Site Visit Notes: Duke Energy Carolinas’ 

Belews Creek Steam Station (March 12, 2008) 

EPA conducted a site visit at Duke Energy Carolinas’ Belews Creek Steam Station 

located in Belews Creek, NC on Wednesday, March 12, 2008 to learn about the 

operations at the plant, specifically the FGD wastewater treatment system. Table 1, 

located at the end of this summary, identifies the site visit participants. 

This summary describes the information collected during the site visit and the pre-site 

visit phone call, which was held on February 1, 2008. 

Plant Overview 

• Belews Creek operates two generating units at the power plant. It is a 

baseload plant with a total generating capacity of 2,400 MW The table 

below contains some general information for each unit. 

Unit 

Installation 

Date 

Capacity 

(MW) 

Particulate 

Control NOx Control SO2 Control 

1 1974 1,200 Cold-side 

ESP 

SCR installed 

8/2003 

Wet FGD – 2/2008 

2 1975 1,200 Cold-side 

ESP 

SCR installed 

2/2004 

Wet FGD – 5/2008 

• Both Units 1 and 2 have cold-side ESPs, which achieve approximately 

99.9 percent removal of fly ash and other particulates. 

• The SCRs have been operating year-round since January 1, 2007. 

• Belews Creek began operating a wet limestone forced oxidation FGD 

scrubber on Unit 1 in February 2008. Belews will begin operating a wet 

limestone forced oxidation FGD scrubber on Unit 2 in early May 2008. 

The plant currently receives four 60-car trains of limestone each month. 

• Belews Creek burns eastern bituminous coal in both units. Belews Creek 

burns approximately 19,000 tons of coal per day and receives two 100-car 

trains each day. Belews Creek stores approximately a 30-day supply of 

coal on site. 

• Belews Creek is located adjacent to Belews Lake, which is approximately 

3,863 acres with 88 miles of shore line. Belews Creek owns 7,000 acres 

adjacent to the lake. The plant operates once-through cooling systems for 

each unit and withdraws approximately one million gallons of water from 

the lake per minute. The plant discharges the cooling water back to the 

Belews Lake after it passes through the condensers. 
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• Belews Creek has 180 employees. 

Ash Handling 

• Belews Creek stated that they have the capability to sluice the fly ash with 

a wet system, but the plant primarily uses a dry fly ash handling system. 

Belews Creek stated that they only occasionally use the wet fly ash 

handling system, and when it is used, the fly ash sluice water is transferred 

to the ash basin. 

• Belews Creek stated that they converted to a dry fly ash handling system 

because of selenium toxicity issues in Belews Lake which were identified 

in 1976. In addition to converting the fly ash system, the plant rerouted 

the discharge point for bottom ash wastewater from Belews Lake to the 

Dan River. 

• The fly ash collected by the ESPs is transferred to silos for temporary 

storage and then trucked to an on-site fly ash landfill. The fly ash landfill 

is also permitted to receive solid waste from the FGD wastewater 

treatment plant. 

• Belews Creek handles the bottom ash using a wet sluicing system. 

• Belews Creek stated that they have a mesh screen to segregate the bottom 

ash solids from the ash sluice water prior to entering the ash basin. 

Belews Creek described the mesh screen operation as similar to a 

vibrating sieve, and that the plant is classifying the bottom ash into 

different size particles. 

• The ash basin also receives the effluent from the FGD wastewater 

treatment system; storm water runoff from fields surrounding the plant; 

coal pile runoff; runoff from the fly ash landfill, gypsum landfill, and 

limestone handling area; and effluent from the sewage treatment lagoon. 

• The ash basin discharges to the Dan River. 

FGD Scrubber 

• Belews Creek uses ball mills to crush limestone to make limestone slurry 

which is used as the sorbent in the scrubber. 

• Each of the scrubbers is designed with four recirculation pumps and four 

spray levels. In Unit 1, the plant has been achieving a 95 percent removal 

of SO2 using only three of the spray levels; therefore, the plant is only 

operating three spray levels. Belews Creek alternates the spray levels that 

are used to keep all of the pumps operating. 
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• Belews Creek stated that it took some time before they started sending 

wastewater from the FGD scrubbers to the FGD wastewater treatment 

system because they had to cycle the FGD slurry in the system to build up 

the solids. The plant operates the scrubber at approximately 15% solids. 

• Belews Creek stated that the design maximum chlorides level in the 

scrubbers is 12,000 ppm. Belews Creek stated that they are operating the 

system between 8,000 and 10,000 ppm. 

• Belews Creek stated that the design coal for the plant has a sulfur content 

of 2.4 lbs SO2/MBTU. The percent sulfur of the coal is 1.5 percent. 

• Belews Creek stated that they will have the capability to add DBA to the 

FGD scrubbers, but they have no plans of using DBA in the near future, 

other than for performance testing, which will be conducted in July 2008. 

The plant does not plan to use DBA for 2009 because it is not currently in 

their budget. 

• Belews Creek stated that the design purge flow rate to the FGD 

wastewater treatment system is 600 gpm (300 gpm for each unit), but 

Belews Creek is estimating that the flow will be approximately 350 gpm 

(for both units combined). On average, Belews Creek now estimates the 

purge flow rate is between 400 and 450 gpm during operation. 

• Belews Creek operates a two-stage hydroclone system to dewater the 

gypsum prior to sending it to vacuum filter belts for final dewatering. The 

blowdown from the scrubbers is sent directly to the primary hydroclones. 

The underflow from the primary hydroclones is sent to the filter feed tank, 

which is then transferred to the vacuum filter belts. The overflow from the 

primary hydroclones is sent to a holding tank and then to the secondary 

hydroclones. The underflow from the secondary hydroclones is returned 

to the scrubber or sent to the filter feed tank. The filter feed tank forwards 

the underflow to vacuum filter belts for dewater the gypsum. The 

overflow from the secondary hydroclones is sent to the purge tank and 

then to the FGD wastewater treatment system. 

• Belews Creek washes the gypsum with service water as it is applied to the 

vacuum filter belts. The vacuum filter belts dry the gypsum to 

approximately 10 percent moisture. 

• Belews Creek transfers the dry gypsum to an uncovered gypsum storage 

area. Belews Creek then trucks the gypsum to a wallboard manufacturer 

in Mount Holly, NC. 

• Belews Creek has a lined landfill for disposal of off-spec gypsum, or for 

gypsum the wallboard manufacturer does not want. 
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• Belews Creek is expecting to produce approximately 250,000 tons of 

gypsum during 2008. Note that neither of the scrubbers will have been 

operating for the entire 2008 calendar year. 

FGD Wastewater Treatment System 

• The FGD wastewater treatment system at Belews Creek consists of three 

processes: physical/chemical separation (hydroxide and sulfide 

precipitation), biological treatment, and constructed wetlands. 

• [CBI information has been removed from this document.] 

• The FGD wastewater treatment system at Belews Creek starts with the 

physical/chemical separation. Figure 1, at the end of this memorandum, 

presents a process flow diagram for the physical/chemical separation 

portion of the wastewater treatment system. 

• The secondary hydroclone overflow from the scrubbers is transferred to a 

purge tank and sent to the equalization tank at the start of the wastewater 

treatment system. Belews Creek stated that the equalization tank also 

receives water from the filtrate sump (which includes filter press filtrate), 

gravity filter backwash reject, backflush waste from the biological 

treatment system, and off-specification biological treatment effluent. 

• From the equalization tank, the wastewater enters three reaction tanks in 

series: reaction tank 1 in which lime is added to increase the pH to 

between 8.5 and 9.2 (target 8.8); reaction tank 2 in which organosulfide is 

added; and reaction tank 3 in which ferric chloride is added. A portion of 

the clarifier sludge is also recycled to reaction tank 1. The wastewater 

flows from reaction tank 3 to a mix chamber where polymer is added. 

• From the mix chamber, the wastewater is split and enters two clarifiers in 

parallel. The clarifiers are solids contact clarifiers that contain a sludge 

bed which attracts the solids in the wastewater. Each of the clarifiers is 

capable of handling 100 percent of the waste stream capacity. The 

overflow from the clarifiers is split and sent through three sand filters in 

parallel. Each of the sand filters can handle 75 percent of the waste stream 

capacity. From the sand filters the wastewater enters a feed tank where 

hydrochloric acid is added to reduce the pH prior to the biological 

treatment system. The target maximum TSS level for the sand filter 

effluent is 50 ppm; however, the plants tries to keep TSS below 20 ppm. 

The sand filters are continuous backwash gravity filters. The filter 

backwash is sent to a sump, then transferred to the equalization tank. 

• The sludge from the clarifiers is transferred to a sludge tank and then to a 

filter press for dewatering. Belews Creek achieves a solids concentration 

of 15 percent in the sludge tank, which is higher than the designed 

percentage, because it forms a better cake in the press. The filter press 
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cake is landfilled in the fly ash landfill and the filtrate is sent to the filtrate 

sump. Each filter press operation produces 28,000-30,000 lbs of filter 

cake. When both FGDs are fully operating, Belews Creek anticipates 

there will be 10 filter press operations per week. Currently, there are 

approximately 5 filter press operations per day. 

• The biological treatment system consists of 16 biological cells, shown in 

Figure 2, at the end of this memorandum. Belews Creek treats the 

wastewater in two stages. Each stage contains eight biological cells 

operated in parallel. Each cell contains an activated carbon bed. Within 

the activated carbon bed, specialized microbes fill the voided areas to 

reduce the nitrogen and metals, specifically selenium, in the wastewater. 

• The wastewater from the sand filters is transferred to a holding tank prior 

to entering a heat exchanger to reduce the temperature to 95oF. Belews 

Creek adds nutrients (molasses-based) to the wastewater as it flows from 

the heat exchanger to the biological system. The nutrients provide a 

source of carbon to feed the bacteria. The wastewater is divided evenly 

among the eight first stage cells. The flow to each cell is sent to 16 

distribution pipes to create an even distribution of flow into the top of the 

cell. The water level in the cells is approximately three feet above the 

activated carbon bed. 

• [CBI information has been removed from this document.] 

• Because the first stage bioreactor cells denitrify the waste stream, they 

produce nitrogen and carbon dioxide gas. To remove the gas from the 

cells, the plant occasionally performs a degassing operation where water is 

sent backwards through the cells, like a backflush, but the flush is only 

long enough for the gas to “burp” out of the system. 

• The effluent from the first stage bioreactor cells is transferred to the first 

stage effluent storage area. The effluent from all eight first stage cells is 

commingled in the storage area. The wastewater is then transferred to the 

second stage of eight parallel cells. Nutrients are added to the wastewater 

as feed for the microbes as the wastewater is transferred. As in the first 

stage, the wastewater is divided evenly among the eight second stage cells 

and each cell has 16 distributor pipes to evenly distribute the flow into the 

cell. 

• The second stage bioreactor cells are primarily anoxic and therefore do not 

produce as much gas as the first stage cells. The second stage cells 

remove the metals remaining in the wastewater. 

• Occasionally the bioreactor cells will need to be backflushed to remove 

the solids that have built up in the system. Belews Creek will send service 

water backwards through each cell, starting at the bottom and pushing the 

solids upward. The cells have a spill over area to collect the backflush 
Page 6

water which is then sent to the equalization tank at the start of the FGD 

wastewater treatment system. 

• From the second stage of the biological treatment system, the wastewater 

enters the wetland supply tank, where cooling water is added to the 

wastewater to reduce the temperature and chlorides level. The plant 

dilutes the wastewater with the cooling water from the heat exchanger 

prior to the biological system at a ratio of 1:1, but they can increase to a 

2:1 ratio (cooling water: FGD wastewater) to keep the chlorides level 

around 4,000 ppm. From the wetlands supply tank, the wastewater enters 

the constructed wetland system. Figure 3, at the end of the memorandum, 

presents a simplified process flow diagram of the constructed wetlands 

treatment system. 

• The first stage of the constructed wetlands consists of two equalization 

tanks which allow further cooling of the wastewater. The wastewater is 

then split to enter two identical constructed wetland treatment trains in 

parallel. The first and second cell of each train (1A, 1B, 2A, 2B) contain 

bulrush. The wastewater then flows over cascading rocks (3A, 3B) and 

enters the third cell containing cattails (4A, 4B). After the cattail cell, the 

wastewater flows over another cascade of rocks (5A, 5B) and then the 

wastewater from the two trains are commingled and discharged to the ash 

basin. 

• Each of the constructed wetlands cells has a geosynthetic clay liner. 

• The first two constructed wetland cells provide a reduced environment 

with anoxic conditions which allow for removal of selenium and mercury. 

• In fall of 2006, Belews Creek planted the plants in the constructed wetland 

cells, but the plants did not take. Therefore, Belews Creek replanted the 

cells. Belews Creek is looking to replant the cells again soon because the 

plants are still not taking in the cells. 

• Belews Creek stated that they are having issues planting the bulrush 

because the plants will not spread throughout the cell. The plant is 

considering adding cattails to the first and second cells because they have 

had better luck with the cattails. Belews Creek stated that if they do plant 

cattails in the cells, then the cattails will probably take over the entire cell 

pushing out the bulrush. Belews Creek stated that this should not make 

much difference because the main purpose of the plants is to produce 

organic matter. 

• Each constructed wetland cell is approximately 2.5 acres and Belews 

Creek planted 13,000 plants in each of the cells. The plants prevent the 

wastewater from channeling through the cells, provide organic material, 

and also provide oxygen to the wastewater. Belews Creek stated that it 

will take several years for the cells to reach full maturity. 
Page 7

• Belews Creek estimated the retention time for the constructed wetland 

system is six to seven days. 

• Belews Creek stated that the redox potential in the constructed wetland 

cells is controlled by the water level. The higher the water level in the 

cells, the more anoxic the conditions. Belews Creek controls the water 

level by adding or removing wooden planks to the overflow weir. The 

water level in the cells is approximately 12 to 15 inches deep. 

• Belews Creek stated that they do not expect the mercury in the wastewater 

to convert to methylmercury because the mercury is present at such low 

concentrations. Belews Creek will not be monitoring the constructed 

wetlands effluent for methylmercury. 

• Belews Creek stated that they are achieving good removals of mercury 

from the constructed wetlands, but the selenium removals have not been as 

good as they expected. 

• Belews Creek stated that there is not much nitrogen reduction in the 

constructed wetlands because most of the nitrogen reduction is 

accomplished in the biological system. 

• Belews Creek does not have limits for metals from the constructed 

wetlands because it is an internal outfall. 

• Belews Creek stated that they decided to have an extensive wastewater 

treatment system because the plant wanted to reach the selenium limit of 

26 ppb for the ash basin effluent prior to the wastewater entering the ash 

basin at the end of the constructed wetland system. Belews Creek stated 

that took a conservative approach and the system ensures that they will 

meet the limit. 

• Effluent from the constructed wetlands is sent to the ash pond where it 

joins with other wastestreams (approximately 5:1 dilution of the FGD 

wastewater occurs here, in addition to the dilution water added at the 

wetlands supply tanks). The ash pond discharges to the Dan River (outfall 

003). 

FGD Wastewater Treatment Data 

• Belews Creek stated that they have NPDES monitoring locations at the 

end of the constructed wetlands system and the discharge from the ash 

basin. Belews Creek stated that they are required by their permit to 

monitor for 10 metals at these locations. 

• Belews Creek is also currently collecting wastewater samples from the 

following sample points: 
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o FGD purge; 

o Equalization tank effluent; 

o FGD clarifier influent; 

o FGD clarifier effluent; 

o Gravity filter effluent/influent to bioreactors; 

o First stage bioreactor effluent; 

o Second stage bioreactor effluent; and 

o Constructed wetland effluent. 

• Since the time of the site visit, Belews Creek reports that samples are now 

being collected within the wetland treatment system. 

• Belews Creek stated that they also plan to begin collecting samples of the 

influent to the constructed wetlands and the effluent from each of the 

individual cells. 

• Belews Creek has been analyzing the samples collected from the above 

sample points for the following analytes: 

o Alkalinity; 

o Chloride; 

o Ammonia; 

o Nitrate/nitrite; 

o Total phosphorus; 

o TSS; 

o Oil and Grease; 

o Total Metals (Hg, B, As, Ag, Cd, Cr, Ni, Se (total and dissolved), 

and Zn); and 

o Selenium speciation (selenite and selenate). 

• The total metals samples have been analyzed using the 200-series methods 

and not the 1600-series low-level methods. Belews Creek plans to collect 

these samples daily for three to six months and then reevaluate sampling 

frequency. 

• Belews Creek stated that monitoring results have shown the FGD 

wastewater treatment system is not removing chlorides or boron. 

• Belews Creek stated that the performance testing for the system will be 

conducted in July 2008. 

FGD Wastewater Treatment Cost Information 

• Belews Creek stated that the treatment vendors are sensitive about the cost 

information associated with their systems because of the competing 

vendors. Belews Creek stated that the costs of their systems will not be 

finalized until September 2008. 
Page 9

• EPA stated that all information can be handled as confidential business 

information if Belews Creek would like. EPA also stated that they would 

appreciate if Belews Creek could separate the cost of the FGD wastewater 

treatment system into the physical/chemical portion, the ABMet® 

biological treatment portion, and the constructed wetlands portion. In 

addition, EPA stated that Belews Creek does not need to provide the final 

cost values, estimates of the total cost will be sufficient. 

• Belews Creek stated that they will collect the cost information for EPA but 

it will be claimed as Confidential Business Information.
Table 1. Site Visit Attendees 

Name Organization (Representing) Telephone E-maJon Arterburn Duke Energy (704) 382-0966 jrarterburn@dukJeff Blackwood Duke Energy (336) 445-0504 jkblackw@dukeBill Kennedy Duke Energy (980) 721-7626 wkennedy@dukMelonie Martin Duke Energy (336) 445-0610 mymartin@dukeDebbie Nispel Duke Energy (317) 838-1957 dnispel@duke-eJay Perkins Duke Energy (704) 875-5348 jperkins@duke-Shannon Todd Duke Energy (336) 445-0428 stodd@duke-eneRobert Wylie Duke Energy (704) 382-4669 rrwylie@duke-eDonna Hill Southern Company (205) 257-5234 dbhill@southernKarrie-Jo Shell EPA/Region 4 (404) 562-9308 shell.karrie-jo@Josh Hall EPA/Office of Water (202) 566-1002 hall.josh@epa.gRon Jordan EPA/Office of Water (202) 566-1003 jordan.ronald@eT.J. Finseth ERG (Contractor to EPA) (703) 994-7130 thomas.finseth@
Figure 1. Process Flow Diagram for Physical/Chemical Separation Portion of FGD Wastewater Treatm

FGD Purge 

EQ Tank 

Lime 

Land

Sludge Tank 

BioReactors 

Sand Filter 

Clarifier 

Filter Pres

Sulfide Ferric Polymer 

Acid 
Figure 2. Process Flow Diagram for Biological Portion of FGD Wastewater Treatment Syste

Sand filter Effluent 

First Stage 

Second Stage 

Cooling Water 

Cooling Water 

Wetland Supply Tank 

First Stage Recycle 

SecondStage Recycle 

Nutrient 

Nutrient 
Figure 3. Process Flow Diagram for Constructed Wetland Portion of FGD Wastewater Treatment 

EQ A EQ B 

1B 2B 3B 4B 5B 1A 2A 3A 4A 5A 

Wetland Supply Tank