0 Good Morning Joe,

Thank you for submitting additional data from Hatfield’s Ferry. We believe that this will be helpful for evaluating comments regarding treatment of FGD wastewater. We would like to ask you some follow-up questions to ensure that we understand the submitted data. We understand that it may be difficult to locate some records because of the deactivation of the facility, however we would appreciate any input that you can offer.

These are the specific questions we would ap preciate your input on regarding the Excel Spreadsheet that you sent us a couple of weeks ago.

1. What method was used for Arsenic in column D (AS - Arsenic) and Column E (HGTGEO - Mercury, Trace, Geochemical Labs)? The MDL is included on the spreadsheet, but we don't know what the quantitation limit and the reporting limit are. Arsenic results in column D were analyzed by 200.7 (ICP). The mercury data from Geochemical Labs was by 245.7. Mercury resu lts presented in Columns F & G were also analyzed by Geochemical Labs. Note that Column G is a duplicate of Column F – see explanation to question #4 below. The West Virginia Department of Environmental Protection (WVDEP) requires us to report down to the MDL on our Discharge Monitoring Reports (DMRs). To be consistent in our re porting across all facilities regardless of location (State), Allegheny’s and now FirstEnergy’s labs report their data to the MDL on our DMRs. The data provided in this spreadsheet was submitted to the PADEP on Hatfield’s DMRs. With that being said, the quantitation level for column D arsenic results from FirstEnergy’s lab is 0.03 mg/L and the mercury quantitation level for Geochemical is 0.03 μg/L.

2. In Column D (AS - Arsenic) one value is reported as <MDL and several are reported as 0. What exactly does a reported value of "0" mean? Were these samples also below the MDL? Does this mean the sample was a nondetect? A zero means the analysis returned a result below the MDL. Initially, our Laboratory Information Management System (LIMS) software would only accept numeric entries. To avoid error messages when entering data below the MDL, numeric va lues less than the MDL were entered into

the database. Sometimes zeros were entered and other times actual values, values below the MDL, from the instrument were entered into the database. Any value entered that

was below the MDL returned a less than the MDL value on the DMR. The software has since progressed and can now handle alpha entries such as <MDL. On the DMR, the actual numeric value for the MDL is returned (e.g. < 0.03 mg/L). Also, in order to calculate averages, values that returned a <MDL may have been converted on the spreadsheet to zero (0), per EPA’s guidance for calculating av erages when some of the data is below the

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Formatted: Font: Italic, Font color: Red3. In Column E (HGTGEO - Mercury, Trace, Geochemical Labs) several values are reported as 0. What exactly does a reported value of "0" mean? Were these samples also below the MDL? Does this mean the sample was a nondetect? Yes, see above explanation to question #2.

4. What is the difference between Column F and Column G, both of which are labeled Hg (245.7)? They are identical. Is the unit on Column G a typo? Yes. Should they both be ug/L? Yes! (The same numbers are reported in the two columns, but the units are different) Why is the sample from 9/17/2013 li sted as below MDL in Column F and zero in

Column G? This is a typo. Somehow when I tran sferred the data to the spreadsheet Column F was duplicated in Column G. Colu mn F and G are identical and the units are in micrograms per liter (μg/L) for both columns. The mg/L listed in Column G is a typo. I suggest you delete Column G. The 9/17/2013 sample in Column G had the MDL converted to zero in order to calculate the average and ob tain the proper sample count. In my hurry to get this to you by the deadline, I missed it. Sorry for the confusion! Also, since Geochemical Labs analyzed the data presented in Columns E & F and the only difference is that the data was pulled from two different LIMS because of the switchover from Allegheny to FirstEnergy, the columns could be combined into one dataset for mercury.

5. What is different about the samples reported between 7/7/2009 and

11/29/2011 and 11/6/2012 and 12/10/2013? Allegheny’s Chemical Lab analyzed all of the arsenic samples between 7/7/2009 and 11/29/20 11, while FirstEnergy’s Beta Lab analyzed arsenic samples from 11/6/2011 through 12/10/2013. Decommissioning Hatfield's Ferry only accounts for data acquired after 10/6/2013. The last generation at Hatfield occurred on 10/6/2013, but in order to drain the FGD system all water was directed through the FGD-WWTP and discharged via Internal Monitoring Point 306 (IMP-306). The samples from 11/6/2012 onwards do not have sample numbers. Was a different method or a different laboratory used? Allegheny and FirstEnergy used two different

versions of the same LIMS software. The switchover occurred in November 2012. The search to pull data from Allegheny’s LIMS includes the Lab ID #, whereas, the search that pulls data from Beta’s LIMS does not. Are these values in different units? For arsenic, the units are the same. Allegheny’s lab only ran 245.1 for mercury, as does Beta Lab, so all of the mercury samples were sent out to Geochemical Labs for 245.7 analysis. Again, the reason the 245.7 results are presented in two different columns (Columns E & F – delete G) are because they were pulled from two different LIMS.

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