April 30, 2012

Via Electronic Mail
Ronald P. Jordan U. S. EPA Headquarters Engineering & Analysis Division (4303T) Ariel Rios Building 1200 Pennsylvania Avenue, N.W. Washington, DC 20460 RE: Pleasant Prairie Monitoring Data - Monthly Sampling Events
Dear Mr. Jordan: Thank you for the opportunity to comment on the draft data from the additional samples taken at Pleasant Prairie Power Plant in September, November, and December 2010, and January 2011. We Energies worked with the Utility Water Act Group (UWAG) to develop the following comments. Requested split sample results for mercury are also provided.
I. GENERAL COMMENTS Data Usability We Energies agrees with EPA’s efforts to identify and flag potentially erroneous (outlier) data points in the Pleasant Prairie data set. However, outlier values should be discarded from the data set and not used for any purpose. Also, there is no discussion of how flagged data points will be used (or excluded) from consideration in calculating the new steam electric effluent guidelines. For example, data points flagged B, Est, F and T indicate potentially significant inaccuracy (bias) in the associated data. Inadequate Treatment System Design and Operations Information In our comments on the draft Sampling Episode Report (SER) for Pleasant Prairie, we noted the lack of some basic technical information regarding treatment system design and operations that is very important to a comprehensive understanding of the analytical results. This information is also key to understanding the conditions under which a certain level of treatment can be reliably achieved. All of those comments also apply to the additional monthly sampling data. However, we reiterate here an essential point:

 EPA’s study plan should have included a comprehensive study of the coal feed stock during each sampling event. It is clear that coal characteristics have a very significant We Energies 231 W. Michigan St. Milwaukee, WI 53203 www.we-energies.com

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impact on flue gas desulfurization (FGD) system chemistry and wastewater treatment. While EPA gathered some information about coal constituents during the sampling events, it should have collected full information about levels of sulfur, metals, and chlorides in the coal, as well as the heating value of the coal being burned during the relevant period for the sampling event. Analytical Methods Descriptions The analytical descriptions in the draft SER and the analytical narratives provided with both the draft SER and the additional monthly sampling data omit some basic information that should be included and would be helpful in making data evaluations and comparisons. We reiterate our request for this basic analytical information, including how trace metals and mercury samples were digested, how dissolved mercury samples were filtered, and how known interferences in FGD matrices were controlled, as stated in our January 31, 2012 comments. Quality Assurance/Quality Control Issues Detections in laboratory preparation blanks (“B” qualifier) — Where EPA detected analytes in laboratory blanks the results are flagged with a “B.” Some “B” qualified results are close to or even below the reporting limit, and thus also flagged with a “J.” For example, the Set 2 effluent iron result (Table B5-11) and the Set 3 phosphorus effluent result (Table B5-12) are flagged with both “J” and “B.” The actual result of the blank is not reported. If the blank were taken into account in the data review process, then the results could be fully evaluated. Without the actual blank results, our ability to evaluate these data points is limited. Problems with ICV, CCV, ICB, CCB, ISA, ISB, CRI or MRL Standard (indicated by a “^”) — This “catch all” mark appears to have been used by EPA to indicate a multitude of possible QC problems that would only be evident from an examination of the raw laboratory data. For ICP/MS, problems with the ICV (initial calibration verification) are supposed to be resolved before analysis proceeds. Also, the CCV analyses (continuing calibration verification,performed once every ten samples) are supposed to be corrected by recalibration and reanalysis. It is unclear why any of the samples would be qualified for either ICV or CCV outliers. MS/MSD QC Excursions (“F”) — Any “F” qualified results should be considered estimated values and excluded from the EPA dataset. The “F” flag appears on the following FGD effluent data: Set 1 COD, Cyanide, Phosphorus, Silver Set 2 COD

II. SPECIFIC COMMENTS/SPLIT SAMPLE RESULTS Table B4-3 for Pleasant Prairie includes an incorrect title for column 5. The title indicates that the information in that column is for a bioreactor, but the plant does not have a bioreactor. The title instead should refer simply to effluent samples (from the physical/chemical treatment system).

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EPA requested that Pleasant Prairie provide the split sample influent and effluent mercury data for all the data sets. We did not collect any influent split samples and, therefore, have no influent mercury results. However, as you requested, we are providing the following split sample mercury results for sets 1, 2, 3, and 4 FGD effluent: Pleasant Prairie Split Sample Results - Total Recoverable Hg Data for SP-2

Sampling Date SP-2, Total Rec. Hg, μg/L 09/30/2010 0.207 11/03/2010 0.122 12/08/2010 0.034 01/26/2011 0.143

We appreciate your consideration of our comments. Please contact me at (414) 221-2158 or by e-mail (David.Lee@we-energies.com) if you have any questions regarding our comments. Sincerely,

David M. Lee, P.E. Manager – Water Quality