### MEMORANDUM

TO: Steam Electric Rulemaking Record

FROM: Ryan Novak and Deb Bartram , ERG

DATE: 30 September 2015

SUBJECT: Steam Electric Effluent Guidelines Loadings Methodology

– Break Out of

Combined Ash Loadings

1. I NTRODUCTION /B ACKGROUND

ERG is providing technical support to the U.S. Environmental Protection Agency’s Office of Water, Engineering and Analysis Division (EAD) for development of effluent limitations guidelines and standards (ELGs) for the Steam Electric Power Generating Indust ry.

The U.S. Environmental Protection Agency’s Office of Water, Engineering and Analysis Division (EAD) calculated plant

- specific loadings for the baseline discharges and key technology options considered fo r control of ash transport water for the effluen t limitations guidelines and standards (effluent guidelines) for the Steam Electric Power Generating Industry

. EPA multiplied the plant

- specific ash transport water discharge flow rate for each type of ash transport water ( i.e. , fly ash, bottom ash, or com bined ash transport water) by the appropriate average concentration data set for the type of discharge. Because EPA considered regulatory options that would establish different effluent requirements for fly ash and bottom ash, EPA analyzed the pollutant lo adings and removals for these two wastestreams separately; therefore, EPA separated the loadings for combined ash impoundments into fly ash transport water loadings and bottom ash transport water loadings. This memorandum describes the methodology

and data EPA used to estimate the breakout of pollutant loadings associated with combined ash impoundments among fly ash transport water and bottom ash transport water.

2. E LECTRIC P OWER R ESEARCH I NSTITUTE W ATER C HARACTERIZATION F IELD S TUDIES

In 1988, the Electric Po wer Research Institute ( EPRI ) initiated the Power Plant Integrated Systems

- Chemical Emissions Study (PISCES), a multi

- media chemical assessment study that characterized the distribution of trace substances in air, liquid, and solid wastestreams from

fossil

- fuel

- fired electric utility power plants. EPRI provided EPA with the PISCES Water Characterization Field Study, Sites A

- G reports [EPRI, 1997

- 2001] that summarize the data collected during seven separate sampling episodes to characterize wastewater at coa l

- fired power plants operating impoundments receiving fly ash transport water and/or bottom ash transport

water

. For each of the seven sites sampled, EPA reviewed the reports to determine the characteristics of the ash impoundments ( e.g. , type of wastestre ams entering the impoundment, pollutant concentrations). The sites were identified as operating the following type of ash impoundments:

 Site A

– Combined ash impoundment;Memorandum

30 September 2015 Page 2

 Site B

– Combined ash impoundment;

 Site C

– Combined ash impoundment;

 Site D

– Combin ed ash impoundment;

 Site E

– Combined ash impoundment;

 Site F

– Bottom ash impoundment & combined ash impoundment; and

 Site G

– Combined ash impoundment.

Reports for Sites A through D also provided EPA with information regarding the respective percentage o f pollutant loadings from ash impoundments containing both fly ash and

bottom ash. These reports include table s presenting loadings to the ash impoundments in kg/day associated with each stream entering the impoundment for several metal pollutants. 1 Althou gh the reports for Site E, Site F, and Site G provide EPA with information on flow contributions to the combined ash impoundments, they do not provide the pollutant loadings for each

wastestream.

EPA reviewed the information regarding the plants to determine whether the data were appropriate for use in the analysis. EPA made the following conclusions based on this review:

 Site A was excluded from this analysis of combined ash loadings because the fly

ash transport water is only transferred to the ash impoundment during occasional operation; therefore, the fly ash transport water loadings compared to the bottom

ash transport water loadings were not representative of the operations at a typical plant with both wet fly and bottom ash sluicing.

 Site B was included in the analysis as it consists of both fly and bottom ash

transport water transferred to the ash impoundment.

 Site C was included in the analysis as it consists of both fly and bottom ash

transport water transferred to the ash impoundment.

 Site D consists of two separate plants ( i.e. , Plants A and B). Plant A has wet fly ash and bottom ash handling for all six generating units and Plant B has wet bottom ash for two generating units, but wet fly ash for only one of the two generating units; therefo re, only Plant A fly ash and bottom ash loadings data were included in the analysis. Plant B loadings data were excluded.

Based on this information, EPA used the loadings from the fly ash and bottom ash transport

water streams in these EPRI PISCES reports to determine how the calculated combined ash loadings for each pollutant should be allocated to the fly ash and bottom ash transport water

. Refer to the “Break Out of Combined Ash Loadings Calculation Workbook” for eac h of the tables that present the ash impoundment influent at Site B, Site C, and Site D [ERG, 2015].

1 Table 5

- 1 and Table 5

- 2 from PISCES Water Characterization Field Study: Sites A and B Report (DCN SE01818),

Table 5

- 1 from PISCES Water Characterization Field Study: Site C Report (DCN SE01819), and Table 5

- 1 from PISCES Water Characterization Field Study: Site D Report (DCN SE01820) provide the pollutant

- specific loadings

for all wastestreams ent ering the com bined ash impoundments at those sites

.Memorandum

30 September 2015 Page 3

3. C ALCULATION OF P OLLUTANT

- S PECIFIC L OADINGS R ATIO

EPA used the fly ash transport water and bottom ash transport water loadings presented

in the EPRI PISCES reports for the sites described above to calculate a site

- specific percent loading for fly ash and bottom ash for each pollutant. For each site and available pollutant, EPA calculated the percent of the pollutant loading associated with fly ash and bottom ash relative to the total ash loading. As demonstrated in Figure 1 , for Site C the aluminum fly ash loading is 190 kg/day and the bottom ash loading is 7.8 kg/day; th erefore, EPA calculated a total ash loading of 197.8 kg/day

. EPA determined that 96.06 percent of the total ash aluminum loading is attributed

to the fly ash and 3. 94 percent of the loading is attributed to bottom ash

. Although the impoundment also received other wastes, EPA used only the contributions from fly ash sluice

transport water and bottom ash transport water for this calculation

. EPA performed this calculation for each pollutant available for each of the three sites. Table 1 and Table 2 present the percent loading calculated for fly as h and bottom ash, respectively, for each pollutant at each

site.

Figure 1

. Example Calculation of Percent Aluminum Loadings Associated with

Fly Ash and Bottom Ash at PISCES Site C

Note: The table presented is an abbreviated ver sion of Table 5

- 1 from PISCES Water Characterization Field Study: Site C Report (DCN SE01819).

1

– Samples of plant waste and coal pile runoff were shaken to resuspend solids, rather than allowed to settle like

ash sluice wastes.

2

– Coal pile runoff is an nualized over a year from 5 years of rainfall data.

EPA then calculated an overall average percent loading for fly ash transport water and

bottom ash transport water for each pollutant using the site

- specific percentages , as shown in

Table 1 and Table 2 . Because EPA did not have data available to calculate an average percent loading for fly ash and bottom for all pollutants in the combined ash impoundment dataset, EPA calculated the average percent loading for fly ash and bottom ash based on the pollutants available, 85.9 and 14.1 percent, respectively, and used this value for the allocate th e loading for all other pollutants. Therefore, EPA assumed fly ash transport water and bottom ash transport

water account for 85.9 and 14.1 percent, respectively, of all combined ash loadings (not flow) for those pollutants for which an analyte

- specific va lue could not be calculated using the EPRI data.Memorandum

30 September 2015 Page 4

These average percent loadings for fly ash and bottom ash are presented in Table 3 for each pollutant available. Refer to the “Break Out of Combined Ash Loadings Calculation Workbook”

for the data used in these calculations [ERG, 2015]

. EPA applied the percentages in Table 3 to

allocate the loadings from combined ash impoundment effluent to fly ash transp ort water and bottom ash transport water.

4. R EFERENCES

1. Electric Power Research Institute (EPRI). 1997

- 2001. PISCES Water Characterization Field Study, Sites A

- G. Palo Alto, CA. DCNs SE01818

- 01823

2. ERG. 2015. Eastern Research Group, Inc. Break Out of Combined Ash Loadings Calculation Workbook. ( 30 September ). DCN SE05586A1

.Memorandum 30 September 2015 Page 5

Table 1

. Calculation of Fly Ash Average Percent of Loading for All Three PISCES Plants

Al Sb As Be Ca Cu Fe Hg Ni Se Zn TSS

Fly Ash Site B 92.95% 89.29% 99.08% 96.00% 97.52% 85.96% 71.43% 96.15% 99.54% 81.89%

Fly Ash Site C 96.06% 93.33% 98.36% 83.33% 95.74% 98.04% 90.91% 79.22%

Fly Ash Site D (Plant A) 88.43% 95.59% 77.68% 42.86% 59.83% 41.18% 99.42% 89.74% 92.64%

Fly Ash Average 92.48% 89.29% 96.00% 96.00% 77.68% 79.58% 76.37% 71.43% 77.69% 99.00% 90.33% 84.58%

Note: EPA calculated the average percent loading for fly ash and bottom ash based on the pollutants available, 85.9 and 14.1 percent, respectively, and assumed this value for the percent breakout for the other pollutants for which loads were calculated for combined ash impoundments.

Table 2

. Calculation of Bottom Ash Average Percent of Loading for All Three PISCES Plants

Al Sb As Be Ca Cu Fe Hg Ni Se Zn TSS

Bottom Ash Site B 7.05% 10.71% 0.92% 4.00% 2.48% 14.04% 28.57% 3.85% 0.46% 18.11%

Bottom Ash Site C 3.94% 6.67% 1.64% 16.67% 4.26% 1.96% 9.09% 20.78%

Bottom Ash Site D (Plant A) 11.57% 4.41% 22.32% 57.14% 40.17% 58.82% 0.58% 10.26% 7.36%

Bottom Ash Average 7.52% 10.71% 4.00% 4.00% 22.32% 20.42% 23.63% 28.57% 22.31% 1.00% 9.67% 15.42%

Note: EPA calculated the average percent loading for fly ash and bottom ash based on the pollutants available, 85.9 and 14.1 percent, respectively, and assumed this value for the percent breakout for the other pollutants for which loads were calculated for combined ash impoundments.Memorandum 30 September 2015 Page 6

Table 3 . Percent Loadings for Fly Ash and Bottom Ash in Combined Ash Impoundments

Analyte Percent Loading Fly Ash (%) Percent Loading Bottom Ash (%)

Aluminum 92.5 7.5 Antimony 89.3 10.7

Arsenic 96.0 4.0 Beryllium 96.0 4.0

Calcium 77.7 22.3 Copper 79.6 20.4

Iron 76.4 23.6 Mercury 71.4 28.6

Nickel 77.7 22.3

Selenium 99.0 1.0

Zinc 90.3 9.7

TSS 84.6 15.4

Overall Average 85.9 14.1

Note: The values in this table have been rounded to the tenth decimal place

.