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Questions for Duke Energy (6/24/2014)

Questions Regarding FGD Data Provided for Allen Steam Station

1. For the analytical data, non-detects are provided as “<value” (i.e., <0.01). Is the value provided 

the detection limit (MDL) or reporting limit (RL)? If not the RL, please provide that value.

The value provided is the reporting limit.

2. On the “Analytical Methods” tab, what value is provided in Column C (see table below)? Is this 

the MDL or the RL? If not the RL, please provide that value for each method. Reporting limit. 

Please see correction to method for nitrate in table below. 

3. What is represented in the “RC” tab of the “Allen EPA Coal Data Final 3_38_24.xls” file?

This spreadsheet provides the dates and amounts of refined coal operations. Refined coal 

operations are conducted to receive tax credits under Section 45 of the IRS Code. The solution is 

sprayed onto the coal as the coal is being transferred from the coal pile to the bunker. 

a. What does each column in the spreadsheet represent?

 M-Sorb: calcium bromide solution (~52%)

 M-Sorb Application Rate (lbm/ton): pounds of calcium bromide solution (mass 

basis) per ton of coal

 M-Sorb Application Rate (%): ton of M-Sorb / ton of coal

 S-Sorb: cement kiln dust

 S-Sorb Application Rate (lbm/ton): pounds of cement kiln dust (mass basis) per 

ton of coal

 S-Sorb Application Rate (%): ton of S-Sorb / ton of coal

b. What process does this represent? This process represents refined coal operations. Does it

have any effect on ash transport water or FGD wastewater characteristics? This could 

affect ash transport water and FGD wastewater characteristics both in terms of additional 

From “Analytical Methods” tab in the “Allen EPA Data Final 3_28_14.xlsx” and

“BC EPA Data Final 3_28_14.xlsx” files

Analyte Method RL ?? Notes

As, Be, Ca, Cr, Cu, Ni, Ag, Zn, Se 200.8 (ICP-CRC-MS) 10 ppb May vary with dilution

B,Fe 200.7

Hg (results ≥ 1ppb) 245.1 1 ppb May vary with dilution

Hg (results < 1 ppb) 1631E 1 ppt May vary with dilution

Alkalinity 2320B

Ammonia, Nitrate 350.1 0.04 ppm May vary with dilution

Nitrate 353.1

0.01 

mgN/L May vary with dilution

Br, Cl 300.0 10 ppm May vary with dilution

TKN 351.2 0.1 ppm May vary with dilution

TDS 2540C 10 ppm May vary with dilution

TSS 2540D 4 ppm May vary with dilution

Se Speciation (Applied Speciation) IC-ICP-DRC-MS Variable May vary with dilution
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chemicals added to the water as well as effects on ORP in the scrubber. Currently, the 

industry does not have a full understanding of the effects of these additives. 

4. For the FGD Purge Eff on 10/5/2010, there is a beryllium result of 0 (zero). What does this “0” 

value represent? The “0” value presumably should be <0.05 mg/l; however, we are not able to 

locate the laboratory report at this time. This will need to be confirmed after reviewing the 

laboratory report. 

Update 7/24/14: The laboratory report shows a result of 0.015 mg/L.

5. In the “Analytical” tab, there is a field titled, “Se(UK) (ug/L)”

a. What does this field represent? Total concentration of all unknown selenium species 

observed by the IC-ICP MS

b. Were these values measured or calculated, and what does a value of 0 (zero) represent? 

Measured. A zero value means no unidentified peaks observed by the IC-ICP MS. This 

means all peaks were identified to a known species of selenium. See example below. 

6. In the “Analytical” tab, the concentrations reported for the FGD Purge Eff on 10/9/2010 for 

MeSe(IV), SeCN, and SeMe are “<0”. Is this correct? No What does this represent? This 

appears to be a data entry error. Selenium speciation analysis did not appear to be conducted for 

the samples collected on 10/9/2010. 

Update 7/24/14: selenium speciation was conducted on 10/10/10. MeSe(IV), SeCN, and SeMe 

were reported as non-detect. 

7. Lab reports were provided for the Cliffside and Miami Fort analytical data, but not for Allen 

Steam Station. Please provide the laboratory reports for the Allen analytical data. Duke Energy

is in the process of obtaining the laboratory reports. 
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Update 7/24/14: The laboratory reports available have been provided with this update. 

8. Please confirm the data in column H are for the combined parameter nitrate-nitrite. What 

analytical method was used for these data (9/29/11-12/22/11, 6/3/13-10/22/13)?

EPA Method 353.2

9. Both the Bio Influent and Bio Effluent nitrate-nitrite data for 12/20/11 are listed as 97 mg/L. 

What are the correct values for this day? This will need to be confirmed after reviewing the 

laboratory reports.

Update 7/24/14: Based on the laboratory reports:

Bio Influent: nitrate-nitrate was detected at 97.0 mg/L

Bio Effluent nitrate-nitrite was detected at 1.0 mg/L

10. Effluent concentrations of nitrate-nitrite and selenium were elevated in December 2011. Effluent 

selenium was again elevated in December 2012 / January 2013. What caused these increases in 

effluent concentration? The 12/11 increase was a result of the elevated ORP event. A similar 

more controlled situation occurred in 12/12 – 01/13. 

Questions Regarding FGD Data Provided for Belews Creek Steam Station

1. For the analytical data, non-detects are provided as “<value” (i.e., <0.01). Is the value provided 

the detection limit (MDL) or reporting limit (RL)? If not the RL, please provide that value. 

The value provided is the reporting limit.

2. On the “Analytical Methods” tab, what value is provided in Column C? (See the table above for 

the information provided on the “Analytical Methods” tab.) Is this the MDL or the RL? If not the 

RL, please provide that value for each method. RL

3. Please explain what is represented in the “COMBINED BELEWS CREEK” tab of the “BC EPA 

Coal Data Final 3_28_14.xlsx” file. 

This spreadsheet provides information on the addition of additives to mitigate / assist with deslagging of the boiler. The additives are sprayed onto the coal as the coal is being transferred 

from the coal pile to the bunker. 

a. What does each row in the spreadsheet represent?

 CT300 (ppm): pounds of magnesium hydroxide solution (~60 to 70%) per 

million pounds of coal

 CT600 (ppm): pounds of calcium carbonate per million pounds of coal. 

b. What process does this represent and does it have any effect on ash transport water or 

FGD wastewater characteristics?

This spreadsheet represents the deslagging mitigation process and potentially could 

affect ash transport water and FGD wastewater characteristics. 
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4. For the Bio 1 Inf on 4/26/2011, there is a dissolved selenium result of “<567”. Is this a data entry 

error? The “<” should be deleted. The result for dissolved selenium was 567 ug/l. Also, the 

actual sample date was 4/27/2011. 

5. In the “Analytical” tab, column AM is titled “Th, tot (mg/L).” Do the data in this column 

represent Thorium (chemical symbol Th), or do the data in this column represent Thallium 

(chemical symbol Tl)? Thallium

6. In the “Analytical” tab, the concentrations reported for the Bio 2 Eff on 11/28/2013 for Vanadium

and Thorium/Thallium are “<0”. Is this correct? What does this represent? These results appear 

to be <0.005 mg/L for both vanadium and thallium. We will need to confirm with the laboratory 

reports. 

7. Lab reports were provided for the Cliffside and Miami Fort analytical data, but not for Belews 

Creek Steam Station. Please provide the laboratory reports for the Belews Creek analytical data. 

Duke Energy is in the process of obtaining the laboratory reports. 

Update 7/24/14: The laboratory reports available have been provided with this update. 

8. Please confirm the data in column I are for the combined parameter nitrate-nitrite. What 

analytical method was used for these data (5/15/13-11/28/13)? Method 353.2 

Questions Regarding Information Provided for Cliffside Steam Station

1. Duke Energy provided the following spreadsheets that contain analytical data from the Cliffside 

pilot test:

a. Cliffside Bio Pilot Test.xlsx (CBI);

b. Cliffside EDD File.xlsx (CBI); and

c. Non CBI Cliffside EPA data Final 3_14_14.xlsx

Please confirm whether all the data contained in the “Cliffside Bio Pilot Test” and the “Non CBI 

Cliffside EPA data Final 3_14_14” file are also contained in the “Cliffside EDD File.” The 

Cliffside EDD File begins with sample date 12/7/2011. The “Non CBI Cliffside EPA data Final 

3_14_14” provides results for the FGD purge on 11/1/2011 and 12/5/2011 and the bioreactor 

influent on 12/5/2011. These data are not included in the EDD File. 

2. The “Cliffside EDD File” contains additional information regarding the samples results that is not 

contained in the “Non CBI Cliffside EPA data Final 3_14_14” file, such as the MDL, RL, lab, 

and Flag. Is Duke Energy claiming this additional information as CBI for those sample results 

that are contained in the Non CBI Cliffside EPA data Final 3_14_14” file? No, we were not able 

to easily separate the EDD file. Duke is not claiming CBI on the FGD purge data or the 

bioreactor influent, including information on these results contained in the EDD File. If not, can 

EPA treat all the “bioreactor influent” data in the “Cliffside EDD File” as nonCBI? Yes

3. In the “Cliffside Bio Pilot Test” and “Non CBI Cliffside EPA data Final 3_14_14” files, there are 

certain analytical results that are highlighted green or yellow. Please explain what those colors 

represent. Results were less than the reporting limit

4. For the selenium speciation data submitted for the various sampling points, there is a field titled, 

“Unknown Se.” Were these values measured or calculated, and what does a value of 0 (zero) 

represent? A zero value means no unidentified peaks observed by the IC-ICP MS. This means all 
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peaks were identified to a known species of selenium. See response to #5 under Questions 

Regarding FGD Data Provided for Allen Steam Station.

Questions Regarding Bottom Ash Information Provided

1. For data provided in lab reports for Miami Fort (MFS U6 2012 Bottom Ash Test Lab 

Reports.pdf), please identify the unlabeled column presented after the Reporting Limit (RL) 

column. Method detection level

2. For Miami Fort, please provide the laboratory reports corresponding to the samples collected on 

02/27/2014, as shown in the file named “MFS U8 2012 Bottom Ash Data Duke 2_27_14.xls” 

The samples dates for the bottom ash sluice water were 8-1-2012, 8-8-2012 and 8-9-2012. 

We are classifying the reports as CBI and will be submitted under separate cover. 

3. For the Cliffside plant, please confirm the sample numbers located in the spreadsheet titled 

“Cliffside EDD 6_28_13.xlsx”. Page 2 of the file titled “Cliffside Bottom Ash Lab Report 

6_28_13.pdf” indicates 4 different sample numbers while only 1 sample number is presented in 

the spreadsheet.

The LIMS did not carry over the sample ID correctly. Please find enclosed the revised EDD 

correcting this problem. 

4. For Belews Creek please indicate the sampling events represented by the data presented in 

Appendix B of your comments on the proposed rule, submitted 9/19/2013. The data appears to 

represent the data from the 9/13/12 sampling event (Bottom Ash Belews Creek 9_13_12 Lab 

Report.pdf) and does not include any data from the 6/27/13 sampling event (Bottom Ash Belews 

Creek Report 6_27_13 Lab Report.pdf). Analytical results from both sampling events were used 

to produce the table for Belews Creek in Appendix B. If a parameter was analyzed for both 

sampling events, the average was reported in the table in Appendix B. Averaging was conducted 

for aluminum and manganese. All other parameters were either analyzed on the sample collected 

on 9-13-2012 or the sample collected on 6-27-13. 

5. Please answer the following questions related to the bottom ash sampling results provided for 

East Bend, Cliffside, and Miami Fort:

a. Please provide the Pond/Impoundment Unit ID (e.g., SPD-2) for the pond which bottom ash 

transport water sampled would enter. What is the residence time associated with this pond.

Refer to the ICR Questionnaire, Question D4-2 (as of 2009)

Station

Pond 

Impoundment 

Unit ID

Surface Area 

(ft2)

Depth (ft) Residence Time 

(hrs)

East Bend SPD-1 / Pond 1 2,317,392 36.5 2,965

Miami Fort SPD-1 / Pond-1 1,398,276 35 532

Cliffside SPD-2 3,659,400 60 96
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b. Please provide a detailed description of the sampling method used to collect the samples. 

Specify the location of the bottom ash transport water sample provided (e.g., directly from 

bottom ash sluice pipe discharges into commingled pond or upstream prior to this point), and

whether the sample was a grab or composite sample. Additionally provide duration and 

frequency information for all composite sampling (e.g., 24-hour composite collected every 

hour).

Plant Operations

East Bend

The samples were collected in accordance with Method 1669. All samples 

collected were grab samples while bottom ash was being sluiced. The samples 

were collected directly from the bottom ash sluice water pipe prior to comingling 

with other wastewater sources. Pyrites and bottom ash are sluiced together. 

Miami Fort

The samples were collected in accordance with Method 1669. All samples 

collected were grab samples while bottom ash was being sluiced. The samples 

were collected directly from the bottom ash sluice water pipe prior to comingling 

with other wastewater sources. Pyrites and bottom ash are sluiced together. 

Cliffside

Refer to the document titled “UWAG Bottom Ash Sampling Protocol”. 

Both samples were composite samples collected from the discharge pipe prior to 

comingling with other waste streams.

c. If the sampling protocol described in response to 5.b includes collecting the sample prior to 

the pond and allowing the sample to settle prior to collecting the resultant supernatant, please 

specify how long the bottom ash was in contact with the water prior to collecting the 

supernatant. Please explain whether this sample is meant to represent the ash pond effluent

and, if so, explain how the amount of time the sample was allowed to settle compares to the 

residence time of the pond and why that is appropriate for representing the ash pond effluent.

Not applicable to samples collected at East Bend or Miami Fort. 

Cliffside: The water was in contact with the bottom ash approximately5 hours prior to 

collecting the supernatant. The bottom ash sample was collected in the field in the 

carboy and transported back to the laboratory to collect the supernatant.

d. How often is the bottom ash sluiced at the plant? Please indicate whether samples were 

collected during periods when the bottom ash is not sluiced (i.e., source water is flowing 

through the pipe).

All samples were collected while bottom ash sluice water was being discharged. 

Refer to the ICR Questionnaire, Question C3-3 (based on 2009 operations)

Plant Unit

Average Sluice 

Water Flow Rate 

(gpd)

Typical 

Duration (hpd)

Typical Frequency 

(dpy)

East Bend 2 300,000 24 257

Miami Fort 6 (SE Unit 1) 302,250 4 365

Miami Fort 8 (SE Unit 3) 367,000 4 365
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Cliffside 5 1,152,000 8 10

e. Please provide the associated TSS concentration for the source water and the bottom ash 

samples.

Plant TSS Concentration

East Bend

Cooling tower blowdown is used for bottom ash conveyance and was 

not analyzed for TSS. At the plant intake, which supplies the cooling 

tower, NPDES-reported TSS value for the month (Aug. 2011) was 8 

mg/l.

Miami Fort

For Unit 8, cooling tower blowdown is used for conveying the bottom 

ash. TSS for both cooling tower blowdown and bottom ash was

provided on the submitted spreadsheet (see column “O”). 

For Unit 6, service water is used and was not analyzed for TSS. TSS for 

bottom ash was provided in the submitted spreadsheet (see column “Q”). 

Cliffside Source water was not analyzed for TSS. 

f. Please describe any atypical operations occurring at the plant at the time of sampling (e.g., 

test burn of new coal).

Plant Operations

East Bend Normal operation

Miami Fort

Unit 8 sampling was conducted during refined coal operations.

Date 8-1-12: baseline (prior to refined coal operations)

Date 8-8 and 8-9-2012: during refined coal operations

Cliffside Normal operation

General Clarification

1. The coal data for plants Allen, Belews Creek, Cliffside, Mayo, and Roxboro contain a field

referred to as “Daily Reclaim.” What does the “Daily Reclaim” represent and how does that 

compare to the data presented in the other columns?

Coal samples for the sulfur content/SO2 analysis, etc are collected from the daily reclaim. The 

daily reclaim is the coal that is being transferred from the coal pile to the bunker to fuel the boiler. 

The other columns present the mine name, location and analysis of the coal being shipped and 

received. The percent blend is an estimate of the types of coal being burned that day.