After reviewing the public comments in conjunction with our review of the scientific literature and the Science Advisory Board's comments, we have determined that the no-threshold model is the most appropriate model for assessing the mortality benefits associated with reducing PM2.5 exposure.  Consistent with this finding, we have conformed the previous threshold sensitivity analysis to the current state of the PM science by incorporating a new "Lowest Measured Level" (LML) assessment.  While an LML assessment provides some insight into the level of uncertainty in the estimated PM mortality benefits, EPA does not view the LML as a threshold and continues to quantify PM-related mortality impacts using a full range of modeled air quality concentrations.
	Most of the estimated PM-related benefits in this rule accrue to populations exposed to higher levels of PM2.5.  Of these estimated PM-related mortalities avoided, about 99 percent occur among populations with baseline exposure to annual mean PM2.5 levels at or above 5.8 ug/m[3], which is the lowest air quality level considered in the most recent study of the American Cancer Society cohort by Krewski et al. (2009).  Using the Pope et al. (2002) study, about 91 percent occur among populations with baseline exposure to annual mean PM2.5 levels at or above 7.5 ug/m[3].  Using the Laden et al. (2006) study, about 40 percent occur among populations with baseline exposure to annual mean PM2.5 levels at or above 10 ug/m[3].  It is important to emphasize that we have high confidence in PM2.5-related effects down to the lowest LML of the major cohort studies, which is 5.8 ug/m[3].  This fact is important, because as we estimate PM-related mortality among populations exposed to levels of PM2.5 that are successively lower, our confidence in the results diminishes.  However, our analysis shows that the great majority of the impacts occur at higher exposures.
	It should be emphasized that the monetized benefits estimates provided above do not include benefits from several important benefit categories, including reducing other air pollutants, ecosystem effects, and visibility impairment.  The benefits from reducing other pollutants have not been monetized in this analysis, including reducing 4,400 tons of NOx, 5,800 tons of hydrochloric acid, 5,200 tons of organic HAPS, and 16,000 pounds of mercury each year.  In addition, we were unable to quantify the additional emission reductions that would occur if cement facilities temporarily idle or reduce capacity utilization as a result of this regulation, or the unquantifiable amount of reductions in condensable PM.  Although we do not have sufficient information or modeling available to provide monetized estimates for this rulemaking, we include a qualitative assessment of the health effects of these air pollutants in the RIA for this rule, which is available in the docket.
	In addition, the monetized benefits estimates provided in Table 13 do not reflect the disbenefits associated with increased electricity usage from operation of the control devices.  We estimate that the increases in emissions of NOx, SO2, PM, and CO2 would have disbenefits valued at $210 million to $470 million at a 3% discount rate.  The total monetized benefits estimates of $7.4 billion to $18 billion (2005$, 3 percent discount rate) and $6.7 billion to $17 billion (2005$, 7% discount rate) reflect these energy disbenefits.
	This analysis does not include the type of detailed uncertainty assessment found in the 2006 PM2.5 NAAQS RIA or 2008 Ozone NAAQS RIA.  However, the benefits analyses in these RIAs provide an indication of the sensitivity of our results to various assumptions, including the use of alternative concentration-response functions and the fraction of mortality impacts at low PM2.5 levels.
	The social costs of this rulemaking are estimated at $740 billion (2005$) in the year of full implementation, and the benefits are estimated at $7.4 billion to $18 billion (2005$, 3 percent discount rate) for that same year.  The benefits at a 7 percent discount rate are $6.7 billion to $17 billion (2005$).  Thus, net benefits of this rulemaking are estimated at $6.7 billion to $17 billion (2005$, 3 percent discount rate). The net benefits at a 7 percent discount rate are $6.0 billion to $16 billion (2005$).  Using alternate relationships between PM2.5 and premature mortality supplied by experts, higher and lower benefits estimates are plausible, but most of the expert-based estimates fall between these two estimates.  EPA believes that the benefits are likely to exceed the costs by a significant margin even when taking into account the uncertainties in the cost and benefit estimates.
	A final issue on benefits concerns the air impacts of increases in imports.  When a regulation leads to increases in imports and only the domestic emission changes are considered in a benefit analysis, the question of the impact of emissions from the increased production in other countries should be examined.  The extra emissions may have an impact on the regulating country (the US) and other the countries.  The location of these extra emissions and the pollutants involved are both important.  Our economic modeling does not involve estimates of the origin of the imports.  We also do not have information about the level of control for facilities in other countries.  Thus, estimating disbenefits associated with these increased emissions in other countries was beyond what we were able to do in this analysis.
	However, another limitation of our analysis produces a bias in the opposite direction.  The economic impact analysis estimated a 10 million ton decrease in domestic production.  No emission reductions were estimated as a result of this change in production.  The benefit analysis was based on emission reductions associated with control being applied to all facilities with no change in capacity utilization.  The increase in imports was estimated to be 3 million tons.  Thus we omitted an emission reduction associated with a 10 million ton decrease in production in this country while also omitting an increase in emissions for an increase in production in other countries of less than a third of the domestic decrease.  Of course the net result of these two omissions depends on the relative emission rates of the countries involved. Analysis of benefits for either of these two types of emissions is beyond the current scope of the benefit analysis.
	For more information, please refer to the RIA for this final rule that is available in the docket.
VII.  Statutory and Executive Order Reviews
   A.	Executive Order 12866: Regulatory Planning and Review
      Under section 3(f)(1) of Executive Order 12866 (58 FR 51735, October 4, 1993), this action is an "economically significant regulatory action" because it is likely to have an annual effect on the economy of $100 million or more.  Accordingly, EPA submitted this action to the Office of Management and Budget (OMB) for review under EO 12866 and any changes made in response to OMB recommendations have been documented in the docket for this action.  In addition, EPA prepared a Regulatory Impact Analysis (RIA) of the potential costs and benefits associated with this action.
      When estimating the PM2.5-related human health benefits and compliance costs in Table 14 below, EPA applied methods and assumptions consistent with the state-of-the-science for human health impact assessment, economics and air quality analysis. EPA applied its best professional judgment in performing this analysis and believes that these estimates provide a reasonable indication of the expected benefits and costs to the nation of this rule.  The Regulatory Impacts Analysis (RIA) available in the docket describes in detail the empirical basis for EPA's assumptions and characterizes the various sources of uncertainties affecting the estimates below.
      When characterizing uncertainty in the PM-mortality relationship, EPA has historically presented a sensitivity analysis applying alternate assumed thresholds in the PM concentration-response relationship.  In its synthesis of the current state of the PM science, EPA's 2009 Integrated Science Assessment (ISA) for Particulate Matter concluded that a no-threshold log-linear model most adequately portrays the PM-mortality concentration-response relationship.  In the RIA accompanying this rule, rather than segmenting out impacts predicted to be associated levels above and below a `bright line' threshold, EPA includes a "lowest-measured-level (LML)" that illustrates the increasing uncertainty that characterizes exposure attributed to levels of PM2.5 below the LML for each study.  Figures provided in the RIA show avoided PM mortality impacts predicted relative to the baseline PM2.5 levels experienced by the population receiving the PM2.5 mortality benefit, as well as the lowest air quality levels measured in each of the epidemiology cohort studies.  This information allows readers to determine the portion of PM-related mortality benefits occurring above or below the LML of each study; in general,  our confidence in the size of the estimated reduction PM2.5-related premature mortality decreases in areas where annual mean PM2.5 levels are further below the LML in the cohort studies.  In this analysis, we see that about 99% of the baseline exposure occurs among populations exposed to annual mean PM2.5 levels above 5.8 ug/m[3] (the LML in the most recent study of the American Cancer Society cohort by Krewski et al. (2009)).  Using the Pope et al. (2002) study, about 91 percent occur among populations with baseline exposure to annual mean PM2.5 levels at or above 7.5 ug/m[3].  Using the Laden et al. (2006) study, about 40 percent occur among populations with baseline exposure to annual mean PM2.5 levels at or above 10 ug/m[3].  While the LML analysis provides some insight into the level of uncertainty in the estimated PM mortality benefits, EPA does not view the LML as a threshold and continues to quantify PM-related mortality impacts using a full range of modeled air quality concentrations.
      Table 14 shows the results of the cost and benefits analysis for this rule.
Table 14.  Summary of the Monetized Benefits, Social Costs, and Net Benefits for the final Portland Cement NESHAP and NSPS in 2013(millions of 2005$)[1]
                            Final NESHAP and NSPS

                               3% Discount Rate
                               7% Discount Rate
Total Monetized Benefits[2]
                                    $7,400
                                      to
                                    $18,000
                                    $6,700
                                      to
                                    $17,000
Total Social Costs[3]
                                     $740
                                     $740
Net Benefits
                                    $6,700
                                      to
                                    $17,000
                                    $6,000
                                      to
                                    $16,000
Non-monetized Benefits
4,400 tons of NOx (includes energy disbenefits)

5,200 tons of organic HAPs

5,900 tons of HCl

16,400 pounds of mercury

Health effects from HAPs, NO2, and SO2 exposure

Ecosystem effects

Visibility impairment
                                Final NSPS only

                               3% Discount Rate
                               7% Discount Rate
Total Monetized Benefits[2]
                                                                           $510
                                      to
$1,300
                                                                           $460
                                      to
$1,100
Total Social Costs[3]
                                      $39
                                      $39
Net Benefits
                                                                           $470
                                      to
$1,200
                                                                           $430
                                      to
$1,100
Non-monetized Benefits
6,600 tons of NOx

520 tons of HCl

Health effects from HAPs, NO2, and SO2 exposure

Ecosystem effects

Visibility impairment
                               Final NESHAP only

                               3% Discount Rate
                               7% Discount Rate
Total Monetized Benefits[2]
                                    $7,400
                                      to
                                    $18,000
                                    $6,700
                                      to
                                    $17,000
Total Social Costs[3]
                                     $729
                                     $729
Net Benefits
                                    $6,700
                                      to
                                    $17,000
                                    $6,000
                                      to
                                    $16,000
Non-monetized Benefits
5,200 tons of organic HAPs

5,900 tons of HCl

16,000 pounds of mercury

Health effects from HAPs, SO2 exposure

Ecosystem effects

Visibility impairment
               Alternative: More Stringent NSPS and Final NESHAP

                               3% Discount Rate
                               7% Discount Rate
Total Monetized Benefits[2]
                                    $7,400
                                      to
                                    $18,000
                                    $6,700
                                      to
                                    $17,000
Total Social Costs[3]
                                     $756
                                     $756
Net Benefits
                                    $6,700
                                      to
                                    $17,000
                                    $6,000
                                      to
                                    $16,000
Non-monetized Benefits
7,800 tons of NOx (includes energy disbenefits)

5,200 tons of organic HAPs

5,900 tons of HCl

16,400 pounds of mercury

Health effects from HAPs, NO2, and SO2 exposure

Ecosystem effects

Visibility impairment
[1]All estimates are for the implementation year (2013), and are rounded to two significant figures.
[2] The total monetized benefits reflect the human health benefits associated with reducing exposure to PM2.5 through reductions of directly emitted PM2.5 and PM2.5 precursors such as NOx and SO2. It is important to note that the monetized benefits include many but not all health effects associated with PM2.5 exposure. Benefits are shown as a range from Pope et al. (2002) to Laden et al. (2006). These models assume that all fine particles, regardless of their chemical composition, are equally potent in causing premature mortality because there is no clear scientific evidence that would support the development of differential effects estimates by particle type. The total monetized benefits include the energy disbenefits.
3 The methodology used to estimate social costs for one year in the multimarket model using surplus changes results in the same social costs for both discount rates.

      For more information on the benefits analysis, please refer to the RIA for this rulemaking, which is available in the docket.
 B.  Paperwork Reduction Act
1. Subpart F
The information requirements in the final amendments to subpart F have been submitted for approval to the Office of Management and Budget (OMB) under the Paperwork Reduction Act, 44 U.S.C. 3501 et seq.  The Information Collection Request (ICR) document prepared by EPA has been assigned EPA ICR number 2307.02.
The final amendments to the NSPS for Portland cement plants apply to affected facilities constructed, modified, or reconstructed after June 16, 2008.  The owner or operator of a new kiln is required to keep daily records of clinker production, install and operate PM CEMS for fabric filters used to meet the PM emission limit, and operate NOx and SO2 CEMS.  These requirements are based on the recordkeeping and reporting requirements in the NSPS General Provisions (40 CFR part 60, subpart A) which are mandatory for all operators subject to new source performance standards.  These recordkeeping and reporting requirements are specifically authorized by section 114 of the CAA (42 U.S.C. 7414).  All information submitted to EPA pursuant to the recordkeeping and reporting requirements for which a claim of confidentiality is made is safeguarded according to EPA policies set forth in 40 CFR part 2, subpart B.
	The annual burden for this information collection averaged over the first 3 years of this ICR is estimated to total 2,559 labor-hours per year at a cost of $240,064 per year.  The annualized capital costs are estimated at $45,626 per year and operation and maintenance costs are estimated at $52,450 per year.  Burden is defined at 5 CFR 1320.3(b).
	2. Subpart LLL
      The information collection requirements in this final rule have been submitted for approval to the OMB under the Paperwork Reduction Act, 44 U.S.C. 3501 et seq.  The Information Collection Request (ICR) document prepared by EPA has been assigned EPA ICR number 1801.09.
      In most cases, new and existing kilns and in-line kiln/raw mills at major and area sources that are not already subject to emission limits for THC, mercury, and PM will become subject to the limits and associated compliance provisions in the current rule.  New compliance provisions for mercury will remove the current requirement for an initial performance test coupled with monitoring of the carbon injection rate.  Instead, plants will measure mercury emissions by calculating a 30-day average from continuous or integrated monitors.  Records of all calculations and data will be required.  New compliance procedures will also apply to area sources subject to a PM limit in a format of lbs/ton of clinker.  The owner or operator will be required to install and operate a weight measurement system and keep daily records of clinker production instead of the current requirement to install and operate a PM CEMS.  Cement plants also will be subject to new limits for HCl and associated compliance provisions which include compliance tests using EPA Method 321 and continuous monitoring for HCl for facilities that do not use a wet scrubber for HCl control.  These requirements are based on the recordkeeping and reporting requirements in the NESHAP General Provisions (40 CFR part 63, subpart A) which are mandatory for all operators subject to national emission standards.  These recordkeeping and reporting requirements are specifically authorized by section 114 of the CAA (42 U.S.C. 7414).  All information submitted to EPA pursuant to the recordkeeping and reporting requirements for which a claim of confidentiality is made is safeguarded according to EPA policies set forth in 40 CFR part 2, subpart B.
	The annual burden for this information collection averaged over the first 3 years of this ICR is estimated to total 65,506 labor-hours per year at a cost of $6.4 million per year.  The average annualized capital costs are estimated at $65.5 million per year and average operation and maintenance costs are estimated at $199,378 per year.  Burden is defined at 5 CFR 1320.3(b).
	An agency may not conduct or sponsor, and a person is not required to respond to a collection of information unless it displays a currently valid OMB control number.  The OMB control numbers for EPA's regulations are listed in 40 CFR part 9.
 C.  Regulatory Flexibility Act
 	The Regulatory Flexibility Act (RFA) generally requires an agency to prepare a regulatory flexibility analysis of any rule subject to notice and comment rulemaking requirements under the Administrative Procedure Act or any other statute unless the agency certifies that the rule will not have a significant economic impact on a substantial number of small entities.  Small entities include small businesses, small organizations, and small governmental jurisdictions.
 	For purposes of assessing the impact of this rule on small entities, small entity is defined as:  (1) a small business whose parent company has no more than 750 employees depending on the size definition for the affected NAICS code (as defined by Small Business Administration (SBA) size standards found at http://www.sba.gov/idc/groups/public/documents/sba_homepage/serv_sstd_tablepdf.pdf); (2) a small governmental jurisdiction that is a government of a city, county, town, school district, or special district with a population of less than 50,000; and (3) a small organization that is any not-for-profit enterprise which is independently owned and operated and is not dominant in its field.
   1. Subpart F
After considering the economic impact of this final rule on small entities, I certify that this action will not have a significant economic impact on a substantial number of small entities.  We estimate that 3 of the 26 existing Portland cement entities are small entities which will not incur any impacts under these final amendments unless an affected facility is constructed, modified, or reconstructed.  Based on our economic analysis, 7 new kilns may be constructed during the next five years that will be subject to these NSPS amendments.  One of these kilns may be operated by a Portland cement entity that is classified as a small entity according to the SBA small business size standards.  Of these 7 kilns, this small entity is expected to incur an annualized compliance cost of between 1.0 and 3.0 percent of sales to comply with the final action.
Although this final rule will not have a significant economic impact on a substantial number of small entities, EPA nonetheless has tried to reduce the impact of this rule on small entities by the selection of an emission level based on highly cost-effective controls and specifying monitoring requirements that are the minimum to insure compliance.  In the case where there are overlapping standards between this NSPS and the Portland Cement NESHAP, we have exempted sources from the least stringent requirement thereby eliminated overlapping monitoring, testing and reporting requirements by requiring that the source comply with only the more stringent of the standards.
   2. Subpart LLL
      After considering the economic impact of this final rule on small entities, I certify that this action will not have a significant economic impact on a substantial number of small entities.  We estimate that up to 3 of the 26 existing Portland cement plants are small entities.
      EPA performed a screening analysis for impacts on the three affected small entities by comparing compliance costs to entity revenues. EPA's analysis found that the ratio of compliance cost to company revenue for one small entity (a tribal government) will have an annualized cost of less than 1 percent of sales. The other two small business will have an annualized cost of between 1 and three percent of sales.
	Although this final rule will not impact a substantial number of small entities, EPA nonetheless has tried to reduce the impact of this proposed rule on small entities by setting the final emissions limits at the MACT floor, the least stringent level allowed by law.  In the case where there are overlapping standards between this NESHAP and the Portland Cement NSPS, we have exempted sources from the least stringent requirement thereby eliminating the overlapping monitoring, testing and reporting requirements by requiring that the source comply with only the more stringent of the standards.  In addition, we applied MACT for HCl emissions to major sources only.  The reduced compliance costs for two of the three small entities by a factor of 4.
 D.  Unfunded Mandates Reform Act
 	Title II of the Unfunded Mandates Reform Act (UMRA), 2 U.S.C 1531-1538, requires Federal agencies, unless otherwise prohibited by law, to assess the effects of their regulatory actions on State, local, and tribal governments and the private sector.  Federal agencies must also develop a plan to provide notice to small governments that might be significantly or uniquely affected by any regulatory requirements. The plan must enable officials of affected small governments to have meaningful and timely input in the development of EPA regulatory proposals with significant Federal intergovernmental mandates and must inform, educate, and advise small governments on compliance with the regulatory requirements.
   1. Subpart F
This rule does not contain a Federal mandate that may result in expenditures of $100 million or more for State, local, and tribal governments, in the aggregate, or the private sector in any one year.  As discussed earlier in this preamble, the estimated expenditures for the private sector in the fifth year after promulgation are $50 million.  Thus, this final rule is not subject to the requirements of section 202 and 205 of the UMRA.
This final action is also not subject to the requirements of section 203 of the UMRA because it contains no regulatory requirements that might significantly or uniquely affect small governments.  This final action contains no requirements that apply to such governments, imposes no obligations upon them, and will not result in expenditures by them of $100 million or more in any one year or any disproportionate impacts on them.
   2. Subpart LLL
This rule contains a Federal mandate that may result in expenditures of $100 million or more for State, local, and tribal governments, in the aggregate, or the private sector in any one year.  Accordingly, EPA has prepared under section 202 of the UMRA a written statement which is summarized below.
In developing this rule, EPA consulted with small governments under a plan developed pursuant to section 203 of UMRA concerning the regulatory requirements in the rule that might significantly or uniquely affect small governments.  EPA has determined that this final action contains regulatory requirements that might significantly or uniquely affect small governments because we identified one of the facilities affected by the final rule as tribally owned. EPA developed a plan to permit this tribal entity to have meaningful and timely input into its development.
Consistent with the intergovernmental consultation provisions of section 204 of the UMRA, EPA initiated consultations with the governmental entities affected by this rule.  EPA directly contacted the facility in question to insure it was appraised of this rulemaking and potential implications.  This facility indicated it was aware of the rulemaking and was participating in meetings with the industry trade association concerning this rulemaking.  The facility did not indicate any special issues other than those expressed by the industry in general,   We are assuming that they have the same concerns as those expressed by the other non-tribally owned facilities during the development of this final rule.  Subsequent to proposal, EPA again contacted the Tribal Government by letter with an offer of consultation.  We received no response to that letter.
Consistent with section 205, EPA has identified and considered a reasonable number of regulatory alternatives. EPA carefully examined regulatory alternatives, and selected the lowest cost/least burdensome alternative that EPA deems adequate to address Congressional concerns and to effectively reduce emissions of mercury, THC and PM.  EPA has considered the costs and benefits of the final rule, and has concluded that the costs will fall mainly on the private sector (approximately $479 million).  EPA estimates that an additional facility owned by a tribal government will incur approximately $1.2 million in costs per year.  Furthermore, we believe it is unlikely that State, local and Tribal governments would begin operating large industrial facilities, similar to those affected by this rulemaking operated by the private sector.  EPA has selected regulatory alternatives that represent the MACT floor level of control, which is the least stringent level allowed by law.
   E.  Executive Order 13132:  Federalism
Executive Order 13132 (64 FR 43255, August 10, 1999), requires EPA to develop an accountable process to ensure "meaningful and timely input by State and local officials in the development of regulatory policies that have federalism implications."  "Policies that have federalism implications" is defined in the Executive Order to include regulations that have "substantial direct effects on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government."
These two final rules do not have federalism implications.  They will not have substantial direct effects on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government, as specified in Executive Order 13132.  None of the affected facilities are owned or operated by State governments.  Thus, Executive Order 13132 does not apply to these final rules.
 F.  Executive Order 13175:  Consultation and Coordination with Indian Tribal Governments
 	Subject to the Executive Order 13175 (65 FR 67249, November 9, 2000) EPA may not issue a regulation that has tribal implications, that imposes substantial direct compliance costs, and that is not required by statute, unless the Federal government provides the funds necessary to pay the direct compliance costs incurred by tribal governments, or EPA consults with tribal officials early in the process of developing the proposed regulation and develops a tribal summary impact statement.
1.Subpart F
This final action does not have tribal implications, as specified in Executive Order 13175 (65 FR 67249, November 9, 2000).  It will not have substantial direct effects on tribal governments, on the relationship between the Federal government and Indian tribes, or on the distribution of power and responsibilities between the Federal government and Indian tribes, as specified in Executive Order 13175.  The final rule imposes requirements on owners and operators of specified industrial facilities and not tribal governments.  The only tribally owned source is not affected by the amendments to subpart F.  Thus, Executive Order 13175 does not apply to this action.
2.Subpart LLL
 	EPA has concluded that this action will have tribal implications, because it will impose substantial direct compliance costs on tribal governments, and the Federal government will not provide the funds necessary to pay those costs.  One of the facilities affected by this final rule is tribally owned.  We estimate this facility will incur direct compliance costs that are between 1 to 3 percent of sales.  Accordingly, EPA provides the following tribal summary impact statement as required by section 5(b).
 	EPA consulted with tribal officials early in the process of developing this regulation to provide them meaningful and timely input into its development.  EPA directly contacted the facility in question to insure it was appraised of this rulemaking and potential implications.  This facility indicated it was aware of the rulemaking and was participating in meetings with the industry trade association concerning this rulemaking.  The facility did not indicate any specific concern, and we are assuming that they have the same concerns as those expresses by the other non-tribally owned facilities during the development of this proposed rule.
 G.  Executive Order 13045:  Protection of Children from Environmental Health Risks and Safety Risks
EPA interprets Executive Order 13045 (62 FR 19885, April 23, 1997) as applying to those regulatory actions that concern health or safety risks, such that the analysis required under section 5-501 of the Executive Order has the potential to influence the regulation.  This action is not subject to Executive Order 13045 because it is based solely on technology performance.
 H.  Executive Order 13211:  Actions Concerning Regulations That Significantly Affect Energy Supply, Distribution, or Use
      This proposed rule is not a "significant energy action" as defined in Executive Order 13211, (66 FR 28355, May 22, 2001) because it is not likely to have a significant adverse effect on the supply, distribution, or use of energy.  Further, we have concluded that this proposed rule is not likely to have any adverse energy effects.  This proposal will result in the addition of control equipment and monitoring systems for existing and new sources.

      The final rule under subpart F will result in the addition of alkaline scrubbers to certain kilns to reduce SO2 emissions.  We estimate the additional electrical demand to be 6.9 million kWhr per year by the end of the 2013.
      We estimate that under the final subpart LLL rule the additional electrical demand will be 784 million kWhr per year and the natural gas use will be 672 million cubic feet for existing sources.  At the end of 2013, electrical demand from new sources will be 180 million kWhr per year and natural gas use will be 171 million cubic feet.
 I.  National Technology Transfer and Advancement Act
 	Section 12(d) of the National Technology Transfer and Advancement Act of 1995 ("NTTAA"), Public Law No. 104-113 (15 U.S.C. 272 note) directs EPA to use voluntary consensus standards (VCS) in its regulatory activities unless to do so would be inconsistent with applicable law or otherwise impractical.  Voluntary consensus standards are technical standards (e.g., materials specifications, test methods, sampling procedures, and business practices) that are developed or adopted by VCS bodies.  NTTAA directs EPA to provide Congress, through OMB, explanations when the Agency decides not to use available and applicable VCS.
 	Consistent with the NTTAA, EPA conducted searches through the Enhanced NSSN Database managed by the American National Standards Institute (ANSI).  We also contacted VCS organizations, and accessed and searched their databases.
   1. Subpart F
 	This final rulemaking involves technical standards.  EPA has decided to use the VCS ASME PTC 19.10-1981, "Flue and Exhaust Gas Analyses," for its manual methods of measuring the content of the exhaust gas.  These parts of ASME PTC 19.10-1981 are acceptable alternatives to EPA Methods 3B, 6, 6A, 7, and 7C.  This standard is available from the American Society of Mechanical Engineers (ASME), Three Park Avenue, New York, NY 10016 - 5990.
 	While the Agency has identified 12 other VCS as being potentially applicable to this rule, we have decided not to use these VCS in this rulemaking.  The use of these VCS would have been impractical because they do not meet the objectives of the standards cited in this rule.  See the docket for this rule for the reasons for these determinations.
   1. Subpart LLL
	This final rulemaking involves technical standards.  EPA will use ASTM D6348-03, "Determination of Gaseous Compounds by Extractive Direct Interface Fourier Transform (FTIR) Spectroscopy," as an acceptable alternative to EPA Method 320 providing the following conditions are met:
	(1) The test plan preparation and implementation in the Annexes to ASTM D 6348-03, Sections A1 through A8 are mandatory;
	(2) In ASTM D6348-03 Annex A5 (Analyte Spiking Technique), the percent (%) R must be determined for each target analyte (Equation A5.5).  In order for the test data to be acceptable for a compound, %R must be 70 %R 130.  If the %R value does not meet this criterion for a target compound, the test data is not acceptable for that compound and the test must be repeated for that analyte (i.e., the sampling and/or analytical procedure should be adjusted before a retest).  The %R value for each compound must be reported in the test report, and all field measurements must be corrected with the calculated %R value for that compound by using the following equation:  Reported Result = Measured Concentration in the Stack x 100  % R.
	While the Agency has identified eight other VCS as being potentially applicable to this rule, we have decided not to use these VCS in this rulemaking. The use of these VCS would have been impractical because they do not meet the objectives of the standards cited in this rule. See the docket for this rule for the reasons for these determinations.
 	Under 40 CFR 60.13(i) of the NSPS General Provisions, a source may apply to EPA for permission to use alternative test methods or alternative monitoring requirements in place of any required testing methods, performance specifications, or procedures in the final rule and amendments.
J.  Executive Order 12898:  Federal Actions to Address Environmental Justice in Minority Populations and Low-Income Populations
Executive Order (EO) 12898 (59 FR 7629)(February 16, 1994) establishes federal executive policy on environmental justice.  Its main provision directs Federal agencies, to the greatest extent practicable and permitted by law, to make environmental justice part of their mission by identifying and addressing, as appropriate, disproportionately high and adverse human health or environmental effects of their programs, policies, and activities on minority populations and low-income populations in the United States.
EPA has determined that this proposed rule will not have disproportionately high and adverse human health or environmental effects on minority or low-income populations because it increases the level of environmental protection for all affected populations without having any disproportionately high and adverse human health or environmental effects on any population, including any minority or low-income populations. Additionally, the Agency has reviewed this proposed rule to determine if there was existing disproportionately high and adverse human health or environmental effects on minority or low-income populations that could be mitigated by this rulemaking.  An analysis of demographic data showed that the average of populations in close proximity to the sources, and thus most likely to be effected by the sources, were similar in demographic composition to national averages.
In determining the aggregate demographic makeup of the communities near affected sources, EPA used census data at the block group level to identify demographics of the populations considered to be living near affected sources, such that they have notable exposures to current emissions from these sources.  In this approach, EPA reviewed the distributions of different socio-demographic groups in the locations of the expected emission reductions from this rule.  The review identified those census block groups within a circular distance of a half, 3, and 5 miles of affected sources and determined the demographic and socio-economic composition (e.g., race, income, education, etc.) of these census block groups.  The radius of 3 miles (or approximately 5 kilometers) has been used in other demographic analyses focused on areas around potential sources.,,,  EPA's demographic analysis has shown that these areas in aggregate have similar proportions of American Indians, African-Americans, Hispanics, Whites, and "Other and Multi-racial" populations, and similar proportions of families with incomes below the poverty level as the national average.
EPA defines "Environmental Justice" to include meaningful involvement of all people regardless of race, color, national origin, or income with respect to the development, implementation, and enforcement of environmental laws, regulations, and polices.  To promote meaningful involvement, EPA has developed a communication and outreach strategy to ensure that interested communities have access to this proposed rule, are aware of its content, and have an opportunity to comment during the comment period.  During the comment period, EPA will publicize the rulemaking via EJ newsletters, Tribal newsletters, EJ listservs, and the Internet, including the Office of Policy, Economics, and Innovation's Rulemaking Gateway Web site (http://yosemite.epa.gov/opei/RuleGate.nsf/).  EPA will also provide general rulemaking fact sheets (e.g., why is this important for my community) for EJ community groups and conduct conference calls with interested communities.  In addition, state and federal permitting requirements will provide state and local governments and members of affected communities the opportunity to provide comments on the permit conditions associated with permitting the sources affected by this rulemaking.
This final action establishes national emission standards for new and existing SSI units.  The EPA estimates that there are approximately 93 facilities covered by this rule.  The final rule will reduce emissions of all the listed Hazardous Air Pollutants emitted from this source.  This includes emissions of cadmium, HCl, lead, Hg, and D/F, and other organic hazardous air pollutants.  Adverse health effects from these pollutants include cancer, irritation of the lungs, skin, and mucus membranes, effects on the central nervous system, and damage to the kidneys, and acute health disorders.  The rule will also result in substantial reductions of criteria pollutants such as NOx, PM (total and fine), SO2.  SO2 and NO2 are precursors for the formation of PM2.5 and ozone.  Reducing these emissions will reduce ozone and PM2.5 formation and associated health effects, such as adult premature mortality, chronic and acute bronchitis, asthma, and other respiratory and cardiovascular diseases. (Please refer to the RIA contained in the docket for this rulemaking.)
K.  Congressional Review Act
The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the Small Business Regulatory Enforcement Fairness Act of 1996, generally provides that before a rule may take effect, the agency promulgating the rule must submit a rule report, which includes a copy of the rule, to each House of the Congress and to the Comptroller General of the United States. EPA will submit a report containing this rule and other required information to the U.S. Senate, the U.S. House of Representatives, and the Comptroller General of the United States prior to publication of the rule in the Federal Register. A major rule cannot take effect until 60 days after it is published in the Federal Register. This action is a "major rule" as defined by 5 U.S.C. 804(2).  These final rules will be effective [INSERT DATE 60 DAYS FROM PUBLICATION IN THE FEDERAL REGISTER.

List of Subjects in 40 CFR Part 9
Environmental protection, Reporting and recordkeeping.
List of Subjects in 40 CFR Part 60
 	Environmental protection, Administrative practice and procedure, Air pollution control, Incorporation by reference, Intergovernmental relations, Reporting and recordkeeping requirements.
       List of Subjects in 40 CFR Part 63
Environmental protection, Administrative practice and procedure, Air pollution control, Hazardous substances, and Reporting and recordkeeping requirements.
       .

 Dated:

 Lisa P. Jackson,
 Administrator.

	For the reasons stated in the preamble, title 40, chapter I, of the Code of Federal Regulations is proposed to be amended as follows:

PART 60  -  [AMENDED]
1. The authority citation for part 60 continues to read as follows:
	Authority: 23 U.S.C. 101; 42 U.S.C. 7401-7671q.
Subpart A -- [Amended]
	2.  Section 60.17 is amended by revising paragraph (h)(4) to read as follows:
§60.17  Incorporations by reference.
*  *  *  *  *
	(h)  *  *  *
	(4)  ANSI/ASME PTC 19.10 - 1981, Flue and Exhaust Gas Analyses [Part 10, Instruments and Apparatus], IBR approved for §60.63(i)(2) and (i)(4) of subpart F, Tables 1 and 3 of subpart EEEE, Tables 2 and 4 of subpart FFFF, Table 2 of subpart JJJJ, and §§60.4415(a)(2) and 60.4415(a)(3) of subpart KKKK of this part.
*  *  *  *  *
Subpart F--[AMENDED]
      3.  Section 60.62 is amended as follows:
      a.  Revising the section heading.
      b.  Revising paragraphs (a)(1) and (a)(2)
      c.  Adding paragraphs (a)(3) and (a)(4);
      d.  Revising paragraphs (b)(1) and (b)(2); and
      e.  Adding paragraph (d) to read as follows:
§60.62  Standards.
      (a)  *  *  *
	(1)  Contain particulate matter (PM) in excess of:
	(i)  0.15 kg per metric ton of feed (dry basis) to the kiln (0.30 lb per ton) if construction, reconstruction, or modification of the kiln commences after August 17, 1971 but on or before June 16, 2008.
 	(ii)  0.01 pound per ton of clinker if construction, reconstruction, or modification of the kiln commenced after June 16, 2008.
	(2)  Exhibit greater than 20 percent opacity., except that this opacity limit does not apply to a kiln subject to the PM limit in paragraph (a)(1)(i) of this section that uses a PM continuous emission monitoring system.
	(3)  Exceed 1.50 pounds of nitrogen oxide (NOX) per ton of clinker on a 30-day rolling average if construction, reconstruction, or modification of the kiln commences after June 16, 2008, except this limit does not apply to any alkali bypass installed on the kiln.
	(4)  For sulfur dioxide (SO2) emissions from a kiln for which construction, reconstruction, or modification commences after June 16, 2008.
      	(i)  Exceed 0.4 pounds per ton of clinker on a 30-day rolling average; or
	(ii)  The owner or operator must reduce SO2 emissions exiting the kiln by 90 percent or greater measured across the SO2 control device.
	(b)  *  *  *
 	(1)  Contain PM in excess of:
	(i)  0.050 kg per metric ton of feed (dry basis) to the kiln (0.10 lb per ton) if construction, reconstruction, or modification of the clinker cooler commenced after August 17, 1971 but on or before June 16, 2008.
	(ii)  0.01 pound per ton of clinker if construction, reconstruction, or modification of the clinker cooler commences after June 16, 2008.
	(2)  Exhibit 10 percent opacity, or greater., .except that this opacity limit does not apply to a clinker cooler subject to the PM limit in paragraph (b)(1)(i) of this section that uses a PM continuous emission monitoring system.
*  *  *  *  *
      (d)  If an affected facility subject to this subpart has a different emission limit or requirement for the same pollutant under another regulation in title 40 of this chapter, the owner or operator of the affected facility must comply with the most stringent emission limit or requirement and is not subject to the less stringent requirement.
	4.  Section 60.63 is amended by:
	a.  Revising paragraph (a);
	b.  Revising paragraph (b);
	c.  Revising the first sentence in paragraph (c);
	d.  Adding paragraphs (f) through (n) to read as follows:
§60.63  Monitoring of operations.
      (a)  The owner or operator of any portland cement plant subject to the provisions of this subpart shall record the daily clinker production rates and kiln feed rates. Daily clinker production rates may be calculated from daily feed rates.
	(b)  Clinker Production Monitoring Requirements.  The owner or operator of an affected source subject to an emissions limitation on particulate matter, NOX, or SO2 emissions (lb/ton of clinker) shall install, calibrate, maintain, and operate a permanent weigh scale system, or use another method approved by the Administrator, to measure and record weight rates in tons - mass per hour of the amount of clinker produced.  The system of measuring hourly clinker production must be maintained within +-5 percent accuracy.
      (1) The owner or operator shall determine, record, and maintain a record of the accuracy of the system of measuring hourly clinker production before initial use (for new sources) or within 30 days of the effective date of this rule (for existing sources). During each quarter of source operation, the owner or operator shall determine, record, and maintain a record of the ongoing accuracy of the system of measuring hourly clinker production. The use of a system that directly measures kiln feed rate and uses a conversion factor to determine the clinker production rate is an acceptable method.
      (2) The owner or operator shall record the daily clinker production rates and kiln feed rates.
      (3) The owner or operator shall develop an emissions monitoring plan in accordance with paragraphs (h)(1) through (h)(4) of this section.
      (c)	The owner or operator of a kiln or clinker cooler subject to a PM emissions limit in §60.62 must monitor PM emissions according to the applicable requirements below:
      (1) install and operate a PM continuous emissions monitor in accordance with Performance Specification 11 of appendix B and Quality Assurance Procedure 2 of appendix F to part 60 of this chapter.  The owner or operator must also develop an emissions monitoring plan in accordance with paragraphs (h)(1) through (h)(4) of this section.
      (2) The owner or operator must perform Relative Response Audits annually and Response Correlation Audits every 3 years.
      (3) In order to calculate the 30-day rolling average, collect readings at least every 15 minutes, with at least 2 valid readings during the hour.  Sum the hourly data to daily data and then into a 30-day rolling average.
      (d)  Each owner or operator subject to the NOX emissions limit for a kiln in §60.62(a)(3) shall install, operate, calibrate, and maintain an instrument for continuously monitoring and recording the concentration by volume of NOX emissions into the atmosphere.  If the kiln has an alkali bypass, NOx emission monitoring may be done upstream of any comingled alkali bypass gases.
      (e)  Each owner or operator subject to the SO2 emissions limit in §60.62(a)(4) for a kiln shall install, operate, calibrate, and maintain an instrument for continuously monitoring and recording the concentration by volume of SO2 emissions into the atmosphere.  If complying with the alternative 90 percent SO2 emissions reduction emission limit, you must also continuously monitor and record the concentration by volume of SO2 emissions at the wet scrubber inlet.
	(f)  The owner or operator of each CEMS required under paragraphs (c), (d) and (e) of this section shall install, operate, and maintain each monitoring system according to Performance Specification 2 (40 CFR part 60, appendix B) and the requirements in paragraphs (f)(1) through (5) of this section.
	(1)  The span value of each NOX monitor shall be set at 125 percent of the maximum estimated hourly potential NOX emission concentration that translates to the applicable emission limit at full clinker production capacity.
	(2)  The owner or operator shall conduct performance evaluations of each NOX monitor according to the requirements in §60.13(c) and Performance Specification 2 of Appendix B to part 60.  The owner or operator shall use Methods 7, 7A, 7C, 7D, or 7E of appendix A-4 to part 60 for conducting the relative accuracy evaluations.  The method ASME PTC 19.10-1981, "Flue and Exhaust Gas Analyses," (incorporated by reference-see §60.17) is an acceptable alternative to EPA Method 7 or 7C of Appendix A-4 to part 60.
      (3)  The span value for the SO2 monitor must be set at 125 percent of the maximum estimated hourly potential SO2 emission concentration that translates to the applicable emission limit at full clinker production capacity.
	(4)  The owner or operator must conduct performance evaluations of each SO2 monitor according to the requirements in §60.13(c) and Performance Specification 2 of Appendix B to part 60.  The owner or operator shall use Methods 6, 6A, or 6C of Appendix A-4 to part 60 for conducting the relative accuracy evaluations.  The method ASME PTC 19.10-1981, "Flue and Exhaust Gas Analyses," (incorporated by reference-see §60.17) is an acceptable alternative to EPA Method 6 or 6A of Appendix A-4 to part 60.
	(5)  The owner or operator must comply with the quality assurance requirements in Procedure 1 of Appendix F to part 60 for each monitor, including quarterly accuracy determinations for monitors, and daily calibration drift tests.
      (g)  The owner or operator of each CEMS required under paragraphs (c) through (e) of this section must operate the monitoring system and record data during all periods of operation of the affected facility including periods of startup, shutdown, malfunction, except for continuous monitoring system breakdowns, repairs, calibration checks, and zero and span adjustments.
      (1)  The owner or operator must obtain emission data for at least 18 hours in at least 22 out of 30 successive kiln operating days.  For each valid hour, the owner or operator also must obtain valid exhaust flow rate data, as specified in paragraph (m)(6) of this section.
      (2)  The owner or operator must meet the requirements of §60.13(h) when determining the 1-hour averages of emissions data needed to meet the minimum data requirements specified in paragraph (g)(1) of this section.
      (l)  Each owner or operator of a kiln subject to the NOX emissions limit in §60.62(a)(3) or the SO2 emissions limit in §60.62(a)(4)(i) or (ii) must install, operate, calibrate, and maintain an instrument for continuously measuring and recording the exhaust flow rate to the atmosphere according to the requirements in paragraphs (l)(1) through (9) of this section.
      (1)  The owner or operator must install each sensor of the flow rate monitoring system in a location that provides representative measurement of the exhaust gas flow rate at the sampling location of the NOX and SO2 CEMS, taking into account the manufacturer's recommendations.
      (2)  The flow rate monitoring system must be designed to measure the exhaust flow rate over a range that extends from a value of at least 20 percent less than the lowest expected exhaust flow rate to a value of at least 20 percent greater than the highest expected exhaust flow rate.
      (3)  The flow rate monitoring system must have a minimum accuracy of 5 percent of the flow rate or greater.
      (4)  The flow rate monitoring system must be equipped with a data acquisition and recording system that is capable of recording values over the entire range specified in paragraph (l)(2) of this section.
      (5)  The signal conditioner, wiring, power supply, and data acquisition and recording system for the flow rate monitoring system must be compatible with the output signal of the flow rate sensors used in the monitoring system.
      (6)  The flow rate monitoring system must be designed to complete a minimum of one cycle of operation for each successive 15-minute period.  To have a valid hour of data, the flow rate monitoring system must measure and record at least three of four equally-spaced data values (or at least 75 percent of the total number of values) for each hour (not including startup, shutdown, malfunction, or out-of-control periods).
      (7)  The owner or operator must perform an initial calibration of the flow rate monitoring system according to manufacturer's recommendations
      (8)  The owner or operator must check the accuracy of the monitoring system at least once per year according to manufacturer's recommendations.
      (9)  The owner or operator must operate the flow rate monitoring system and record data during all periods of operation of the affected facility including periods of startup, shutdown, malfunction, except for monitoring system breakdowns, repairs, and calibration checks.
 	(h) Development and Submittal (Upon Request) of Monitoring Plans. If you demonstrate compliance with any applicable emission limit through performance stack testing or other emissions monitoring, you must develop a site-specific monitoring plan according to the requirements in paragraphs (o)(1) through (4) of this section. This requirement also applies to you if you petition the EPA Administrator for alternative monitoring parameters under paragraph (n) of this section and §63.8(f). If you use a BLDS, you must also meet the requirements specified in paragraph (n)(5) of this section.
(1) For each continuous monitoring system (CMS) required in this section, you must develop, and submit to the permitting authority for approval upon request, a site-specific monitoring plan that addresses paragraphs (o)(1)(i) through (iii) of this section. You must submit this site-specific monitoring plan, if requested, at least 60 days before your initial performance evaluation of your CMS.
      (i) Installation of the CMS sampling probe or other interface at a measurement location relative to each affected process unit such that the measurement is representative of control of the exhaust emissions (e.g., on or downstream of the last control device);
      (ii) Performance and equipment specifications for the sample interface, the pollutant concentration or parametric signal analyzer, and the data collection and reduction systems; and
      (iii) Performance evaluation procedures and acceptance criteria (e.g., calibrations).
      (2) In your site-specific monitoring plan, you must also address paragraphs (o)(2)(i) through (iii) of this section.
      (i) Ongoing operation and maintenance procedures in accordance with the general requirements of §63.8(c)(1), (c)(3), and (c)(4)(ii);
      (ii) Ongoing data quality assurance procedures in accordance with the general requirements of §63.8(d); and
      (iii) Ongoing recordkeeping and reporting procedures in accordance with the general requirements of §63.10(c), (e)(1), and (e)(2)(i).
      (3) You must conduct a performance evaluation of each CMS in accordance with your site-specific monitoring plan.
      (4) You must operate and maintain the CMS in continuous operation according to the site-specific monitoring plan.
 	5.  Section 60.64 is amended by:
	a.  Revising paragraph (b) introductory text and paragraph (b)(1); and
 	b.  Adding paragraphs (b)(5) and (b)(6); and
	c.  Adding paragraph (c).
§60.64  Test methods and procedures.
*  *  *  *  *
      (b)  The owner or operator must determine compliance with the PM standard in §60.62(a)(1) as follows:
      (1)  The emission rate (E) of PM must be computed for each run using the Equation 1 of this section:
							(Eq. 1)
Where:
E = emission rate of particulate matter, kg/ metric ton (lb/ton) of kiln feed;
Cs = concentration of particulate matter, g/dscm (gr/dscf);
Qsd = volumetric flow rate of effluent gas, dscm/hr (dscf/hr);
P = total kiln feed (dry basis) rate, metric ton/ hr (ton/hr). For kilns constructed, modified or reconstructed on or after [INSERT DATE OF PUBLICATION OF THIS PROPOSED RULE IN FEDERAL REGISTER], p = total kiln clinker production rate; and
K = conversion factor, 1000 g/kg (7000 gr/lb).
*  *  *  *  *
      (5)  The owner or operator of a kiln (including any associated alkali bypass and clinker cooler) that is constructed, modified or reconstructed on or after [INSERT DATE OF PUBLICATION OF THIS PROPOSED RULE IN FEDERAL REGISTER], must conduct a performance test every 5 years following the initial performance test.  Kilns (including any associated alkali bypass and clinker cooler) constructed, reconstructed, or modified after August 17, 1971 but on or before June 16, 2008 must conduct a performance test every 5 years.
      (6)  Any sources other than kilns (including associated alkali bypass and cooler) subject to the 10 percent opacity limit must follow the appropriate monitoring procedures in §63.1350 of this chapter.
       (c)  The owner or operator must calculate and record the 30-day rolling emission rate of NOX and SO2 as the total of all hourly emissions data for a cement kiln in the preceding 30 days, divided by the total tons of clinker produced in that kiln during the same 30-day period using Equation 2 of this section:
							(Eq. 2)
Where:
E = emission rate of NOX or SO2, kg/metric ton (lb/ton) of clinker production;
Cs = concentration of NOX or SO2, g/dscm (gr/dscf);
Qsd = volumetric flow rate of effluent gas, dscm/hr (dscf/hr);
P = total kiln clinker production rate, metric ton/hr (ton/hr).; and
K = conversion factor, 1000 g/kg (7000 gr/lb).

	6.  Section 60.66 is revised to read as follows:
§60.66 Delegation of authority.
      (a)  This subpart can be implemented and enforced by the U.S. EPA or a delegated authority such as a State, local, or tribal agency.  You should contact your U.S. EPA Regional Office to find out if this subpart is delegated to a State, local, or tribal agency within your State.
      (b)  In delegating implementation and enforcement authority to a State, local, or tribal agency, the approval authorities contained in paragraphs (b)(1) through (4) of this section are retained by the Administrator of the U.S EPA and are not transferred to the State, local, or tribal agency.
      (1)  Approval of an alternative non-opacity emission standard.
      (2)  Approval of a major change to test methods under §60.8(b).  A "major change to test method" is defined in 40 CFR 63.90.
      (3)  Approval of a major change to monitoring under §60.13(i).  A "major change to monitoring" is defined in 40 CFR 63.90.
      (4)  Approval of a major change to recordkeeping/reporting under §60.7(b) through (f).  A "major change to recordkeeping/reporting" is defined in 40 CFR 63.90.

Appendix B  -  [AMENDED]
      7.  Appendix B to 40 CFR Part 60 is amended to read as follows:
	a.  Revise Performance Specification 12A.
	b.  Add Performance Specification 12B.
Appendix B to Part 60  -  Performance Specifications
	* * * * *
Performance Specification 12A -- Specifications and Test Procedures For Total Vapor Phase Mercury Continuous Emission Monitoring Systems in Stationary Sources
1.0  Scope and Application
      1.1  Analyte.  The analyte measured by these procedures and specifications is total vapor phase Hg in the flue gas, which represents the sum of elemental Hg (Hg[o], CAS Number 7439-97-6) and oxidized forms of gaseous Hg (Hg[+2]), in concentration units of micrograms per cubic meter (μg/m[3]).
	1.2  Applicability.
	1.2.1  This specification is for evaluating the acceptability of total vapor phase Hg continuous emission monitoring systems (CEMS) installed at stationary sources at the time of or soon after installation and whenever specified in the regulations.  The Hg CEMS must be capable of measuring the total concentration in ug/m[3] of vapor phase Hg, regardless of speciation, and recording that concentration at standard conditions on a wet or dry basis.  These specifications do not address measurement of particle bound Hg.
	1.2.2  This specification is not designed to evaluate an installed CEMS's performance over an extended period of time nor does it identify specific calibration techniques and auxiliary procedures to assess the CEMS's performance.  The source owner or operator, however, is responsible to calibrate, maintain, and operate the CEMS properly.  The Administrator may require, under section 114 of the Clean Air Act, the operator to conduct CEMS performance evaluations at other times besides the initial performance evaluation test.  See §§60.13(c) and 63.8(e)(1).
	1.2.3  Mercury monitoring approaches not entirely suited to these specifications may be approvable under the alternative monitoring or alternative test method provisions of §60.13(i) and §63.8(f) or §60.8(b)(3) and §63.7(f), respectively.
2.0  Summary of Performance Specification
	Procedures for determining CEMS relative accuracy, linearity, and calibration drift are outlined. CEMS installation and measurement location specifications, data reduction procedures, and performance criteria are included.
3.0   Definitions
	3.1  Continuous Emission Monitoring System (CEMS) means the total equipment required to measure a pollutant concentration.  The system generally consists of the following three major subsystems:
	3.2  Sample Interface means that portion of the CEMS used for one or more of the following: sample acquisition, sample transport, sample conditioning, and protection of the monitor from the effects of the stack effluent.
	3.3  Hg Analyzer means that portion of the Hg CEMS that measures the total vapor phase Hg mass concentration and generates a proportional output.
	3.4  Data Recorder means that portion of the CEMS that provides a permanent electronic record of the analyzer output.  The data recorder may provide automatic data reduction and CEMS control capabilities.
	3.5  Span Value means the measurement range as specified in the applicable regulation or other requirement.  If the span is not specified in the applicable regulation or other requirement, then it shall be a value approximately equivalent to two times the emission standard.  Unless otherwise specified, the span value may be rounded up to the nearest multiple of 10.
	3.6  Measurement Error Test means a test procedure in which the accuracy of the concentrations measured by a CEMS at three or more points over its measurement range is evaluated using reference gases.  For Hg CEMS, elemental and oxidized Hg (Hg[0] and mercuric chloride, HgCl2) gas standards of known concentration are used for this procedure.
      3.7  Measurement Error (ME) means the absolute value of the difference between the concentration indicated by the CEMS and the known concentration of a reference gas, expressed as a percentage of the span value, when the entire CEMS, including the sampling interface, is challenged.
      3.8  Calibration Drift (CD) means the absolute value of the difference between the CEMS output response and either an upscale Hg reference gas or a zero-level Hg reference gas, expressed as a percentage of the span value, when the entire CEMS, including the sampling interface, is challenged after a stated period of operation during which no unscheduled maintenance or repair took place.
	3.9  Relative Accuracy Test Procedure means a test procedure consisting of at least nine test runs, in which the accuracy of the concentrations measured by a CEMS is evaluated by comparison against concurrent measurements made with a reference method (RM).  Relative accuracy tests repeated on a regular, on-going basis are referred to as relative accuracy test audits or RATAs.
	3.10  Relative Accuracy (RA) means the absolute mean difference between the pollutant concentrations determined by the CEMS and the values determined by the RM plus the 2.5 percent error confidence coefficient of a series of tests divided by the mean of the RM tests.  Alternatively, for sources with an average RM concentration less than 5.0 micrograms per standard cubic meter (μg/scm), the RA may be expressed as the absolute value of the difference between the mean CEMS and RM values.
4.0   Interferences [Reserved]
5.0   Safety
	The procedures required under this performance specification may involve hazardous materials, operations, and equipment.  This performance specification may not address all of the safety problems associated with these procedures.  It is the responsibility of the user to establish appropriate safety and health practices and determine the applicable regulatory limitations prior to performing these procedures.  The CEMS user's manual and materials recommended by the RM should be consulted for specific precautions to be taken.
6.0  Equipment and Supplies
	6.1  CEMS Equipment Specifications.
	6.1.1  Data Recorder Scale.  The Hg CEMS data recorder output range must include the full range of expected Hg concentration values in the gas stream to be sampled including zero and the span value.
	6.1.2  The Hg CEMS design should also provide for the determination of CD and ME at a zero value (zero to 20 percent of the span value) and at upscale values (between 50 and 100 percent of the span value).  The Hg CEMS must be constructed to permit the introduction of known concentrations of Hg and HgCl2 separately into the sampling system of the CEMS immediately preceding the sample extraction filtration system such that the entire CEMS can be challenged.
	6.2  Reference Gas Delivery System. The reference gas delivery system must be designed so that the flowrate exceeds the sampling system flow requirements of the CEMS and that the gas is delivered to the CEMS at atmospheric pressure.
	6.3  Other equipment and supplies, as needed by the reference method used for the Relative Accuracy Test Procedure.  See Section 8.6.2.
7.0  Reagents and Standards
	7.1  Reference Gases.  Reference gas standards are required for both elemental and oxidized Hg (Hg and mercuric chloride, HgCl2).  The use of National Institute of Standards and Technology (NIST)-traceable standards and reagents is required.  The following gas concentrations are required.
	7.1.1  Zero-level.  0 to 20 percent of the span value.
	7.1.2  Mid-level.  50 to 60 percent of the span value.
	7.1.3  High-level.  80 to 100 percent of the span value.
	7.2  Reference gas standards may also be required for the reference methods.  See Section 8.6.2.
8.0  Performance Specification Test Procedure
	8.1  Installation and Measurement Location Specifications.
	8.1.1  CEMS Installation.  Install the CEMS at an accessible location downstream of all pollution control equipment.  Place the probe outlet or other sampling interface at a point or location in the stack (or vent) representative of the stack gas concentration of Hg.  Since the Hg CEMS sample system normally extracts gas from a single point in the stack,  a location that has been shown to be free of stratification for Hg or, alternatively, SO2 is recommended.  If the cause of failure to meet the RA test requirement is determined to be the measurement location and a satisfactory correction technique cannot be established, the Administrator may require the CEMS to be relocated.  Measurement locations and points or paths that are most likely to provide data that will meet the RA requirements are described in Sections 8.1.2 and 8.1.3 below.
	8.1.2  Measurement Location.  The measurement location should be (1) at least two equivalent diameters downstream of the nearest control device, point of pollutant generation or other point at which a change of pollutant concentration may occur, and (2) at least half an equivalent diameter upstream from the effluent exhaust.  The equivalent duct diameter is calculated according to Method 1 in appendix A-1 to this part.
	8.1.3  Hg CEMS Sample Extraction Point.  Use a sample extraction point either (1) no less than 1.0 meter from the stack or duct wall, or (2) within the centroidal velocity traverse area of the stack or duct cross section.  This does not apply to cross-stack, in-situ measurement systems.
	8.2  Measurement Error (ME) Test Procedure.  Sequentially inject each of at least three elemental Hg reference gases (zero, mid-level, and high level, as defined in Section 7.1), three times each for a total of nine injections. Inject the gases in such a manner that the entire CEMS is challenged.  Do not inject the same gas concentration twice in succession.  At each reference gas concentration, determine the average of the three CEMS responses and subtract the average response from the reference gas value.  Calculate the measurement error (ME) using Equation 12-1 by expressing the absolute value of the difference between the average CEMS response (A) and the reference gas value (R) as a percentage of the span (see example data sheet in Figure 12A - 1).  For each reference gas, the absolute value of the difference between the CEMS response and the reference value shall not exceed 5 percent of the span value.  If this specification is not met, identify and correct the problem before proceeding.  Repeat the measurement error test procedure using oxidized Hg reference gases.
							(Equation 12A-1)
	8.3  Seven-Day Calibration Drift (CD) Test Procedure.
	8.3.1  CD Test Period.  While the affected facility is operating  normally, or as specified in an applicable regulation, determine the magnitude of the CD once each day (at 24-hour intervals, to the extent practicable) for 7 consecutive unit operating days according to the procedures in Sections 8.3.2 and 8.3.3.  The 7 consecutive unit operating days need not be 7 consecutive calendar days.  Use either Hg° or HgCl2 standards for this test.
	8.3.2  The purpose of the CD measurement is to verify the ability of the CEMS to conform to the established CEMS response used for determining emission concentrations or emission rates.  Therefore, if periodic automatic or manual adjustments are made to the CEMS zero and upscale response settings, conduct the CD test immediately before these adjustments, or conduct it in such a way that the CD can be determined.
	8.3.3  Conduct the CD test using the zero gas specified and either the mid-level or high-level gas as specified in Section 7.1.  Sequentially introduce the reference gases to the CEMS at the sampling system of the CEMS immediately preceding the sample extraction filtration system.  Record the CEMS response (A) for each reference gas and, using Equation 12A-2, subtract the corresponding reference value (R) from the CEMS value, and express the absolute value of the difference as a percentage of the span value (see also example data sheet in Figure 12A - 2).   For each reference gas, the absolute value of the difference between the CEMS response and the reference value shall not exceed 5 percent of the span value.  If these specifications are not met, identify and correct the problem before proceeding.
						(Equation 12A-2)
	8.4  Relative Accuracy (RA) Test Procedure.
	8.4.1  RA Test Period.  Conduct the RA test according to the procedure given in Sections 8.4.2 through 8.4.6 while the affected facility is operating normally, or as specified in an applicable subpart.  The RA test may be conducted during the CD test period.
	8.4.2  Reference Methods (RM).  Unless otherwise specified in an applicable subpart of the regulations, use Method 29, Method 30A, or Method 30B in appendix A-8 to this part or American Society of Testing and Materials (ASTM) Method D6784 - 02 (incorporated by reference, see §60.17) as the RM for Hg concentration.  For Method 29 and ASTM Method D6784-02 only, the filterable portion of the sample need not be included when making comparisons to the CEMS results.  When Method 29, Method 30B, or ASTM D6784 - 02 is used, conduct the RM test runs with paired or duplicate sampling systems and use the average of the vapor phase Hg concentrations measured by the two trains.  When Method 30A is used, paired sampling systems are not required.  If the RM and CEMS measure on a different moisture basis, data derived with Method 4 in appendix A-3 to this part shall also be obtained during the RA test.
	8.4.3  Sampling Strategy for RM Tests.  Conduct the RM tests in such a way that they will yield results representative of the emissions from the source and can be compared to the CEMS data.  The RM and CEMS locations need not be immediately adjacent. Locate the RM measurement points in accordance with section 8.1.3 of Performance Specification 2 (PS 2) in this appendix.  It is preferable to conduct moisture measurements (if needed) and Hg measurements simultaneously, although moisture measurements that are taken within an hour of the Hg measurements may be used to adjust the Hg concentrations to a consistent moisture basis.  In order to correlate the CEMS and RM data properly, note the beginning and end of each RM test period for each paired RM run (including the exact time of day) on the CEMS chart recordings or other permanent record of output.
	8.4.4  Number and Length of RM Test Runs.  Conduct a minimum of nine RM test runs.  When Method 29, Method 30B, or ASTM D6784 - 02 is used, only test runs for which the paired RM trains meet the relative deviation criteria (RD) of this PS shall be used in the RA calculations.  In addition, for Method 29 and ASTM D6784 - 02, use a minimum sample time of 2 hours and for Methods 30A and 30B use a minimum sample time of 30 minutes.
Note: More than nine sets of RM test runs may be performed. If this option is chosen, RM test run results may be excluded so long as the total number of RM test run results used to determine the CEMS RA is greater than or equal to nine. However, all data must be reported including the excluded test run data.
	8.4.5  Correlation of RM and CEMS Data.  Correlate the CEMS and the RM test data as to the time and duration by first determining from the CEMS final output (the one used for reporting) the integrated average pollutant concentration for each RM test period.  Consider system response time, if important, and confirm that the results are on a consistent moisture basis with the RM test.  Then, compare each integrated CEMS value against the corresponding RM value.  When Method 29, Method 30B, or ASTM D6784 - 02 is used, compare each CEMS value against the corresponding average of the paired RM values.
	8.4.6  Paired RM Outliers.
	<IP_ADDRESS>  When Method 29, Method 30B, or ASTM D6784 - 02 is used, outliers are identified through the determination of relative deviation (RD) of the paired RM tests.   Data that do not meet the RD criteria must be flagged as a data quality problem and may not be used in the calculation of RA.  The primary reason for performing paired RM sampling is to ensure the quality of the RM data.  The percent RD of paired data is the parameter used to quantify data quality. Determine RD for paired data points as follows:
	 				(Equation 12A-3)
	Where:  Ca and Cb are the Hg concentration values determined from the paired samples.
	<IP_ADDRESS>  The minimum performance criteria for RM Hg data is that RD for any data pair must be <= 10 percent as long as the mean Hg concentration is greater than 1.0 ug/m[3].   If the mean Hg concentration is less than or equal to 1.0 ug/m[3], the RD must be <= 20 percent or < 0.2 ug/m[3] absolute difference.  Pairs of RM data exceeding these RD criteria should be eliminated from the data set used to develop a Hg CEMS correlation or to assess CEMS RA.
	8.4.7  Calculate the mean difference between the RM and CEMS values in the units of micrograms per cubic meter (ug/m[3]), the standard deviation, the confidence coefficient, and the RA according to the procedures in Section 12.0.
	8.5  Reporting.  At a minimum (check with the appropriate EPA Regional Office, State or local Agency for additional requirements, if any), summarize in tabular form the results of the CD tests, the linearity tests, and the RA test or alternative RA procedure, as appropriate.   Include all data sheets, calculations, charts (records of CEMS responses), reference gas concentration certifications, and any other information necessary to confirm that the CEMS meets the performance criteria.
9.0   Quality Control [Reserved]
10.0   Calibration and Standardization [Reserved]
11.0   Analytical Procedure
	For Method 30A, sample collection and analysis are concurrent.  For the other RM, post-run sample analyses are performed.  Refer to the RM employed for specific analytical procedures.
12.0   Calculations and Data Analysis
	Calculate and summarize the RA test results on a data sheet similar to Figure 12A - 3.
	12.1  Consistent Basis.  All data from the RM and CEMS must be compared in units of micrograms per standard cubic meter (ug/scm), on a consistent and identified moisture basis. The values must be standardized to 20°C, 760 mm Hg.
	12.1.1  Moisture Correction (as applicable).  If the RM and CEMS measure Hg on a different moisture basis, they will need to be corrected to a consistent basis.  Use Equation 12A - 4a to correct data from a wet basis to a dry basis.
	 		(Equation 12A-4a)
Use Equation 12A-4b to correct data from a dry basis to a wet basis.
      	(Equation 12A-4b)
	Where:  Bws is the moisture content of the flue gas from Method 4, expressed as a decimal fraction ( e.g. , for 8.0 percent H2O, Bws= 0.08).
      34.2 Arithmetic Mean.  Calculate ,the arithmetic mean of the differences (di) of a data set as follows:
      						(Equation 12A-5)
	Where:  n = Number of data points.
	12.3  Standard Deviation.  Calculate the standard deviation, Sd, as follows:
					(Equation 12A-6)
	Where:	Algebraic sum of the individual differences .
      34.3 Confidence Coefficient (CC).  Calculate the 2.5 percent error confidence coefficient (one-tailed), CC, as follows:
						(Equation 12A-7)
	12.4  Relative Accuracy.  Calculate the RA of a set of data as follows:
						(Equation 12A-8)
	Where:
|| = Absolute value of the mean of the differences (from Equation 12A-5)
|CC| = Absolute value of the confidence coefficient (from Equation 12A-7)
 = Average reference method value
13.0   Method Performance
	13.1  Measurement Error (ME).  For both Hg[0] and HgCl2, the ME shall not exceed 5 percent of the span value at the zero-, mid-, and high-level reference gas concentrations.
	13.2  Calibration Drift (CD).  The CD shall not exceed 5 percent of the span value on any of the 7 days of the CD test.
	13.3  Relative Accuracy (RA).  The RA of the CEMS must be no greater than 20 percent of the mean value of the RM test data in terms of units of ug/scm.  Alternatively, if the mean RM is less than 5.0 ug/scm, the results are acceptable if the absolute value of the difference between the mean RM and CEMS values does not exceed 1.0 ug/scm.
14.0   Pollution Prevention [Reserved]
15.0   Waste Management [Reserved]
16.0   Alternative Procedures [Reserved]
17.0   Bibliography
	17.1  40 CFR part 60, appendix B, "Performance Specification 2 -- Specifications and Test Procedures for SO2 and NOX Continuous Emission Monitoring Systems in Stationary Sources."
	17.2  40 CFR part 60, appendix A, "Method 29 -- Determination of Metals Emissions from Stationary Sources."
	17.3  40 CFR part 60, appendix A, "Method 30A  -  Determination of Total Vapor Phase Mercury Emissions From Stationary Sources (Instrumental Analyzer Procedure).
	17.4  40 CFR part 60, appendix A, "Method 30B  -  Determination of Total Vapor Phase Mercury Emissions From Coal-Fired Combustion Sources Using Carbon Sorbent Traps."
	17.5  ASTM Method D6784 - 02, "Standard Test Method for Elemental, Oxidized, Particle-Bound and Total Mercury in Flue Gas Generated from Coal-Fired Stationary Sources (Ontario Hydro Method)."
18.0   Tables and Figures
	Table 12A - 1. T-Values
                                     n[a]
                                    t0.975
                                     n[a]
                                    t0.975
                                     n[a]
                                    t0.975
2
                                                                         12.706
                                                                              7
                                                                          2.447
                                                                             12
                                                                          2.201
3
                                                                          4.303
                                                                              8
                                                                          2.365
                                                                             13
                                                                          2.179
4
                                                                          3.182
                                                                              9
                                                                          2.306
                                                                             14
                                                                          2.160
5
                                                                          2.776
                                                                             10
                                                                          2.262
                                                                             15
                                                                          2.145
6
                                                                          2.571
                                                                             11
                                                                          2.228
                                                                             16
                                                                          2.131
[a]The values in this table are already corrected for n - 1 degrees of freedom. Use n equal to the number of individual values.
	Figure 12A - 1. ME Determination

                                     Date
                                     Time
                        Reference
Gas Value (ug/m[3])
                        CEMS
Measured
Value (ug/m[3])
                              Absolute
Difference
                                  (ug/m[3])
                             ME
(% of span value)
Zero level

 Average

Mid level

Average

High level

  Average

	Figure 12A-2.  7-Day Calibration Drift Determination

                                     Date
                                     Time
                        Reference
Gas Value (ug/m[3])
                        CEMS
measured
value (ug/m[3])
                              Absolute
Difference
                                  (ug/m[3])
                             CD
(% of Span Value)
                                  Zero level

                                    Upscale
                                 (Mid or High)

		Figure 12A-3.  Relative Accuracy Test Data

                                    Run No.

                                     Date

                                  Begin Time

                                   End Time
                           RM Value      (ug/m[3])
                                  CEMS Value
                                  (ug/m[3])

                                  Difference
                                  (ug/m[3])

                                  Run Used ?
                                   (Yes/No)

                                     RD[1]
                                       1

                                       2

                                       3

                                       4

                                       5

                                       6

                                       7

                                       8

                                       9

                                      10

                                      11

                                      12

                         Average Values

                                                                                Arithmetic Mean Difference:
                                                                                Standard Deviation:
                                                                                Confidence Coefficient:
                                                                                T-Value:
                                                                                % Relative Accuracy:
                                                                                | (RM)avg  -  (CEMS)avg | :

        1    Calculate the RD only if paired samples are taken using RM 30B, RM 29, or ASTM 6784-08.  Express RD as a percentage or, for very low RM concentrations (<= 1.0 ug/m[3]), as the absolute difference between Ca and Cb.

Performance Specification 12B  -  Specifications and Test Procedures For Monitoring Total Vapor Phase Mercury Emissions from Stationary Sources Using a Sorbent Trap Monitoring System

1.0  Scope and Application

      The purpose of Performance Specification 12B (PS 12B) is to establish performance benchmarks for, and to evaluate the acceptability of sorbent trap monitoring systems used to monitor total vapor-phase mercury (Hg) emissions in stationary source flue gas streams.  These monitoring systems involve continuous repetitive in-stack sampling using paired sorbent media traps with periodic analysis of the time-integrated samples.  Persons using PS 12B should have a thorough working knowledge of Methods 1, 2, 3, 4, 5 and 30B in appendices A-1 through A-3 and A-8 to this part.

      1.1  Analyte.  The analyte measured by these procedures and specifications is total vapor phase Hg in the flue gas, which represents the sum of elemental Hg (Hg[o], CAS Number 7439-97-6) and gaseous forms of oxidized Hg (i.e., Hg[+2]) in mass concentration units of micrograms per dry standard cubic meter (μg/dscm).

1.2  Applicability.
	1.2.1  These procedures are only intended for use under relatively low particulate conditions (e.g., monitoring after all pollution control devices).  This specification is for evaluating the acceptability of total vapor phase Hg sorbent trap monitoring systems installed at stationary sources at the time of, or soon after, installation and whenever specified in the regulations.  The Hg monitoring system must be capable of measuring the total concentration of vapor phase Hg (regardless of speciation), in units of ug/dscm.
	1.2.2  This specification contains routine procedures and specifications designed to evaluate an installed sorbent trap monitoring system's performance over time; Procedure 5 of appendix F to this part contains additional procedures and specifications which may be required for long term operation.  In addition, the source owner or operator is responsible to calibrate, maintain, and operate the monitoring system properly.  The Administrator may require the owner or operator, under section 114 of the Clean Air Act, to conduct performance evaluations at other times besides the initial test to evaluate the CEMS performance.  See §60.13(c) and 63.8(e)(1).
2.0  Principle

      Known volumes of flue gas are continuously extracted from a stack or duct through paired, in-stack, pre-spiked sorbent media traps at appropriate nominal flow rates. The sorbent traps in the sampling system are periodically exchanged with new ones, prepared for analysis as needed, and analyzed by any technique that can meet the performance criteria.  For quality-assurance purposes, a section of each sorbent trap is spiked with Hg[0] prior to sampling.  Following sampling, this section is analyzed separately and a specified minimum percentage of the spike must be recovered.  Paired train sampling is required to determine method precision.

3.0  Definitions
	3.1  Sorbent Trap Monitoring System means the total equipment required for the collection of gaseous Hg samples using paired three-partition sorbent traps.
	3.2  Relative Accuracy Test Procedure  means a test procedure consisting of at least nine runs, in which the accuracy of the total vapor phase Hg concentrations measured by the sorbent trap monitoring system is evaluated by comparison against concurrent measurements made with a reference method (RM).  Relative accuracy tests repeated on a regular, on-going basis are referred to as relative accuracy test audits or RATAs.
	3.3  Relative Accuracy (RA) means the absolute mean difference between the pollutant (Hg) concentrations determined by the sorbent trap monitoring system and the values determined by the reference method (RM) plus the 2.5 percent error confidence coefficient of a series of tests divided by the mean of the RM tests.  Alternatively, for low concentration sources, the RA may be expressed as the absolute value of the difference between the mean sorbent trap monitoring system and RM values.
	3.4  Relative Deviation (RD) means the absolute difference of the Hg concentration values obtained with a pair of sorbent traps divided by the sum of those concentrations, expressed as a percentage.  RD is used to assess the precision of the sorbent trap monitoring system.
	3.5  Spike Recovery means the mass of Hg recovered from the spiked trap section, expressed as a percentage of the amount spiked.  Spike recovery is used to assess sample matrix interference.
4.0   Interferences [Reserved]
5.0   Safety
	The procedures required under this performance specification may involve hazardous materials, operations, and equipment.  This performance specification may not address all of the safety problems associated with these procedures.  It is the responsibility of the user to establish appropriate safety and health practices and determine the applicable regulatory limitations prior to performing these procedures.
6.0  Equipment and Supplies
	6.1  Sorbent Trap Monitoring System Equipment Specifications.
	6.1.1  Monitoring System.  The equipment described in Method 30B in appendix  A-8 to this part shall be used to continuously sample for Hg emissions, with the substitution of three-section traps in place of two-section traps, as described below.  A typical sorbent trap monitoring system is shown in Figure 12B-1.
	6.1.2  Three-Section Sorbent Traps.  The sorbent media used to collect Hg must be configured in traps with three distinct and identical segments or sections, connected in series, to be separately analyzed.  Section 1 is designated for primary capture of gaseous Hg.  Section 2 is designated as a backup section for determination of vapor-phase Hg breakthrough.  Section 3 is designated for QA/QC purposes.  Section 3 shall be spiked with a known amount of gaseous Hg[0] prior to sampling and later analyzed to determine the spike (and hence sample) recovery efficiency.

   Figure 12B-1.  Typical Sorbent Trap Monitoring System (only one trap and associated sampling system is illustrated).

	6.1.3  Gaseous Hg[o] Sorbent Trap Spiking System.  A known mass of gaseous Hg[0] must be spiked onto section 3 of each sorbent trap prior to sampling.  Any approach capable of quantitatively delivering known masses of Hg[0] onto sorbent traps is acceptable.  Several technologies or devices are available to meet this objective.  Their practicality is a function of Hg mass spike levels.  For low levels, NIST-certified or NIST-traceable gas generators or tanks may be suitable, but will likely require long preparation times.  A more practical, alternative system, capable of delivering almost any mass required, employs NIST-certified or NIST-traceable Hg salt solutions (e.g., Hg(NO3)2).  With this system, an aliquot of known volume and concentration is added to a reaction vessel containing a reducing agent (e.g., stannous chloride); the Hg salt solution is reduced to Hg[0] and purged onto section 3 of the sorbent trap by using an impinger sparging system.
	6.1.4  Sample Analysis Equipment.  Any analytical system capable of quantitatively recovering and quantifying total gaseous Hg from sorbent media is acceptable provided that the analysis can meet the performance criteria in Table 12B-1 in Section 9 of this performance specification.  Candidate recovery techniques include leaching, digestion, and thermal desorption.  Candidate analytical techniques include ultraviolet atomic fluorescence (UV AF); ultraviolet atomic absorption (UV AA), with and without gold trapping; and in-situ X-ray fluorescence (XRF).
7.0  Reagents and Standards

	Only NIST-certified or NIST-traceable calibration gas standards and reagents shall be used for the tests and procedures required under this performance specification.  The sorbent media may be any collection material (e.g., carbon, chemically-treated filter, etc.) capable of quantitatively capturing and recovering for subsequent analysis, all gaseous forms of Hg in the emissions from the intended application.  Selection of the sorbent media shall be based on the material's ability to achieve the performance criteria contained in this method as well as the sorbent's vapor phase Hg capture efficiency for the emissions matrix and the expected sampling duration at the test site.

8.0  Performance Specification Test Procedure

	8.1  Installation and Measurement Location Specifications.

	8.1.1  Selection of Monitoring Site.  Sampling site information should be obtained in accordance with Method 1 in appendix A-1 to this part.  Place the probe inlet at a point or location in the stack (or vent) downstream of all pollution control equipment and representative of the stack gas concentration of Hg.  A location that has been shown to be free of stratification for Hg or, alternatively, SO2 is recommended.  An estimation of the expected stack Hg concentration is required to establish a target sample flow rate, total gas sample volume, and the mass of Hg[0] to be spiked onto section 3 of each sorbent trap.

	8.1.2  Pre-sampling Spiking of Sorbent Traps.  Based on the estimated Hg concentration in the stack, the target sample rate and the target sampling duration, calculate the expected mass loading for section 1 of each sorbent trap (see Section 12.1 of this performance specification).  The pre-sampling spike to be added to section 3 of each sorbent trap shall be within +- 50 percent of the expected section 1 mass loading.  Spike section 3 of each sorbent trap at this level, as described in Section 6.1.3 of this performance specification.  For each sorbent trap, keep a record of the mass of Hg[o] added to section 3.  This record shall include, at a minimum, the identification number of the trap, the date and time of the spike, the name of the analyst performing the procedure, the method of spiking, the mass of Hg[o] added to section 3 of the trap (μg), and the supporting calculations.

	8.1.3 Pre-monitoring Leak Check.  Perform a leak check with the sorbent traps in place in the sampling system.  Draw a vacuum in each sample train.  Adjust the vacuum in each sample train to ~15" Hg.  Use the gas flow meter to determine leak rate.  The leakage rate must not exceed 4 percent of the target sampling rate.  Once the leak check passes this criterion, carefully release the vacuum in the sample train, then seal the sorbent trap inlet until the probe is ready for insertion into the stack or duct.

	8.1.4  Determination of Flue Gas Characteristics.  Determine or measure the flue gas measurement environment characteristics (gas temperature, static pressure, gas velocity, stack moisture, etc.) in order to determine ancillary requirements such as probe heating requirements (if any), sampling rate, proportional sampling conditions, moisture management, etc.

	8.2  Monitoring.

	8.2.1  System Preparation and Initial Data Recording.  Remove the plug from the end of each sorbent trap and store each plug in a clean sorbent trap storage container.  Remove the stack or duct port cap and insert the probe(s) with the inlet(s) aligned perpendicular to the stack gas flow. Secure the probe(s) and ensure that no leakage occurs between the duct and environment.  Record initial data including the sorbent trap ID, start time, starting gas flow meter readings, initial temperatures, set points, and any other appropriate information.

	8.2.2  Flow Rate Control.  Set the initial sample flow rate at the target value from section 8.1.1 of this performance specification.  Then, for every operating hour during the sampling period, record the date and time, the sample flow rate, the gas flow meter reading, the stack temperature (if needed), the flow meter temperatures (if needed), temperatures of heated equipment such as the vacuum lines and the probes (if heated), and the sampling system vacuum readings.  Also, record the stack gas flow rate and the ratio of the stack gas flow rate to the sample flow rate.  Adjust the sampling flow rate to maintain proportional sampling, i.e., keep the ratio of the stack gas flow rate to sample flow rate within +- 25 percent of the reference ratio from the first hour of the data collection period (see section 12.2 of this performance specification).  The sample flow rate through a sorbent trap monitoring system during any hour (or portion of an hour) that the unit is not operating shall be zero.

	8.2.3  Stack Gas Moisture Determination.  If data from the sorbent trap monitoring system will be used to calculate Hg mass emissions, determine the stack gas moisture content using a continuous moisture monitoring system or other means acceptable to the Administrator, such as the ones described in §75.11(b) of this chapter.  Alternatively, for combustion of coal, wood, or natural gas in boilers only, a default moisture percentage from §75.11(b) of this chapter may be used.

	8.2.4  Essential Operating Data.  Obtain and record any essential operating data for the facility during the test period, e.g., the barometric pressure for correcting the sample volume measured by a dry gas meter to standard conditions.  At the end of the data collection period, record the final gas flow meter reading and the final values of all other essential parameters.

	8.2.5  Post-monitoring Leak Check.  When the monitoring period is completed, turn off the sample pump, remove the probe/sorbent trap from the port and carefully re-plug the end of each sorbent trap.  Perform a leak check with the sorbent traps in place, at the maximum vacuum reached during the monitoring period.  Use the same general approach described in section 8.1.3 of this performance specification.  Record the leakage rate and vacuum.  The leakage rate must not exceed 4 percent of the average sampling rate for the monitoring period.  Following the leak check, carefully release the vacuum in the sample train.

	8.2.6  Sample Recovery.  Recover each sampled sorbent trap by removing it from the probe and seal both ends.  Wipe any deposited material from the outside of the sorbent trap.  Place the sorbent trap into an appropriate sample storage container and store/preserve it in an appropriate manner.

	8.2.7  Sample Preservation, Storage, and Transport.  While the performance criteria of this approach provide for verification of appropriate sample handling, it is still important that the user consider, determine, and plan for suitable sample preservation, storage, transport, and holding times for these measurements.  Therefore, procedures in recognized voluntary consensus standards such as those in ASTM D6911-03 "Standard Guide for Packaging and Shipping Environmental Samples for Laboratory Analysis" should be followed for all samples.

	8.2.8  Sample Custody.  Proper procedures and documentation for sample chain of custody are critical to ensuring data integrity.  Chain of custody procedures in recognized voluntary consensus standards such as those in ASTM D4840-99 "Standard Guide for Sample Chain-of-Custody Procedures" should be followed for all samples (including field samples and blanks).

8.3  Relative Accuracy (RA) Test Procedure

	8.3.1   For the initial certification of a sorbent trap monitoring system, a RA Test is required.  Follow the basic RA test procedures and calculation methodology described in Sections 8.4.1 through 8.4.7 and 12.4 of PS 12A in this appendix, replacing the term "CEMS" with "sorbent trap monitoring system".

	8.3.2  Special Considerations.  The type of sorbent material used in the traps must be the same as that used for daily operation of the monitoring system; however, the size of the traps used for the RA test may be smaller than the traps used for daily operation of the system.  Spike the third section of each sorbent trap with elemental Hg, as described in section 8.1.2 of this performance specification.  Install a new pair of sorbent traps prior to each test run.  For each run, the sorbent trap data shall be validated according to the quality assurance criteria in Table 12B-1 in Section 9.0, below.

	8.3.3   Acceptance Criteria.  The RA of the sorbent trap monitoring system must be no greater than 20 percent of the mean value of the RM test data in terms of units of ug/scm.  Alternatively, if the RM concentration is less than or equal to 5.0 ug/scm, then the RA results are acceptable if the absolute difference between the means of the RM and sorbent trap monitoring system values does not exceed 1.0 ug/scm.

9.0  Quality Assurance and Quality Control (QA/QC)

      Table 12B-1 summarizes the QA/QC performance criteria that are used to validate the Hg emissions data from a sorbent trap monitoring system.  Failure to achieve these performance criteria will result in invalidation of Hg emissions data, except where otherwise noted.

TABLE 12B-1.    QA/QC  CRITERIA  FOR  SORBENT  TRAP MONITORING  SYSTEM OPERATION AND CERTIFICATION
QA/QC TEST OR SPECIFICATION

                              Acceptance Criteria

                                   Frequency

                            Consequences if Not Met

Pre-monitoring leak check

<=4% of target sampling rate

Prior to monitoring
Monitoring shall not commence until the leak check is passed

Post-monitoring leak check

<=4% of average sampling rate

After monitoring

Invalidate the data from the paired traps or, if certain conditions are met, report adjusted data from a single trap (see Section <IP_ADDRESS>)

Ratio of stack gas flow rate to sample flow rate

Hourly ratio may not deviate from the reference ratio by more than +- 25%.

Every hour throughout monitoring period

Invalidate the data from the paired traps or, if certain conditions are met, report adjusted data from a single trap (see Section <IP_ADDRESS>)
Sorbent trap section 2 breakthrough

<=5% of Section 1 Hg mass

Every sample

Invalidate the data from the paired traps or, if certain conditions are met, report adjusted data from a single trap (see Section <IP_ADDRESS>)

Paired sorbent trap agreement
<=10% Relative Deviation (RD) if the average concentration is  > 1.0 ug/m[3]

< 20% RD if the average concentration is < 1.0 ug/m[3]

Results also acceptable if absolute difference between concentrations from paired traps is <= 0.03 ug/m[3]

Every sample
Either invalidate the data from the paired traps or report the results from the trap with the higher Hg concentration

Spike Recovery Study
Average recovery between 85% and 115% for each of the 3 spike concentration levels
Prior to analyzing field samples and prior to use of new sorbent media
Field samples shall not be analyzed until the percent recovery criteria has been met
Multipoint analyzer calibration
Each analyzer reading within +- 10% of true value and r[2]0.99
On the day of analysis, before analyzing any samples
Recalibrate until successful
Analysis of independent calibration standard

Within +- 10% of true value
Following daily calibration, prior to analyzing field samples
Recalibrate and repeat independent standard analysis until successful

Spike recovery from section 3 of both sorbent traps

75-125% of spike amount

Every sample
Invalidate the data from the paired traps or, if certain conditions are met, report adjusted data from a single trap (see Section <IP_ADDRESS>)

Relative Accuracy
RA <= 20.0% of RM mean value; or if RM mean value
< 5.0 ug/scm, absolute difference between RM and sorbent trap monitoring system mean values <= 1.0 ug/scm
RA specification must be met for initial certification
Data from the system are invalid until a RA test is passed

Gas flow meter calibration

An initial calibration factor (Y) has been determined at 3 settings; for mass flow meters, initial calibration with stack gas has been performed.  For subsequent calibrations, Y within + 5% of average value from the most recent 3-point calibration
At 3 settings prior to initial use and at least quarterly at one setting thereafter
Recalibrate meter at 3 settings to determine a new value of Y

Temperature sensor calibration
Absolute temperature measured by sensor within +- 1.5% of a reference sensor
Prior to initial use and at least quarterly thereafter
Recalibrate; sensor may not be used until specification is met

Barometer calibration
Absolute pressure measured by instrument within +- 10 mm Hg of reading with a NIST-traceable barometer
Prior to initial use and at least quarterly thereafter
Recalibrate; instrument may not be used until specification is met

10.0  Calibration and Standardization

	10.1  Gaseous and Liquid Standards.  Only NIST certified or NIST-traceable calibration standards (i.e., calibration gases, solutions, etc.) shall be used for the spiking and analytical procedures in this performance specification.

	10.2  Gas Flow Meter Calibration.  The manufacturer or supplier of the gas flow meter should perform all necessary set-up, testing, programming, etc., and should provide the end user with any necessary instructions, to ensure that the meter will give an accurate readout of dry gas volume in standard cubic meters for the particular field application.

	10.2.1  Initial Calibration.  Prior to its initial use, a calibration of the flow meter shall be performed.  The initial calibration may be done by the manufacturer, by the equipment supplier, or by the end user.  If the flow meter is volumetric in nature (e.g., a dry gas meter), the manufacturer, equipment supplier, or end user may perform a direct volumetric calibration using any gas.  For a mass flow meter, the manufacturer, equipment supplier, or end user may calibrate the meter using a bottled gas mixture containing 12 +- 0.5% CO2, 7 +- 0.5% O2, and balance N2, or these same gases in proportions more representative of the expected stack gas composition.  Mass flow meters may also be initially calibrated on-site, using actual stack gas.

	<IP_ADDRESS>  Initial Calibration Procedures.  Determine an average calibration factor (Y) for the gas flow meter, by calibrating it at three sample flow rate settings covering the range of sample flow rates at which the sorbent trap monitoring system typically operates. Either the procedures in section 10.3.1 of Method 5 in appendix A-3 to this part or the procedures in section 16 of Method 5 in appendix A-3 to this part may be followed.  If a dry gas meter is being calibrated, use at least five revolutions of the meter at each flow rate.

	<IP_ADDRESS> Alternative Initial Calibration Procedures.  Alternatively, the initial calibration of the gas flow meter may be performed using a reference gas flow meter (RGFM). The RGFM may be either: (1)  A wet test meter calibrated according to section 10.3.1 of Method 5 in appendix A - 3 to this part; (2)  A gas flow metering device calibrated at multiple flow rates using the procedures in section 16 of Method 5 in appendix A - 3 to this part; or (3)  A NIST - traceable calibration device capable of measuring volumetric flow to an accuracy of 1 percent.  To calibrate the gas flow meter using the RGFM, proceed as follows:  While the sorbent trap monitoring system is sampling the actual stack gas or a compressed gas mixture that simulates the stack gas composition (as applicable), connect the RGFM to the discharge of the system.  Care should be taken to minimize the dead volume between the sample flow meter being tested and the RGFM. Concurrently measure dry gas volume with the RGFM and the flow meter being calibrated for a minimum of 10 minutes at each of three flow rates covering the typical range of operation of the sorbent trap monitoring system.  For each 10-minute (or longer) data collection period, record the total sample volume, in units of dry standard cubic meters (dscm), measured by the RGFM and the gas flow meter being tested.

	<IP_ADDRESS> Initial Calibration Factor.  Calculate an individual calibration factor Yi at each tested flow rate from section <IP_ADDRESS> or <IP_ADDRESS> of this  performance specification (as applicable), by taking the ratio of the reference sample volume to the sample volume recorded by the gas flow meter.  Average the three Yi values, to determine Y, the calibration factor for the flow meter.  Each of the three individual values of Yi must be within +-0.02 of Y.  Except as otherwise provided in sections <IP_ADDRESS> and <IP_ADDRESS> of this performance specification, use the average Y value from the three level calibration to adjust all subsequent gas volume measurements made with the gas flow meter.

	10.2.2  Initial On-Site Calibration Check.  For a mass flow meter that was initially calibrated using a compressed gas mixture, an on-site calibration check shall be performed before using the flow meter to provide data.  While sampling stack gas, check the calibration of the flow meter at one intermediate flow rate typical of normal operation of the monitoring system.  Follow the basic procedures in section <IP_ADDRESS> or <IP_ADDRESS> of this performance specification. If the onsite calibration check shows that the value of Yi, the calibration factor at the tested flow rate, differs by more than 5 percent from the value of Y obtained in the initial calibration of the meter, repeat the full 3-level calibration of the meter using stack gas to determine a new value of Y, and apply the new Y value to all subsequent gas volume measurements made with the gas flow meter.

	10.2.3 Ongoing Quality Control.  Recalibrate the gas flow meter quarterly at one intermediate flow rate setting representative of normal operation of the monitoring system. Follow the basic procedures in section <IP_ADDRESS> or <IP_ADDRESS> of this performance specification. If a quarterly recalibration shows that the value of Yi, the calibration factor at the tested flow rate, differs from the current value of Y by more than 5 percent, repeat the full 3-level calibration of the meter to determine a new value of Y, and apply the new Y value to all subsequent gas volume measurements made with the gas flow meter.

	10.3  Calibration of Thermocouples and Other Temperature Sensors.  Use the procedures and criteria in section 10.3 of Method 2 in appendix A - 1 to this part to calibrate in-stack temperature sensors and thermocouples.  Calibrations must be performed prior to initial use and at least quarterly thereafter.  At each calibration point, the absolute temperature measured by the temperature sensor must agree to within +-1.5 percent of the temperature measured with the reference sensor, otherwise the sensor may not continue to be used.

	10.4  Barometer Calibration.  Calibrate the barometer against another barometer that has a NIST-traceable calibration.  This calibration must be performed prior to initial use and at least quarterly thereafter. At each calibration point, the absolute pressure measured by the barometer must agree to within +-10 mm Hg of the pressure measured by the NIST-traceable barometer, otherwise the barometer may not continue to be used.

	10.5  Calibration of Other Sensors and Gauges.  Calibrate all other sensors and gauges according to the procedures specified by the instrument manufacturer(s).

	10.6  Analytical System Calibration.  See section 11.1 of this performance specification.

11.0  Analytical Procedures

	The analysis of the Hg samples may be conducted using any instrument or technology capable of quantifying total Hg from the sorbent media and meeting the performance criteria in section 9 of this performance specification.

	11.1  Analyzer System Calibration.  Perform a multipoint calibration of the analyzer at three or more upscale points over the desired quantitative range (multiple calibration ranges shall be calibrated, if necessary). The field samples analyzed must fall within a calibrated, quantitative range and meet the necessary performance criteria. For samples that are suitable for aliquotting, a series of dilutions may be needed to ensure that the samples fall within a calibrated range. However, for sorbent media samples that are consumed during analysis (e.g., thermal desorption techniques), extra care must be taken to ensure that the analytical system is appropriately calibrated prior to sample analysis. The calibration curve range(s) should be determined based on the anticipated level of Hg mass on the sorbent media. Knowledge of estimated stack Hg concentrations and total sample volume may be required prior to analysis. The calibration curve for use with the various analytical techniques (e.g., UV AA, UV AF, and XRF) can be generated by directly introducing standard solutions into the analyzer or by spiking the standards onto the sorbent media and then introducing into the analyzer after preparing the sorbent/standard according to the particular analytical technique. For each calibration curve, the value of the square of the linear correlation coefficient, i.e., r [2] , must be >= 0.99, and the analyzer response must be within +-10 percent of reference value at each upscale calibration point. Calibrations must be performed on the day of the analysis, before analyzing any of the samples. Following calibration, an independently prepared standard (not from same calibration stock solution) shall be analyzed. The measured value of the independently prepared standard must be within +-10 percent of the expected value.

	11.2  Sample Preparation.  Carefully separate the three sections of each sorbent trap. Combine for analysis all materials associated with each section, i.e., any supporting substrate that the sample gas passes through prior to entering a media section (e.g., glass wool, polyurethane foam, etc.) must be analyzed with that segment.

	11.3  Spike Recovery Study.  Before analyzing any field samples, the laboratory must demonstrate the ability to recover and quantify Hg from the sorbent media by performing the following spike recovery study for sorbent media traps spiked with elemental mercury.  Using the procedures described in sections 6.2 and 12.1 of this performance specification, spike the third section of nine sorbent traps with gaseous Hg[0], i.e., three traps at each of three different mass loadings, representing the range of masses anticipated in the field samples. This will yield a 3 x 3 sample matrix. Prepare and analyze the third section of each spiked trap, using the techniques that will be used to prepare and analyze the field samples. The average recovery for each spike concentration must be between 85 and 115 percent. If multiple types of sorbent media are to be analyzed, a separate spike recovery study is required for each sorbent material. If multiple ranges are calibrated, a separate spike recovery study is required for each range.

	11.4  Field Sample Analyses.  Analyze the sorbent trap samples following the same procedures that were used for conducting the spike recovery study. The three sections of each sorbent trap must be analyzed separately (i.e., section 1, then section 2, then section 3). Quantify the total mass of Hg for each section based on analytical system response and the calibration curve from section 11.1 of this performance specification.  Determine the spike recovery from sorbent trap section 3. The spike recovery must be no less than 75 percent and no greater than 125 percent. To report the final Hg mass for each trap, add together the Hg masses collected in trap sections 1 and 2.

12.0  Calculations, Data Reduction, and Data Analysis

	12.1  Calculation of Pre-Sampling Spiking Level.  Determine sorbent trap section 3 spiking level using estimates of the stack Hg concentration, the target sample flow rate, and the expected monitoring period.  Calculate Mexp, the expected Hg mass that will be collected in section 1 of the trap, using Equation 12B-1.  The pre-sampling spike must be within +- 50 percent of this mass.

					(Equation 12B-1)

Where:
Mexp = Expected sample mass (ug)
Qs = Sample flow rate (L/min)
ts =  Expected monitoring period (min)
Cest = Estimated Hg concentration in stack gas (ug/m[3])
10[-3] = Conversion factor (m[3]/L)

Example calculation: For an estimated stack Hg concentration of 5 μg/m[3], a target sample rate of 0.30 L/min, and a monitoring period of 5 days:

Mexp = (0.30 L/min)(1440 min/day)(5 days)(10[-3] m[3]/L)(5 μg/m[3]) = 10.8 μg

A pre-sampling spike of 10.8 μg +-50 percent is, therefore, appropriate.

	12.2  Calculations for Flow-Proportional Sampling.  For the first hour of the data collection period, determine the reference ratio of the stack gas volumetric flow rate to the sample flow rate, as follows:

                  			(Equation 12B-2)

Where:
Rref = Reference ratio of hourly stack gas flow rate to
      hourly sample flow rate
Qref = Average stack gas volumetric flow rate for first hour
      of collection period (scfh)
Fref = Average sample flow rate for first hour of the
      collection period, in appropriate units (e.g.,
      liters/min, cc/min, dscm/min)
K = Power of ten multiplier, to keep the value of Rref between 1 and 100. The appropriate K value will depend on the selected units of measure for the sample flow rate.

Then, for each subsequent hour of the data collection period, calculate ratio of the stack gas flow rate to the sample flow rate using Equation 12B-3:

                                  (Equation 12B-3)

Where:
Rh = Ratio of hourly stack gas flow rate to hourly sample
     flow rate
Qh = Average stack gas volumetric flow rate for the hour
    (scfh)
Fh = Average sample flow rate for the hour, in appropriate units (e.g., liters/min, cc/min, dscm/min)
K = Power of ten multiplier, to keep the value of Rh between 1 and 100. The appropriate K value will depend on the selected units of measure for the sample flow rate and the range of expected stack gas flow rates.

Maintain the value of Rh within +-25 percent of Rref throughout the data collection period.

	12.3  Calculation of Spike Recovery.  Calculate the percent recovery of each section 3 spike, as follows:

                          		(Equation 12B-4)

Where:
%R = Percentage recovery of the pre-sampling spike
M3 = Mass of Hg recovered from section 3 of the sorbent
     trap, (μg)
Ms = Calculated Hg mass of the pre-sampling spike, from section 8.1.2 of this performance specification, (μg)

	12.4  Calculation of Breakthrough.  Calculate the percent breakthrough to the second section of the sorbent trap, as follows:

                  		(Equation 12B-5)

Where:
%B = Percent breakthrough
M2 = Mass of Hg recovered from section 2 of the sorbent
    trap, (μg)
M1 = Mass of Hg recovered from section 1 of the sorbent
     trap, (μg)

	12.5  Calculation of Hg Concentration.  Calculate the Hg concentration for each sorbent trap, using the following equation:

                         		(Equation 12B-6)

Where:
C = Concentration of Hg for the collection period,
    (μg/dscm)
M* = Total mass of Hg recovered from sections 1 and 2 of
     the sorbent trap, (μg)
Vt = Total volume of dry gas metered during the collection period, (dscm). For the purposes of this performance specification, standard temperature and pressure are defined as 20 ̊C and 760 mm Hg, respectively.

	12.6  Calculation of Paired Trap Agreement.  Calculate the relative deviation (RD) between the Hg concentrations measured with the paired sorbent traps:

                   	(Equation 12B-7)

Where:
RD = Relative deviation between the Hg concentrations from
     traps "a" and "b" (percent)
Ca = Concentration of Hg for the collection period, for
     sorbent trap "a" (μg/dscm)
Cb = Concentration of Hg for the collection period, for
     sorbent trap "b" (μg/dscm)

      12.7  Calculation of Relative Accuracy. Calculate the relative accuracy as described in Section 12.4 of PS 12A in this appendix.

      12.8  Data Reduction.  Typical monitoring periods for normal, day-to-day operation of a sorbent trap monitoring system range from about 24 hours to 168 hours.  For the required RA tests of the system, smaller sorbent traps are often used, and the "monitoring period" or time per run is considerably shorter (e.g., 1 hour or less).  Generally speaking, to validate sorbent trap monitoring system data, the acceptance criteria for the following five QC specifications in Table 12B-1 above must be met for both traps: (a) the post-monitoring leak check; (b) the ratio of stack gas flow rate to sample flow rate; (c) section 2 breakthrough; (d) paired trap agreement; and (e) section 3 spike recovery.

	12.8.1  For routine day-to-day operation of a sorbent trap monitoring system, when both traps meet the acceptance criteria for all five QC specifications, the two measured Hg concentrations shall be averaged arithmetically and the average value shall be applied to each hour of the data collection period.

	12.8.2  To validate a RA test run, both traps must meet the acceptance criteria for all five QC specifications.  However, as specified in Section 12.8.3 below, for routine day-to-day operation of the monitoring system, a monitoring period may, in certain instances, be validated based on the results from one trap.

	12.8.3  For the routine, day-to-day operation of the monitoring system, when one of the two sorbent trap samples or sampling systems either: (a) fails the post-monitoring leak check; or (b) has excessive section 2 breakthrough; or (c) fails to maintain the proper stack flow-to-sample flow ratio; or (d) fails to achieve the required section 3 spike recovery, provided that the other trap meets the acceptance criteria for all four of these QC specifications, the Hg concentration measured by the valid trap may multiplied by a factor of 1.111 and then used for reporting purposes.  Further, if both traps meet the acceptance criteria for all four of these QC specifications, but the acceptance criterion for paired trap agreement is not met, the owner or operator may report the higher of the two Hg concentrations measured by the traps, in lieu of invalidating the data from the paired traps.