PART B OF THE SUPPORTING STATEMENT

FOR THE INFORMATION COLLECTION REQUEST PACKAGE THAT WILL

SUPPORT DEVELOPMENT OF STEA M ELECTRIC POWER GENERATING

EFFLUENT GUIDELINES

U.S. ENVIRONMENTAL PROTECTION AGENCY

February 22, 2010PART B OF THE SUPPORTING STATEMENT

1. QUESTIONNAIRE OBJECTIVES , KEY VARIABLES, AND OTHER
PRELIMINARIES

1(a) Questionnaire Objectives

The primary objective of this Information Co llection Request (ICR) is to gather and update information about fossil- and nuclear-fue led steam electric power plants to support technical analyses that EPA will use to develop revised effluent guidelines for the steam electric power generating industry. More specificall y, through this ICR, EPA will administer a questionnaire to power plants in order to obtai n sufficient information to develop an industry profile and to assess the pollutant reductions, costs, and economic achie vability of candidate pollution control technologies, management practices , and process changes. This information is necessary to fulfill requirements established by the Clean Water Act and to inform Agency decision making about the appropr iate course of regulatory ac tion to address the pollutants present in wastewater discharges from steam electric power plants. While EPA has obtained certain information through a recently-completed study of the steam electric power generating industry and through public sources, it has determin ed that there are no existing sources for the sufficiently-detailed plant- and generator-level data that will be co llected through this ICR (questionnaire).

1(b) Key Variables

EPA will use the information collected from the questionnaire to gain knowledge of current steam electric processes, characterize and quantify the pollutants currently discharged by the industry, assess technical and economic achievability of available controls, and assess potential environmental impacts. The in formation collected will provide EPA with owner/operator-level, plant-level, and/or genera ting unit-level data on pr ocesses, production, and costs that complement, and go beyond, data that are available from public sources. EPA is investigating the following key va riables as they relate to th e potential technology options for
this industrial sector:

• Proper Characterization and Classifica tion of the Steam Electric Industry;

• Baseline Estimates of Pollutants Discharged in Steam Electric Process Wastewater;

• BMPs and Pollution Prevention Opport unities that can Reduce Pollutant Discharges;

• Best Available and Best Demonstrated Technologies for Effluent Limitations Guidelines and Standards;

• Potential Environmental Impacts of St eam Electric Process Wastewater; and

• Costs and Economic Impacts of Candidate Pollutant Control Technologies and
Practices.

B-1Please see Part A, Section 4(b)(i) of th is ICR Supporting Statement for detailed information on the data to be collected by the questionnaire.

1(c) Terminology

Within the sample frame (defined in Section 2(b) below), EPA has classified the fuel usage for each plant within the scope of the ICR. This plant fuel classification is based on the types of fuels used by each of the generating units operating at the plant. The plant fuel
classifications are determined in a hierarchical manner as follows:

First, all coal plants are identified:

• Coal: one or more units uses coal as its pr imary or secondary fuel. This includes coal units using integrated gasifi cation combined cycle (IGCC);

Second, all petroleum coke plants are identified:

• Petroleum Coke: one or more units uses pe troleum coke as its primary or secondary fuel (and the plant is not alrea dy classified as a coal plant);

Third, plants for which all the units have the same primary fuel type are classified as follows:

• Gas (all units have gas as the primary fuel type, but do not use combined cycle steam turbines);

• Gas-Combined Cycle (all units have gas as the primary fuel type and use combined cycle steam turbines);

• Oil (all units have oil as the primary fuel type);

• Nuclear (all units are nuclear);

Finally, the remaining plants with units havi ng different fuel types are classified as
combinations as follows:

• Combination (Gas and Gas-Combined Cycle);

• Combination (Gas and Oil);

• Combination (Gas-Combi ned Cycle and Oil);

• Combination (Gas and Gas-Comb ined Cycle and Oil); and

• Combination (Gas-Combined Cy cle and Nuclear and Oil).

B-22. STATISTICAL APPRO ACH FOR THE SURVEY

The statistical approach c onsiders the survey’s targ et population, the available information in the sample frame, the sample desi gn, and sources of error. The following sections describe each component in detail.

2(a) Target Population

The principal task in the development of a sa mple survey design is establishing a clear, concise description of the survey’s target population . The target population consists of the entire set of elements on which inferences will be made from the collected survey data. The definition should clearly identify every elem ent of the target population so that all non-population elements can be excluded. For this survey, EPA has defi ned the target population to be all fossil- and nuclear-fueled steam electric power plants in the U.S. that report as operating under North American Industry Classification System (NAICS) code 22. In addition to plant-level information, EPA intends to collect information a bout all units at each pl ant. EPA will develop both plant-level and unit-leve l estimates from the data.

2(b) Sample Frame

A sample frame is a list or set of procedures fo r identifying all elements of a target population. In addition to listing population elem ents, sample frames contain such additional information as addresses and key characteristics of the population that will be used to draw samples. Sample frames are essential to the quality of surveys because sample elements are
drawn from them.

Because the target population consists of a ll fossil- and nuclear-f ueled steam electric power plants in the U.S. that report as ope rating under NAICS code 22 and their corresponding generating units, EPA has created a sample frame of all such plants and generating units. This
frame consists of information obtained from databases that are maintained by the Energy Information Administration (EIA), a statistical ag ency of the U.S. Department of Energy (DOE) that collects information on existing electric ge nerating plants and associated equipment to
evaluate the current status and potential trends in the industry. The source of the information comes primarily from the 2007 Electric Generator Report (Form EIA-860) and is supplemented by information found in Form EIA-923 and a su rvey conducted by EPA’s Office of Resource Conservation and Recovery (ORCR). In addition, EPA identified two facilities that started operations after 2007 and has obtained information about them.

Collectively, the data sources provided key information for each steam electric plant with a NAICS code of 22 such as county, state, Nort h American Electric Reli ability Council (NERC) region, business size (small or non-small), and regul atory status (i.e., regulated by public service commission). Also included is the number of each type of generating unit operated at the plant, an identifier that specifies th e fuel classification of each generating unit for the plant, and an identifier for the plant fuel classification that is based on the fuel classifications of the generating

B-3units (e.g., coal, gas-combined cycle, nuclear). In addition, the ORCR survey results and the EIA-923 data set provide information on the pres ence of ponds and landfills at the plant along with the materials that are stored or disposed in the pond/landfill. The sample frame also includes details on each generating unit reported in the EI A-860 data set classified as a steam electric generating unit based on the primary NAICS code, such as prime mover and fuel (fossil or nuclear), nameplate capacity (in megawatts), un it fuel classification, and the plant where the generating unit is housed. EPA considers that it has created a sample frame for this ICR that is complete relative to the defined target populatio n. The sample frame contains information on 1,203 plants containing 2,589 generati ng units that are within sc ope of the data collection objectives of the questionnaire.

2(c) Sample Design

The steam electric questionnaire is comprise d of multiple parts. Some parts of the questionnaire focus on gathering general informa tion and financial data from each plant selected to receive the questionnaire. Other questionnaire parts are st ructured to collect technical information about certain aspects of power plant operations and will be distributed to a subset of the plants receiving the que stionnaire. For example, Parts B and C collect information about ash handling and FGD operations at coal, oil and pe troleum coke plants, while Part H collects information about operations at nuclear plants. See Part A, Section 2(b)(i) of this Supporting Statement for details on the quest ionnaire parts and the specific types of plants that would receive each part.

Through this ICR, EPA intends to collect info rmation from the industry using a stratified cluster-based sample design. The stratification feat ure of the design is discussed further below. Within each stratum, a cluster sample will be collected. A cluster sample is a probability sample in which each sampling unit is a collection, or clus ter, of elements from the target population. Here the sampling unit is a plant which is co mprised of a collection of generating units (elements). EPA intends to send th e questionnaire to a sample (subset ) of plants that is generated by implementing the sample design. Each selected plant would be required to complete the questionnaire for every generating unit at the plan t. By requiring only a subset of plants to respond to the questionnaire, the survey burden would be greatly reduced. EPA would select plants in a manner that would be st atistically representative of all plants in the target population.

The following subsections describe how th e sample frame will be stratified, the population sizes for each stratum, the sample sele ction process, and the precision estimates used to derive the estimated sample size.

(i) Stratification

B-4 The sample design will stratify plants, primar ily by their plant fuel classification and regulatory status. Stratification involves selecting one or more characteristics of interest and dividing the members of the populat ion into strata based on thos e characteristics. Stratified sampling consists of selecting a sample from within each stratum, then combining them to constitute the total sample. Ther e are several benefits that result from a stratified sample design, including:• Ensuring that the sample contains representatives from every stratum;

• Improving the precision of parameter estimates;

• Allowing important parameters to be es timated at the stratum level; and

• Allowing certain subpopulations of particular interest to be sa mpled at a greater
rate than others.

To select plants that would receive questionnaire s, EPA intends to use the following stratification
variables:

All Plants:

• Plant Fuel Classification . EPA’s sample frame identifies the plant fuel classification for each plant. EPA intends to stratify by plant fu el classification to ensure that the sample design selects plan ts in each fuel type, because there are
inherent differences due to th e type of fuel used at the plant. For those plants classified as “Combination”, the sample frame further delineates them by the specific fuels that comprise the combinati on. The plant fuel classification strata
are as follows:

o Coal;

o Petroleum Coke;

o Gas;

o Gas-Combined Cycle;

o Oil;

o Nuclear;

o Combination (Gas and Gas-Combined Cycle);

o Combination (Gas and Oil);

o Combination (Gas-Combi ned Cycle and Oil);

o Combination (Gas and Gas-Comb ined Cycle and Oil); and

o Combination (Gas-Combined Cy cle and Nuclear and Oil).

• Regulatory Status. EPA’s sample frame identifies whether the plant is regulated or non-regulated. EPA intends to stratify by regulatory status to ensure that the sample design selects both regulated a nd non-regulated plants, due to inherent
differences between them. Each stratum defined by plant fuel classification will be segregated into two strata (regulated and non-regulated).

Coal and Petroleum Coke Plants:

EPA’s sample frame includes additional inform ation about coal plants, which will be used to select a subset of coal plants that will receive additional questions (i.e., Parts E, F and G of the questionnaire). To minimize burden to sma ll entities, EPA will only collect this additional information from plants that are not operated by small entities. EPA intends to collect information from plants that have ponds and/or landfills containing coal combustion residues (i.e., coal ash or flue gas desulfurization (FGD) wastes). The pond/landfill strata are as follows:

B-5• Small entities;

• Non-small entities:

o Pond only – FGD: Contains all coal plants identified in the sample frame as having a pond with FGD waste as one of its contents, but not a landfill;

o Pond only – no FGD: Contains all coal plants that have an ash pond that does not also receive FGD waste, but has no landfill;

o Landfill only – FGD: Contains all coal plants that have a landfill with FGD waste as one if its contents, but no pond containing coal combustion residues (CCR);

o Landfill only – no FGD: Contains all coal plants that have a landfill that
contains ash but with no FGD wastes , and did not report operating a CCR pond;

o P onds and landfill: Contains all plants that have both ponds and landfills that contain CCR (either as h or FGD wastes). To minimize the number of strata, no distinction in plants here is made by FGD status. EPA believes a sufficient number of plants with pond s (both with and w ithout FGD waste) and landfills (both with and without F GD waste) will be selected from the previous four non-small entity strata so that a further breakdown of those plants that have both a pond and a landfill is unnecessary; and

o No Ponds or landfills: Contains all plants that did not report storing or disposing of ash or FGD wastes in a pond or landfill.

In addition to coal plants, petroleum coke pl ants that are not identified as small entities will also receive Parts E, F, and G of the questionnaire. However, insufficient information was available to determine which petr oleum coke plants had ponds and/or landfills so they will not be stratified by pond/landfill status.

Accounting for NERC Region:

EPA is also interested in cap turing regional differences in th e industry as measured by the NERC region of the plant. However, rather than stratify the sample frame explicitly by NERC region, EPA will assure geographic diversity in the sample by using a systematic sampling approach within each stratum. Stratum me mbers will be sorted by NERC region and every k th

member of the stratum will be se lected systematically, (where k is the ratio of the stratum population size to the stratum sample size, rounded to the nearest intege r). As a result, the representation of each NERC region in the sample should be proportional to the size of the population.

In addition, EPA is interested in capturing in formation from a representative sample of plants in terms of plant capacity (as defined by the nameplate capac ity of generati ng units within the plant). EPA considered nameplate capacity as a stratification variable in the design but decided not to stratify in this manner as prel iminary analysis showed that the systematic sampling of plants within each stratum described above will provide a distribution of plants in terms of capacity that meets EPA’s objectives.

B-6(ii) Population Sizes for Each Stratum

Table B-1 displays the number of plants with in the sample frame, as well as the number of generating units within these plants, for each type of plant fuel clas sification and regulatory status. For those plants labeled as “Combination,” a further breakdown was done by the specific fuels used in the plant.

Table B-1. Numbers of Plants and Generating Units by Plant Fuel Classification and Regulatory Status in Sample Frame

Plant Fuel
Classification Regulatory
Status Number of Plants (Sample Frame) Number of Generating Units at

these Plants a Regulated 343 966 Non-Regulated 150 339 Coal

Unknown 2 2 Regulated 131 318 Gas Non-Regulated 57 142 Regulated 95 126 Gas-Combined Cycle Non-Regulated 278 379 Regulated 31 52 Nuclear Non-Regulated 32 48 Regulated 23 55 Oil Non-Regulated 20 38 Regulated 0 0 Petroleum Coke Non-Regulated 9 9 Regulated 1 5 Combination: Gas-CC
and Nuclear and Oil Non-Regulated 0 0 Regulated 2 6 Combination: Gas-CC
and Oil Non-Regulated 0 0 Regulated 20 69 Combination: Gas and

Gas-CC Non-Regulated 6 23 Regulated 1 4 Combination: Gas and
Gas-CC and Oil Non-Regulated 0 0 Regulated 1 4 Combination: Gas and
Oil Non-Regulated 1 4

Total 1,203 2,589
a Plants can have multiple generating units with different fuel types. For example, of the 1307 (966+339+2) generating units at coal plants, 103 use something other than coal as their primary or secondary fuel.

Table B-1 indicates that 1,203 fossil- and nucle ar-fueled steam electric power plants and 2,589 generating units exist within the sampling fram e. There are 495 coal plants that contain a total of 1,307 generating units. Coal plants compri se about 41 percent of all plants, and their generating units make up half of all generating units at all plants. Of the 495 coal plants, 303

B-7(with 886 generating units) contain a pond and/or landfill containing coal combustion residues. Table B-2 displays the number of coal plants and corresponding number of generating units by each stratum associated with pond and/or landfill status defined in the previous section. Fiftyfive coal plants are classified as being operated by a small busine ss. These plants, in addition to the 143 coal plants that did not re port storage or dispos al of ash or FGD wastes in a pond and/or landfill, are not part of the target population for coal plants that will receive Parts E, F, and G of the questionnaire. In addition, EPA has excluded two coal plants containing a total of nine generating units from the sample frame for Part s E, F, and G of the questionnaire to limit the potential burden imposed on these plants recogn izing that they may be required to provide additional data not covered by this ICR.

Table B-2. Numbers of Coal Plants (and Co rresponding Generating Units) by Stratum in Sample Frame

Business Size Pond/Landfill Number of
Coal Plants Number of Generating
Units at these Plants

Small All 55 121 Pond Only – FGD 39 122 Pond Only – No FGD 99 313 Landfill Only – FGD 18 34 Landfill Only – No FGD 55 142

Both Pond and Landfill 84 256 Non-Small

No Pond or Landfill 143 310

Total 493 a 1298 a

a EPA excluded two coal plants (containing nine total generating units) from the sample frame for Parts E, F, and G of the questionnaire.

(iii) Sample Selection

Most parts of the questionnaire focus on gathering information from all coal and petroleum coke-fired power plants. Thus, all pl ants with a fuel classification of “Coal” or
“Petroleum Coke” will be selected with certaint y (i.e., probability of selection equal to one), except for Parts E, F, and G. In addition, for st rata with ten or fewer plants, EPA assumed that the sample would include all plants, while the mi nimum number of plants sampled would be ten within strata containing more th an ten plants. As such, all re gulated and non-regulated plants with a plant fuel classification of “Combination” (except gas and gas-combined cycle) will also be selected with certainty. For the remaining non -regulated and regulated plants with plant fuel classifications of gas, gas-combined cycle, oil, nuclear, and combination (gas and gas-combined cycle), 30 percent of the plants will be randomly selected to receive the questionnaire while adhering to the ten plant minimum per stratum. Based on this sampling design, a total of 734 plants would be selected to receive the ques tionnaire. EPA assumes a 10 percent non-response rate, based upon EPA’s experience in administering similar effluent guidelines questionnaires, which would result in a net sample size of 661. Table B-3 shows the number of plants that
would be selected to receive th e questionnaire by the strata form ed by plant fuel classification

B-8and regulatory status. EPA has determined that the sample size resulting from this design is sufficient to meet the objectives of this survey.

Table B-3. Number of Plants in Sample Frame and Number of Plants to be Selected for Questionnaire, by Plant Fuel Clas sification and Regulatory Status

Plant Fuel
Classification Regulatory
Status Number of Plants (Sample Frame) Number of Plants to Sample
Regulated a 343 343 Non-Regulated a 150 150 Coal a

Unknown a 2 2 Regulated 131 39 Gas Non-Regulated 57 17 Regulated 95 29 Gas-Combined Cycle Non-Regulated 278 83 Regulated 31 10 Nuclear Non-Regulated 32 10 Regulated 23 10 Oil Non-Regulated 20 10 Regulated a 0 0 Petroleum Coke a Non-Regulated a 9 9 Regulated a 1 1 Combination: Gas-CC
and Nuclear and Oil a Non-Regulated a 0 0 Regulated a 2 2 Combination: Gas-CC
and Oil a Non-Regulated a 0 0 Regulated 20 10 Combination: Gas and

Gas-CC Non-Regulated a 6 6 Regulated a 1 1 Combination: Gas and
Gas-CC and Oil a Non-Regulated a 0 0 Regulated a 1 1 Combination: Gas and
Oil* Non-Regulated a 1 1

Total 1,203 734

a All plants in stratum are to be selected with certainty (probability equal to one).

The exact number of generating units selected for the sample will not be known prior to the sample draw and must be estimated because the number of generating units varies by plant and thus will depend on the specific set of plants selected. Genera ting units within plants that are selected with certainty will automatically be in cluded in the sample. For those plants in a stratum that will be sampled at 30 percent, EPA estimated the corresponding number of generating units as 30 percent of the total number of generating units in th e stratum. Table B-4 displays the number of generati ng units for each unit fuel classi fication. For example, of the 144 oil units in the sample frame, 51 of them are at pl ants that will be selected with certainty and an additional 93 oil units are at plants that are to be sampled at 30 pe rcent. Thus, the number of oil
units estimated to be selected for the questionnaire is 51 + 0.30 * 93 = 79. Overall, information

B-9from approximately 1,714 generating units would be included in the survey based on 734 plants selected for the survey.

Table B-4. Number of Generating Units in Sample Frame and Approximate Number to be Selected for Questionnaire, by Unit Fuel Classification

Unit Fuel
Classification Number of Units (Sample Frame) Estimated Number of
Units to be Selected for Survey

Coal a 1,206 1,206

Gas 557 200

Gas-CC 567 184

Nuclear 104 34

Oil 144 79

Petroleum Coke a 11 11

Total 2,589 1,714

a All generating units in these unit fuel classifi cations are at plants selected with certainty (probability equal to one).

Parts E, F, and G of the questionnaire will be sent to all petroleum coke plants and a subset of coal and petroleum coke plants ope rated by non-small entities that contain either a pond and/or a landfill containing coal combusti on residues (i.e., coal ash or FGD waste). (Insufficient information was available to dete rmine which petroleum coke plants had ponds and/or landfills, so all three non-sm all petroleum coke plants will r eceive Parts E, F, and G.) For those strata of coal plants listed in Table B-2 wh ere information is to be collected, 30 percent of the plants will be randomly select ed to receive parts E, F, a nd G of the questionnaire. In addition, EPA has identified seven coal plants with in these strata that have leachate collection systems. EPA has decided to sample these seven plants with certainty to ensure information on leachate collection systems is captured in the qu estionnaire responses. These seven plants will be included in the sample selection process so th at a total of 30 percent of coal plants will be selected. Based on these calculations, a total of 94 coal plants would be se lected to receive parts E, F, and G of the questionnaire. Table B-5 s hows the number of coal plants that would be selected to receive parts E, F, and G of the questionnaire by stratum. Assuming a 10% nonresponse rate within each stratum, EPA expects a net sample size of 85 plants. As a result of these calculations and assumptions, EPA estimated that having 94 coal plants receive parts E, F, and G of the questionnaire would meet its objectives.

The exact number of generating units selected for the sample will not be known prior to the sample draw and must be estimated as th e number of generating units varies by plant and thus depends on the specific plants selected. With in each stratum, the ratio of generating units to plants in the sample frame was multiplied by th e number of sampled plants to estimate the number of generating units selected for the sample. For example, on average, there are 122/39=3.13 generating units per co al plant for pond only coal plan ts with FGD wastes in the pond. Thus, the estimated number of generating units in the sample for this stratum would be 3.13 * 12 sampled plants = 38 generating units. Th e final two columns of Table B-5 display the

B-10number of generating units in th e sample frame from coal plants as well as the approximate number of generating units from coal plants for parts E, F, and G of the questionnaire. As a result of these calculations, approximately 272 generating units from coal plants would be represented in parts E, F, and G of the questionnaire.

Table B-5. Numbers of Coal Plants (and Co rresponding Generating Units) by Stratum in the Sample Frame as well as to be Selected for Parts E, F, and G of the Questionnaire

Business
Size Pond/Landfill Number
of Coal

Plants (Sample Frame) Number of
Coal Plants
Selected for Parts E, F, and
G of Questionnaire Number of Generating
Units at the
Coal Plants in Sample Frame Estimated
Number of Generating

Units in Sample

Small All 55 0 121 0 Pond Only – FGD 39 12 122 38 Pond Only – No

FGD 99 30 313 95

Landfill Only –

FGD 18 10 34 19

Landfill Only –

No FGD 55 17 142 44

Both Pond and
Landfill 84 25 256 76 Non-Small

No Pond or
Landfill 143 0 310 0

Total 493 94 1298 272

Note that Table B-5 only contains informa tion on coal plants. Also, there are three petroleum coke plants operated by non-small entities (each having one generating unit) that will be sent parts E, F, and G of the questionnaire. In addition, Part E (but no t Parts F and G) will be sent to the 230 oil, gas, nuclear, gas-combined cycle, and combination plants identified in the
final column of Table B-3 that would be selected for the overall questionnaire.

Table B-6 below provides the summary of the design.

B-11Table B-6. Summary of Population, Sample and Subsample Sizes

Number of Plants in: Stratum Population Sample Subsample

Coal – Small business 55
- 0 Coal – Pond Only –FGD 39
- 12 Coal – Pond Only –no FGD 99 - 30
Coal – Landfill Only – FGD 18
- 10
Coal – Landfill Only – No FGD 55
- 17
Coal – Both Pond and Landfill 84
- 25
Coal – No Pond and Landfill 143
- 0

Gas 188 56

- Gas-Combined Cycle (CC) 373 112
- Nuclear 63 20
- Oil 43 20
- Pet Coke 9 9
- Combination: Gas-CC and Nuclear and
Oil 1 1
-

Combination: Gas-CC and Oil 2 2
- Combination: Gas and Gas-CC 26 16
- Combination: Gas and Gas-CC and Oil 1 1

Combination: Gas and Oil 2 2

Total 1201 239 94

The population size is the number of plants in the stratum. From the population, we selected a sample to receive the questi onnaire. The subsample will be required to respond to some additional parts of the questionnaires.

(iv) Precision Estimates for the Given Sample Sizes

Because a sample of plants will be given the questionnaire rather than all plants within the target population, it follows that some degree of uncertainty will be associated with estimates made from the data collected from the questionna ires. The precision of these estimates depends on both the sample design and the sample size – th at is, the number of plants that would be selected. One measure of precision is the width of the confidence interval for the estimate. Confidence intervals provide a range of values for a particular estimate that would be likely if the study were repeated an infinite number of tim es. Thus, when using 95 percent confidence intervals, 95 percent of such intervals would include the true va lue, if we could take an infinite number of samples. The binomial distribution is often used as the basis of sample designs and can be used to estimate precision. The binomial di stribution applies to situ ations where there are only two outcomes (yes or no) to a dichotomous question such as “Are residues generated by cleaning operations?”

B-12 The presence or absence of the attribute for a particular plant is a dichotomous, or binary,
variable. The binomial distribut ion models these data based on the notion of obtaining nationalestimates of the percentage or proportion of plan ts in the target populatio n (or a subset of the target population) that have a particular attri bute. The binomial dist ribution also provides
estimates of the variance that is used to calculate the confiden ce intervals. Because a proportion of 0.5 (or 50 percent) results in the largest possible variance for the binomial distribution, EPA assumed that the probability of one outcome wo uld be 0.5 (e.g., cleaning operation residues are generated at 50 percent of the plan ts). In other words, if the po pulation value is any value other than 50 percent, the survey estimate will be more precise – in statistical expectation – than it would be if the population value is 50 percent.

Because EPA is developing a national rule, it is primarily concerned with the precision of the overall plant-level and generating unit-level es timates, rather than estimates made within strata. Consequently, in estimating the overa ll sample size, EPA assumed more stringent requirements for overall plant-level and genera ting unit-level estimates than estimates for specific plant fuel or unit fuel cl assifications. Given a sample size of 734 plants described in the previous section, EPA would e xpect to receive completed questionnaires for 661 plants (assuming a 10 percent non-respons e rate). Under these assump tions, the sample would be expected, with 95 percent confidence, to yield sufficient data to estimate the value of an unknown proportion to within +/- 3. 5 percent of its true value for the target population (i.e., plants). For example, if 30 pe rcent of the responding plants indicate they generate cleaning residues, then there is 95 pe rcent confidence that 30 percent +/- 3.5 percent (i.e. between 26.5 percent and 33.5 percent) of the entire populat ion of plants generate cleaning residues.

Based on estimated sample of 1,714 generati ng units, the sample (similarly accounting for plant non-response) would be expected, with 95 percen t confidence, to yield sufficient data to estimate the value of an unknown pr oportion to within +/- 2.5 percen t of its true value for the target population (i.e., generating units). For example, if 30 pe rcent of the generating units generate cleaning residues, then there is 95 pe rcent confidence that 30 percent +/- 2.5 percent (i.e. between 27.5 percent and 32.5 pe rcent) of the entire populati on of generating units generate cleaning residues. The precision estimates associ ated with national plant-level and unit-level estimates are calculated based on proportion estimat es from Part I of the questionnaire, a part sent to all sampled plants. Othe r questionnaire parts (e.g., Parts B th rough H) will be sent to only a subset of the plant fuel classifications and thus will have a smaller sample size (and, as a result, less precision).

Based on the sample size of 94 coal plants with a pond and/or landfill for parts E, F, and G of the survey, EPA would expect to receive completed questionnaires for 85 of these plants (assuming a 10 percent non-respons e rate). Under these assump tions, the sample would be expected, with 95 percent confidence, to yield sufficient data to estimate the value of an unknown proportion to within +/- 9.2 percent of its true value for the target population (i.e., coal plants with ponds/landfills). Fo r example, if 30 percent of th e coal plants collect landfill leachate, then there is 95 percent confidence that 30 percent +/- 9.2 percent (i.e. between 20.8 percent and 39.2 percent) of the en tire population of coal plants with a pond or landfill collect
landfill leachate.

B-13All of these precision targets will hold wh en the proportion’s true (unknown) value is equal to 0.5, and even greater precision is expect ed when the true value of the proportion is not equal to 0.5.

2(d) Sources of Error

In developing the sample design, as describe d previously, EPA considered the estimated precision targets for data collected from the targ et population. EPA also considered potential
error that could be associated with estimates cal culated from the collected data, due to sources associated with sampling, such as response rates, as well as non-sampling sources of error, such as processing error.

(i) Response Rates

In developing the sample design, EPA cons idered both unit (questionnaire) and item (question) non-response. EPA expects that the response rate would be relatively high for this mandatory survey effort, which would be conduc ted under the authority of Section 308 of the
Clean Water Act. The cover letters and instructi ons for the questionnaire would explain the legal authority, responsibility to respond, reasons for th e questionnaire, and penalty for non-response.
EPA would use reminder letters a nd/or telephone calls to remind respondents of the duty to respond under Section 308 of the Clean Water Act. If possible, EPA would seek the endorsement of the major trade associations, wh ich would be expected to increase the response rate from its members. EPA recognizes that some non-response is unavoidable, and in past survey efforts, EPA has waived the duty to respond in extreme and rare cases (e.g., natural disasters) which also might o ccur for this survey effort.

The sample size estimates presented in Section 2(c)(iii) have been adjusted to help ensure that the effective sample sizes (i.e., respondents) woul d be sufficient for precision requirements when the non-response rate equals 10 percent. (This assumption of a 10 percent non-response rate is based upon a typical effl uent guidelines questionnaire.) In addition to increasing the initial sample size, EPA would strive to improve the response rate by reminder letters and/or telephone calls. Furthermore, after receiving the responses, EPA intends to adjust the questionnaire weights for any non-response and to re view publicly availabl e information in order to determine if non-respondents appear to have different characteristic s than respondents. EPA
would examine these characteri stics both for the entire indus try and for subgroups in the analyses. For any differences, EPA intends to determine the major caus es, and to incorporate appropriate adjustments for bias. (Bias is th e difference between the expected value of an estimate and the true value of a parameter or quantity being estimated. If the data collection process generates estimates that are consistently (or on average) above or consistently below the true value, the data colle ction process is biased.)

B-14 To minimize item non-response, EPA’s subject matter experts have worked closely with industry to develop questions that would be easy to understand with clearly defined and familiar terms, are formatted in a logical sequence, and would request data that are readily available within the industry. In this manner, EPA expect s to minimize inaccurate or incomplete response of the questions that can occur due to misunderstanding or misinter pretation of questions and theunintentional skipping of questions by respondent s. Additionally, EPA would operate an e-mail helpline to assist respondents with the que stionnaire. After receipt of the completed questionnaires, EPA intends to conduct exte nsive follow-up with respondents for any item nonresponse. If necessary, EPA would impute responses to key questions in our analyses.

(ii) Processing Errors

Processing errors can occur when questionnaire responses are code d, edited, and entered into the database. The design and implementation of th e questionnaire database would employ a number of quality assurance techniques to reduce the frequency of such errors. These techniques would include the following:

• Electronic questionnaires will directly tran sfer responses into a survey database

• Computerized comparison of selected re sponses to detect inconsistencies and illogical responses;

• Computerized analyses to screen for out-of-range and inconsistent numerical values; and

• Computerized analyses to detect mi ssing numerical data and missing units.

3. PRETESTS AND PILOT TESTS

EPA does not intend to pre-te st the questionnaire. For more than 30 years, EPA’s Engineering and Analysis Division has conducted surveys of numerous industrial sectors to collect information to support regulation develo pment activities in the effluent guidelines program. While EPA develops different questionnaires for ea ch industry, there are common elements for all industries. The questionnaires co llect the same basic data such as information about processes, treatment, and fi nancial status. Thus, when EP A develops a questionnaire for a particular industry, it generally tailors the questions for specific terms and processes used by that industry. In past years, EPA has relied predominantly on active participation by trade groups in reviewing the questionnaires. In EPA’s experience, such collaboration generally tends to better reflect the industry at large than pre-tests. For this reason, EPA considers additional review through the pre-test process to be unnecessary for this industry.

4. COLLECTION METHODS AND FOLLOW-UP

Please See Part A, Section 5(b) of this ICR for this information.

B-155. DATA PREPARATION AND ANALYSIS

5(a) Data Preparation

Upon receipt of completed questionnaires, EPA and its contractors would review the questionnaires for completeness and CBI claims. All questionnaires will al so be reviewed for consistency and reasonableness and follow-up calls will be conducted as needed to clarify inconsistencies found in the respon ses. Reviewed questionnaire fi les will then be uploaded into the questionnaire database. Once the data are up loaded into the database, numerous electronic QA activities would be performed and the resu lts would be provided to engineering and
economic staff for further resolution and documenta tion. This database would then be used to perform data analyses.

5(b) Analysis

In support of making decisions that will a ffect rulemaking, EPA will use the responses from this questionnaire to help answer the following questions:

• What pollutants are currently discharged by power plants and what technologies/practices are being used to treat power plants wastestreams?

• Are process changes, BMPs, treatment te chnologies, or recycle/reuse processes feasible options to reduce pollutant discharges from st eam electric power plants?

• Is subcategorization of the steam electr ic power generating industry appropriate, and if so, what is the co rrect subcategorization?

• What are the available technologies for re ducing pollutant discharges associated with waste streams of concern, such as FGD scrubber purge, ash handling, process equipment cleaning wastes, and other wastewaters?

• What pollutant reductions and other bene fits would be realized by implementing candidate regulatory options?

• What are the costs for operators to impl ement technologies, process changes, and best management practices to reduce po llutant discharges? How do these costs impact the economics of the steam electric industry?

The objectives of the information collecti on would be achieved by the statisticallydesigned sample survey because the resulting infe rences and analyses would be as statistically unbiased and as precise as is pr acticable. EPA intends to apply sample weights derived from the statistical sample design and adjust for non-respon se to the data during statistical analysis. Weighting the data would allow inferences to be made about all eligible plants and generating units, including those that did not respond to the questionnaires. Another advantage is that weighted estimates would have smaller variance s than unweighted estimates. EPA also intends

B-16B-17 to evaluate whether estimates could be impr oved by post-stratifying the detailed questionnaire data using the data collected from the surve y. EPA would use accepted statistical methods for survey statistics, such as those described in Sampling Techniques (Cochran, 1977) and Survey Sampling (Kish, 1965).

See Part A, Section 2(b) of this Informa tion Collection Request for a detailed discussion of the technical and economic analyses.

EPA intends to use the following contractor s to assist in conducting this survey:

Sample Frame Preparation and Analysis : Eastern Research Group 14555 Avion Parkway
Suite 200 Chantilly, VA 20151

Questionnaire Development and Analysis Support (Financial/Economic Data)
Abt Associates Inc.
55 Wheeler Street Cambridge, MA 02138

Statistical Design and Analysis : Battelle 505 King Avenue Columbus, OH 43201

6. REFERENCES

Cochran, W.G. (1977). Sampling Techniques . New York: Wiley.

Kish, L. (1965). Survey Sampling . New York: Wiley.