Information Requested regarding the Belews Creek Steam Station and Marshall Steam Station 

Bottom Ash Sampling Data Provided in Comments 

1. What selection criteria did Duke Energy use to identify Belews Creek and Marshall Steam 

Station as plants to sample? Are there any other bottom ash data associated with other Duke 

plants? EPA requests that bottom ash sampling data be provided for all Duke Energy plants for 

which data are available. 

Response: 

We selected Belews Creek and Marshall due to the close proximity of the stations to our in-house 

sampling personnel. Belews Creek and Marshall were also selected because we knew the plants 

would be operating and, thus, generating bottom ash sluice water. Also, we were able to determine 

that we could safely access the bottom ash sluice water discharge pipe. 

Additional bottom ash data has been collected for the East Bend Steam Station. Responses to the 

questions are provided in the document “Additional Bottom Ash Data: East Bend”. 

In addition, bottom ash sulfide samples were collected at Cliffside and Cayuga. These samples were 

provided to UWAG for analysis. Duke Energy does not have the UWAG laboratory reports, but 

these reports are available through UWAG. Duke Energy did collect a split sample from Cliffside 

and the analytical report is included in this submission. Refer to “Cliffside Bottom Ash Lab Report 

6_28_13” and “Cliffside EDD 6_28_13.” 

Bottom ash samples were collected from Miami Fort 6 and 8 as part of testing of additives for 

compliance with pending air regulations. This data is being claimed Confidential Business 

Information (CBI) and is being provided in the folder labeled “MFS Bottom Ash”. 

EPA did not specifically request responses to the questions for additional bottom ash data. Given the 

timeframe of the information request, responses to these questions for Cliffside or Miami Fort were 

not completed. 

Bottom ash data from Cayuga and Gibson were collected at the request of legal counsel during fuel 

additive testing and is not being produced. 

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

transport water sampled would enter. Please provide the dimensions for this pond including 

surface area, depth, and residence time. Also, please identify what other wastestreams flow into 

this impoundment and their relative contributions. 

Response: 

Refer to the ICR Questionnaire, Question D4-2 

Station 

Pond 

Impoundment 

Unit ID 

Surface Area 

(ft2

) Depth (ft) Residence Time (hrs) 

Belews Creek SPD-2 14,897,520 36.5 96 

Marshall Pond 1 6,664,680 35.5 96 

Belews Creek (refer to the ICR Questionnaire, Question D3-2) 
Wastestream Flow 

Bottom ash sluice water 3,520,800 gpd / 295 dpy

Fly ash sluice water 230,400 gpd / 20 dpy

Treated FGD wastewater 700,000 gpd / 365 dpy

Landfill leachate 10,000 gpd / 365 dpy

Boiler fireside cleaning water 83,000 gpd / 3 dpy

Coal pile runoff 128181 gpd / 124 dpy

Air heater cleaning water 664,000 gpd / 3 dpy

Reverse osmosis reject water 150 gpm ; 24 hpd / 365 dpy

Ion exchange wastewater 340,000 gpd / 9 dpy

Floor Drain wastewater unknown

Marshall (refer to the ICR Questionnaire, Question D3-2) 

Wastestream Flow 

Bottom ash sluice water 3,020,000 gpd / 365 dpy

Fly ash sluice water 9,888,000 gpd / 2 dpy

Treated FGD wastewater 1,308,000 gpd / 365 dpy

Mill Reject Sluice Water 131,000 gpd / 365 dpy

Boiler blowdown 2,000 gpd / 365 dpy

Coal pile runoff 162,134 gpd / 129 dpy

Filter backwash 7,000 gpd / 365 dpy

Reverse osmosis reject water 194,000 gpd / 365 dpy

Ion exchange wastewater 20,000 gpd / 56 dpy

Clarifier sludge 8,000 gpd / 365 dpy

Once-through cooling water 80,000 gpd / 365 dpy

Limestone pile runoff 2,000 gpd / 129 dpy

Gypsum pile runoff 5,000 gpd / 129 dpy

Boiler fireside cleaning 77,925 gpd / 4 dpy

Air heater cleaning water 326,000 gpd / 3 dpy

Track hopper sump 70,000 gpd / 365 dpy

Landfill runoff (FGD residue landfill) 5,000 gpd / 365 dpy

Sanitary 7,000 gpd / 365 dpy

Stormwater 8,330,000 gpd / 129 dpy

Floor Drain wastewater unknown

3. For each plant, identify what chemicals are added to the wastestream upstream of the sample 

location or to the sample during settling. 

Response: 

Station Chemicals Added 

Belews Creek No chemicals added 

Marshall No chemicals added 
4. Please provide a more detailed description of the sampling method beyond "collected in 

accordance with Method 1669." Please specify the location of the bottom ash transport water 

sample provided (e.g., directly from bottom ash sluice pipe discharge into commingled pond or 

upstream prior to this point). Please specify 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). 

Response: 

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. 

5. 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). 

Response: 

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

Refer to the ICR Questionnaire, Question C3-3 

Plant Unit 

Average 

Sluice Water 

Flow Rate 

(gpd) 

Typical 

Duration 

(hpd) 

Typical 

Frequency 

(dpy) 

Belews Creek 1 880,200 6 262 

Belews Creek 2 880,200 6 285 

Marshall 1 1,832,400 5 267 

Marshall 2 1,832,400 5 240 

Marshall 3 900,000 6 336 

Marshall 4 900,000 6 332 

6. Please identify how long the bottom ash was in contact with the water prior to collecting the 

supernatant. How does this sample settling time compare to the retention time of the surface 

impoundment identified in question #2? 

Response: 

Belews Creek: The water was in contact with the bottom ash approximately 6 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. 

Marshall: The water was in contact with the bottom ash approximately 3 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. 
7. For each plant, please provide additional details regarding the source water sampling locations: 

a. Please specify the location of the source water samples provided. Please indicate whether 

the plant discharge is upstream or downstream of intake water location (i.e., does any of the 

plant's effluent contribute to intake water)? 

Response: 

Plant Source Water Sample Location Plant Discharge 

Belews Creek Tap @ the service water intake 

Intake water is from Belews Lake. The 

ash pond discharges to the Dan River 

downstream of Belews Lake. 

Marshall Tap @ the service water intake 

Discharge and intake are both on Lake 

Norman. The discharge is to the surface 

water whereas; the service water intake 

is located at a depth of approximately 30 

feet below the surface water elevation. 

b. Does the plant treat the intake water prior to use in the bottom ash sluicing system. If so, 

how is the intake water treated? 

Response: 

Plant Bottom Ash Sluice Water Treatment 

Belews Creek No treatment 

Marshall No treatment 

c. Does the plant recycle any process wastewater for use in the bottom ash sluicing system. 

If so, how? 

Response: 

Plant Plant Recycle Water 

Belews Creek No 

Marshal No 

8. For each plant, please provide the associated TSS concentration for the source water and the 

bottom ash samples. 

Response: 

Plant TSS Concentration 

Belews Creek Sample was not analyzed for TSS. 
Marshall Sample was not analyzed for TSS. 

9. For each plant, describe any atypical operations occurring at the plant at the time of sampling 

(e.g., test burn of new coal). 

Response: 

Plant Operations 

Belews Creek Normal operation. 

Marshall Normal operation 

10. For each plant, please provide the flow rate of the wastewater at the time of sampling, as well 

as the average annual bottom ash discharge flow rate. 

Response: 

See response for Question 5 above regarding the average annual bottom ash discharge flow rate. 

The flow rate was not recorded at the time of sampling.