herc ulaneum Title V permit, the Missouri SIP for lead, and information provided in the Secti on 114 ICR response from The Doe Run Company, we have determined that there have been adva nces in emission control measures since the 1999 Primary Lead Smelting MACT stan dard. The following paragraphs discuss these advances and improvements.

The 1999 MACT lead emission li mit for primary lead smelting was set at 1 lb/ton. The limit is a facility-wide emission limit that applies to the aggregation of emissions discharged from the air pollution control de vices used to control emissi ons from the following sources:

 Sinter machine;

 Blast furnace;

 Dross furnace;

 Dross furnace charging location;

 Blast furnace and dross furnace tapping location;

 Sinter machine charging location;

 Sinter machine discharge end;

 Sinter crushing and si zing equipment; and

 Sinter machine area.

A facility-wide limit format was used b ecause it was consistent with SIPs, the commingling of exhaust gases from processes to a single stack made it impo ssible to set limits for individual sources, it gave th e facilities more flex ibility in complying with the standard, and it promoted pollution prevention by giving each facility the abilit y to meet the emission limit through any combination of source reduc tion and control t echnology options.

The 1999 MACT lead limit was set using the lead emission limits from the lead SIPs for the states in which primary lead smelting sources were operational at the time of the rulemaking. EPA took each of the three lead SIP limits, in lb/day, divided them by the corresponding lead production capacity, in tons/day, and calculated a l ead emission rate in lb/ton. The results were as follows:

ASARCO - Missouri 1.0 lb/ton ASARCO - Montana 1.0 lb/ton Doe Run - Missouri 0.84 lb/ton

The values were ranked and the median value (1.0 lb/ton) was select ed as representative of the MACT floor.

Since the MACT standard was promulga ted, the industry has undergone significant changes. Two of the three faci lities have shut down. As discussed above, the only remaining primary lead smelting facility is the Doe Run sm elter at Herculaneum, Missouri. Because the Doe Run facility is located in an area desi gnated as non-attainment for the lead National6 Ambient Air Quality Standard (NAA QS), the facility is subject to control requirements under the Missouri SIP for lead. In an effort to meet th e lead NAAQS, Missouri revised the lead SIP as it applied to the Doe Run facility in 2000, 2002 and 2007, requiring numerous emissions reducing measures and improvements to add-on control devices, processes, a nd work practices. SIP requirements are also incorporated into Doe Run’s Title V permit.

The SIP requirements, implemented after the 1999 MACT standard, were considered in our technology review. Th e SIP requirements, summarized below, are described in detail in the 2007 revision of SIP prepared by the Missouri DNR (available at http://www.dnr.mo.gov/ENV/apcp/doc s/2007revision.pdf). The SIP addresses process, process fugitives, and fugitive lead emi ssions and requires enhancements of existing emission control technology, adding or upgradi ng enclosures, process change s and limitations, and work practices.

Under the SIP, fugitive dust emissions are controlled by comprehensive work practices including road watering and auto matic sprinklers, using regene rative sweepers to remove dust from paved surfaces to reduce emissions from traf fic, maintaining a minim um water content for ore concentrate and for baghouse dust that is loaded into railcars, and inspecting the siding that encloses buildings (followed by prompt repairs if needed).

Our review found that the practices implem ented under the SIP to control fugitive dust emissions have resulted in reducti ons in these emissions. As a re sult of the SIP requirements, we find that all feasible practices a nd controls available for control of fugitive dust emissions in this industry have already been implemented. Ther efore, EPA did not find further applicable practices or controls that s hould be required under the MACT to reduce fugitive emissions.
Baghouses are the most comm on control devices used to control process and process fugitive emissions of lead compounds at the He rculaneum facility with the exception of the process emissions from the sinter machine, which are controlled by a combination of devices in series: electrostatic precipitator, baghouse, and acid plant (for control of sulfur dioxide). The buildings that house the blast furnaces, dross furnaces , and refinery kettles are also exhausted to a baghouse. Improvements to existing emission controls required by the SIP include the installation of pleated f ilters to lower the air-to-cloth rati o for baghouses, increased ventilation and improved ventilation hoods at the blast furn ace, and using reverse flow technology for baghouse cleaning. SIP-required measures also included the in stallation of enclosures for unloading ore concentrate, sinter storage, and the sides of th e sinter machin e (which are evacuated to a baghouse).

Process changes implemented in response to the SIP to reduce emissions include a process control system for the injection of ai r through the blast furnace tuyeres located at the bottom of the blast furnace, limitations on indivi dual process and overall plant throughputs, and limiting specific operations to only certain times of the day when the impact on ambient air concentrations is less. Emissions from malfuncti ons will be reduced by alarms that sound when the baghouse fan malfunctions, an interlock system to restrict air flow into the blast furnace when the baghouse is not operating properly, and cameras for the dr oss and refinery kettles to detect kettle failure (i.e., when a plume of smoke is detected from the stack, the kettle burner can be immediately shut off and the problem corrected).7 Under the SIP, technological improvements have also been made to the refining operations at the Doe Run facility. Under the current MACT, refining ope rations are not subject to the lead emission limit becau se at the time the MACT stan dards were developed, emissions from refining were considered f ugitive in nature. In response to the SIP requirements, the Doe Run facility has enclosed the refining and casting operations a nd now exhausts the emission from the refining kettles as well as th e refining building to baghouses.

Recent stack tests show that these improvement s have resulted in emissions substantially lower than are allowed under the current MACT ru le. To assess the impa cts of the technological improvements, lead emissions data from 2008 we re compared with em issions data from 2000. Data from 2008 was selected becau se it reflects the many technol ogical improvements that have been implemented at the facility since the MACT rule prom ulgation. Emissions data from earlier years would not account for all of the emission reducing changes th at have been implemented at the Doe Run facility given that some of the improvements we re not implemented until 2007 and 2008. In 2008, lead emissions fro m the smelter operations sinter ing, blast furnace and drossing (i.e. from the main stack) were 13.31 TPY and emissions from the baghouse controlling emissions from the blast furnace and dross plant building (i.e., baghouse 7) were 1.81 TPY for a total of approximately 15.1 TPY. At the 2008 le ad production rate of 149,500 tons, the emission rate at Doe Run was about 0.2 lb/ton, an 80 pe rcent reduction from the current MACT limit of 1 lb/ton.

The 2008 emissions of 13.31 TPY from sintering, blast furn ace operations, and drossing operations, represent nearly 70 perc ent of total facility-wide lead emissions and reflect the annual rate of emissions achievable as a result of the technological improvements that have been made since 1999. EPA believes that the level of emi ssions in 2008 support the lowering of the MACT limit to be consistent with the demo nstrated level of performance.

In order to establish an emission limit that would properly reflect the facility performance, EPA used the actual 2008 annual emi ssions from the sinteri ng, blast furnace and drossing operations (i.e. 13.31 TPY) and then accounted for variability using the 95 percent confidence upper predictive limit (UPL). The 95 percent confidence UPL fo r the lead emissions is 14.8 tons. The use of the UPL to account for variability in emissions and the emissions data used in the calculation is discussed in Attachment 1 2

. To estimate the plant wide e mission limit that EPA is pr oposing, the technology-based emissions level for sintering, blast furnace a nd dross furnace operations (i.e., 14.8 TPY) was added to the other risk-based em ission levels established for th e other emission sources at the facility. The development of the plant wide emis sion limit is described in the preamble to the proposed rule.

3.0 CONCLUSION

This review identified several developments in practices, controls or processes that have been implemented in the primary lead smelting source category since the 1999 MACT promulgation. The primary l ead smelting source category cu rrently includes one operating facility compared to three at the time the MA CT rule was promulgated. The one remaining8 facility, The Doe Run Resources Corporation, has implemented numerous work practices to control fugitive emissions and additional enclos ures and improvements to add-on controls to address process and process fugi tive emissions since the 1999 MA CT. Additionally, refinery operation emissions, which were formerly fug itive, are now captured and exhausted through a baghouse.

The improvements identified in this review were all re quirements imposed on the Doe Run facility through the Missouri Lead SIP in or der to comply with the lead NAAQS. As a result, current emissions data indicate an approxi mate 80 percent plant wide reduction in lead emissions since the MACT was promulgated. Although these lead emission reductions are not the result of the MACT requirements, EPA be lieves that the current demonstrated emission levels represent an achievable performance and that a reduction in the standard is warranted to bring the standard in line with actual performance.

To determine the emissions level on which the new emission limit would be based, EPA used the 2008 emissions for the f acility as reported in the Sec tion 114 ICR response for the main stack emission (which includes the sintering, blast furnace, and drossing operations), and considered variability based on recent stack tests. EPA calculated that the new emission limit should be based on a 14.8 tons per year cont ribution from the sint ering, blast furnace,and drossing operations (i.e. the main stack). This 14.8 tons per y ear should be included in the calculation of the facility-wide l ead emission limit taking into c onsideration any other necessary emission reductions resulting fro m the residual risk analysis being conducted under Section 112(f)(2) for the source category.

4.0 REFERENCES

1. Letter from Curran, D.Y., Stinson Morrison H ecker LLP to S. Nizi ch, US Environmental Protection Agency, Response from The Doe Run Resources Corpor ation to EPA’s December 4, 2009, Section 114 Information Collec tion Request, February 5, 2010.9 

## ATTACHMENT 1

VOC and Organic HAP Emissi ons from the Main Stack

During the original MACT development in 1997, VOC emissions testing was performed by the EPA on the uncontrolled bl ast furnace exhaust at the Doe Run smelter to determine the magnitude of organic HAP emi ssions from primary lead blast furnaces. The emissions data obtained indicated low (part per billion) levels of several organic HAP compounds. The five compounds with the highest measured emi ssion rates were benzene (62 ppb, 0.29 lb/hr), methylene chloride (50 ppb, 0.26 lb/hr), acetaldehy de (60 ppb, 0.15 lb/hr), carbon disulfide (33 ppb, 0.15 lb/ hr), and formaldehyde (87 ppb, 0.15 lb/ hr). Combined, the measured organic HAP emissions totaled 2.3 lb/hr, which is equivalent to an annual e mission rate approaching 10 tons per year. At the time of the original MACT development, EPA believed these levels of organic HAP emissions were not significant enough to warra nt regulation and were far below what the EPA has historically considered achievable with add-on controls (e.g., thermal oxidizers). The EPA generally considers thermal oxidizers capable of achieving a 98 percent emission reduction or an outlet concentration of 20 ppm, whichever is greater. As stated above, organic HAP concentrations at primary lead smelters range from 33 to 87 ppb, or thr ee orders of magnitude less than what the EPA has considered achievabl e with thermal oxidizers. Therefore, the EPA believes that it is technically in feasible to reduce organic HAP em issions from primary lead blast furnaces through the use of add-on controls.

EPA evaluated 2008 VOC and the 2005 NEI orga nic HAP data to determine whether it was feasible to require reductions in organic HAP emissions. Data was analyzed from the Doe Run emission inventory (as supplied to the St ate of Missouri) and the 2005 NEI. VOC data reported in Doe Run emission i nventories lists total VOC emi ssions in 2008 of 2.21 TPY. Information on individual organi c HAP emissions and total VOC from the 2005 NEI lists total VOC emissions of 2.56 TPY and organic HAP emi ssions of about 0.06 TPY, or about 2 percent of total VOC. Applying this pe rcentage to the 2008 total VOC emissions results in 2008 organic HAP emissions of approximatel y 0.04 TPY, far below the 10 TP Y reported in the original MACT.

Using the 2005 NEI data for the Doe Run fac ility, VOC emissions are approximately 43 times the level of organic HAP emissions. Applying this ratio to the concen trations reported in the original MACT of 33 to 87 ppb (or 0.033 to 0.087 ppm), we estimate total VOC concentrations to be between 1.4 ppm and 3.7 ppm at the Doe Run facility. These VOC concentration levels (1.4 to 3.7 ppm) are well below the 4 ppm detection limit of the measurement methods currently available fo r VOC. We believe it is technically and economically impracticable to m easure VOC’s at these levels.

Recent information on a thermal oxidizer us ed to control orga nic emissions from a cement kiln showed that the thermal oxidizer wa s capable of reducing VOC emissions to 4 ppmv (at 7 percent oxygen), a level that is at least three or ders of magnitude grea ter than the organic HAP concentrations meas ured at the Doe Run facility. At higher VOC concentrations, for example 15 ppmv and above, a thermal oxidizer will have a removal efficiency of about 9810 percent. At lower VOC concentr ations of about 3 ppm v, a thermal oxidizer’s removal efficiency is expected to be no better than 50 percent. The estimated VOC concentrations at the Doe Run facility are estimated to be 1.4 to 3.7 ppm, thus an even lower removal efficiency is likely. Additionally, the use of thermal oxidizers has various significant adverse environmental consequences, including increase in emissions of criteria pollutan ts, and significant extra energy utilization, with attendant increases in carbon dioxide (CO2) gas emissions.

Based on these considerations, EPA has dete rmined that the VOC emissions from this facility do not warrant consideration for re gulation under the section 112(d)(6) technology review.11 

## ATTACHMENT 2

Variability and Upper Predictive Limit Calculation Main Stack Lead Emissions

In assessing sources’ performance, EPA may consider variability both in identifying which performers are “best” and in assessi ng their level of performance. Brick MACT , 479 F. 3d at 881-82; see also Mossville Envt’l Action Now v. EPA

, 370 F.3d 1232, 1241–42 (D.C. Cir 2004) (EPA must exercise its j udgment, based on an evaluation of the relevant factors and available data, to determine the level of emissi ons control that has been achieved by the best performing sources considering these sources’ operating variability).
Variability in lead producers’ performance has a number of causes. For emissions of lead compounds that are controlled by baghouses, the va riability is chiefly due to variations in performance of the control device for which both r un-to-run and test-to-test variability must be accounted. 1

In determining a plant-wide emission limit, we used a nnual emissions discharged from the air pollution control devices used to control lead emissions from the Doe Run primary lead smelter. For this rule, we used the 2008 e missions reported by Doe Run to the State of Missouri. Variability was added only to the main stack emissions as the emission levels for the other sources had required risk-based emission levels.
We assessed variability using a statistical formula designed to estimate an emissions level that is equivalent to the sour ce’s performance based on future compliance tests. Specifically, the calculated limit is an upper prediction limit (UPL ) calculated with the Student’s t-test using the TINV function in Microsoft Excel®. The Student’s t-test has al so been used in other EPA rulemakings (e.g., NESHAP for Portla nd Cement Manufacturing; NSPS for Hospital/Medical/Infectious Wast e Incinerators; NESH AP for Industrial, Commercial, and Institutional Boilers and Process He aters) in accounting for variabilit y. A prediction interval for a future observation is an interval that will, wi th a specified degree of confidence, contain the next (or some other pre-specifi ed) randomly selected observati on from a population. In other words, the prediction interval estimates what the upper bound of future values will be, based upon present or past samples taken. The UPL cons equently represents the value which we can expect the mean of future observations (3-run aver age for lead) to fall below within a specified level of confidence, based upon the results of an independent sample from the same population. In other words, if we were to randomly select a future test condition fr om any of these sources (i.e., average of 3 runs or 30-day average) we can be 95 percent confident that the reported level will fall at or below the UPL value. Use of th e UPL is appropriate in this rulemaking because it sets a limit any single or future source can meet based on the source’s past performance.

1 Run-to-run variability is essentially within-test variability, and encompasses variability in individual runs comprising the compliance test, and includes uncertainties in correlation of monitoring parameters and emissions, and imprecision of stack test methods and laboratory analysis. 72 FR at 54877 (Sept. 27, 2007). Test-to-test variability results from variability in pollution device control efficiencies over time (depending on many factors, including for fabric filters the point in the maintenance cy cle in which a fabric filter is tested). Test-to-test variability can be termed long-ter m variability. 72 FR at 54878.12 This formula uses a pooled variance (in the s 2 term) that encompasses all the data-point to data-point variability. Where variability was calculated using the UPL statistical approach, we used the sample standard deviation calculated from the emissions data distributions for lead. The standard deviation is the common measure of the dispersion of th e data set around an average. We note here that the methodology accounts for bot h short-term and long-term variability and encompasses run-to-run and te st-to-test variability.
We adopted a form of the UPL equation that has been used in more recent rulemakings. See 75 FR 54970 (September 9, 2010), 75 FR 32020 (June 4, 2010) and 75 FR 31905 (June 4, 2010). The UPL used in this proposed rule is calculated by:

Where:

x  ̄ = 2008 annual emissions n = the number of test runs m = the number of test runs in the compliance average

s 2 = observed variance t = student t distribution statistic

This calculation was performed usin g the following Excel functions:

95 percent UPL = 2008 annual emissions + [STDEV(Test Runs) x TINV(2 x probability, n-1 degrees of freedom)*SQRT((1/n)+(1/m))], for a one-tailed t- value, probability of 0.05, and sample size of n

Figure 1 provides presents the UPL calculation using the recent stack test data for the main stack at the Doe Run Herculaneum facility. Figure 2 provides is a listing of stack test results used in the calculation of the UPL

.13 Figure 1 - UPL Calculations for Main Stack Lead Emission

UPL Pooled Variance=
Runs 2001-2008
1 2.28
2 2.35
3 3.15
4 2.85
5 0.47
6 0.58
7 0.39
8 0.43
9 0.40

ni = number test runs = 9

Total Number of sources = 1

n =Total # test runs = 9

8

This step is for QC only:

means 1.4335

1.4335 13.31 Main Stack Pb emissions (tons/yr) ‐ 2008 EI
Mean =

Pooled Variance = 1.42101

m= number future runs = 3 Method 12 test quarterly (3 runs/test)

Term1 0.4444

Term2 0.6316

Squared root Term2 0.7947

t

‐ statistic = quantile t

‐ distribution with df degrees of freedom at .95 confidence level = 1.859548033

UPL POOLED VARIANCE = 14.78779913 Doe Run Main Stack Pb

Emissions, lb/hr

NOTE: the pvalue for the t-statistic is calculated as: 2*alpha, where 1-alpha is desired confidence, so if 99% confidence is de sired then alpha=0.01 and 2*alpha=2*(0.01) 

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n m        14 Figure 2 - Doe Run Herculaneum St ack Test Data from Section 114 ICR Response

Source Year of Test Run # Emissions Tests Results for Pb (lb/hr) Production during testing (tons Pb/hr) Emissions rate during testing (lb Pb/ton Pb produced)
Main Stack 2001 1 6.07
2 4.95
3 3.13
2002 1 20.24 8.88 2.28
2 20.87 8.88 2.35
3 27.99 8.88 3.15
2003 1 25.2 8.83 2.85
2 11.92 25.38 0.47
3 14.62 25.38 0.58
2004 1 6.85 17.50 0.39
2 7.46 17.50 0.43
3 6.99 17.50 0.40
2006 1 3.3
2 4
3 4
2008 1 10.81
2 17.49
3 19.23