Exhibit 7
Kanawha River Plant

Glasgow, West Virginia

Sierra Club Evaluation of Compliance with 1-hour SO2 NAAQS

October 25, 2011

Conducted by:

Steven Klafka, P.E., BCEE

Wingra Engineering, S.C.

Madison, Wisconsin
Sierra Club Evaluation of Compliance with 1-hour SO2 NAAQS

October 25, 2011

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1. Introduction

The Sierra Club prepared an air modeling impact analysis to help USEPA, state and local air 

agencies identify facilities that are likely causing violations of the one-hour sulfur dioxide (SO2) 

national ambient air quality standard (NAAQS). This document describes the results and procedures 

for an evaluation conducted for the Kanawha River Plant located in Glasgow, West Virginia.

The dispersion modeling analysis predicted ambient air concentrations for comparison with the onehour SO2 NAAQS. The modeling was performed using data provided to the Sierra Club by 

regulatory air agencies and through other common sources described below.

2. Compliance with the One-Hour SO2 NAAQS

2.1 One-Hour SO2 NAAQS

The one-hour SO2 NAAQS takes the form of a three-year average of the 99th-percentile of the annual 

distribution of daily maximum one-hour concentrations, which cannot exceed 75 ppb.1 Compliance 

with this standard was verified using USEPA’s AERMOD air dispersion model, which produces air 

concentrations in units of μg/m3. The one-hour SO2 NAAQS of 75 ppb equals 196.2 μg/m3, and this 

is the value used for determining whether modeled impacts exceed the NAAQS.2 The 99thpercentile of the annual distribution of daily maximum one-hour concentrations corresponds to the 

fourth-highest value at each receptor for a given year.

2.2 Modeling Results

Modeling results for Kanawha River Plant are summarized in Table 1. It was determined that based 

on either currently permitted emissions or measured actual emissions, the Kanawha River Plant is 

estimated to create downwind SO2 concentrations which exceed the 1-hour NAAQS. 

The currently approved and measured actual emission rates used for the modeling analysis are 

summarized in Table 2. Based on the modeling results, emission reductions from current rates 

considered necessary to achieve compliance with the 1-hour NAAQS were calculated and presented 

in Table 3. 

 

1 USEPA, Applicability of Appendix W Modeling Guidance for the 1-hour SO2 National Ambient Air Quality Standard, 

August 23, 2010.

2 The ppb to μg/m3 conversion is found in the source code to AERMOD v. 11103, subroutine Modules. The conversion 

calculation is 75/0.3823 = 196.2 μg/m3.
Sierra Club Evaluation of Compliance with 1-hour SO2 NAAQS

October 25, 2011

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Predicted exceedences of the 1-hour NAAQS for SO2 extend throughout West Virginia to a 

maximum distance of 50 kilometers.

Figure 1 provided as an appendix to this report shows the extent of NAAQS violations throughout 

the entire 50 kilometer modeling domain.

Figure 2 provides a close-up local view of NAAQS violations.

Air quality impacts in West Virginia are based on a background concentration of 91.6 μg/m3. This is 

the 2008-10 design value for Cabell County, West Virginia. This is the lowest measured background 

concentration in the state and so may under-predict compliance with the NAAQS.

2.3 Conservative Modeling Assumptions

A dispersion modeling analysis requires the selection of numerous parameters which affect the 

predicted concentrations. For the enclosed analysis, several parameters were selected which underpredict facility impacts. 

Assumptions used in this modeling analysis which likely under-estimate concentrations include the 

following:

x Allowable emissions based on a 24-hour average were used to determine compliance with 

the 1-hour average NAAQS. Emissions during any 1-hour period may be higher than 

assumed for the modeling analysis.

x No consideration of facility operation at less than 100% load. Stack parameters such as exit 

flow rate and temperature are typically lower at less than full load, reducing pollutant 

dispersion and increasing predicted air quality impacts.

x No consideration of building or structure downwash. These downwash effects typically 

increase predicted concentrations near the facility.

x No consideration of off-site sources. These other sources of SO2 will increase the predicted 

impacts.
Sierra Club Evaluation of Compliance with 1-hour SO2 NAAQS

October 25, 2011

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Table 1 - SO2 Modeling Results for Kanawha River Plant Modeling Analysis

Location Emission 

Rates

Averaging

Period

99th Percentile 1-hour Daily Maximum (μg/m3) Complies 

with 

Impact Background Total NAAQS NAAQS?

West Virginia

Allowable 1-hour 10,782.4 91.6 10,874.0 196.2 No

Maximum 1-hour 9,124.1 91.6 9,215.7 196.2 No

Table 2 - Modeled SO2 Emissions from Kanawha River Plant

Stack

ID

Unit

ID

Allowable Emissions3

24-hour Average

(lbs/hr)

Maximum Emissions4

1-hour Average

(lbs/hr)

S01 Unit 1 2,668.7

Unit 2 2,656.6

Stack Total All Units 6,240.0 5,325.3

Table 3 - Required Emission Reductions for Compliance with 1-hour SO2 NAAQS 

Location

Acceptable Impact

(NAAQS - Background)

99th Percentile

1-hour Daily Max

(μg/m3)

Required

Total Facility

Maximum Emission

Reduction

(%)

Required

Total Facility

Maximum Emission

Rate

(lbs/hr)

West Virginia 104.6 99.0 60.5

 

3 Allowable emissions are limitations in Permit No: R30-03900006-2009 issued May 28, 2009 by WVDEP. 4 Maximum emissions are measured hourly rates reported for 2010 in USEPA, Clean Air Markets - Data and Maps.
Sierra Club Evaluation of Compliance with 1-hour SO2 NAAQS

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3. Modeling Methodology

3.1 Air Dispersion Model

The modeling analysis used USEPA’s AERMOD program, version 11103. AERMOD, as available 

from the Support Center for Regulatory Atmospheric Modeling (SCRAM) website, was used in 

conjunction with a third-party modeling software program, AERMOD View, sold by Lakes 

Environmental Software. 

3.2 Control Options

The AERMOD model was run with the following control options:

x One-hour average air concentrations

x Regulatory defaults

x Flagpole receptors

To reflect a representative inhalation level, a flagpole height of 1.5 meters was used for all modeled 

receptors. This parameter was added to the receptor file when running AERMAP, as described in 

Section 4.4.

An evaluation was conducted to determine if the modeled facility was located in a rural or urban 

setting using USEPA’s methodology outlined in Section 7.2.3 of the Guideline on Air Quality 

Models.5 For urban sources, the URBANOPT option is used in conjunction with the urban 

population from an appropriate nearby city and a default surface roughness of 1.0 meter. Methods 

described in Section 4.1 to determine whether rural or urban dispersion coefficients were used.

3.3 Output Options

The AERMOD analysis was based on five years of recent meteorological data. The surface 

measurements were obtained from the Charleston Yeager Airport located 14 miles northwest of the 

Kanawha River Plant and were supplemented with upper air measurements from the station at 

Blacksburg/Roanoke, Virginia. The modeling analyses used one run with five years of sequential 

meteorological data from 2006-2010. Consistent with USEPA’s Modeling Guidance for SO2

NAAQS Designations, the MXDYBYYR and MAXDCONT output options were used to create a 

table of fourth-high one-hour SO2 impacts.6 This provided a file of one-hour SO2 concentrations 

 

5 USEPA, Revision to the Guideline on Air Quality Models: Adoption of a Preferred General Purpose (Flat and Complex 

Terrain) Dispersion Model and Other Revisions, Appendix W to 40 CFR Part 51, November 9, 2005. 6 USEPA, Area Designations for the 2010 Revised Primary Sulfur Dioxide National Ambient Air Quality Standards, 

Attachment 3, March 24, 2011, pp. 24-26.
Sierra Club Evaluation of Compliance with 1-hour SO2 NAAQS

October 25, 2011

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consistent with the form of the one-hour SO2 NAAQS. It is from these files that the maximum onehour SO2 value was determined and reported. 

Please refer to Table 1 for the modeling results. Please see the supporting figures for a presentation 

of concentration isopleths.

4. Model Inputs

4.1 Geographical Inputs

The “ground floor” of all air dispersion modeling analyses is establishing a coordinate system for 

identifying the geographical location of emission sources and receptors. These geographical 

locations are used to determine local characteristics (such as land use and elevation), and also to 

ascertain source to receptor distances and relationships.

The Universal Transverse Mercator (UTM) NAD83 coordinate system was used for identifying the 

easting (x) and northing (y) coordinates of the modeled sources and receptors. Stack locations were 

obtained from facility permits and prior modeling files provided by the West Virginia Department of 

Environmental Protection. The stack locations were then verified using aerial photographs.

The facility was evaluated to determine if it should be modeled using the rural or urban dispersion 

coefficient option in AERMOD. A GIS was used to determine whether rural or urban dispersion 

coefficients apply to a site. Land use within a three-kilometer radius circle surrounding the facility 

was considered. USEPA guidance states that urban dispersion coefficients are used if more than 50% 

of the area within 3 kilometers has urban land uses. Otherwise, rural dispersion coefficients are 

appropriate.7 

USEPA’s AERSURACE model Version 08009 was used to develop the meteorological data for the 

modeling analysis. This model was also used to evaluate surrounding land use within 3 kilometers. 

Based on the output from the AERSURFACE, approximately 19% of surrounding land use around 

the airport was of urban land use types including: 21 – Low Intensity Residential, 22 – High 

Intensity Residential, and 23 - Commercial/Industrial/Transportation.

This is less than the 50% value considered appropriate for the use of urban dispersion coefficients. 

Based on the AERSURFACE analysis, it was concluded that the rural option would be used for the 

modeling summarized in this report. Please refer to Section 4.5.3 for a discussion of the 

AERSURFACE analysis.

 

7 USEPA, Revision to the Guideline on Air Quality Models: Adoption of a Preferred General Purpose (Flat and Complex 

Terrain) Dispersion Model and Other Revisions, Appendix W to 40 CFR Part 51, November 9, 2005, Section 7.2.3.
Sierra Club Evaluation of Compliance with 1-hour SO2 NAAQS

October 25, 2011

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4.2 Emission Rates and Source Parameters

The modeling analyses only considered SO2 emissions from the facility. Off-site sources were not 

considered. Concentrations were predicted for two scenarios shown in Table 2: 

1) approved or allowable emissions based on permits issued by the regulatory agency, and 

2) measured actual hourly SO2 emissions obtained from USEPA’s Clean Air Markets 

Database. To assure realistic emission rates were used, emissions from both units were 

combined and the hour with the maximum total facility emissions was used to determine the 

actual emissions.

Stack parameters and emissions used for the modeling analysis are summarized in Table 4. Stack 

S01 exhausts both units at the facility. The emissions are the total for both units.

Table 4 – Kanawha River Plant Stack Parameters and Emissions

Description S01 (WVDEP ID #CS012)

X Coord. [m] 462971

Y Coord. [m] 4228837

Base Elevation [m] 189.51

Release Height [m] 99.36

Gas Exit Temperature [°K] 430.928

Gas Exit Velocity [m/s] 14.344

Inside Diameter [m] 5.995

Allowable Emission Rate [g/s] 786.2

Maximum Emission Rate [g/s] 671

The above stack parameters and emissions were obtained from regulatory agency permit files.8 9 The 

analysis was conducted based on 100% operating load using maximum exhaust flow rates and 

emission rates. Operation at less than full capacity loads was not considered. This assumption tends 

to under-predict impacts since stack parameters such as exit flow rate and temperature are typically 

lower at less than full load, reducing pollutant dispersion and increasing predicted air quality 

impacts. Stack location, height and diameter were verified using aerial photographs, and flue gas 

flow rate and temperature were verified using combustion calculations.

 

8 WVDEP, Permit No. R30-03900006-2009, May 28, 2009.

9 WVDEP, Stack parameters provided in the file ‘emit.txt.’
Sierra Club Evaluation of Compliance with 1-hour SO2 NAAQS

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4.3 Building Dimensions and GEP

No building dimensions or prior downwash evaluations were available. Therefore this modeling 

analysis did not address the effects of downwash which may increase predicted concentrations.

4.4 Receptors

For Kanawha River Plant, three receptors grids were employed:

1. A 100-meter Cartesian receptor grid centered on Kanawha River Plant and extending out 5 

kilometers.

2. A 500-meter Cartesian receptor grid centered on Kanawha River Plant and extending out 10 

kilometers.

3. A 1,000-meter Cartesian receptor grid centered on Kanawha River Plant and extending out 

50 kilometers. 50 kilometers is the maximum distance accepted by USEPA for the use of the 

AERMOD dispersion model.10

A flagpole height of 1.5 meters was used for all these receptors.

Elevations from stacks and receptors were obtained from National Elevation Dataset (NED) GeoTiff 

data. GeoTiff is a binary file that includes data descriptors and geo-referencing information 

necessary for extracting terrain elevations. These elevations were extracted from 1 arc-second (30 

meter) resolution NED files using USEPA’s AERMAP program, v. 11103. 

4.5 Meteorological Data

To improve the accuracy of the modeling analysis, recent meteorological data for the 2006 to 2010 

period were prepared using the USEPA’s program AERMET which creates the model-ready surface 

and profile data files required by AERMOD. Required data inputs to AERMET included surface 

meteorological measurements, twice-daily soundings of upper air measurements, and the 

micrometeorological parameters surface roughness, albedo, and Bowen ratio. One-minute ASOS 

data were available so USEPA methods were used to reduce calm and missing hours.11

This section discusses how the meteorological data was prepared for use in the one-hour SO2

NAAQS modeling analyses. AERMET v. 11059 was used for these tasks.

 

10 USEPA, Revision to the Guideline on Air Quality Models: Adoption of a Preferred General Purpose (Flat and 

Complex Terrain) Dispersion Model and Other Revisions, Appendix W to 40 CFR Part 51, Section A.1.(1), 

November 9, 2005.

11 USEPA, Area Designations for the 2010 Revised Primary Sulfur Dioxide National Ambient Air Quality Standards, 

Attachment 3, March 24, 2011, p. 19.
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4.5.1 Surface Meteorology

Surface meteorology was obtained for Charleston Yeager Airport located 14 miles northwest of the 

Kanawha River Plant. Integrated Surface Hourly (ISH) data for the 2006 to 2010 period were 

obtained from the National Climatic Data Center (NCDC). The ISH surface data was processed 

through AERMET Stage 1, which performs data extraction and quality control checks. 

4.5.2 Upper Air Data

Upper-air data are collected by a “weather balloon” that is released twice per day at selected 

locations. As the balloon is released, it rises through the atmosphere, and radios the data back to the 

surface. The measuring and transmitting device is known as either a radiosonde, or rawindsonde. 

Data collected and radioed back include: air pressure, height, temperature, dew point, wind speed, 

and wind direction. The upper air data were processed through AERMET Stage 1, which performs 

data extraction and quality control checks.

For Kanawha River Plant, the concurrent 2006 through 2010 upper air data from twice-daily 

radiosonde measurements obtained at the most representative location were used. This location was 

the Blacksburg/Roanoke, Virginia measurement station. These data are in Forecast Systems 

Laboratory (FSL) format and were downloaded in ASCII text format from NOAA’s FSL website.

12 

All reporting levels were downloaded and processed with AERMET.

4.5.3 AERSURFACE

AERSURFACE is a non-guideline program that extracts surface roughness, albedo, and daytime 

Bowen ratio for an area surrounding a given location. AERSURFACE uses land use and land cover 

(LULC) data in the U.S. Geological Survey’s 1992 National Land Cover Dataset to extract the 

necessary micrometeorological data. LULC data was used for processing meteorological data sets 

used as input to AERMOD.

AERSURFACE v. 08009 was used to develop surface roughness, albedo, and daytime Bowen ratio 

values in a region surrounding the meteorological data collection site. AERSURFACE was used to 

develop surface roughness in a one kilometer radius surrounding the data collection site. Bowen 

ratio and albedo was developed for a 10 kilometer by 10 kilometer area centered on the 

meteorological data collection site. These micrometeorological data were processed for seasonal 

periods using 30-degree sectors. Seasonal moisture conditions were considered average with no 

months with continuous snow cover.

 

12 Available at: http://esrl.noaa.gov/raobs/ 
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4.5.4 Data Review

Missing meteorological data were not filled as the data file met USEPA’s 90% data completeness 

requirement.13 The AERMOD output file shows there were 2.4% missing data.

The representativeness of airport meteorological data is a potential concern in modeling industrial 

source sites.14 The surface characteristics of the airport data collection site and the modeled source 

location were compared. Since the Charleston Yeager Airport is located close to Kanawha River

Plant (i.e. 14 miles), this meteorological data set was considered appropriate for this modeling 

analysis.

5. Background SO2 Concentrations

Background concentrations were determined consistent with USEPA’s Modeling Guidance for SO2

NAAQS Designations.15 To preserve the form of the one-hour SO2 standard, based on the 99th

percentile of the annual distribution of daily maximum one-hour concentrations averaged across the 

number of years modeled, the background fourth-highest daily maximum one-hour SO2

concentration was added to the modeled fourth-highest daily maximum one-hour SO2

concentration.16 

Background concentrations were based on the 2008-10 design value measured by the ambient 

monitors located in West Virginia.

17

Air quality impacts in West Viginia and the supporting figures are based on a background 

concentration of 91.6 μg/m3. This is the 2008-10 design value for Cabell County, West Virginia. 

This is the lowest measured background concentration in the state and so may under-predict 

compliance with the NAAQS.

6. Reporting

All files from the programs used for this modeling analysis are available to regulatory agencies. 

These include analyses prepared with AERSURFACE, AERMET, AERMAP, and AERMOD. 

 

13 USEPA, Meteorological Monitoring Guidance for Regulatory Modeling Applications, EPA-454/R-99-05, February 

2000, Section 5.3.2, pp. 5-4 to 5-5. 14 USEPA, AERMOD Implementation Guide, March 19, 2009, pp. 3-4.

15 USEPA, Area Designations for the 2010 Revised Primary Sulfur Dioxide National Ambient Air Quality Standards, 

Attachment 3, March 24, 2011, pp. 20-23. 16 USEPA, Applicability of Appendix W Modeling Guidance for the 1-hour SO2 National Ambient Air Quality Standard, 

August 23, 2010, p. 3. 17 http://www.epa.gov/airtrends/values.html