Additional Bottom Ash Samples

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: 

Samples were collected at the East Bend Generating Station. The sample results are provided in the 

East Bend Bottom Ash spreadsheet. 

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) 

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

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

Wastestream Flow 

Bottom ash sluice water 188 gpm / 24 hpd / 365 dpy

Boiler blowdown 1 gpm / 24 hpd / 365 dpy

Coal pile runoff 105 gpm / 24 hpd / 126 dpy

Filter backwash 27,000 gpd / 52 dpy

Ion exchange wastewater (regeneration waste) 23 gpm / 24 hpd / 365 dpy

Miscellaneous Plant usage 452 gpm / 24 hpd / 362 dpy

Vacuum Filter Pump Seal Water 132 gpm / 24 hpd / 365 dpy

Cooling tower overboard 990 gpm / 24 hpd / 365 dpy

Landfill runoff (uncapped landfill) 119 gpm / 24 hpd / 365 dpy

Sanitary 30 gpm / 24 hpd / 365 dpy

General runoff 30 gpm / 24 hpd / 126 dpy

Floor Drain wastewater 880 gpm / 24 hpd / 365 dpy

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 

East Bend 

No chemicals added for ash sluicing, but bottom ash 

sluice water system draws from cooling tower 

circulating water, which is treated with de minimis
concentrations of HEDP, H2SO4, and (summer only) 

hypochlorite. It is likely none of these would be 

detectable in the bottom ash sluice water. 

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: 

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. 

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). 

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) 

East Bend 2 300,000 24 257 

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: 

For East Bend, the supernatant was not collected. Instead the entire bottom ash sample was 

collected and sent to the laboratory for analysis. 

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 

East Bend Tap @ the service water intake 

Service water intake is on the Ohio 

River upstream of plant discharges 

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 

East Bend 

Intake water is screened to remove gross contaminants. Bottom 

ash sluice water system draws from cooling tower circulating 

water, which is treated with de minimis concentrations of HEDP, 

H2SO4, and (summer only) hypochlorite. 

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

If so, how? 

Response: 

Plant Plant Recycle Water 

East Bend 

No; bottom ash sluice water system draws from cooling 

tower circulating water, which is process water but not 

wastewater. 

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

bottom ash samples. 

Response: 

Plant TSS Concentration 

East Bend 

Intake sample was not analyzed for TSS; NPDESreported TSS value for the month (Aug. 2011) was 8 

mg/l. 

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 

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

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