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Federal Register / Vol. 86, No. 232 / Tuesday, December 7, 2021 / Proposed Rules reflected in the control strategy, there would be no way to confirm that the actual emissions were below the modeled limits within the period under review.
B. Monitoring Network Considerations Section 110a2Bi of the CAA
requires states to establish and operate air monitoring networks to compile data on ambient air quality for all criteria pollutants. The EPAs monitoring requirements are specified by regulation in 40 CFR part 58. These requirements are applicable to state, and where delegated, local air monitoring agencies that operate criteria pollutant monitors.
In section 4.5 of Appendix D to 40 CFR
part 58, the EPA specifies the minimum requirements for SO2 monitoring sites to be classified as state or local air monitoring stations SLAMS. SLAMS
produce data that are eligible for comparison with the NAAQS, and therefore, the monitor must be an approved federal reference method FRM or federal equivalent method FEM, per section 2 of Appendix C to 40 CFR part 58. In St. Bernard Parish, LDEQ operates a SLAMS monitor at Chalmette-Vista EPA Site ID 22087
0007, 24 E Chalmette Circle. In addition, LDEQ operates a special purpose monitor SPM at Meraux EPA
Site ID 220870004, 4101 Mistrot Drive.
C. Data Considerations and Proposed Determination a. Monitor Data Under 40 CFR 58.15, monitoring agencies must certify, on an annual basis, data collected at all SLAMS by FRM, FEM, and special purpose monitors SPMs that meet EPA quality assurance requirements. In doing so, monitoring agencies must certify that the previous year of ambient
concentration and quality assurance data are completely submitted to AQS
and that the ambient concentration data are accurate to the best of their knowledge.
The one-hour SO2 design values at Chalmette Vista and Meraux monitoring sites within the St. Bernard area for the 20132020 period are shown below.

69213

therefore cannot be used, on its own, to determine that the St. Bernard Parish area attained by the attainment date.
b. Modeling Data
LDEQ and Rain developed the onehour SO2 emission limits contained in the August 2, 2018 AOC to ensure compliance with the SO2 NAAQS. The emission limits in the AOC were TABLE 120132020 ONE-HOUR DEeffective August 2, 2018. The LDEQ
SIGN VALUES FOR THE ST. BERNARD undertook an additional modeling analysis which also incorporated the AREA
amended stack parameters and utilized Chalmette Meraux more recent allowable emission rates vista design from other contributing sources, an Years design value value expanded receptor grid, and covered all ppb ppb operating scenarios. The additional 20132015
114
19 modeling used the most recent version 20142016
82
16 of AERMOD and followed EPAs 20152017
73
13 guidance for SIP modeling for SO2.20
20162018
59
10
The analysis included modeling 20172019
44
7 20182020
42
8 allowable emissions and stack parameters for different operational stages at the Rain facility, including The attainment date for the area was stand-alone operations for the waste October 4, 2018. In order for the EPA to heat boiler and the pyroscrubber as well determine that the area attained by the as transition stages between the two October 4, 2018 attainment date based modes of operation; a summary of the solely on air quality monitoring data, results is given in Table 2. The the design value based upon complete, modeling demonstration approved in quality-assured monitored air quality the nonattainment SIP demonstrates data from three consecutive years 20152017 at each eligible monitoring that compliance with the emission site must be equal to or less than 75 ppb limits and required stack parameters in the AOC provide for attainment, with for the one-hour standard, and air predicted SO2 concentrations near just quality modeling would need to show below the NAAQS if the emission that there was an air quality monitor limits and stack parameters are met.21
located in the area of maximum Additional, more detailed discussion of concentration.
Although the one-hour SO2 design the States modeling is contained in the values at the Chalmette Vista TSD for the EPAs proposed Approval monitoring site located within the St.
and Promulgation of Implementation Bernard area show a downward trend of Plans; Louisiana Attainment SO2 concentrations less than 75 ppb for Demonstration for the St. Bernard Parish the one-hour standard beginning with 2010 SO2 Primary National Ambient Air the 20152017 design value, this Quality Standard Nonattainment Area monitor is not located in the area of published on February 8, 2019 84 FR
maximum predicted concentration, and 2801.

TABLE 2SUMMARY OF LDEQ SUPPLEMENTAL MODELING RESULTS FOR THE ST. BERNARD PARISH SIP USING THE
EMISSION LIMITS AND STACK PARAMETERS FROM THE AOC
Operational stage
Model design value
lotter on DSK11XQN23PROD with PROPOSALS1

Waste Heat Boiler Stack Alone
Pyroscrubber Stack Alone
Transition between Pyroscrubber Stack to the Waste Heat Boiler Stack transitional stage with maximum design value.

c. Record of Compliance As noted, when relying on modeling of allowable emissions to support a determination of whether an area has attained by its attainment date, the EPA
20 See Appendix A, page A1 of the SO
2 Nonattainment Area Guidance.

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must also look at whether the control strategy in the SIP has been fully implemented and whether the relevant sources in an area are complying with the emission limits and stack parameters required in the SIP. As 21 See
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discussed above, the modeling, based on the August 2, 2018 AOC limits, shows attainment of the NAAQS with maximum modeled concentrations just below the 75 ppb standard. Emissions higher than modeled limits and/or
Table 2.

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190.8 g/m3 72.9 ppb.
176.6 g/m3 67.4 ppb.
185.6 g/m3 70.9 ppb.

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