UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON,D.C. 20460

Ms. Michalene Reilly

Manager, Environmental Services

March 10, 2014 OFFICE OF WATER
Hoosier Energy Rural Electric Cooperative

P.O. Box 908

Bloomington, IN 47402-0908

Dear Ms. Reilly:

We received the comments submitted by Hoosier Energy Rural Electric Cooperative 

(Hoosier) regarding EPA's proposed effluent limitations guidelines and standards (ELGs) for 

the steam electric power generating point source category (78 FR 34432). We are writing to 

you because we have concluded that based on review of the Hoosier comments and the 

Utility Water Act Group (UWAG) comments, which Hoosier endorses, additional 

information is either needed or would be useful in evaluating the comments with respect to 

fly ash and bottom ash wastewater characterization. In some cases, clarification is needed in 

order to properly interpret, validate,

and evaluate the ash data submitted. We are therefore asking that you provide the 

information described below in order to ensure that the Agency appropriately considers 

your submission.

As you are aware,EPA is operating with a deadline for taking final action on the 

steam electric ELGs. We are thus requesting that any additional information you provide in 

response to this letter be received by EPA no later than March 31,2014.

Information Requested from the Frank E. Ratts Generating Station

Hoosier Energy provided data on 32 samples of bottom ash and fly ash pond effluent 

collected between September 2008 and December 2009 at the Frank E. Ratts Generating 

Station for a Reasonable Potential to Exceed analysis of nine parameters for a permit 

renewal. Additionally, Hoosier provided data on 29 samples of fly ash pond effluent and 28 

samples of bottom ash pond effluent collected for mercury analysis.

1. Please provide any fly ash or bottom ash transport water data (i.e., wastewater 

samples of the transport water prior to commingling or mixing with other 

wastestreams in the ash pond). Please provide paired source water sample data where 

available. 

 We only have effluent data for ash pond discharges. 

2. Please provide any fly ash and/or bottom ash pond effluent data collected since

December 2009. Attached. 

3. For the pond effluent data supplied in your comment letter, as well as any additional 

pond effluent data supplied in response to this request, please provide the 

Pond/Impoundment Uni t IDs (e.g., SPD-2) from the 2009 EPA questionnaire for the 

ponds from which

bottom ash and fly ash pond effluent samples were collected. Bottom Ash Pond 

is SPD-1 and the Fly Ash Pond is SPD-2 (Only two active ponds) 
Internet Address (URL) • http./lwww 

epa.gov

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Please provide the dimensions for each pond, including surface area, depth, and residence 

time. We do not have the dimensions of the ponds. The surface area of 

SPD-1 (bottom ash pond) is estimated to be 283,140 ft 2 . The surface area 

of SPD-2 (fly ash pond) is estimated to be 870,000 ft 2 . The depths and 

residence times are unknown; the ponds were designed to have average 

depths of 8 ft. (bottom ash) and 10 ft. (fly ash) for the ponds. The depths 

today would be considerably less. 

Also, please identify what other wastestreams flow into each impoundment and their 

relative contributions. Bottom ash pond; 90% BA sluice water, 8% Coal pile runoff, 1% 

Air Preheater Wash water (non-chemical metal cleaning wastes) and 1% stormwater. 

Fly ash pond; 88% FA sluice water, 1% non-chemical metal cleaning wastes 1% 

stormwater and 10% Other wastewater (boiler blowdown, reverse osmosis reject water, 

green sand filter backwash). 

4. For any fly ash or bottom ash transport water data collected, please provide the Pond/ 

Impoundment Unit ID (e.g., SPD-2) for the pond which fly ash or 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. See answers to question 3 (there is only 

one active bottom ash and one active fly ash pond at the Ratts Station).

5. Describe any solids separation processes and treatment procedures associated with fly ash 

and/or bottom ash transport water or pond effluent. For example, does the plant use 

dewatering bins to separate solids from the ash transport water? Please identify if these 

solids separation processes and/or treatment procedures are located upstream or 

downstream of the sample location. Settling in the ash ponds is the only solid separation 

process. Settling occurs upstream of effluent sampling. 

6. Please identify what chemicals are added to the wastewater upstream of the sample 

location or to the sample during settling. None. 

7. Please provide a more detailed description of the sampling method beyond "collected in 

accordance with Method 1669." Low level mercury sampling is conducted by 

a c o n t r a c t l a b o r a t o r y in accordance with Method 1669; “ c l e a n h a n d s / d i r t y 

hands” technique. I have asked the laboratory to provide a detailed 

description. 

Specify the location of the pond effluent samples provided (e.g., collected from pond 

overflow weir prior to entering discharge canal) and whether each 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). The bottom ash pond 

effluent samples are collected from a manhole immediately downstream of the pond’s 

discharge point, no other water combines with the pond effluent. The fly ash pond 

samples are taken from the discharge pipe prior to entering a ditch that flows to the 

White River. All samples were grab samples. 

8. How often is fly ash and bottom ash sluiced at the plant (provide both the daily frequency 

and duration for typical operating practices)? Both bottom ash and fly ash is 

sluiced daily. Bottom ash is sluiced an average of 8 hours per 

day and fly ash is sluiced an average of 16 hours per day. 
Please identify whether source water is continuously transferred to the ash pond even 

when fly ash and/or bottom ash are not being sluiced. N o , source water is not 

continuously transferred to the ash pond when fly ash and/or bottom ash are not being 

sluiced. Indicate whether samples were collected during periods when the bottom ash is 

not sluiced (i.e., source water is flowing through the sluice pipe). Samples were taken at 

the discharge of the ash ponds and sampling was done during the first shift when it is 

likely that ash was being sluiced, but it is possible some samples were taken when ash 

was not being sluiced. 

9. Please indicate whether any significant discharges lie upstream of the plant's White River 

intake that may contribute to background levels of pollutants (i.e., mining/ excavation 

activities, facilities which discharge into the river). There are numerous significant 

dischargers upstream of the intake including municipal wastewater treatment plants for 

the cities of Anderson, Muncie, Indianapolis, Bloomington, Bedford and several others. 

These plants have major industrial dischargers to their systems. Three coal-fired power 

plants also discharge into the White River upstream of the Ratts intake. The 2,000 

megawatt Indianapolis Power & Light Petersburg Station is only 0.5 miles upstream. 

10. Please provide additional details regarding the source water sampling locations:

a. Please specify the location of the source water samples provided and 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)? Source water 

samples are taken from the river water pumps at the intake. This is upstream of 

the plant discharges; none of the plant's effluent contributes to intake water. 

b. Does the plant treat the intake water prior to use in the fly ash or bottom ash 

sluicing systems? No. If so, how is the intake water treated?

c. Does the plant recycle any process wastewater for use in the fly ash and/or bottom 

ash sluicing system. This includes any recycling of the pond effluent from the ash 

ponds. If so, how? No. 

11. Please provide the associated TSS concentration for the source water, fly ash, and bottom

ash samples. TSS analysis was not done on the samples; they were collected for RPE 

analysis for metals and sulfates. TSS analysis is done weekly for both bottom ash and fly 

ash pond effluents. Bottom ash pond samples averaged 8.0 mg/l TSS with a maximum daily 

value of 43.6 mg/l and fly ash pond samples averaged 11.1 mg/l with a maximum daily 

value of 44.4 mg/l during the last permit cycle (data taken from NPDES Permit Renewal 

Application filed on 2 March 2010). 

12. Please provide the flow rate of the wastewater at the time of sampling, as well as the 

average annual bottom ash discharge flow rate. Sluice rates are provided with 

additional analytical results, effluent flow is not directly monitored from the 

ponds. Please also provide sluice flow for all mercury results presented in Attachment 

2 of your comment letter. Done. 

13. Describe any atypical operations occurring at the plant at the time of any sampling (e.g.,

test bum of new coal). There were no test burns of new coal during sampling. Testing of 

several sorbents for air pollution control injection (direct injection of sorbents into flue gas) 

did occur during some wastewater sampling. In 2008 during a 19 day period in February – 

March, a 19 day period in April and an 8 day period in May tests were done with limestone, 

hydrated lime and lime kiln dust injection respectfully. From November 14 – 15 in 2011 tests 

were done with dry sorbent injections of Trona (sodium sesquicarbonate), sodium carbonate 

and activated carbon. 
14. What basis was used for determination of atypical high pollutant levels from the 

White River which were excluded from calculations? Only a few samples were 

recommended for exclusion due to high source water levels of pollutants. On 

11/4/08 the river water levels of arsenic, chromium and zinc were 114, 165 and 163 

ug/L respectfully. On 7/7/09 arsenic was 865 ug/L and chromium was 57 ug/L. This 

compares to river water levels of BDL (7 ug/L) arsenic, 3.8 ug/L chromium and 40 

ug/L zinc without these high samples. In the additional data provided, on 

11/17/2011 it is obvious that high source water levels of lead caused high levels of 

lead in the pond discharges. The same effect occurred on 11/18/2011 for lead and 

copper. It is apparent that elevated levels of pollutants in the source water can affect 

discharge levels. 

Please indicate what may have caused such high levels in the White River water 

column during these sampling periods. As you can see in the answer to question 

9, there is no lack of significant dischargers to the White River upstream of 

the Ratts Station. Any of them or others could cause elevated levels of 

pollutants in the river. 

15. What basis was used for determination of improper handling or analyses of the water 

samples by the contractors which were excluded from calculations? It was not

improper handling or analyses of the water samples by laboratory contractors that 

lead to excluding two results. It was heavy equipment contractors doing 

dredging work in the ash ponds that we believe lead to high mercury levels. 

These were the only times that dredging activities occurred during effluent 

sampling and the affects were pronounced. In August 2007 the mercury 

concentration in the fly ash pond sample was 16.4 ng/L versus an average 

concentration of 2.76 ng/L w/o that sample. In October 2007 the mercury 

concentration in the bottom ash pond sample was 10.46 ng/L versus an average 

of 1.52 ng/L w/o that sample. 

Information Requested from the Merom Generating Station (Plant ID 03719)

Please provide the same data and supporting details as detailed above for the Merom Generating

Station. The Merom Station has a dry fly ash handling system and uses dewatering bins with 

water recirculation for bottom ash handling. Although the bottom ash handling system will 

discharge wastewater, it goes to a wastewater treatment plant not to a pond, and we have not 

sampled this wastestream separately. 

Attachment 1 provides guidelines for submitting analytical data (and supplemental 

information) under this request.

We appreciate your help in providing the information described above in a 

timely manner. If you have any questions, please do not hesitate to call me at 202-566-

1003.

Sincerely

Engineering and Analysis Division