Oklahoma department of environmental quality

For the NAAQS analyses, G-P used receptor spacing identical to the spacing for the significant impact analysis. For each pollutant, these receptors extended out to the SID. The SID for PM, NOx, and SO₂ are 0.8, 4.5, and 5.25 km, respectively. If the maximum impact location is in an area with receptor spacing greater than 100 m, then G-P also performed a refined analysis with additional receptors spaced apart at 100 m intervals.

As discussed in the result section, preliminary modeling of the proposed project indicated a significant impact (i.e., maximum impact at or above the PSD significance levels) for NO₂, SO₂, and PM₁₀. Therefore, PSD review requires G-P to perform a full air quality analysis to demonstrate compliance with the PSD Class II Increments. The Increment impact analysis predicts the maximum ambient air concentration due to all Mill sources and off-site sources within the screening areas that affect or consume increment. The total of these concentrations must be less than the PSD Increment, as listed in Table D-18.

In contrast to the NAAQS/AAQS analysis, the Increment inventory includes increases or decreases in actual emissions for non-major sources only after the minor source baseline date, and increases or decreases in emissions for major sources due to a change in the method of operation after the major source baseline date. Because the Mill is a major source, all emission increases after the major source baseline due to a change in the method of operation consume increment. The Mill was constructed after the major source baseline date for SO₂ and PM₁₀, 1975. Thus, the NAAQS inventory for PM₁₀ and SO₂ emissions from the Muskogee Mill are also the complete inventory of increment-affecting emissions from the Mill. Table D-13 above lists the NAAQS inventory emission rates for these pollutants.

The inventory reflects the following conservative assumptions. Baseline emissions for all Yankee dryer emissions are set to zero. Actual emissions on the PSD baseline date were above zero for sources 11 through 14 as these sources existed in 1988. The analysis included the proposed RTO and did not include the credit from the shut-down of the existing RTO. PSD Baseline emissions for Stack 1 and Stack 3 sources reflect the average of 2002 and 2003 fuel usage. In 1988, all boilers were burning fuel oil. Emission factors for fuel oil are greater than natural gas emission factors. By assuming heat input for Boiler 1 (one of two boilers exhausting through Stack 1) was provided by gas instead of oil, the estimated baseline emissions are conservatively low, yielding a higher amount of emissions that affect increment.

A full analysis must include the emissions of competing sources. In contrast to the NAAQS analysis, the PSD Increment analysis includes emissions only from competing sources that affect increment. ODEQ identified several sources within 60 km of the Mill that consume increment. G-P modeled all PSD-consuming competing sources. Table D-20 presents modeling parameters of competing sources identified by ODEQ included in the analysis. As a conservative measure, the analysis used the potential emission rates for each pollutant affected by increment, regardless of source status during the baseline.

For the PSD Increment analyses, G-P used receptor spacing identical to the spacing for the NAAQS analyses.