UNITED STATES ENVIRONMENTAL PROTE C T I ON AGEN CY WASHIN G TON , D

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March 10, 2014 Ms. Michalene Reilly Manager , Environmental Services Hoosier Energy Rural E lectric Cooperative P.O. Box 908 Bloomington , IN 47402-0908 Dear Ms. Reilly: OFFICE OF WATER

We received the comments submitted by Hoosier Energy Rural Electric Cooperative (Hoos ier) regarding EPA ' s proposed effluent limitations guidelines and standards (ELGs) for th e 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 (UWA G) comments , which Hoo s ier 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 , vali date , and evaluate the ash data s ubmitted. We are therefore asking that you provide the information described be low in order to ens ure that the Agency appropriately considers your s ubmission. As yo u are aware , E PA 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 th e Frank E. Ratts Generating Stat ion 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 paramet e rs for a permit renewal. Additionall y , Hoosier provided data on 29 samp les of fly ash pond effluent and 28 samples of bottom ash pond effluent collected for mercury analysis. 1
. Pl ease 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 sam ple data where available. 2. Please provide any fly ash and/or bottom ash pond effluent data collected s ince Dec ember 2009
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. For the pond effluent data supp lied in your comment letter, as well as any additiona l pond effluent data supplied in response to this request, please provide the Pond/Impoundm ent 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 collect ed
. Please pro v ide the

I n te rne t Address (URL) • http ./lwww epa . gov R ecyc l e d/ Re c yc lable • Pnnted with Vegeta ble Oil Based Inks on 100% Postconsumer

. Process Chlorine Free Recycled Paperdimensions for each pond, including surface area, depth, and residence time. Also, please identify what other wastestreams flow into each impoundment and their re lative contributions. 4. For any fly ash or bottom ash transport water data co llected , plea se 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. 5. Describe any solids separa tion 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 th e sample location. 6. Please identify what chemicals are added to th e wastewater upstream of the sample location or to the samp le during settling. 7. Please provide a more detailed description of the sampling method beyond "collected in accordance w ith Method 1 669." 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). 8. How often is fly ash and bottom ash slu iced at the plant (provide both the daily frequency and duration for typical operating practic es)? Please identify wh ether source water is continuously transferred to the ash pond even 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 sl uice pipe). 9. Please indicate whether any significant discharges lie upstream of the plant's White Ri ver intake that may contribute to background levels of pollutants (i.e., mining/ excavation activities, facilities which discharge into the river). 10. Please provide additional details regarding the so urce water sampling locations: a. Please specify the loca tion of the source water samples provid ed and indicate whether the plant discharge i s upstream or downstream of intake water location (i.e., does any of the plant 's effluent contribute to intake water)? b. Does the plant treat the intake water prior to use in the fly ash or bottom ash sluicing systems. If so, ho w is the intake water treated? c. Doe s the plant recycle any process wastewater for use in the fly ash and /or bottom ash s lui cing system. This includes any recycling of the pond effluent from the ash ponds. If so, how? 11. Please provide the associated T SS concentration for the source water, fly ash, and bottom ash samples. 12. Please provide the flow rate of the wastewa ter at the time of sampling, as well as the average annual bottom ash discharge flow rate. Please also provide s luice flow for all mercury resu lt s presented in Attachment 2 of your comment letter. 13. Describe any atypical operations occurring at the plant at the time of any sampling (e.g., test bum of new coal).14. What basis was u se d for determination of atypical hi gh pollutant levels from the White River whi ch were excl uded from calculations? Pl ease indi cate what may have caused such high levels in the White River wate r co lumn durin g these samplin g p eri ods
. 15. What basis was used for d etermination of im proper h andlin g or analyses of the water sampl es by the co nt racto r which were excluded from calcu lat io ns? Inform ation Requestedfrom th e Mero m Generating Sta ti on (Plan t ID 03719) Plea se prov ide the same data and supportin g d eta il s as detail ed above for the Merom Generatin g Station. Attachment 1 provi de s guidelines for submittin g an a ly ti cal data (and supplemental informatio n) under thi s request. We app rec iate your help in pro v iding the information de scribed above in a timely manner. If you have any questions , pl ease do not hes itate to call me at 202-5 66-1003
. Sincerely,

Eng ineering and Ana lys i s Divis ionATTACHMENT 1 G uid elines for Submitting Analytical Data for the Steam Electr ic Power Gene rating Effluent G ui delines Rulemaking

This document provides guidance regarding the submissio n of analytical data in response to the proposed Steam Electric ELGs, including the type of supplemental information that should be provided along with any analytical data, in order to ensure that EPA can use the data to inform its analyses for the final action. The data you submit should reflect typical operatin g co nditions and be represe ntative of properly operating treatment systems. Data you su bmit sho uld be relevant to fly ash transport water, bottom ash transpo rt water, or ash pond effluent. Imp ortant Considerations
• The data provided should include both treated and untreated wastewater. • Samp le s should be collected prior to commingling the wastewater with any other wastestreams. • For wastewater collected from surface impoundments or other systems containing multipl e types of wastes, the w a stewater s hould compri se at least 75% oft h e influent wastewate r vo lume and influent pollutant mass load in g. Furthermore , the data submitted s ho uld specifically identify all sources of wastewater and th e es timated co ntribu tio n to wastewater volumes and pollutant loadings. • Pollutant data should be collected using sufficiently se nsitive, EPA-app roved analytica l methods in 40 CFR Part 136 appropriate for the po ll utant concentrations present in th e wastewater.

Data Subm iss i on Format and C riteria To facilitat e EPA's analysis and u se ofthe analytical data, the data should be sub mitted using the format provided in the Microsoft Exce l Workbook titled "Analytical Data T able." The Analytical Data Tabl e workbook provides t he content, structure, and format for the analytical data submission. Included within the workbook are two separate spreads heets. The spreadsheet titled
" Data Table Structure" provides the table for entering the ana lytical data. Included in the table are three examp le entries to p rov ide some context of how to populate eac h of the fie lds in the table. Additi o na ll y , th e spreadsh eet titled "Field D escriptions " describes each fi eld included in the table. Provide the individual sample results associated with the sampling locations. Entries that average multi pl e results for a sampling point are of limited use. The follo wing is the information that should be provided for each individual samp ling result, as applicable (see the "F ield D escrip tion s" spreadsheet for more details):
• Plant Survey I D (from the Questionnaire for the Steam Electric Effluent Guidelines); • Plant Name;• Date Sample Co lle cte d ; • Analyte (for m etal s, including whether it is total recoverable or dissolved); • CAS Number ; • Analytical Method; • Type of Sample Co llected (e.g
. , grab, 24 -hour composite); • Type of Sample Analyzed (e.g., total recove rable , dissolved) • Units; • Non

- Detect Indicator; • Concentration; • J-Value Concentration; • Detection Limit; • Reporting Limit ; • Dilution Factor ; • Qualifiers; • Qualifier Description ; • Wastest ream rep resented by result ; • Flow rate; and • Sample point description. For EPA to evaluate whether the data provided are valid and of sufficient quality for use in th e loadings analyses and/or limitation s development , the fo ll owing suppl ementa l information should accompany any submitted analytical data , as applicable:
• Plant Survey ID (f rom the Questionnaire for the Steam Electric Effluent Guide lines); • Plant Name; • SE Unit IDs associated with each sample (ba sed on response s to the Questionnaire for the Steam Electric Ejjluent Guidelines); • Chemicals and dosages added to the treatment system, including location of injection points; • Process flow diagram of the system sampl ed, including identifying the specific samp le locations for which data are being provided ; • Identify the date when the system began operating; • Description of all wastestreams that contribute to the sample location and the associated contribution from each wastestream (e.g. , percent of flow contribution); and • Identification of whether any data or supplemental information sub mitted to EPA is considered confidential business information.