January 31, 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 Sampling Episode Report No. 6 5 59 (June 20

- 25, 2010)

Dear Mr. Jordan:

Thank you for the opportunity to comment on the draft Sampling Episode Report (SER) for the
June 20

- 25, 2010 sampling event at Pleasant Prairie Power Plant

. We Energies worked closely with the Utility Water Act Group (UWAG) to develop the following comments.

I. GENERAL COMMENTS

Incorporation of Additional Data Collected

In addition to the analytical results in the SER, Pl easant Prairie supplied four additional sets of samples taken in four separate months: September 2010, November 2010, December 2010, and January 2011. Examination of the full data set is necessary to reach any general conclusions. For that reason, we urge EPA to supply the additional data as soon as reasonably possible, so that we can evaluate the entire data set in the proper context.

Data U sability

W e Energies agrees with EPA’s efforts to identify and flag potentially erroneous (outlier) data point s in the Pleasant Prairie data set. However, the identified outliers are still general ly included in calculating four

- day averages and other analyses. If a value is an outlier, then it should be discarded from the data set and not used for any purpose.

Also, there is no discussion in the SER 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. We Energies

231 W. Michigan St. Milwaukee, WI 53203

www.we

- energies.com

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Inadequate Treatme nt System Design and Operations Information

The SER lacks some basic technical information that is very important to a comprehensive understanding of the analytical results. This informatio n is also key to understanding the conditions under which a certain level of treatment can be reliably achieved.

System Design Information

The SER should include, at a minimum, the following information:

1. daily retention time s for each stage of the treatment system; and

2. dimensions and water volume sizes for all individual components of the treatment system, including each holding tank, reaction tank, and clarifier

.

Some of the above information has been provided to EPA either prior to or during sampling events or through EPA’s Information Collection Request (ICR). W e Energies urges EPA to integrate this information into the SER so that the data can be understood in the specific context of the Pleasant Prairie treatment system.

System Operations Information

In addition, EPA should provide information on the facility’s load on each of the sampling days. While the SER states the design megawatt capacity of Pleasant Prairie, it does not indicate the actual megawatt output for each day of sampling. There is no way of determining, based on the SER, whether the facility was operating at full capacity. Daily actual load information is also important to understanding the sampling event results.

Also, EPA’s study plan should have included a comprehen sive study of the coal feed stock during each sampling event. It is clear that coal characteristics have a very significant 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.

Dissolv ed M etals and M ercury D ata

The accurate measurement of dissolved mercury (Hg) and metals in FGD wastewaters is challenging. EPA defines dissolved as metals or Hg associated with particles ≤ 0.45  m or ionic that will pass through a 0.45  m filter. This definition is an operational definition and there are many types of filters rated at 0.45  m (e.g. capsule, flat membrane, etc.). Metals and Hg associated with colloids (i.e. particles < 1  m in size and the vast majority < 0.45  m) can be an important fr action of the element present in FGD wastewaters. The fraction of < 0.45  m colloids removed (retained) during filtrations varies according to the type of filter used. The phenomenon is called colloidal trapping. Capsule filters tend to retain a larger fraction of the

< 0.45  m colloids than do other filter types. This situation can lead to significant differences in

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“dissolved” metals and Hg data depending on the filter used. EPA should consider this fact when evaluating and using dissolved metals or Hg data in developing the steam electric effluent guidelines.

Analytical M ethods D escriptions

The analytical descriptions in S ection 4 and the analytical narratives omit some basic information that should be included and would be helpful in making data evaluations and comparisons. Section 4 should be revised to include basic analytical information as follows:

1. How were the trace metals samples digested? Was a heated strong acid leach digestion patterned after EPA method 200.2 used or some other alternative digestion? Were the metals samples preserved to pH < 2 at least 24 hours prior to digestion (total recoverable) or analysis (dissolved)?

2. How were the Hg samples digested? Was the bromine monochloride digestion done at room temperature, he ated, by method 1631E appendix A, etc.?

3. Were individual grab samples for Hg and some other parameters flow

- proportion ally composited? If so was the compositing done physically prior to analysis or was the “compositing” done arithmetically after the in dividual analysis of each sample?

4. How were the dissolved Hg samples filtered?

5. Was a bubbler

- based 1631E approach used by EPA’s Hg laboratory?

6. How are known interferences in FGD matrices controlled? For example, chloride is a
known interferent in the COD method and the concentration must be carefully controlled
to achieve accurate results

.

7. More information is needed in the analytical narratives for matrix spikes and MS duplicates (MS/MSD) that fail. For example, if f ailed recoveries are cl ose to the acceptance range (87% when the limit is 90 to 100%) then the data can be used with qualification . However, if the recoveries are significantly be low the method acceptance
criteria then the data should not be used.

Calculating Averages

EPA has chosen to calculate four

- day averages of the major constituents throughout the SER. We question the validity of using four

- day averages to characterize the data. For purposes of setting limits, the use of four

- day averages would not be appropriate becau se it would minimize the variability among the data points. At best, the use of the four

- day averages only provides a "snapshot" of general trends. For all other purposes, we urge EPA to avoid averaging the data points.

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Also, the EPA uses the following approach when calculating averages: “ If at least one result was above the quantitation limit, then 1⁄2 the quantitation limit was used in the average calculation for all results that were less than the quantitation limit and the result is reported with
a le ss than sign (“<”) ” (SER page 4

- 1). This approach introduces arbitrarily estimated data into the calculations. A more consistent and conservative approach would be to use the quantitation
limit in the calculations as is done when all results are below th e quantitation limit.

Cyanide Interferences

All of the 40 CFR Part 136 approved cyanide methods are subject to numerous interferences, especially in complex sample matrices. The methods were originally designed for use with discharges from metal plating facilities where cyanide was known to be present. Most of the interferences result in false positives, and many of these are caused by sulfide and other reduced sulfur compounds which may be present in FGD wastewater. Other compounds that

can cau se false positives under the right conditions are organosulfides, thiosulfates, nitrites and other nitrogen compounds. Some of these compounds can actually cause cyanide to be produced during the acid distillation procedure of the method. The procedures for removing interferences provided in the methods are often not effective, and complex samples, such as FGD wastewater, may also contain unknown interferences. It is entirely possible that most if not all of the reported cyanide detections could be sampl e matrix interferences. Therefore, EPA should use caution when interpreting its cyanide results.

II. SPECIFIC COMMENTS

Corrections

A handful of edits and corrections are marked within the body of the draft SER ( attached ). The
most notable corrections are as follows:

 In Section 2. Facility Overview, the capacity should be stated as 594 MW net for each of the two generating units.

 In Section 2.1 FGD Scrubber System, the unit of measure for the rate of gypsum generation should be pounds per hour instead of tons per hour.

 In Section 2.2.1 Physical/Chemical Separation, the draft report incorrectly states that treated effluent was transferred to the Metal Cleaning Basin. While it is possible to send treated effluent to that basin, it has not be en done. The effluent was instead directed to the filtrate sump to be recirculated to the scrubber.

F low Data

A footnote below Table 3

- 3 requested that we provide the flow rate for the influent to the FGD wastewater treatment system from the secondary h ydrocyclone as well as the hourly average flow rates for the effluent from the FGD wastewater treatment system. Accordingly, the hourly average flow rates for the effluent are provided in the attached Excel document. The influent flow rate is only availa ble as an estimate of 60 gpm based on changes in the equalization tank

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level during the sampling episode. These flow rates have been entered into Table 3

- 3 in the attached copy of the draft SER.

Total Phosphorus

EPA (TestAmerica, TA) and UWAG (Alabama Power Company, APC) used similar colorimetric methods to measure total phosphorus in the samples from the 4DSSS. TA used EPA method
365.1 and APC used SM4500P

- E. EPA and UWAG phosphorus data were comparable for SP

2 but not SP

- 1 (see Table P4

- 1 ) . The comparison suggests that the EPA data underestimates the total phosphorus concentration at SP

- 1. The analytical narrative in Appendix B indicates detectable phosphorus in the method blank for SP

- 1 samples but no MS/MSD analysis was performed on any of the SP

- 1 samples. The MS/MSD analysis on the EPA SP

- 2 sample produced low percent recoveries (i.e. 62% and 65%) indicating possible low bias caused by matrix interference and the sample was qualified as a minimum value. It is possible that a
similar m atrix interference was present in the EPA SP

- 1 samples and was responsible for the apparent underestimation of total phosphorus.

TABLE P4

- 1 . Comparison of 4

- Day Averages of EPA & UWAG Split Sample

Phosphorus Data

Source

- > UWAG EPA Processing

- > Total Total
SP / Parameter

- > Phosphorus (ppm ) Phosphorus

(ppm )

SP

- 1 5.42 < 0.347

SP

- 2 0.05 < 0.0506

Miscellaneous Issues

In the analytical narrative in Appendix B, Frontier Geosciences (FGS) validates their EPA
method 1631 E calibration using a linear regression correlation factor criterion of > 0.995. This statement is misleading because method 1631 E does not allow a linear regression calibration
curve. Rather

, method 1631 E uses a mean calibration factor (CFm) which is a simple arithmetic mean of the five or more individual calibration factors. The acceptance criteria for the method 1631E calibration are an RSD of < 15% for the five or more CF’s and recovery between 75

- 125% at the method reporting limit of 0.5 ppt. FGS m ay want to revise the analytical narrative to clarify this situation.

In the SER data A ppendix A, the ratio of Q L (reporting limit) to MDL (detection limit) for EPA method 200.7 averages ~ 20 with a range of range ~ 3 to 55. The expected ratio is 3

- 5 as
shown for EPA method 200.8 QL /M D L’s listed in the SER. The reason for this situation is not

clear. Are the MDL’s too low or the Q L’s too high for the elements with elevated ratios?

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Many of the EPA chromium (Cr) data in the SER tables are qualified (flagged) “^” with the
statement “ ICV, CCV, I CB, CCB, ISA, ISB, CRI, or MRL standard: Instrument relate d QC
exceeds the control limits .” However, the Test America (TA) EPA method 200.8 analytical narrative (Appendix B) makes no mention of any quality control (QC) issues associated with the Cr analyses. Should the Cr data be flagged or not?

We appreciate your consideration of our com ments. Please contact me at (414) 221

- 2158 or by

e

- mail (David.Lee@we

- energies.com) if you have any questions regarding our comments or attachments

.

Sincerely,

David M. Lee, P

. E

. Manager

– Water Quality

Attachments : 1) We Energies Mark

- up of SER 2) Excel Spreadsheet for Treatment Facility Flow Data