## Appendix J

Supplemental Modeling Demonstration, William H. Zimmer Facility

Introduction

This document supports the redesignation request for the Campbell

- Clermont partial nonattainment area in the State of Ohio and the Commonwealth of Kentucky. This nonattainment area encompasses emissions from the Walter C. Beckjord facility. There are no other significant sources of SO 2 emissions with in the nonattainment area that warrant inclusion in the modeling analysis. As can be seen from the inventory included

in the redesignation request , the SO 2 emissions from the point sources comprise

99.95% of the 201 4 SO 2 emissions in the entire nonattainm ent area. Notably , violations at this monitor were determined to be caused by emissions from the Walter C. Beckjord facility located along the Ohio River in Ohio east of the monitor. On September 1,

2014 1 , the Walter C. Beckjord facility ceased operation s. Ohio EPA was notified of the permanent shutdown on October 14, 2014. (Appendix B and I of the redesignation
request ) There are no other significant point sources of SO 2 emissions located in the nonattainment area. Within the portion of Campbell County, KY that is a part of this area there are 11 sources which combined emit less than one ton per year (tpy) of SO 2

. (Appendix C of the redesignation request ) There are no oth er point sources of SO 2 emissions in the portion of Clermont County, OH that is a part of this area.

Located south (and slightly east) of the monitor, but outside of the nonattainment area, is the William H. Zimmer facility (see Figure 1). It was deter mined during the nonattainment designation process that emissions from the William H. Zimmer facility likely do not impact the violating monitor at question, and therefore, the nonattainment area was not expanded to encompass this facility. To support the previous conclusion, Ohio EPA performed an extensive meteorology, emissions and back

- trajectory analysis and has included this analysis as Appendix D of the redesignation request . This analysis concludes that it was in fact the Walter C. Beckjord facilit y that caused the violations and not the William H. Zimmer facility.

1 The letter contained in Appendix B identifies the permanent shutdown of all units occurred on October 1, 2014. However, a review of CAMD emissions showed that all the units ceased operation by September
1, 2014.Figure 1: Location of monitor 21-037-3002 the William H. Zimmer Station.

In support of this conclusion, Ohio EPA conducted a supplemental modeling analysis to determine the location of maximum impact from emissions originating from the William H. Zimmer facility as well as a conservative extrapolation of monitored values to the point of maximum impact. The supplemental modeling was performed due to the proximity of the William H. Zimmer facility to the nonattainment area and the level of emissions from this source. Ohio EPA determined that the significant distance (30 to 35 km), prevailing winds, and emission reductions from sources located to the west of the nonattainment area did not warrant the inclusion of these sources in a supplemental modeling analysis. This is consistent with U.S. EPA’s Ohio Area Designations For the 2010 SO2 Primary National Ambient Air Quality Standard technical support document. The analysis presented in this document further demonstrates that emissions from William H. Zimmer do not impact the nonattainment area to a significant degree and that emissions from William H. Zimmer are not likely to cause exceedances both at the

monitor location or

in the entirety of the nonattainment area.

Modeling Approach

Per U.S. EPA’s SO 2 nonattainment area SIP guidance,

“Appendix A of this document contains modeling guidance supplemental to that provided in the preamble to the final rulemaking promulgating the 2010 S02 NAAQS and in 40 CFR part 51, Appendix W. Appendix A of this document has also been updated to respond to issues raised during the comment period relatedto the September 2011 draft SO 2 Guidance Document. This guidance clarifies

the EPA's recommendations on how to conduct refined dispersion modeling under Appendix W to support th e implementation of the 2010 SO 2 NAAQS.”

Per the SO 2 n onattainment area SIP g uidance, five years of National Weather Service data is sufficient to repres ent attainment of the standard. The purpose of this demonstration, determining the location of maximum impact of emissions from William H. Zimmer and demonstrating that these emis sions will not cause exceedances in the

nonattainment area , necessitates that the limited period of time for which monitor data is

available after the shutdown of the Walter C. Beckjord facility is replicated by the modeling analysis. As such , five years of meteorological data was not used, but a limited meteorological dataset from August 30, 2014 to February 28, 2015, inclusive,

was modeled . This period of time represents the most recent period of time for which the Walter C. Beckjord facility is shutdown and data is available

. As a full three years of data are not available, the modeled form of the standard is expressed as the 99 th
percentile of the available 192 maximum daily values. For a time period of 192 days

, the form of the standard of both monitored and modeled values is represented by th e second highest maximum daily value.

The recommended dispersion model for SIP modeling for SO 2 is the American Meteorological Society/Environmental Protection Agency Regulatory Model (AERMOD) modeling system. There are two input data processors that are regulatory components of the AERMOD modeling system: AERMET, a meteorological data preprocessor that incorporates air dispersion based on planetary boundary layer turbulence structure and scaling concept s, and AERMAP, a terrain data preprocessor that incorporates complex terrain using United States Geological Survey (USGS) Digital Elevation Data. Additionally, Ohio EPA utilized the AERMINUTE module to incorporate 1

- minute ASOS meteorological data into th e hourly surface input file. Ohio EPA utilized the most up

- to

date versions of AERMOD and the associated preprocessors available at the time of the modeling analyses. These are as follows: AERMOD version 14134, AERMET version 14134, AERMINUTE version 142 37, and AERMAP version 11103.

The intent of this supplemental modeling is to demonstrate that the William H. Zimmer facility does not cause or contribute to an exceedance of the standard not only at the violating monitor, but across the entirety of the nonattainment area. For this purpose,

Ohio EPA collected monitor data for the August 30, 20 14 through February 28, 2015 period, when the entirety of the Walter C. Beckjord facility is known to have zero emissions. Using this monitor data, Ohio EPA modeled all sources at the William H. Zimmer facility at 1 gram per second. Using the modeled imp acts at receptors across the nonattainment area, as well as the location of the monitor, Ohio EPA scaled the 99 th
percentile of monitor data for this period to represent a maximum predicted impacted in

the nonattainment area as a whole. As described below , this modeling is conservative in its treatment of constant emissions, the assumption that a one

- to

- one ratio between monitored concentrations and impacts in the nonattainment area is present, and its consideration of only the spatial, and not temporal, r elationship between monitor and

modeled values.Meteorological Data

In order to generate meteorological input data for use with AERMOD, AERMET, along with AERMINUTE and AERSURFACE preprocessing for the modeling domain was conducted to generate the surface (.sfc) and profile (.pfl). Ohio EPA used the AERMINUTE pre

- processing module. This module accepts as input 1

- minute ASOS meteorological surface observations, calculates an hourly average for each hour in the modeled time period, and substitutes a ny missing values from the co

- located ISHD surface data. Use of AERMINUTE reduces the number of calm hours present in the input files, and these enhanced hourly files are therefore considered more representative of local meteorological conditions.

Met eorolog ical data from August 30, 2014 through February 28, 2015 from the Cincinnati, OH surface stati on (Station # 93814 ) located at the Covington/Greater Cincinnati Airport in Kentucky and the Wilmington, OH up per air station (Station #

13841 ) located at the Wilmington Airborne Park airport were used in these analyses. These sites were determined to be represen tative of the nonattainment area

. AERSURFACE was run using twelve sectors and four seasons for the surface station

location

.

Emission Sources

Thr ee emission sources (two egress points) from William H. Zimmer were included in the modeling analysis. The relevant release point parameters for the two egress points

included in the analysis are presented in Table 1, below. As described previously , the emission rate of all units was set to 1 gram/second to allow for a straightforward scaling

of modeled values to monitored concentrations. All emissions sources included in the modeling analysis were treated as point sources.

Source

ID Source Description Easting (X) Northing

(Y) Base

Elevation Stack

Height Temperature Exit Velocity Stack

Diameter SO2

(m) (m) (m) (m) (K) (m/s) (m) (g/s)

B006_ZM Main Boiler Unit 1 Stack 740462.3 4305892 155.4 174 328 16.971 12.8 1

AUX_AB Aux Blr AB Comn Stack 740391.7 4305630 155.3 91 604 26.3 3.35 1
Table 1 : Modeled SO2 e mission sources, William H. Zimmer.

Receptors

A receptor grid of 1000 meter spacing was placed within the boundaries of the

nonattainment area. Initial screening

- level modeling indicated that the maximum impact

of William H. Zimmer occurs within approximately 1 km of the facility. The center of the nonattainment area itself is located approximately 20 km (11.5 km at the closest point)

from the Wi lliam H. Zimmer emission units, and as such, a fine receptor grid was deemed unnecessary to capture significant concentration gradients. Limiting the number of receptors was also necessary to maintain reasonable file sizes to conductpost

- processing and a nalysis of modeled outputs. In addition to this grid, a single

receptor was placed in the monitor location. A second modeling grid, using 50 meter spacing to 3 km, was performed to determine the location of Zimmer’s maximum impact. This finer grid was pl aced based on screening level modeling analysis.

Results

As stated previously, the modeling analysis was conducted to determine the location of maximum impact from emissions originating from the William H. Zimmer facility and to conservatively demonstrate, using monitored values, that emissions from William H.

Zimmer will not cause an ex ceedance of the standard anywhere within the

nonattainment area . The 2 nd highest modeled maxi mum daily value for the time period (99 th percentile) at the recept or represent ing the monitor was 0.18731  g/m 3

. Ohio EPA

determined that the 2 nd highest maximum modeled value across all receptors in th e
nonattainment area was 0. 40866  g/m 3 , and used this value for the extrapolation analysis.

To extrapolate these values based on monitor data, Ohio EPA determined that the 2 nd
highest maximum daily value recorded during the August 30, 2014 to February 28, 2015 period to be 24 ppb. Using the modeled impacts ab ove, Ohio EPA used a simple ratio to scale this value to the poi nt of maximum impact in the nonattainment area, as follows:

0

. 18731

24 ppb = 0

. 40866

X

Using the 2 nd highest maximum daily value across all receptors in the n onattainment
area, 0.40866  g/m 3

, in the ratio above yields a maximum concentration of 52.4 ppb.

T he conservatively extrapolated value is below the standard.

Ohio EPA considers this demonstration highly conservative for several reasons. Firstly, the modeling assumed continuous operation of all units at the William H. Zimmer facility, which is not reflective of normal operating conditions, in particular the two auxiliary

boilers. These units operated only 676 hours in 2013 and 1,167 hours in 2014. Secondly, the extrapolat ion implicitly assumes that all ambient SO 2 recor ded at the monitor location originates from William H. Z imme r. Lastly, the temporal relationship

between the monitor data an d model ed data was not considered. By accounting only for the spatial relationship between modeled and monitor values, the extrapol ation

assumes that the 99 th percentile impacts occur simultaneously across the entirety of nonattainment area, including at the monitor location. This provides an additional layer of conservatism to the analysis. When modeled values and monitor values are paired in time, the first

- highest maximum extrapolated impact was determined to be 30 ppb.

An additional extrapolation of modeled impacts was performed based on actual emissions data from the William H. Zimmer facility. The highest annual emissions from years 2010

- 2014 occurred in 2010, when the William H. Zimmer facility emitted 19,388.1 tons of SO 2

. This annual emission rate was converted to an average emissionrate of 557.73 grams/second. Using this value, and the results of the extrapolation

demonstration above, Ohio EPA used the following ratio to estimate the impacts of emissions from the William H. Zimmer plant at both the receptor location and at the point of highest impact in the nonattainment area:

2 grams / second

0

. 40866 ug / m 3 = 557

. 73 grams / second

X ug / m 3

The solution to this equation, 113.96  g/m 3 (43.56 ppb) is well below the standard of 75 ppb and indicates that emissions from the William H. Zimmer facility are unlikely to

cause an exceedance of the standar d across the entirety of the nonattainment area. Substituting the modeled results at the monitor location, 0.18731  g/m 3 , into the above ratio yields an estimated impact of 52.23  g/m 3 (19.96 ppb). This extrapolation is remarkable in its consistency with the monitor data for periods when the Walter C. Beckjord facility was not operational and with the previous extrapolation based on monitor data. These results, as well as the consisten cy of these analyses with monitor values, provide strong additional support for Ohio EPA’s contention that the closure of

the Walter C. Beckjord facility will provide for attainment of the standard in the entirety

of the nonattainment area and that emissio ns from William H. Zimmer will not cause or

contribute to an exceedance of the standard.

Analysis of wind rose data from the Covington/Greater Cincinnati Airport for the first highest and second highest maximum daily concentrations recorded at the monitor during the August 30, 2014 through February 28, 2015 period support the conclusion that the analysis conducted by Ohio EPA is highly conservative and indicates that

emissions from William H. Zimmer are not contributing to elevated monitor readings.

The f irst highest maximum daily value recorded during this period was 34 ppb, occurring on January 14, 2015 at 9:00 AM. Monitor values remained elevated until 12:00 PM on the same day. The second highest maximum daily value of 24 ppb occurred on January 6, 20 15 at 7:00 PM. Concentrations recorded at the monitor were elevated from January 6, 2015 at 5:00 AM until 12:00 AM on January 7, 2015. The wind roses for these perio ds are shown in Figure 2 , below

.Figure 2 : KCVG wind roses, January 6 and January 14, 2015.The data shown in Figure 2 indicates that winds were primarily from the West and

Northwest during the times when the highest and second highest monitored values were recorded. This suggests that emission s from William H. Zimmer were not impacting the monitor, or the nonattainment area, during these times. An analysis of hourly emissions, monitor values, and wind directions, prese nted in Appendix K of this redesignation submittal confirms that when emissions from the Walter C. Beckjord facility are eliminated from analysis, the wind directions primarily impacting the monitor

are from the West and Northwest , and that at no time when the Walter C. Beckjord facility was not operating was an hourly monit or value above 34 ppb recorded

. Thus, the extrapolation analysis performed based on modeled impacts represents a highly conservative estimate of the impact of emissions from William H. Zimmer on both the

monitor and the nonattainment area as a whole. Fur ther, Ohio EPA determined that point of maximum impact of emissions from Zimmer during the modeled time period was located approximately 1.4 km to the southeast from the largest source at the

William H. Zimmer facility

. From the point of this maximum impa ct to the point of maximum impact within the nonattainment area, there is a decrease in concentration of

84%.

These analyses , as well as the ana lysis presented in Appendix K

, further support the results of the trajectory ana lysis presented in Appendix D , and demonstrate that the impacts of Zimmer are minimal at both the monitor location and the entirety of the

nonattainment area

. These results are consistent with the predominant winds in the area, which originate primarily from the south and southwest. Additional wind rose data is presented in Appendix K.