Hunton & Williams LLP • Counsel to UWAG • 1900 K Street, N.W. • Washington, D.C. 20006 

Steering/Audit Committee 

Angela M. Grooms, 

Chairman 

C. Richard Bozek 

Rayburn L. Butts 

Alan E. Gaulke 

M. R. (Mick) Greeson 

David M. Lee 

James F. Stine 

John G. Valeri, Esq. 

Kerry M. Whelan 

Judson White 

February 1, 2010 FILE NO.: 29142. 070324 

VIA ELECTRONIC MAIL 

Mr. Ronald P. Jordan 

U. S. Environmental Protection Agency 

Engineering & Analysis Division 

1200 Pennsylvania Avenue, N.W. 

Mail Code 4303T 

Washington, DC 20460 

RE: Comments on EPA’s Draft Glossary for the Steam Electric Effluent Guidelines 

Rulemaking ICR, Docket No. EPA-HQ-OW-2009-0819 

Dear Ron: 

On behalf of the Utility Water Act Group (UWAG), thank you providing us with the draft 

glossary for the steam electric effluent guidelines questionnaire (Questionnaire or ICR, noticed in 

74 Fed. Reg. 55,837 (Oct. 29, 2009)). UWAG requests that the Agency fully consider these 

comments before submitting a revised ICR to the Office of Management and Budget. We also 

request that EPA provide a written response to these comments, as it will for all comments 

submitted by the original December 28 comment deadline. 

UWAG would welcome further dialogue with EPA on these comments, as there are several 

major areas where more clarity is needed. Please note that the attachments to this letter contain 

many recommendations for substantive changes to the glossary and the Questionnaire. 

I. Definitions of “Wastewater Treatment System” and “Wastewater Treatment Unit” in 

Part D and Glossary 

UWAG said in its December 28, 2009 comments on the Questionnaire that the instructions 

to Part D are confusing. Unfortunately, the new glossary does not resolve the confusion. 

EPA’s concept appears to be to divide the world into two categories of wastewater 

treatment systems, “pond/impoundment systems” and others (which might be called – and EPA 

sometimes does – “non-pond” systems but are more often referred to as “wastewater treatment” 

systems). 
Mr. Ronald P. Jordan 

Page 2 

February 1, 2010 

EPA’s definition of “wastewater treatment system” is “a combination of one or more 

‘wastewater treatment units,’ other than ponds/impoundments, designed to achieve wastewater 

treatment.” ICR, p. D-1. EPA defines “wastewater treatment units” to include “primary settling 

ponds/impoundments, chemical precipitation, pH adjustment, clarification, biological reactor, 

thickeners, filters, and constructed wetlands.” Id. The inclusion of only primary settling 

ponds/impoundments in this definition suggests that no other types of ponds (e.g., secondary 

settling ponds, recirculating holding ponds, polishing ponds) are included within “wastewater 

treatment units” or “wastewater treatment systems.” This interpretation is reinforced by the note 

on p. D-1 of the ICR.1

EPA’s definition of “pond/impoundment systems” is “a treatment system consisting of one 

or more ponds/impoundments.” Id. As we read these definitions, a pond/impoundment system is 

comprised solely of ponds or impoundments, and a “wastewater treatment system” is comprised of 

other types of treatment units and only primary settling ponds. Therefore, any treatment system 

that has, for instance, a clarifier and any type of pond other than a primary settling pond, is not a 

“pond/impoundment system” and also is not a “wastewater treatment system.” 

EPA should retain the definition of “pond/impoundment system” but change the definition 

of “wastewater treatment system” to include any type of pond that occurs within a treatment 

system with other types of units. UWAG recommends that “wastewater treatment system” be 

defined as “a combination of one or more ‘wastewater treatment units,’ including

ponds/impoundments, designed to achieve wastewater treatment, except that ‘wastewater 

treatment system’ does not include systems in which ponds/impoundments are the only units.” 

The definition of “wastewater treatment units” should be revised as follows: “a unit operation used 

to remove pollutants from process wastewater. Wastewater treatment units include, but are not 

limited to, ponds, chemical precipitation, pH adjustment, clarification, biological reactor, 

thickeners, filters, and constructed wetlands.” 

We urge EPA to revise these definitions and the instructions to Part D and provide UWAG 

with an opportunity to review the revised texts. Otherwise, many respondents are likely to be 

confused and unable to provide the information that EPA is seeking. 

 

1

 The note states: “If a settling pond/impoundment is part of a broader ‘wastewater treatment system’ containing 

non-pond units (e.g., a primary settling pond/impoundment unit in a biological wastewater treatment system), it is 

not considered part of a pond/impoundment system.” 
Mr. Ronald P. Jordan 

Page 3 

February 1, 2010 

II. The Definition of “Leachate” Should be Revised 

EPA’s proposed definition of leachate is too broad. The definition in part provides 

“[l]iquid, including any suspended or dissolved constituents in the liquid . . . that pass through the 

containment structure (e.g., bottom, dikes, berms) of a surface impoundment.” The definition 

specifically includes “the terms seepage, leak, and leakage, which are generally used in reference 

to leachate from an impoundment.” Under this definition, EPA’s plans for leachate sampling 

under Part G of the questionnaire are very expansive. Apparently, it would require each seep from 

a surface impoundment (no matter how de minimis) to be sampled if the seep occurred during the 

sampling period set by the Questionnaire. 

 UWAG recommends that the definition of “leachate” be limited to drainage from 

landfills, as indicated in Attachment A. If EPA persists with plans to sample “leachate” from 

surface impoundments, it will be an incredibly burdensome task to characterize a very minor 

flow. EPA says it plans to require 175 facilities to respond to Part G, and anticipates only about 

50 plants “actually operate leachate collection systems and therefore would collect and analyze 

wastewater samples.” Supporting Statement, p. 2-2 (footnote b to Table 2-1). This is a gross 

underestimation due to the broad definition of leachate. It is more likely that all - or almost all - 

of the 175 facilities required to fill out Part G will have to collect samples, and some of them will 

have to collect samples at multiple sites. 

Many surface impoundments include toe drains, relief wells, or similar drainage systems as 

part of overall structural integrity. These drains are used to enhance structural stability and to 

provide a controlled outlet for water to reduce the potential for internal erosion through or under 

the dam. There are many different types of drainage systems (including finger drains, chimney 

drains, blanket drains, trench drains, seepage berms, and relief wells). Many surface 

impoundments use a mix of different types of drainage systems. Some surface impoundments 

have more than 40 toe drains or drainage pipes, all of which may, taken collectively, produce a 

very small flow rate of a few drops per minute to 10 gallons per minute. It is unjustifiable to 

require facilities to sample the many toe drains or drainage pipes from surface impoundments 

when the flows involved are minor and the expense of sampling is significant. 

For landfills with leachate collection systems, it may be possible to design an appropriate 

sampling procedure that is not overly burdensome. But the inclusion of any “leachate” sampling 

from surface impoundments would be overly burdensome. 
Mr. Ronald P. Jordan 

Page 4 

February 1, 2010 

III. Definition of “Plant” is Too Broad and Imposes Additional Burdens 

EPA proposes to define “Plant” as: “Includes all contiguous and non-adjoining property 

and equipment that is under operational control of the facility, including non-adjoining landfills, 

surface impoundments, and outfall structures.” This very broad definition will cause several 

problems for respondents. First, many facilities contain equipment and structures that are not 

owned by the plant operator, but are owned by other entities. For example, as UWAG explained in 

its original comments, at some sites the plant operator is in charge of units that are owned in their 

entirety by unrelated corporations or groups of entities. The plant operator may oversee all 

operations related to the unit, but the operator usually does not have access to the financial 

information for the unit. This is particularly the case when a unit on the facility grounds is owned 

by an unregulated entity. In that instance, there are often legal barriers to sharing information 

between the regulated power plant operator and the unregulated owner of the unit. The proposed 

definition of “Plant” as including all “property and equipment under the operational control of the 

facility” would apparently make the plant operator responsible for reporting on the unit it is 

operating, but does not own, but because of financial restriction, the plant operator cannot be 

responsible for collecting some of the types of information EPA is requesting. Therefore, the plant 

operator is in an untenable position – it cannot legally obtain the information that EPA is requiring. 

Also, including all non-adjoining property under the control of the facility as part of the 

“Plant” creates unique burdens in some cases. Some plants control off-site landfills that may be 

many miles away from the facility. In some cases, these off-site landfills are owned by other 

entities, but remain under the control of the facility. In such situations, the facility receiving the 

Questionnaire incurs the burdens of gathering information about an off-site facility that is distant 

from the facility and may be dependent on the off-site operator to supply the necessary information 

for the questionnaire. 

For these reasons, UWAG recommends that the definition of “Plant” be revised in two 

ways. First, it should exclude any on-site or off-site equipment, structures, or parcels owned by 

entities other than the questionnaire recipient. Second, non-adjoining landfills, surface 

impoundments, and outfall structures should not be included within the definition unless they are 

owned by the facility and directly used by the facility. 

IV. EPA Should Use Quantitation Levels for Data Reporting and the Glossary Should 

Include a Definition of “Quantitation Level”

The Questionnaire requires reporting of existing FGD metals data as less than the 

detection limit (question B3-3). UWAG recommends that EPA collect only data above the 

appropriate quantitation level (QL) (also known as method reporting limit (MRL), minimum 
Mr. Ronald P. Jordan 

Page 5 

February 1, 2010 

level, method quantification level (MQL), or limit of quantitation). Data below the QL are 

highly variable and are not reliable for compliance monitoring and therefore should not be 

included in EPA’s regulatory effort. 

Most existing data sets are almost certainly reported by laboratories using instrument 

detection limits (IDL) determined by replicate analyses of an ideal dilute acid reagent blank or 

dilution of a low calibration standard. IDL’s serve as a guide of instrument (method) sensitivity. 

However, the actual method detection limits (MDLs) are sample matrix dependent and may vary 

as the sample matrix varies. This situation is particularly true for complex, elevated TDS FGD 

wastewaters where the true matrix-specific MDL is likely several fold higher than the IDL. Very 

few, if any, laboratories have matrix-specific MDLs on FGD wastewaters. 

EPA should not request data that are less than the QL. Even though QLs are derived 

from IDLs, the use of QLs will lessen the chance of reporting inaccurate data. In addition, some 

laboratories report existing data as less than the Practical Quantitation Limit (PQL) which has 

been approved for compliance monitoring in some states. Because FGD wastewater may require 

dilution to lower the TDS levels prior to analysis by Method 200.8, the sample-specific 

quantitation limit is the most appropriate level to use when reporting data. The sample-specific 

quantitation limit is the appropriate QL for a unique sample multiplied by the total dilution from 

the original sample at which a unique sample was quantified. 

EPA should also request any significant modifications to the standard EPA method used 

to obtain the existing metals data in FGD wastewaters. For example, if a respondent is reporting 

data obtained using a standard inductively coupled plasma-mass spectrometry (ICP-MS) method 

incorporating an interference control technology such as a dynamic reaction cell (DRC) or 

collision cell (CRC), then the modification should be provided in the Questionnaire response. 

For example, EPA Method 200.8 modified for CRC-ICP-MS using helium as the cell gas for all 

metals except selenium where hydrogen is used as the cell gas. 

The Questionnaire requests that the nominal quantitation limit stipulated for the standard 

EPA method employed should be used to calculate the sample-specific quantitation limit. For 

many methods (e.g., EPA 200.7 and EPA 200.8), no nominal QL is given in the method. Again, 

the Questionnaire should request the sample-specific quantitation limit based on the laboratory’s 

QL. For example, if the appropriate QL is 5 ppb and the sample was diluted 10 fold prior to 

being analyzed, then the sample specific quantitation limit would be 50 ppb (i.e., 5 x 10). 

This methodology for reporting data should apply to any new data required by EPA, such 

as the leachate data in Part G. 
Mr. Ronald P. Jordan 

Page 6 

February 1, 2010 

In addition, UWAG recommends the following definition for “quantitation level”: 

The lowest concentration at which the entire analytical system 

gives a recognizable signal and acceptable calibration point (see 

EPA method 1638 section 18.26). The MRL can be calculated by 

multiplying laboratory-determined MDL by 3.18 and rounding 

result to nearest multiple of 1, 2, 5, 10, etc. in accordance with 

procedures used by EAD and described in EPA Draft National 

Guidance for the Permitting, Monitoring, and Enforcement of 

Water Quality-Based Effluent Limitations Set Below Analytical 

Detection/Quantitation Levels, March 22, 1994 (see EPA method 

1638 page 39). 

V. Definitions of Air Heater Cleaning Wash Water, Boiler Fireside Cleaning Wash 

Water, and Boiler Tube Cleaning Wash Water Should be Revised 

EPA proposes to define air heater cleaning wash water as “Any water or cleaning solution 

used for or generated from cleaning the air heater.” This definition – and the similar definitions 

for boiler fireside cleaning wash water and boiler tube cleaning wash water – blur the current 

distinction in 40 CFR Part 423 between metal cleaning wastes and chemical metal cleaning wastes 

by not distinguishing between water-only rinses and rinses that mix water and chemicals. EPA 

should be careful to gather information in a manner that allows it to distinguish between water 

used by itself for cleaning purposes and water used with other substances to clean. By mandating 

that air heater cleaning wash water includes both water-only rinses and water and chemical rinses, 

EPA is likely to gather data in a way which lumps the two types of cleaning together. This is not 

appropriate, as the water quality of the two types of cleaning wash waters will be different. For 

example, water-only rinses may be appropriate for reuse or recycling, but EPA will not be able to 

evaluate possible reuses if it combines water-only rinses and chemical rinses into the same 

category. 

VI. Glossary Includes Terms that Are Not Found Within the Questionnaire 

The glossary includes some terms that do not appear in the version of the Questionnaire 

that was released for public comment in October 2009. It is difficult to assess the appropriateness 

of a defined term for purposes of the Questionnaire when we do not know the context in which the 

term will be used. The new terms included in the glossary but not appearing in the October 

version of the Questionnaire include: carbon capture wastewater, cost of service, floor drain 

wastewater, gypsum pile, SCR catalyst washing, and uncontaminated stormwater. 
Mr. Ronald P. Jordan 

Page 7 

February 1, 2010 

Based on these new terms, it appears that EPA is making some significant changes to the 

Questionnaire. UWAG urges EPA to provide it with an additional opportunity to review the full 

Questionnaire before it is sent to the Office of Management and Budget. We believe such a review 

would be mutually beneficial, and is warranted due to the complexity of the Questionnaire and its 

importance to the overall rulemaking. 

VII. FGD Terminology, Revised Figure B-1, and New Figure B-2 

UWAG has reviewed EPA’s revised FGD terminology and the new Figure B-1. In the 

attachment, UWAG has provided some recommendations for revisions to the FGD terms. We 

believe the revised terms will be clearer to a majority of industry personnel than the terms EPA 

proposed. We have also revised Figure B-1, which illustrates a typical FGD scrubber system 

(Attachment B) and have provided new Figure B-2, which illustrates a single pass scrubber 

system. 

VIII. EPA Has Failed to Define Some Key Terms 

In its original comments, UWAG listed many key terms that would benefit from definition 

and would improve the clarity of the Questionnaire for respondents. Some of the terms remain 

undefined by the new glossary. Those terms include the following: 

 byproducts 

 storage 

 disposal 

 permanently 

 temporarily 

 closed 

 retired 

 idle 

 extended period of time 

 normal operation 

 Eastern bituminous/western bituminous 

 mechanically aided 

 residence time 

 episode 

We reiterate that these terms should be clarified with proper definitions. To illustrate the problem 

of leaving these terms undefined, respondents will have no way of knowing what EPA means 
Mr. Ronald P. Jordan 

Page 8 

February 1, 2010 

when it requires respondents to “provide information for all steam electric generating units which 

were operated in 2009, including systems which have been idle for an extended period of time.” 

Questionnaire, p. A-24 (emphasis added). UWAG urges EPA to clarify all of these terms and to 

provide UWAG with an adequate opportunity to review the new definitions. 

Additionally, EPA has bolded some terms in the glossary without providing definitions 

(see, e.g., “byproducts” within the definition of “non-contact cooling water,” “surface waters” 

within the definition of “NPDES permit,” and “disposal” within the definition of zero discharge). 

If EPA is preparing definitions for these terms, please provide them to UWAG as soon as possible 

for our review. 

Please see Attachment A for additional comments on individual definitions, and 

Attachments B and C for diagrams illustrating two types of FGD scrubber systems. 

UWAG would be glad to meet with EPA to explore these issues in more detail. Please call 

me if you have any questions about these comments. 

Very truly yours, 

Donna B. Hill 

Chair, Effluent Guidelines Committee 

Attachments 
Attachment A

EPA Definition UWAG Comment 

Aerobic biological reactor – A tank in which 

material is converted from an unwanted form 

into a desired form by microorganisms in the 

presence of free oxygen. 

UWAG recommends rewording the 

definition as follows: “A tank in which 

material is converted from one form into 

another form by microorganisms in the 

presence of free oxygen.” 

Air heater cleaning wash water – Any water 

or liquid cleaning solution used for or generated 

from cleaning the air heater. 

See discussion above. 

Anaerobic biological reactor – A tank in 

which material is converted from an unwanted 

form into a desired form by microorganisms not 

in the presence of free oxygen. 

UWAG recommends rewording the 

definition as follows: “A tank in which 

material is converted from one form into 

another form by microorganisms not in the 

presence of free oxygen.” 

Background concentration – The 

concentration of a substance in an 

environmental media (air, water, or soil) that 

occurs naturally or is not the result of human 

activities.

UWAG recommends rewording the 

definition as follows: “The concentration of 

a substance in an environmental media (air, 

water, or soil) that is not associated with 

plant processes or activities.”

This rewording is necessary for consistency 

in how background concentrations in intake 

water are treated under Clean Water Act 

regulations. See, e.g., 40 CFR 122.45(g). 

Base load unit – A unit normally operated to 

produce electricity at an essentially constant rate 

and runs continuously. 

Reword the definition as follows: “A unit 

normally operated to produce electricity at 

an essentially constant rate and which 

typically runs for extended periods of time.” 

Boiler fireside cleaning wash water – Any 

water or liquid cleaning solution used for or 

generated from cleaning the boiler fireside.

See discussion above. 

Boiler tube cleaning wash water – Any water 

or liquid cleaning solution used for or generated 

from cleaning the boiler tubes.

See discussion above. 

Reword the definition as follows: “Any 

water or liquid cleaning solution used for or 

generated from cleaning the interior surface 

of boiler tubes.” 
2 

EPA Definition UWAG Comment 

Bottom ash – The heavier ash particles that are 

not carried out of the boiler with the flue gas, 

and which settle in the furnace or are dislodged 

from furnace walls. Includes boiler slag 

collected in wet-bottom furnaces. Economizer 

ash is included when it is collected with bottom 

ash. 

This definition should be consistent with the 

current definition of “bottom ash” within 40 

CFR § 423.11: “The term bottom ash 

means the ash that drops out of the furnace 

gas stream in the furnace and in the 

economizer sections. Economizer ash is 

included when it is collected with bottom 

ash.” 

Unless this definition is consistent with the 

common industry-specific definition, EPA is 

likely to find that recipients provide 

erroneous answers. 

Carbon capture system – An air pollution 

control system intended to reduce emissions of 

carbon dioxide. Includes both post-combustion 

and pre-combustion carbon capture/reduction 

technologies.

Replace the definition with the following: 

“An air pollution control system that 

removes carbon dioxide from a 

manufacturing or power generation process 

for beneficial reuse (i.e., enhanced oil 

recovery, food processing, chemical 

manufacturing) or for permanent storage. 

Capture systems include post-combustion, 

pre-combustion, and oxy-fired combustion.” 

Chemical precipitation/flocculation – Process 

involving the addition of chemicals to alter the 

physical state of dissolved and suspended solids 

and facilitate their removal by sedimentation.

There should be separate definitions for 

chemical precipitation and flocculation. The 

definition of chemical precipitation should 

be reworded as follows: “Process involving 

the addition of chemicals to alter the 

physical state of dissolved and suspended 

solids and facilitate their removal by 

sedimentation or filtration.” 

See definition for flocculation below. 

Clarification – A sedimentation process to 

remove solid particles from a liquid stream by 

gravitational force.

Reword the definition as follows: “A 

sedimentation process to remove solid 

particles from a liquid stream usually by 

gravitational force.” 

Coal pile runoff – The runoff from or through 

any coal storage pile. 

Revise the definition to be identical to the 

current Part 423 definition: “The rainfall

runoff from or through any coal storage 

pile.” 
3 

EPA Definition UWAG Comment 

Coal washing – Coal washing, also known as 

coal cleaning, entails separating out foreign 

material from coal in a liquid medium and may 

also include processes to remove ash, sulfur and 

moisture. The liquid medium may be combined 

with finely ground heavier minerals, such as 

magnetite, in a dense medium fluid, better to 

effect separation of unwanted rock and mineral 

matter from coal particles. 

Reword the definition as follows: Coal 

washing, also known as coal cleaning, 

entails separating out foreign material from 

coal in a liquid medium and may also 

include processes to remove ash, sulfur and 

moisture. The liquid medium may be 

combined with finely ground heavier 

minerals, such as magnetite, in a dense 

medium fluid, to achieve better separation 

of unwanted rock and mineral matter from 

coal particles 

Cogeneration plant – A plant that produces 

electricity and another form of useful thermal 

energy (such as heat or steam), used for 

industrial, commercial, heating, or cooling 

purposes. 

UWAG recommends revising the definition 

as follows: “A generating facility, 

otherwise known as a combined heat and 

power plant, that produces electricity and 

another form of useful thermal energy (such 

as heat or steam), used for industrial, 

commercial, heating, or cooling purposes.” 

Cost of service – A ratemaking concept used 

for the design and development of rate 

schedules to ensure that the filed rate schedules 

recover only the cost of providing the electric 

service at issue . This concept attempts to 

correlate the utility’s costs and revenue with the 

service provided to each of the various customer 

classes. 

This definition is not in the published 

version of the ICR. UWAG cannot 

adequately comment on the definition 

without seeing it used in context. 

UWAG believes the following definition is 

better than the EPA definition, but again the 

appropriateness of the definition will depend 

on its usage: 

“The total costs incurred by a company in 

providing utility services, and which usually 

refers to annual costs unless otherwise 

specified. This amount, which consists of 

estimated operating expenses, depreciation, 

taxes, a return on the rate base (investment), 

and possibly other costs, is used to design 

and establish regulated ‘cost-based’ rates.”

Cycling unit – A unit used in a constant and 

specific cycle. For example, a unit that runs 

daily, but reduces capacity or shuts off at night 

would be a cycling unit. 

Reword definition as follows: A unit for 

which operation is undulated through a 

generally routine cycle. For example, a 

cycling unit may run daily, but reduce 

capacity or shut off at night. 

Detection limit – The minimum result which See discussion above regarding the use of 
4 

EPA Definition UWAG Comment 

can be reliably discriminated from a blank (for 

example, with a 99% confidence level). 

Quantitation Levels. 

Replace the definition with the definition of 

Method Detection Limit (MDL) from 40 

CFR Part 136.2(f): “The minimum 

concentration of an analyte (substance) that 

can be measured and reported with a 99% 

confidence that the analyte concentration is 

greater than zero as determined by the 

procedure set forth in Appendix B of Part 

136.” 

Discharge – The conveyance of process

wastewater to: (1) surface waters; or (2) a 

publicly owned, privately owned, federally 

owned, combined, or other treatment works. 

The definition should be identical to the 

definition of “discharge” set forth in the 

Clean Water Act regulations. See 40 CFR 

122.2. 

Dry FGD system – Dry FGD system, also 

referred to as semi-dry FGD system, captures 

sulfur dioxide from flue gas by a spray dryer 

absorption process that produces calcium sulfite 

with low moisture content. 

Reword definition as follows: “Dry FGD 

system, also referred to as semi-dry FGD 

system, captures sulfur dioxide from flue 

gas by a spray dryer absorption process that 

produces calcium sulfite with low moisture 

content.

FGD scrubber purge – Process wastewater

that exits an FGD scrubber system (typically 

from a solids separation process) and that is 

transferred to a wastewater treatment system or 

discharged. Note: The scrubber purge stream 

may be the same as the FGD slurry blowdown

stream if the plant does not operate a solids 

separation system prior to wastewater 

treatment.

FGD scrubber purge – As depicted in 

Figure B-1, process wastewater that exits an 

FGD scrubber system (typically from a 

solids dewatering process such as 

hydroclone overflow) and that is transferred 

to a wastewater treatment system or 

discharged. Note: The scrubber purge 

stream may be the same as the FGD slurry 

blowdown stream if the plant does not 

operate a solids dewatering system prior to 

wastewater treatment.

FGD slurry blowdown – Slurry water that 

exits an FGD scrubber absorber to control the 

solids/chlorides levels in the FGD scrubber 

absorber. FGD slurry blowdown is typically 

transferred to a solids separation process. 

FGD slurry blowdown – As shown in 

Figure B-1, slurry that exits an FGD 

scrubber absorber to control the 

concentration of suspended solids in the 

FGD scrubber absorber. FGD slurry 

blowdown is typically transferred to a solids 

dewatering process. 
5 

EPA Definition UWAG Comment 

FGD slurry preparation process water – 

Water used for the preparation of FGD slurry 

water (e.g., water that is added to ball mills for 

limestone slurry preparation). 

FGD reagent preparation water – As 

shown in Figure B-1, water used for the 

preparation of FGD reagent slurry (e.g., 

water that is added to ball mills for 

limestone slurry preparation). 

FGD slurry water – All water that enters into, 

is used within, or recycles through the FGD 

scrubber absorber. FGD slurry water is 

replenished by make-up water and the solids 

level is controlled by FGD slurry blowdown. 

FGD reagent slurry – As shown in Figure 

B-1, slurry stream providing all of the 

reagent and a portion of the water to the 

FGD scrubber absorber. 

FGD solids – Any solid material generated by 

the FGD scrubber system. This may also be 

called FGD sludge (e.g., calcium sulfite and 

calcium sulfate). 

FGD solids – As shown in Figure B-1, any 

solid material generated by the FGD 

scrubber system. This may also be called 

FGD sludge (e.g., calcium sulfite and 

calcium sulfate). 

FGD solids separation – The process that 

separates FGD slurry blowdown into two 

separate streams: the solids-rich stream (i.e. 

underflow) that contains FGD solids and the 

solids-lean stream (i.e. overflow) that contains 

water and fines. 

FGD primary solids dewatering – As 

shown in Figure B-1, the process that 

separates FGD slurry blowdown into two 

separate streams: the solids-rich stream (i.e. 

underflow) that contains FGD solids and the 

solids-lean stream (i.e. overflow) that 

contains water and fines. Hydrocyclone (or 

hydroclone), thickener, settling pond, and 

gypsum stacking are examples of FGD 

primary solids dewatering.

FGD solids separation recycle – The FGD 

wastewater that is returned to the FGD 

scrubber absorber following the FGD solids 

separation process.

FGD reclaim water – As shown in Figure 

B-1, the FGD wastewater from the solids 

dewatering process that is used as FGD 

Reagent Preparation Water or FGD 

scrubber purge.

Flocculation We recommend adding the following 

definition for flocculation: “A process 

where colloids come out of suspension in 

the form of floc or flakes. The action differs 

from precipitation in that, prior to 

flocculation, colloids are merely suspended 

in a liquid and not actually dissolved in a 

solution.” 
6 

EPA Definition UWAG Comment 

Forced generator outage – The hours for any 

failure, misoperation, or malfunction that results 

in the immediate automatic or manual removal 

of a generating unit from connection to the 

transmission system, or that prevents such 

connection from being accomplished when 

desired. 

UWAG recommends changing the defined 

term to “forced generating unit outage.” 

Reword the definition as follows: “The 

removal of a generator from the connection 

with the transmission grid, either 

automatically or manually, that has not been 

scheduled. These outages are usually the 

result of a mechanical failure of a critical 

component of the generating system.”

Gypsum wash water – Process wastewater 

generated during the solids dewatering 

operation or gypsum or gypsum solids. 

UWAG recommends changing the term to 

“cake wash water.” 

Reword the definition as follows: “Water 

used to wash/displace dissolved solids from 

gypsum cake.” 

Hydrocyclone or hydroclone - equipment 

used to separate solids from slurry using 

centripetal force. 

Independent power producer – A corporation, 

person, agency, authority, or other legal entity 

or instrumentality that owns or operates 

facilities for the generation of electricity for use 

primarily by the public, and that is not a utility.

Replace the definition with the following: 

“Also known as nonutility power producers, 

these facilities are wholesale electricity 

producers that operate within the franchised 

service territories of host utilities and are 

usually authorized to sell at market-based 

rates. Unlike traditional electric utilities, 

independent power producers do not possess 

transmission facilities or sell electricity in 

the retail market.” 

This definition is based on the EIA 

definition of “independent power producer.” 

Intermediate unit – A unit that not used in a 

constant and specific cycle. The unit is instead 

used more sporadically on an as needed basis 

when energy requirements are less than peak 

load but more than base load. 

Reword the definition to add the word “is” 

in the first line after “that.” 

Leachate – Liquid, including any suspended or 

dissolved constituents in the liquid that has 

percolated through or drained from waste or 

other materials emplaced in a landfill, or that 

See discussion above. 

Reword the definition as follows: 

“Liquid, including any suspended or 
7 

EPA Definition UWAG Comment 

pass through the containment structure (e.g., 

bottom, dikes, berms) of a surface 

impoundment. Leachate also includes the terms 

seepage, leak, and leakage, which are generally 

used in reference to leachate from an 

impoundment.

dissolved constituents in the liquid, that has 

percolated through or drained from waste or 

other materials emplaced in a landfill.” 

Nameplate capacity –The full-load continuous 

rating of a generator, prime mover, or other 

electric power production equipment under 

specific conditions as designated by the 

manufacturer. Installed generator nameplate 

rating is usually indicated on a nameplate 

physically attached to the generator. 

Reword the definition as follows: “The fullload continuous nominal rating of a 

generator, prime mover, or other electric 

power production equipment under specific 

conditions as designated by the 

manufacturer. Installed generator nameplate 

rating is usually indicated on a nameplate 

physically attached to the generator.” 

Natural wetlands – An area created naturally, 

not man-made, that is saturated by surface or 

ground water with vegetation adapted for life 

under those soil conditions, as swamps, bogs, 

fens, marshes, and estuaries.

Reword the definition as follows: “A 

natural area (not man-made) that is saturated 

by surface or ground water with vegetation 

adapted for life under those soil conditions, 

as swamps, bogs, fens, marshes, and 

estuaries.” 

NOx control system – An air pollution control 

system that removes NOx from air emissions. 

Types of NOx control systems include, but are 

not limited to, the following: selective catalytic 

reduction (SCR), selective non-catalytic 

reduction (SNCR), overfire air, and low NOx

burners.

Reword the definition as follows: “An air 

pollution control system that prevents NOx 

formation during fuel combustion or

removes NOx from flue gas. Types of NOx

control systems include, but are not limited 

to, the following: selective catalytic 

reduction (SCR), selective non-catalytic 

reduction (SNCR), overfire air, and low 

NOx burners.” 

Peaking unit – A unit normally used only 

during peak-load periods of electricity demand. 

Reword the definition as follows: “A unit 

normally used only during peak-load 

periods of electricity demand, or as an 

example, needed to replace the loss of 

another unit.” 

pH Adjustment – Decreasing the acidity or 

alkalinity of a substance by adding alkaline or 

acidic materials, respectively. 

We recommend the definition be amended 

as follows: “Changing the acidity or 

alkalinity of a substance by adding alkaline 

or acidic materials.” 
8 

EPA Definition UWAG Comment 

Plant – Includes all contiguous and nonadjoining property and equipment that is under 

operational control of the facility, including 

non-adjoining landfills, surface impoundments, 

and outfall structures. 

See discussion above. 

Pond/impoundment – A natural topographic 

depression, man-made excavation, or diked area 

formed from earthen materials or man-made 

materials or a combination of them, which is 

designed to hold an accumulation of liquid 

process wastes or process wastes containing free 

liquids, and which is not an injection well. 

Examples of ponds/impoundments include 

holding, storage, settling, and aeration pits, 

ponds, and lagoons. 

We recommend that EPA clarify this 

definition to specify that it does not include 

building sumps and outdoor 

collection/transfer concrete basins. 

Power marketers – Business entities engaged 

in buying and selling electricity. Power 

marketers do not usually own generating or 

transmission facilities. Power marketers, as 

opposed to brokers, take ownership of the 

electricity and are involved in interstate trade. 

These entities file with the Federal Energy 

Regulatory Commission (FERC) for status as a 

power marketer. 

Reword the definition as follows: “Business 

entities engaged in buying and selling 

electricity. Power marketers do not usually 

own generating or transmission facilities. 

Power marketers, as opposed to brokers, 

take ownership of the electricity and may be

involved in interstate trade. These entities 

file with the Federal Energy Regulatory 

Commission (FERC) for status as a power 

marketer. 

Primary purpose – Provides the predominant 

source of revenue for the plant. The principal 

reason for which the plant operates. 

Reword the definition as follows: “The 

process or manufacturing activity that 

provides the predominant source of revenue 

for the plant. The principal reason for which 

the plant operates.” 

Quantitation Level (Also known as Method 

Reporting Limit, Minimum Level, Minimum 

Quantification Level (MQL) or Limit of 

Quantitation) 

The lowest concentration at which the entire 

analytical system gives a recognizable 

signal and acceptable calibration point (see 

EPA Method 1638 section 18.26). The 

MRL can be calculated by multiplying 

laboratory-determined MDL by 3.18 and 

rounding result to nearest multiple of 1, 2, 5, 

10, etc. in accordance with procedures used 

by EAD and described in EPA Draft 

National Guidance for the Permitting, 

Monitoring, and Enforcement of Water 
9 

EPA Definition UWAG Comment 

Quality-Based Effluent Limitations Set 

Below Analytical Detection/Quantitation 

Levels, March 22, 1994 (see EPA Method 

1638 page 39). 

Sample-specific Detection Limit The appropriate MDL for a unique sample 

multiplied by the total dilution from the 

original sample at which a given sample was 

analyzed. For example, if the appropriate 

MDL is 5 ppb and the sample was diluted 

5% during sample digestion and then had to 

be diluted another 10 fold prior to being 

analyzed, then the sample specific detection 

limit would be 52.5 ppb (i.e., 5 x 1.05 x 10).

Sample-specific nominal Quantitation Limit The appropriate MQL for a unique sample 

multiplied by the total dilution from the 

original sample at which a unique sample 

was quantified. For example, if the 

appropriate MQL is 20 ppb and the sample 

was diluted 5% during sample digestion and 

then had to be diluted another 10 fold prior 

to being analyzed (quantified), then the 

sample specific quantitation limit would be 

210 ppb (i.e., (20 x 1.05 x 10). 

Scheduled generator outage – The hours 

during which the generating unit is offline due 

to planned, scheduled repairs, maintenance, or 

upgrades, such as routine repetitive maintenance 

and repair that have been programmed into the 

power schedule. 

UWAG recommends changing the defined 

term to “scheduled generating unit outage.” 

Single-pass scrubber - a scrubber designed 

such that there is no recycle of slurry to the 

absorber. See Figure B-2. 

Solids dewatering – The process that removes 

water from the solids-rich stream generated in 

the solids separation process. Typically a 

vacuum belt filter or a vacuum drum filter is 

used in this process. FGD solids such as 

gypsum are produced by this process.

UWAG recommends changing the defined 

term to “FGD secondary solids dewatering.” 

Reword the definition as follows: As 

depicted in Figure B-1, the process that 

removes water from the solids-rich stream 

generated in the primary dewatering

process. Typically, a vacuum belt filter or 

vacuum drum filter is used in this process. 
10 

EPA Definition UWAG Comment 

FGD solids such as gypsum are produced 

by this process. A wet FGD system may not 

have a secondary solids dewatering system.

Utility – Any entity that generates, transmits, or 

distributes electricity and recovers the cost of its 

generation, transmission or distribution assets 

and operations, either directly or indirectly, 

through cost-based rates set by a separate 

regulatory authority (e.g., State Public Service 

Commission), or is owned by a governmental 

unit or the consumers that the entity serves. 

Examples of these entities include: investorowned entities, public power districts, public 

utility districts, municipalities, rural electric 

cooperatives, and State and Federal agencies. 

Electric utilities may have Federal Energy 

Regulatory Commission approval for 

interconnection agreements and wholesale trade 

tariffs covering either cost-of-service and/or 

market-based rates under the authority of the 

Federal Power Act. 

The term should be “electric utility” rather 

than “utility.” 

Vacuum drum filter – A system that consists 

of a tank containing a rotating drum covered 

with a cloth filter. A vacuum is used to pull 

water through the cloth filter to dewater the 

solids. Also referred to as a rotary drum filter.

Revise the definition as follows: “A solids 

dewatering system that consists of a tank 

containing a rotating drum covered with a 

cloth filter. A vacuum is used to pull water 

through the cloth filter to dewater the solids. 

Also referred to as a rotary drum filter.” 

Vacuum filter belt – A system that uses a 

vacuum to remove water by pulling it through a 

revolving filter belt.

Revise the definition as follows: “A solids 

dewatering system that uses a vacuum to 

remove water from solids by pulling it 

through a revolving filter belt.” 

Variable O&M costs – Operation and 

maintenance costs that vary directly in 

proportion to the amount of electricity generated 

by a plant. 

As UWAG originally commented, there are 

several possible ways to calculate variable 

O&M costs. The definition provides no 

guidance on the calculation. EPA needs to 

specify which variable O&M calculation 

should be used to ensure consistency of 

information. 

Waste coal – Usable material that is a 

byproduct of previous coal processing 

operations. Waste coal is usually composed of 

Reword the definition as follows: “Usable 

material that is a byproduct of previous coal 

processing operations. It is also known as 
11 

EPA Definition UWAG Comment 

mixed coal, soil, and rock (mine waste). Most 

waste coal is burned as-is in unconventional 

fluidized-bed combustors. For some uses, waste 

coal may be partially cleaned by removing some 

extraneous noncombustible constituents. 

Examples of waste coal include fine coal, coal 

obtained from a refuse bank or slurry dam, 

anthracite culm, bituminous gob, and lignite 

waste. 

mixed or secondary coal. Waste coal is 

usually composed of mixed coal, soil, and 

rock (mine waste). Most waste coal is 

burned as-is in unconventional fluidized-bed 

combustors. For some uses, waste coal may 

be partially cleaned by removing some 

extraneous noncombustible constituents. 

Examples of waste coal include fine coal, 

coal obtained from a refuse bank or slurry 

dam, anthracite culm, bituminous gob, and 

lignite waste. 

Wastewater treatment unit – A unit operation 

used to remove pollutants from process 

wastewater. Wastewater treatment units 

include, but are not limited to, primary settling 

ponds, chemical precipitation, pH adjustment, 

clarification, biological reactor, thickeners, 

filters, and constructed wetlands.

Revise the definition as follows: “A unit 

operation used to remove pollutants from 

process wastewater. Wastewater treatment 

units include, but are not limited to, ponds, 

chemical precipitation, pH adjustment, 

clarification, biological reactor, thickeners, 

filters, and constructed wetlands.” 

Wastewater treatment system – A 

combination of one or more wastewater 

treatment units, other than 

ponds/impoundments, designed to achieve 

wastewater treatment.

Revise the definition as follows: “A 

combination of one or more ‘wastewater 

treatment units,’ including ponds/ 

impoundments, designed to achieve 

wastewater treatment, except that 

‘wastewater treatment system’ does not 

include systems in which ponds/ 

impoundments are the only units.” In the 

Questionnaire, information is collected 

separately (see Part D, section 3) for 

wastewater treatment systems that include 

only pond/impoundment units. 

Zero discharge – Disposal of process and/or 

non-process wastewaters other than by direct 

discharge to surface water or by indirect 

discharge to a POTW. Examples include 

evaporation, deep-well injection, hauling, 

and/or offsite recycle/recovery. 

Reword the definition as follows:

“Disposal of process and/or non-process 

wastewaters other than by direct discharge

to surface water or by indirect discharge to 

a POTW. Examples include evaporation, 

deep-well injection, hauling, and/or 

onsite/offsite recycle/recovery. 
Attachment B
Attachment C

Figure B-2 

Single Pass Scrubber 

FGD Reagent

Preparation

FGD

Scrubber

Absorber

AbsorberMakeupWater

Scrubbed Flue Gas to Stack

FGD ReagentPreparation Water

FGD Reagent

Flue Gas In

Oxidation Air(if necessary) FGD Slurry Discharge

To FGD WastewaterTreatment System

Single Pass

FGD Reagent Slurry Scrubber