Desoto Parish Support Document

   
Desoto Parish Support Document    1

On March 2, 2015, a consent decree (CD) was filed in the United States District Court for the Northern District of

California, San Francisco Division, which settled a suit between the United States Environmental Protection

Agency (US EPA), the Sierra Club, and the Natural Resources Defense Council (Case No. 13‐cv‐03953). The CD

requires US EPA to promulgate remaining area designations under the Primary National Ambient Air Quality

Standard (NAAQS) for Sulfur Dioxide (SO2) in three phases: by July 2, 2016; December 31, 2017; and

December 31, 2020.

The first phase of required designations address, in part, sources that according to US EPA’s Air Markets

Database emitted more than 16,000 tons of SO2 or emitted more than 2,600 tons of SO2 and had an average

emission rate of 0.45 lbs of SO2/mmbtu or higher in 2012. Three such facilities were identified in Louisiana,

including one located in De Soto Parish and two in Calcasieu Parish. Dolet Hills Power Station (DHPS), owned and

operated by CLECO Corporation (CLECO), was identified as the source in De Soto Parish. The facility emitted

20,887 tons of SO2 and had an emission rate of 0.80 lbs of SO2/mmbtu in 2012. Therefore, the ambient air in the

surrounding area, De Soto Parish, must be characterized.

De Soto Parish is located in the northwest corner of Louisiana. The parish encompasses 875.58 square miles and

has a population of 27,142 according to the latest census data. Mansfield is the parish seat with a population of

5,0061

. As of September 1, 2015, the Louisiana Department of Environmental Quality (LDEQ) recognizes

519 permitted facilities in the parish, with only 10 representing Title V facilities. Being an area rich in oil and

natural gas, 99% of the minor source facilities are sector related. Two facilities in the parish are major sources of

SO2, see figure 1 and table 1.

Figure 1: De Soto Parish Permitted Facilities
Desoto Parish Support Document    2

DHPS is a fossil fuel‐fired steam/electric generation facility located near Mansfield in De Soto Parish. The facility

currently operates under the following permits:

 Title V Permit Number 0760‐00001‐V2, issued September 20, 2013 and amended on August 4, 2014;

 Acid Rain Title IV Permit Number 0760‐00001‐IV3, issued September 20, 2013; and

 Prevention of Significant Deterioration Permit Number PSD‐LA‐117(M‐5), issued December 17, 2007.

At 14,177 tons of SO2 emitted in 2014, the facility is by far the largest SO2 emitter in De Soto Parish and has seen an

overall reduction of SO2 emissions2

. As one of the two facilities in the parish that are major sources of SO2, DHPS

accounts for 90% of the total SO2 emitted in the parish, see table 1 and figure 2. Consequently, the facility’s

impact in the area represents the single deciding factor in the area designation under the 2010 SO2 NAAQS.

Table 1: De Soto Parish Major SO2 Sources2

Agency Interest

Number Facility 2014 SO2 Emissions(TPY)

585 CLECO Power LLC - Dolet Hills Power Station 14,177

328 International Paper Company - Mansfield Mill 1,557

Figure 2: De Soto Parish SO2 Emissions2

0

5000

10000

15000

20000

25000

30000

35000

Emissions in TPY

Parish Total

Dolet Hills

Remaining

Facilities
Desoto Parish Support Document    3

According to a letter from CLECO to US EPA dated August 19, 2015, CLECO intends to install and operate an ambient

air monitor prior to the end of 2015, see appendix A.

The facility utilized the draft SO2 NAAQS Designations Source Oriented Monitoring Technical Assistance Document

dated December 2013, in its efforts to utilize AERMOD, version 14134, to select a location that would appropriately

and sufficiently monitor ambient air in proximity to the SO2 source. As suggested, the modeling was conducted

using hourly normalized actual emissions retrieved from the continuous emissions monitoring system (CEMS),

current stack parameters and temperatures, building downwash, and a Cartesian receptor grid extending to 20 km

from DHPS. The grid was constructed using receptors spaced 100 meters (m) apart along the property line to 2 km

out, 250 m spacing from 2 km to 10 km from the property line, and 500 m spacing from 10 km to 20 km from the

property line. The model was run using five years of meteorological data. This worst case scenario model produced

10 of the 14 top ranked receptors along the southeast property boundary. Due to the clustering of the impacted

receptors, LDEQ concurs with CLECO that one monitor located southeast of the facility will sufficiently characterize

the ambient air in the vicinity of DHPS.

In an effort to expedite the collection of usable data, CLECO will conduct monitoring in two phases. Temporary

monitoring utilizing a trailer mounted monitoring station will be conducted at a location near the proposed long‐

term monitor. Upon completion of construction, the long‐term monitoring will commence.

CLECO plans to utilize the data from the monitor to provide support to the LDEQ and US EPA in the area designation

process for the 2010 SO2 NAAQS. Therefore, the monitor will be sited and operated in a manner equivalent to the

State and Local Air Monitoring Station . Specifically, data processing will follow the procedures detailed in 40 CFR 50

Appendix T; and the monitoring data will be subject to reporting and data collection requirements prescribed in

40 CFR 58.15 and 58.16, and will satisfy applicable criteria in 40 CFR 58 Appendices A, C, and E.

The data provided by the new monitoring station will allow for an accurate characterization of air quality nearest the

source of SO2 without ambiguity. Currently, the ambient air surrounding the facility is not monitored and not

otherwise characterized by reliable modeling data. At this time, it cannot be determined if the ambient air

surrounding DHPS is meeting or not meeting the 2010 SO2 NAAQS. LDEQ recommends that US EPA initially

promulgate the area in De Soto Parish as unclassifiable and use the data collected with the aforementioned monitor

later in the redesignation process. This would allow US EPA to make a final determination regarding the area’s

attainment of the 2010 SO2 NAAQS using quality assured monitoring data.

Ambient SO2 is a pollutant that arises from direct emissions, and concentrations are generally expected to be

highest relatively close to the source. Since it is appropriate to evaluate each potential area on a case‐by‐case basis,

LDEQ further recommends that only a portion of De Soto Parish be designated as unclassifiable. As shown above,

DHPS accounts for 90% of the SO2 emitted in the parish. Additionally, the worst case modeling provided by CLECO

supports LDEQ’s assertion that the facility has minimal impact at greater distances. Given this unique situation, the

unclassifiable area should be limited to the southeast quadrant of the parish bounded by United States Highway 84

on the north, United States Highway 171 on the west, and the parish boundary on the east and south, see figure 3.

Should EPA prefer to designate the entirety of the parish by July 2, 2016, LDEQ recommends that the remainder also

be designated as unclassifiable, as it contains no sources with actual 2014 SO2 emissions in excess of 2000 TPY.
Desoto Parish Support Document    4

Figure 3: De Soto Parish Recommended Unclassifiable Area

                                                            

1 United States Census Bureau: “De Soto Parish QuickFacts from the US Census Bureau.” September 2015 2 2014 Emissions Reporting & Inventory Center, Louisiana Department of Environmental Quality, Office of Environmental

Services, Emission Inventory Group. Released July 6, 2015. Downloaded September 1, 2015.
Appendix A:

Dolet Hills Power Station – Siting for

Source‐Specific SO2 Ambient Monitoring


Siting for Source-Specific SO2 Ambient Monitoring 

for Dolet Hills Power Station

CLECO Corporation

Pineville, Louisiana

Submitted to:

CLECO Corporation

Pineville, LA

Prepared by:

CLECO Corporation

2500 City West Boulevard, Suite 1700

Houston, Texas 77042

CB&I Project No 154165

August 19, 2015
CLECO CORPORATION

DOLET HILLS POWER STATION 

PINEVILLE, LOUISIANA

Table of Contents

List of Tables ....................................................................................................................................... ii

List of Figures...................................................................................................................................... ii

List of Appendices............................................................................................................................... ii

List of Acronyms and Abbreviations................................................................................................. iii

1.0 Background ............................................................................................................................ 1-1

1.1 SO2 Emission Sources in DHPS...................................................................................... 1-2

1.2 Description of Surrounding Area ..................................................................................... 1-2

1.3 SO2 Emission Sources in Desoto Parish ......................................................................... 1-2

2.0 Monitor Siting Methodology .................................................................................................. 2-1

2.1 Step-Wise Procedure for Monitoring Site Selection......................................................... 2-1

2.2 Modeling Domain and Receptor Network ........................................................................ 2-2

2.3 Air Quality Model............................................................................................................. 2-2

2.4 Meteorological Data ........................................................................................................ 2-2

2.5 Stack Parameters and Emission Rates ........................................................................... 2-2

2.6 Building Downwash......................................................................................................... 2-3

3.0 Results .................................................................................................................................... 3-4

3.1 Normalized Emission Rate Modeling............................................................................... 3-4

3.2 Proposed Location of Monitor.......................................................................................... 3-7

4.0 Monitoring Installation and Data Processing ....................................................................... 4-1

4.1 Description of Monitoring System.................................................................................... 4-1

4.2 Regulatory Compliance................................................................................................... 4-1

4.3 Data Processing and Reporting....................................................................................... 4-2

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CLECO CORPORATION

DOLET HILLS POWER STATION 

PINEVILLE, LOUISIANA

List of Tables

Table 1-1 Details of SO2 Emission Source in DHPS – Unit 1

Table 1-2 SO2 Emission Sources within Desoto Parish

Table 1-3 SO2 Emission Sources Adjacent to Desoto Parish within 20 Km from DHPS

Table 3-1 Priority Ranking for 1-Hour SO2 Monitoring Site – Short Term (August to November)

Table 3-2 Priority Ranking for 1-Hour SO2 Monitoring Site – Long Term (All Months)

Table 3-3 Frequency Distribution of Highest Daily 1-Hour Impact for August-November CY 2010-2014

Table 3-4 Frequency Distribution of Highest Daily 1-Hour Impact for CY 2010-2014

List of Figures

Figure 1-1 Dolet Hills Power Station

Figure 1-2 Dolet Hills Lignite Mine Area Close-up

Figure 1-3 SO2 Emission Sources in Desoto Parish – 2013 Data

Figure 2-1 Receptor Network for Modeling for Monitor Siting Analysis

Figure 2-2 Wind Rose – August-November 2010-2014

Figure 2-3 Wind Rose – 2010-2014 – All Months – Shreveport

Figure 3-1 Dolet Power Station, Top 10 Receptors, August-November

Figure 3-2 Dolet Hills Power Station – All Top Ten Receptors

Figure 3-3 Location of Proposed SO2 Monitor for Dolet Hills

Figure 3-4 Location of Proposed SO2 Monitor for Dolet Hills – Close up 1

Figure 3-5 Location of Proposed SO2 Monitor for Dolet Hills – Close up 2

Figure 4-1 Typical SO2 Monitoring Station

Figure 4-2 Typical SO2 Monitoring Station Set-up

List of Appendices

Appendix 1 Hourly Emission and Stack Parameters for Unit 1 Used in Modeling (in USB Drive)

Appendix 2 Model Input/Output Files (on USB Drive)

Appendix 3 LDEQ Air Monitoring Siting Form 

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CLECO CORPORATION

DOLET HILLS POWER STATION 

PINEVILLE, LOUISIANA

List of Acronyms and Abbreviations

μg/m3 micrograms per cubic meter

AQS Air Quality System

BPIP Building Profile Input Program 

CEMs continuous emission monitoring system 

CLECO CLECO Corporation 

DHPS Dolet Hills Power Station 

ft feet

km kilometers

LDEQ Louisiana Department of Environmental Quality 

m meters

MMBTu/hr Million British Thermal Units per Hour

NAAQS National Ambient Air Quality Standard 

NDV normalized design value 

R6 Region 6 

SO2 sulfur dioxide 

TAD Technical Assistance Document 

USEPA U.S. Environmental Protection Agency

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CLECO CORPORATION

DOLET HILLS POWER STATION 

PINEVILLE, LOUISIANA

1.0 Background

The U.S. Environmental Protection Agency (USEPA) issued the final primary National Ambient Air Quality 

Standard (NAAQS) for 1-hour sulfur dioxide (SO2) on June 2, 2010 (2010 SO2 standard). On August 5, 2013, the 

USEPA published a notice announcing designation of nonattainment for the 2010 SO2 standards, based on 

certified ambient air quality monitoring data for the years 2009-2011 that showed these areas exceeding the 

standard. For all other areas, the USEPA developed and proposed a Data Requirement Rule that would require 

states to gather and submit additional information characterizing SO2 in areas with larger SO2 emissions. The 

information will be used by the USEPA for future area designations.

Separately, in a consent decree signed with the Sierra Club in the District Court in Northern California on March 2, 

2015, the USEPA is required to complete area designations with available monitoring data within 16 months of 

date of the consent decree. Also, for areas without adequate monitoring data, the area designations are to be 

completed in two phases by December 31, 2020.

The current schedule on area designation for consent decree affected sources requires the States to submit 

updated recommendations and supporting information to the USEPA by September 18, 2015. The USEPA will 

notify the States with any intended modifications no later than January 2, 2016 (120-day letter). The States can 

submit additional information to the USEPA by April 8, 2016.

The Dolet Hills Power Station (DHPS) in Desoto Parish, Louisiana, owned by CLECO Corporation (CLECO) has 

been identified as one of the large sources of SO2 emissions affected by the consent decree. In addition, the 

DHPS is the largest SO2 emissions source in Desoto Parish, and consequently, its impact in the vicinity may 

decide the area designation under the 2010 SO2 standard.

CLECO plans to gather ambient monitoring data for SO2 in the vicinity of the DHPS to provide supporting 

information to both the Louisiana Department of Environmental Quality (LDEQ) and the USEPA Region 6 

(USEPA R6) in the area designation process for 1-hour SO2 NAAQS. Due to the schedule of the designation 

process described earlier, CLECO plans to start monitoring as soon as possible. The monitoring will be conducted 

and the monitoring data will be processed following the USEPA ambient monitoring guidelines for SO2. 

This document describes the methodology of selection of the monitoring site in conformance with the USEPA 

guidelines and the location of the selected site. CLECO requests approval from LDEQ and USEPA R6 on the 

selected location of the monitoring and the monitoring data processing methodology described in this document 

so that the monitored data could be certified and used in the area designation process. 

Installation of a permanent monitor may require resolution of several logistical issues such as access to power, 

security, and leasing of the location, all of which could take some time. Due to the urgency of gathering 

monitoring data to meet the deadlines for submittal to the agencies, CLECO is planning to use a two-phase 

strategy as follows:

• Phase 1(Short-term) Monitoring: CLECO will start monitoring as soon as possible with a temporary 

trailer-mounted monitoring station for 3 to 4 months (expected August 2015 through November 2015), 

while all logistical issues are resolved regarding the location of a longer term monitoring site.

• Phase 2 (Long-term) Monitoring: Start monitoring at the longer term monitoring site after 3 to 4 

months and close down the temporary monitoring site.

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DOLET HILLS POWER STATION 

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1.1 SO2 Emission Sources in DHPS

Unit 1 at the DHPS is a 7,600 million British Thermal Units per hour (MMBTu/hr) coal-fired boiler and the only 

continuous SO2 emission source in the facility. The emissions are vented to the atmosphere via the Unit 1 stack

(EQT 02). The facility also operates a diesel-fired emergency generator and a diesel-fired fire pump, which run 

intermittently.

Table 1-1 shows details of the Unit 1 boiler as in the current Title V air permit. Figure 1-1 shows the layout of the 

site with the location of the Unit 1 stack.

Table 1-1: Details of SO2 Emission Source in DHPS – Unit 1

Source Name Source ID

UTM Easting 

(X)

UTM 

Northing (Y)

Stack 

Height

Stack 

Diameter

(m) (m) (ft) (ft)

1-78

Unit 1 Boiler EQT 02 446284.1 3544210.3 525 25

Reference: Title V operating permit issued September 20, 2013

1.2 Description of Surrounding Area

Figure 1-2 shows a Google Earth view of the area surrounding the facility, which is primarily rural in nature and 

heavily wooded on all sides. The nearest city is Mansfield, Louisiana, approximately 12 kilometers (km) to the 

west of the facility. There are no major roads near the facility. 

CLECO owns a large tract of land surrounding the facility shown as shaded green areas in Figure 1-2. Most of 

these areas are unfenced and have unrestricted access to the public. The Dolet Hills mine, in which CLECO has 

an ownership stake, also owns tracts of lands around the facility as shown in red lines in Figure 1-2. Again, most 

of these areas have no fences and are unrestricted to the public. 

1.3 SO2 Emission Sources in Desoto Parish

Unit 1 of the DHPS facility is the major SO2 emission source in the Desosto Parish. Figure 1-3 shows the 

locations of permitted SO2 emission sources near the facility and most of these emission sources are small

compared to Unit 1. The nearest large emission source for SO2 is the International Paper—approximately 14 km 

north of the facility. Table 1-2 shows the actual emissions of SO2 from sources within Desoto Parish for last three 

calendar years. Table 1-3 shows all other SO2 emissions from sources adjacent to Desoto Parish within 20 km of 

the DHPS facility.

Table 1-2: SO2 Emission Sources within Desoto Parish

Facilities Within Desoto Parish

2013 2012 2011

tons/yr % of Total tons/yr % of Total tons/yr % of Total

CLECO Unit 1 14612 99.8% 20887 99.7% 20875 99.9%

Other CLECO Sources 0.03 0.0002% 0.03 0.0001% 0.03 0.0001%

Other Off-site Sources 36 0.2% 58 0.3% 20 0.1%

Total in Desoto Parish 14648 100.0% 20945 100.0% 20895 100.0%

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Table 1-3: SO2 Emission Sources Adjacent to Desoto Parish within 20 Km from DHPS

Facilities Within Desoto Parish

2013 2012 2011

tons/yr % of Total tons/yr % of Total tons/yr % of Total

CLECO Unit 1 14612 91.7% 20887 92.8% 20875 92.3%

International Paper

(Outside Desoto Parish) 1296 8.1% 1569 7.0% 1722 7.6%

Other Off-site Sources

(Outside Desoto Parish) 34 0.2% 51 0.2% 14 0.1%

Total 14648 100.0% 20945 100.0% 20895 100.0%

The data show that Unit 1 is the major source impacting the SO2 ambient concentration in Desoto Parish and a 

source-oriented monitoring of the DHPS facility (primarily Unit 1) will provide a representative ambient air quality 

data for SO2 in this parish, which could be used for the area designation process for the 1-hour SO2 NAAQS.

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DOLET HILLS POWER STATION 

PINEVILLE, LOUISIANA

2.0 Monitor Siting Methodology

The USEPA has published a Technical Assistance Document (2013 Monitoring TAD) for selection of monitoring 

sites for SO2 designation (SO2 NAAQS Designation Source Oriented Modeling Technical Assistance Document –

Draft dated December 2013). The TAD (Appendix A) provides an example of modeling used for selection of 

monitor placement using normalized emissions. This methodology was used in the selection of the monitoring 

site for the DHPS monitoring. The methodology is described below.

2.1 Step-Wise Procedure for Monitoring Site Selection

The USEPA acknowledged in the TAD that modeling is a powerful tool that could be used for selection of siting 

for monitor(s) provided the modeling is conducted with current USEPA procedures. The goal of the modeling will 

be to select candidates of monitoring sites based on ”likely” areas of “high” concentrations from the operation of

the source based on at least three years of historical meteorological data. Once a set of priority locations are 

identified, logistical issues such as security, access to power, and data access are considered to finalize the 

monitoring location(s). 

One important aspect of the modeling for monitoring site selection is that normalized emissions rather than actual

emissions are used. The use of normalized emissions can be used when modeling to inform monitor siting 

decisions because the goal of the modeling is not to determine the attainment status of an area, but to identify the 

location or locations of ambient SO

2 

concentration maxima. The normalization of the emissions preserves the 

relative magnitude of emissions forecast at each receptor by the model and the spatial distribution of modeled 

normalized design values (NDV). To normalize the emissions, the actual hourly emissions are divided by a 

reference emission rate, which can be the overall highest emission rate or any alternative reference emission 

rate. This normalized emission is then input to the model using hourly stack parameters to calculate the NDV at 

the receptors.

The USEPA has provided a scoring strategy to prioritize the monitoring sites amongst all receptors based on NDV 

concentration and frequency of having the 1-hour daily maximum concentration. This scoring strategy follows a 

step-wise procedure as follows:

1. Calculate the NDV at each receptor and rank from highest to lowest receptor. Rank of 1 means the 

highest design value.

2. Using the MAXDAILY output option in AERMOD, determine each day’s highest normalized 

concentration and receptor. The MAXDAILY option in AERMOD outputs each receptor’s highest 

concentration for each modeled day. 

3. Using the output from step 2, determine the number of days each receptor is the highest 

concentration for the day among all receptors. 

4. Rank the results from step 3 from highest to lowest number of days. Rank of 1 means the highest 

number of days having the daily maximum value. 

5. For each receptor, add the concentration rank and the day rank. The lowest possible score is 2, 

meaning the receptor was the highest overall normalized design value and also had the highest 

number of days where the receptor was the highest concentration for the day. 

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DOLET HILLS POWER STATION 

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This strategy provides a list of receptor locations, ranked in general order of desirability with regard to potentially 

siting permanent source-oriented SO2 monitors. This scoring strategy was used in the site selection for the DHPS 

monitoring. 

2.2 Modeling Domain and Receptor Network

As described in the 2013 Monitoring TAD, a Cartesian receptor grid extending to 20 km from the DHPS was used 

in the modeling. The spacing of the receptor grid followed LDEQ guidance and was as follows:

• Along property line – receptors spaced 100 meters (m) apart

• From property line to 2 km – receptors spaced 100 m apart

• From 2 km to 10 km – receptors spaced 250 m apart

• From 10 km to 20 km – receptors spaced 500 m apart

Figure 2-1 shows the receptor grid around the facility.

2.3 Air Quality Model

The latest version of the USEPA’s AERMOD model (version 14134) was used for the analysis using all regulatory 

default parameters. 

2.4 Meteorological Data

It is not feasible to find the exact location of the highest NDV and frequency receptor in future years from historical 

meteorological and stack data. However, the use of five years of data is expected to exclude the outliers and 

provide a reasonable estimate of the “most likely” location of the high impacts from the source(s) being monitored, 

which will be representative of the background air quality in the region. 

The latest five years of surface and upper air hourly meteorological data (2010-2014) from the nearest national 

weather station at Shreveport, Louisiana, was used in the modeling. This weather station is approved by LDEQ 

for air impact modeling of sources in Desoto Parish. For the Phase 1 (short-term) monitoring, the analysis was 

completed with the meteorological data between August and November for calendar years 2010-2014.

Figure 2-2 and Figure 2-3 show the five-year wind rose for the time period for Phase 1 short-term (August to 

November) and Phase 2 long-term (all months) monitoring. Both the wind roses show prevailing wind directions 

from south-southeast and from north-northwest.

2.5 Stack Parameters and Emission Rates

As mentioned earlier, hourly values of normalized emission rate were used in the model using the HOUREMIS 

keyword in the AERMOD model. In addition, actual hourly stack gas flow rate and stack gas temperatures were 

used concurrent with the hourly emissions to develop a realistic distribution of the normalized impacts. 

Hourly normalized emissions of SO2 were obtained by obtaining the hourly emission data from the continuous 

emission monitoring system (CEMs) as reported by the facility to USEPA under the Acid Rain Program and 

dividing each hour of data by the maximum hourly rate over the entire span of calendar years 2010-2014. The 

hourly stack gas flow rate and temperature data were also obtained from the CEMs data at the facility; however, 

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CLECO CORPORATION

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these were not normalized and actual hourly values were used. Appendix 1 shows the raw data from the CEMs 

and the data processing to convert the units suitable for input to AERMOD model. These hourly data were used 

in the AERMOD via an external file using the HOUREMIS keyword.

2.6 Building Downwash

Building downwash was considered in the modeling to obtain a realistic normalized impact. The major 

building/structure causing downwash to the Unit 1 stack is the boiler building. All other buildings and structures 

were insignificant for aerodynamic downwash; however, they were included in the analysis using the USEPA’s 

Building Profile Input Program (BPIP). The input/output from the BPIP is included in Appendix 2.

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3.0 Results

3.1 Normalized Emission Rate Modeling

The NDVs were calculated as the 5-year average of the 98th percentile of normalized concentrations at each 

receptor. The top 200 NDV receptors were considered for frequency analysis. The frequency of occurrence of 

the maximum daily impact at each of these top 200 receptors were calculated based on modeling with AERMOD 

using the MAXDAILY keyword and counting the number of days of maximum daily impact at each of the 

receptors. All the top 200 receptors from NDV modeling were then ranked by frequency of maximum daily 1-hour 

impact. The overall rank was calculated by adding the NDV rank and frequency rank and reranking the sum. The 

processing of the top 200 receptors for ranking is shown in spreadsheets included in Appendix 2. 

Table 3-1 and Table 3-2 show the top ten receptors ranked per the USEPA procedure for the short-term (August 

to November meteorological data) and long-term (all months) for the calendar years 2010-2014. The model input 

and output files are in Appendix 2.

Table 3-1: Priority Ranking for 1-hour SO2 Monitoring Site – Short Term (August to November)

Easting 

(m)

Northing 

(m)

NDV 

Concentrati

on (μg/m3)

No. of 

Days Max 

Occurred

% Max 

Day 

Occurred

Rank by 

NDV 

Concentrati

on

(RNDV)

Rank By 

Frequency 

of 

Occurrence 

(RF)

Score

1 

(RNDV 

+ RF)

Final 

Rank by 

Score 1 

447007.45 3542933.34 0.11186 10 1.9% 3 15 18 1

447007.18 3543033.86 0.10594 14 2.6% 11 11 22 2

443490 3545050 0.11221 1 0.2% 1 24 25 3A

447007.73 3542832.83 0.11194 2 0.4% 2 23 25 3B

447008 3542732.32 0.10932 5 0.9% 6 20 26 4

443690 3544850 0.11147 1 0.2% 4 24 28 5

443890 3544950 0.11051 1 0.2% 5 24 29 6

443890 3545050 0.10913 1 0.2% 7 24 31 7

443690 3545150 0.10813 1 0.2% 8 24 32 8

447090 3542850 0.10747 1 0.2% 9 24 33 9

447190 3542650 0.10663 1 0.2% 10 24 34 10A

447290 3542450 0.10579 3 0.6% 12 22 34 10B

Note: The NDV is based on 5-yr average of 98th percentile concentration using normalized hourly emissions and hourly actual stack gas flow 

rate and temperature. The meteorological data for all 5 years were limited to the months of August, September, October, and November, 

which is the expected duration of Phase 1 (short-term) monitoring.

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Table 3-2: Priority Ranking for 1-Hour SO2 Monitoring Site – Long Term (All Months)

Note: The NDV is based on 5-yr average of 98th percentile concentration using normalized hourly emissions and hourly actual stack gas flow 

rate and temperature. The meteorological data for all 5 years were limited to all months of the calendar years, which is the expected duration 

of Phase 2 (long-term) monitoring.

Figure 3-1 and Figure 3-2 show the location of the top ten ranked receptors for the short-term and long-term 

monitoring. In both cases, the top ten receptors are clustered primarily along the southeast corner of the facility 

and secondarily on the west of the facility, approximately 2 km from the Unit 1 stack. 

Table 3-3 and Table 3-4 show the comparison of the frequency of the highest daily impacts in the southeast and 

west areas of the facility. Clearly, the highest impacts are “more likely” to occur within the cluster of receptors in 

the southeast of the facility, both for short-term and long-term monitoring.

UTM E UTM N

NDV 

Concentration 

(μg/m3)

No. of 

Days Max 

Occurred

% Max 

Day 

Occurred

Rank by NDV 

Concentration

(RNDV)

Rank By 

Frequency 

of 

Occurrence 

(RF)

Score 1 

(RNDV 

+ RF)

Rank by 

Score 1 

443590 3544250 0.15936 10 0.7% 1 25 26 1

447190 3542150 0.15596 8 0.6% 2 26 28 2

447008.55 3542531.29 0.14859 29 2.1% 19 12 31 3

447150.79 3542214.23 0.15508 3 0.2% 3 31 34 4

447173.39 3542292.07 0.1524 1 0.1% 4 33 37 5

447173.46 3542392.58 0.15092 2 0.1% 6 32 38 6B

447190 3542050 0.15228 1 0.1% 5 33 38 6A

442990 3544450 0.14984 5 0.4% 11 29 40 7B

443240 3544200 0.15043 1 0.1% 7 33 40 7A

443890 3544150 0.15021 2 0.1% 9 32 41 8B

447053.04 3542474.58 0.15032 1 0.1% 8 33 41 8A

447008 3542732.32 0.14503 30 2.1% 31 11 42 9B

447050.28 3542214.8 0.14711 21 1.5% 24 18 42 9A

447190 3542350 0.15003 1 0.1% 10 33 43 10

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Table 3-3: Frequency Distribution of Highest Daily 1-Hour Impact for August-November,

CY 2010-2014

Receptor 

Cluster 

Location* 

Receptor 

Ranking

Frequency of 

Daily Maximum

Southeast 1 1.9%

2 2.6%

3B 0.4%

4 0.9%

9 0.2%

10A 0.2%

10B 0.6%

Total Southeast 6.6%

West 3A 0.2%

5 0.2%

6 0.2%

7 0.2%

8 0.2%

Total West 1.0%

* Location is with respect to the facility

Table 3-4: Frequency Distribution of Highest Daily 1-Hour Impact for CY 2010-2014

Receptor 

Cluster 

Location* 

Receptor 

Ranking

Frequency of 

Daily Maximum

Southeast 2 0.6%

3 2.1%

4 0.2%

5 0.1%

6A 0.1%

6B 0.1%

9A 1.5%

9B 2.1%

10 0.1%

Total Southeast 6.9%

West 1 0.7%

7A 0.1%

7B 0.4%

8B 0.1%

Total West 1.3%

*Location is with respect to the facility

3-6
CLECO CORPORATION

DOLET HILLS POWER STATION 

PINEVILLE, LOUISIANA

3.2 Proposed Location of Monitor

CLECO plans to utilize a single monitor to characterize the ambient air quality for 1-hour SO2 around the DHPS 

facility because of the proximity of the top ten ranked receptors to the facility. All of the top ten ranked receptors 

have unrestricted access for the public, and therefore, represent ambient air quality. Logistical issues and siting 

criteria are considered to make a decision on the siting of the monitor as described below.

From the modeling of daily maximum 1-hour concentration and as shown in Tables 3-3 and 3-4, there is greater 

likelihood of occurrence of the daily maximum values in the southeast area of the facility than the west of the 

facility, both during Phase 1 (short-term) and Phase 2 (long-term) monitoring. The southeast receptors are

located closer to the facility property which will ensure better security of the monitoring station. The southeast 

location has better access from the facility and electrical power lines, which will be important for installation and 

servicing of the monitoring station. For these reasons, CLECO plans to locate the monitoring station in the 

southeast of the facility at or near the receptors which ranked within the top ten from the normalized emission rate 

modeling using the USEPA methodology. 

As shown in Figure 3-1 and Figure 3-2, all of the potential top ten monitoring locations in the southeast are 

surrounded by trees. 40 CFR 58 Appendix E (Probe and Monitoring Path Criteria for Ambient Air Quality 

Monitoring dated 3/18/2015) Section 5 specifies the spacing requirements from trees. Trees can provide surfaces 

for SO2 adsorption or reactions. Trees can also act as obstructions in cases where they are located between the 

air pollutant sources or source areas and the monitoring site, and where the trees are of a sufficient height and 

leaf canopy density to interfere with the normal airflow around the probe, inlet, or monitoring path. To reduce this 

possible interference/ obstruction, 40 CFR 58 Appendix E specifies that the probe, inlet, or at least 90 percent of 

the monitoring path must be at least 10 m or further from the drip line of trees.

To meet these siting criteria, CLECO proposes to site the monitor at the location shown in Figure 3-3. A closeup view of the location is shown in Figure 3-4. This location is within the cluster of locations within top ten ranked 

locations from the modeling with normalized emissions. The location is near the CLECO property and therefore 

can be readily accessed by CLECO personnel for servicing but also avoids the gas pipelines in the area to avoid 

safety issues. This location also meets the definition of “ambient air’ due to unrestricted public access. The trees 

around this area will be cut by CLECO to meet the siting criteria for SO2 monitoring per 40 CFR 58.

The proposed monitoring location is approximately 320 feet northeast of the model ranked Receptor No. 3 for 

long-term monitoring (see Figure 3-2) and closer to the facility as shown in Figure 3-5. The proposed location is 

within 400 feet south of the receptor ranked 4 for short-term monitoring analysis (Figure 3-1). The Unit 1 stack is 

approximately 5,500 feet from model ranked Receptor No. 3, so the shift in location from the receptors is less 

than 6 percent of the distance to the Unit 1 stack. Moreover, the proposed monitoring location is aligned in the 

same wind direction and is closer to the facility, and therefore, is expected to have similar impacts as the model 

ranked Receptor No. 3 and near the cluster of top ten receptors from the modeling analysis.

3-7
CLECO CORPORATION

DOLET HILLS POWER STATION 

PINEVILLE, LOUISIANA

4.0 Monitoring Installation and Data Processing

For continuous monitoring of the 1-hour concentrations, CLECO is proposing a sampling system, analyzer, 

instrument rack, and a data logger to comply with the regulatory requirements. As mentioned in Section 1.0, 

CLECO plans to start monitoring immediately (Phase 1) with a temporary monitoring station, while preparing the 

site for long-term monitoring (Phase 2). For Phase 1 (short-term) monitoring during the initial August-November 

2015 period, CLECO is proposing to use a trailer-mounted system for speedy deployment. The trailer will contain 

all required analyzer, data logger, and associated systems and will be located at the proposed location shown in 

Figure 3-5. The permanent monitor for long-term monitoring will be also located in this area. Electric power will be 

provided to the monitoring station from nearby electric lines. 

4.1 Description of Monitoring System

Figure 4-1 shows a typical diagram of the monitoring station. The monitoring components consist of an analyzer 

(Teledyne - API or Thermo) for monitoring SO2 in ambient air as well as a multi-gas calibrator (e.g., API T1700 

model) that generates calibration gas for the monitoring system. The analyzer will use U-V fluorescence 

methodology, which is the automated federal equivalent method for monitoring of SO2.

The data acquisition for this project consists of one data logger and a cellular modem to allow daily system 

monitoring via a remote location. The data logger will manage calibrations, alarms, analog and digital 

inputs/outputs, data processing, and short-term data storage (approximately 30 days) of all measured parameters 

in case of a communication failure. All data will be provided in the USEPA’s Air Quality System (AQS) format. 

The analyzer, calibrator, and data logger will be installed in an environmentally controlled National Electrical 

Manufacturer’s Association (NEMA) 4-rated 19-inch instrument rack (enclosed in a trailer for the rental). This 

instrument rack is designed to be located near the DHPS in a location to be determined.

CLECO also proposes to install and operate an on-site meteorological monitoring station to measure local 

weather data which could be correlated with the ambient monitoring data. The meteorological tower will allow 

CLECO to analyze the SO2 monitoring data for anomalies and outliers. CLECO proposes to use a standard, 10 m 

freestanding meteorological tower with lightning protection and grounding at a suitable location within the facility 

meeting the siting criteria for meteorological towers per 40 CFR 58 Appendix E.

The meteorological tower will monitor hourly values of wind speed, wind direction, atmospheric stability (via sigma 

Theta method or SRDT method) by calculation, temperature, barometric pressure, relative humidity, precipitation, 

and solar radiation. 

4.2 Regulatory Compliance

The design, implementation, operation, quality assurance, and data reporting for the proposed Ambient 

Monitoring Station will meet or exceed the requirements included in the following regulations and guidance 

documents:

• USEPA, “Quality Assurance Handbook for Air Pollution Measurement Systems, Volume I –

Principles,” EPA-600/9-76-005, Office of Research and Development, Research Triangle Park, North 

Carolina, January 1976.

4-1
CLECO CORPORATION

DOLET HILLS POWER STATION 

PINEVILLE, LOUISIANA

• USEPA, “Quality Assurance Handbook for Air Pollution Measurement Systems, Volume II – Ambient 

Air Specific Methods,” EPA-600/4-77-027a, Office of Research and Development, Research Triangle 

Park, North Carolina, May 1977.

• USEPA, “Quality Assurance Handbook for Air Pollution Measurement Systems, Volume IV –

Meteorological Measurements,” EPA-600/4-82-060, Office of Research and Development, Research 

Triangle Park, North Carolina, August 1989.

• USEPA, “Meteorological Monitoring Guidance for Regulatory Modeling Applications,” EPA-454/R-99-

005, Office of Air Quality Planning and Standards, Research Triangle Park, NC, February 2000.

• USEPA, “Interim Guidelines and Specifications for Preparing Quality Assurance Project Plans,” EPA600/4-83-004, Office of Research and Development, Research Triangle Park, North Carolina, 

February 1983.

• USEPA “SO2 NAAQS Designations Source-Oriented Monitoring Technical Assistance Document 

(TAD),” EPA-450/4-87-007, Office of Air Quality Planning and Standards, Research Triangle Park, 

North Carolina, December 2013, Draft. 

• USEPA 40 CFR part 58 – “Ambient Air Quality Surveillance,” Appendices A, C, and E. 

• USEPA 40 CFR part 51 – “Data Requirements Rule for the 1-Hour SO2 Primary National Ambient Air 

Quality Standards (NAAQS),” May 2014, Proposed Rule.

• USEPA Automated Equivalent Method: EQSA-0495-100 UV Fluorescence Detection of SO2.

• LDEQ “Ambient Air Quality Standards,” Chapter 7 of LAC 33:III

4.3 Data Processing and Reporting

Quality assurance of the data obtained from the monitoring system will be per the requirements 40 CFR 58 

Appendix A. A Quality Management Plan and Quality Assurance Project Plan will be developed for the project 

prior to the data collection. Visual checks on the monitoring system will be conducted once a week to assure that 

the monitors have not been damaged. Preventive monitoring tests will be conducted each quarter and system 

audits and calibrations will be conducted as needed.

The system functionality will be checked remotely on a daily basis on all weekdays and the data will be 

downloaded once each week for processing. The data processing will follow the procedures detailed in 

40 CFR 50 Appendix T (Interpretation of Primary National Ambient Air Quality Standard for Sulfur Oxides dated 

4/6/2015). The data with all quality assurance procedures will be submitted to LDEQ for certification and upload 

to the USEPA’s AQS. 

4-2
CLECO CORPORATION

DOLET HILLS POWER STATION 

PINEVILLE, LOUISIANA

Figures
CLECO CORPORATION

DOLET HILLS POWER STATION 

PINEVILLE, LOUISIANA

Figure 1-1: Dolet Hills Power Station
CLECO CORPORATION

DOLET HILLS POWER STATION 

PINEVILLE, LOUISIANA

Figure 1-2: Dolet Hills Lignite Mine Area Close-up
CLECO CORPORATION

DOLET HILLS POWER STATION 

PINEVILLE, LOUISIANA

Figure 1-3: SO2 Emission Sources in Desoto Parish – 2013 Data
CLECO CORPORATION

DOLET HILLS POWER STATION 

PINEVILLE, LOUISIANA

Figure 2-1: Receptor Network for Modeling for Monitor Siting Analysis
CLECO CORPORATION

DOLET HILLS POWER STATION 

PINEVILLE, LOUISIANA

Figure 2-2: Wind Rose – August-November 2010-2014
CLECO CORPORATION

DOLET HILLS POWER STATION 

PINEVILLE, LOUISIANA

Figure 2-3: Wind Rose – 2010-2014 – All Months – Shreveport
CLECO CORPORATION

DOLET HILLS POWER STATION 

PINEVILLE, LOUISIANA

Figure 3-1: Dolet Power Station, Top 10 Receptors, August-November
CLECO CORPORATION

DOLET HILLS POWER STATION 

PINEVILLE, LOUISIANA

Figure 3-2: Dolet Hills Power Station – All Top Ten Receptors
CLECO CORPORATION

DOLET HILLS POWER STATION 

PINEVILLE, LOUISIANA

Figure 3-3: Location of Proposed SO2 Monitor for Dolet Hills 
CLECO CORPORATION

DOLET HILLS POWER STATION 

PINEVILLE, LOUISIANA

Figure 3-4: Location of Proposed SO2 Monitor for Dolet Hills – Close up 1

Note: 

The proposed monitoring location is approximately 330 feet northeast of the receptor ranked 3 for long-term monitor 

siting analysis and 400 feet south of receptor no 4 for short-term monitor siting analysis.
CLECO CORPORATION

DOLET HILLS POWER STATION 

PINEVILLE, LOUISIANA

Figure 3-5: Location of Proposed SO2 Monitor for Dolet Hills – Close Up 2

Notes: 

1: The proposed location is near CLECO property boundary and has unrestricted access to the public (i.e. no fences 

or restrictions existing or planned)

2: The trees around the monitor will be cut to meet the siting criteria of 40 CFR 58 Appendix E.
CLECO CORPORATION

DOLET HILLS POWER STATION 

PINEVILLE, LOUISIANA

Figure 4-1 – Typical SO2 Monitoring Station 
CLECO CORPORATION

DOLET HILLS POWER STATION 

PINEVILLE, LOUISIANA

Figure 4-2 – Typical SO2 Monitoring Station Set-up
CLECO CORPORATION

DOLET HILLS POWER STATION 

PINEVILLE, LOUISIANA

Appendix 1

Hourly Emission and Stack Parameters for Unit 1 

Used in Modeling 

(On USB Drive)
CLECO CORPORATION

DOLET HILLS POWER STATION 

PINEVILLE, LOUISIANA

Appendix 2

Model Input/Output Files 

(On USB Drive)
CLECO CORPORATION

DOLET HILLS POWER STATION 

PINEVILLE, LOUISIANA

Appendix 3

LDEQ Monitoring Siting Form for SO2 Monitor at DHPS 
Appendix 3

LDEQ Site/Monitor Information Form

Site Name: Dolet Hills Power Station

Site Address: Mansfield, LA

City & County: Desoto Parish

Site Coordinates: Lat: 32 Deg 1 min 51.24 sec and Long: 93 Deg 34 min 8.88 sec 

(at Unit 1 Stack)

Site Elevation (m): 74

Criteria Pollutants Monitored: Sulfur Dioxide (SO2) 

Other Parameters: Meteorological data such as wind speed, wind direction, 

ambient temperature, solar radiation, and relative humidity. The meteorological 

tower will be located within the facility.

Nearest Meteorological Site: Shreveport, LA

(‘onsite’ is met tower present at this site)

Photographs to and from each cardinal direction attached?: No. The site is 

being cleared of trees. Photographs will be submitted after clearance. Google 

Earth maps included at this time.

Name(s) of Report Preparer(s) : Arijit Pakrasi, CB&I

Date: August 26, 2015

Phone Number: (281) 531-3106
Site Map

Provide map of site and surrounding terrain and features, up to 100 meters.

Map notes

The DHPS is shown at the center of the map
Monitor Information

Pollutants

SO2

Manufacturer API-Teledyne or Thermo Electron

Model TBD

Serial number TBD

Scale of representation

MICro, MIDdle, Neighborhood, Urban

Source-oriented in a primarily rural area

Averging time 1-, 8-, 24-hour 1-hour

Objective (Population, Max concentration, 

Background, Transport)

Source Impact for providing supporting data for 1-hour 

SO2 area designation at the Desoto Parish 

Height of probe above ground(m) >4

Distance from obstruction (m) 15 m minimum in all directions

Type of obstruction (Wall, Tree, etc) Trees

Distance from roadway (m) Nearest roadway is at 185 m distance (between DHPS and 

Dolet Mines). This roadway is not open to public and there 

are approximately 15-20 vehicles on this road per day

Unrestricted airflow (Yes, No) Yes. In all directions

Designation (NCore, SLAMS,etc) SLAM equivalent

Siting Criteria Met (Yes, No) Yes

Note: See report for more details on the monitor.
Area Information

Street Name

Traffic Count 

(Vehicles/day)

Unpaved road between DHPS and Dolet Mines –

inaccessible to public –used by only the facility and 

mine personnel.

15-20

Direction Predominant Land Use (Industry, Residential, Commercial or Agriculture)

North Rural: Small trees surrounding the station and a small industrial 

activity approximately 300 m distance

East Rural: Small trees surrounding the station

South Rural: Combination of small and larger trees surrounding the 

station

West Rural: Larger trees surrounding the station and a conveyor belt for 

coal and an unpaved roadway approximately 200 m distance 

Direction Obstructions Height (m) Distance (m)

North Small trees 10 20

East Small trees 10 25

South Small trees 10 17

West Larger trees 20 20

Note: This table is for large obstructions that affect the entire site, such as large clusters of trees 

or entire buildings. Individual obstructions, such as walls, single trees, other monitors, etc, 

should be entered in the Monitor Information table.

Direction Topographic Features

(hills, valleys, rivers, etc.)

General Terrain

(flat, rolling, rough)

North None within 10 km Flat

East None within 10 km Flat

South None within 10 km Flat

West None within 10 km Flat

Comments: The figures below show the proposed location of the SO2 monitoring 

station. 
Proposed Location of SO2 Monitor for Dolet Hills Power Station (DHPS)

Approximate Coordinates: 

Lat: 32 degrees 01 minutes 0.5.66 seconds N 

Long: 93 Degrees 33 minutes 41.97 seconds W 
Area Surrounding the Proposed SO2 Monitor for Dolet Hills Power Station