Final Notes from Site Visit at Constellation Energy Generation Group’s Brandon 

Shores Power Plant on March 8, 2010 

EPA conducted a site visit at Constellation Energy Generation Group’s Brandon Shores 

Power Plant (Brandon Shores) located in Baltimore, MD on March 8, 2010 to learn about 

the operations at the plant, specifically the flue gas desulfurization (FGD) wastewater 

treatment system. These notes describe the information collected during the site visit. 

Table 1, located at the end of these notes, identifies the site visit participants. A process 

flow diagram for the FGD system (Attachment 1) and a process flow diagram for the 

FGD wastewater treatment system (Attachment 2) are provided as attachments to the 

notes. 

Plant Overview 

 The Fort Smallwood Road Complex, owned by Constellation Energy and operated by 

Constellation Power Source Group (CPSG), consists of two co-located power plants: 

 Brandon Shores Generating Station; 

 Herbert A. Wagner Generating Station (4 units for a combined 1043 MWnominal); 

o Unit 1: 133 MW - Fuel oil and natural gas; 

o Unit 2: 136 MW - Eastern bituminous coal; 

o Unit 3: 359 MW - Eastern bituminous coal; 

o Unit 4: 415 MW - Fuel oil; 

o Once through cooling; 

o No FGD systems; 

o NOx control: Low NOx burners operating on Units 2 & 3, SCR system on 

Unit 3 and SNCR system on Unit 2, both operated during ozone season; 

o Particulate control: ESPs on Units 1, 2 & 3; 

o Dry fly ash: trucked off-site and beneficially used or landfilled; and 

o Wet bottom ash: Conveyed wet, dewatered, then loaded from storage silos 

onto trucks for disposal. 

 Brandon Shores consists of two coal-fired generating units with a nominal power 

generation of 1,370 MW. The table below contains some general information for the 

two generating units. 

Unit 

Installation 

Date 

Capacity 

(MW) 

Particulate 

Control NOx Control SO2 Control 

1 May 1984 685 Hot-side 

ESP 

SCR 

operational 

May 2000 

Wet FGD began 

operation December 

2009 

2 May 1991 685 Hot-side 

ESP 

SCR 

operational 

May 2000 

Wet FGD began 

operation February 

2010 
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 Both units burn an eastern bituminous coal from approximately 5 different sources. 

The primary coal is central Appalachian coal. The chlorine content of the coal is less 

than 1 percent. 

 Brandon Shores is testing a northern Appalachian coal (2% sulfur content) and 

foreign coals. The plant is considering different coals for business reasons and boiler 

needs. 

 Brandon Shores keeps approximately 40 to 50 days of coal on site. Coal is delivered 

by barge. 

 Both units operate hot-side ESPs which remove 99% of the fly ash. 

 Brandon Shores injects Powdered Activated Carbon (PAC) downstream of the ESP 

and upstream of the FGD system for increased mercury removal. Brandon Shores 

installed a baghouse immediately downstream of the PAC addition to capture the 

mercury-impregnated PAC material. The system is a pulse jet baghouse. The PAC 

material is collected in hoppers, conditioned and disposed of in an off-site landfill. 

This material is handled separately from the fly ash collected in the ESPs. 

 Brandon Shores injects hydrated lime downstream of the hot-side ESP and upstream 

of the FGDs for sulfur trioxide removal. The presence of sulfur trioxide inhibits the 

Powdered Activated Carbon’s ability to remove Hg. 

 The outfall of the existing wastewater treatment plant is MP601. The FGD 

wastewater treatment system has an internal outfall (MP801). There is a combined 

NPDES outfall (001) which receives all the Brandon Shores wastewaters as well as 

wastewater from the four units at Wagner. This outfall discharges to saline (brackish) 

water. 

FGD System 

 Both units operate limestone forced oxidation wet FGD systems. A process flow 

diagram for the FGD system is included as an attachment 1. Both FGD systems have 

a dual flow tray/perforated plate. 

 Brandon Shores receives its limestone via barge. The limestone is moved via 

conveyor and transferred to the on-site ball mills. Brandon Shores uses the ball mills 

to crush the limestone and create the limestone slurry used in the FGD system. 

 Brandon Shores uses effluent from the Anne Arundel County Cox Creek Water 

Reclamation Facility as the source for its FGD make-up water. 

 The FGD systems can remove up to 98% of the sulfur dioxide, but typically achieves 

95% removal of sulfur dioxide. 
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 The FGD systems have a pH set point of between 5 and 6 S.U., depending on the 

operating conditions. The limestone slurry is used to maintain a pH of 5.85 S.U. 

 At this time, the plant is maintaining the chlorides level in the FGD systems between 

8,000 to 12,000 ppm. 

 The plant blows down from the FGD system when the absorber reaches a density 

between 1.07 and 1.16, which at the time of the site visit, could be every day or every 

four days. The blowdown will last 4 to 12 hours depending on the size of the 

particles. 

 The blowdown from the system is transferred to the primary hydrocyclones (one per 

unit with common spare). The underflow from the primary hydrocyclones is 

transferred to the vacuum belt filer for dewatering. Brandon Shores washes the 

gypsum as it is applied to the belt to reduce the chlorides in the gypsum. Brandon 

Shores has several contracts to sell the gypsum. 

 The plant can store some gypsum on site for a temporary period to wait for the market 

to need the gypsum. However, if a buyer cannot be found in a certain time frame, the 

gypsum is disposed in an off-site landfill, which is owned by Constellation Energy. 

 The filtrate from the vacuum belt filters is transferred to the reclaim tank. 

 The overflow from the primary hydrocyclones can be returned to the absorber or 

transferred to the secondary hydrocyclones (one per unit with common spare). The 

underflow from the secondary hydrocyclones is transferred to the reclaim tank, which 

is returned to the absorber. The overflow from the secondary hydrocyclones is 

transferred to the purge tank and then pumped to the FGD wastewater treatment 

system. 

FGD Wastewater Treatment System 

 Brandon Shores operates the FGD wastewater treatment system 24 hours a day, 7 

days a week.

 The secondary hydrocyclone overflow collected in the purge tank is transferred to the 

FGD wastewater treatment system. 

 From the purge tank, the FGD wastewater is pumped to the equalization tank. 

Wastewater forwarding pumps then split the equalization tank effluent between two 

treatment trains. A block flow diagram for the treatment trains is included as 

attachment 2. 
Page 4 

 The temperature of the water coming into the equalization tank is approximately 

112°F to 115°F; however, the filtrate water from the wastewater filtrate sumps is not 

as warm and reduces the wastewater temperature to approximately 90°F. 

 The primary flocculation clarifier can receive 600 of the 900 gpm. The clarifier 

removes the fines, which make up the bulk of the solids. The effluent from the 

clarifier is approximately 50-100 ppm TSS, which equates for approximately 95-98% 

solids removal. The clarifier underflow is transferred to the sludge holding tank. 

Clarifier overflow is sent back to either the water reclaim tank (for reuse in the 

scrubber) or to the FGD wastewater treatment equalization tank. 

Physical/Chemical Treatment 

 The FGD wastewater treatment system receives 300 of the 900 gpm. The system 

consists of a physical/chemical treatment train (which began operating in early 

December 2009) and three sequencing batch reactors. 

 From the equalization tank, the wastewater is pumped to reaction tank 1, where the 

plant adds lime slurry (calcium oxide hydrate). The system can also add an 

organosulfide (TMT-15) at this point. The lime increases the pH to 8.6 to 9.2 S.U. 

Metal hydroxides are generated and precipitated. 

 Water flows by gravity to reaction tank 2, where Brandon Shores adds ferric chloride 

to the wastewater. Iron hydroxides are generated and other metal hydroxides are coprecipitated. 

 After leaving reaction tank 2, Brandon Shores adds a flocculating polymer to the 

stream, which is transferred to a solids contacting clarifier. Some of the underflow 

from the clarifier is recycled to reaction tank 1 to act as seed crystals to help 

precipitate out the solids. Depending on the blanket level, the remainder of the 

underflow sludge is transferred to the sludge holding tank. 

 The plant adds hydrochloric acid to the clarifier overflow to adjust the pH to between 

6 and 6.8 S.U., as it is being transferred to the sequencing batch reactor (SBR) 

influent equalization tank. 

 Brandon Shores adds the chemicals in the order described to maximize the amount of 

solids in the system prior to building floc. Additionally, bench scale tests showed that 

organosulfide was more effective when added prior to ferric chloride. 

Sequencing Batch Reactors (SBR) 

 The SBRs receive the physical/chemical treatment effluent and may also receive 

overflow from the service tank or backwash reject off the tertiary sand filter for 

dilution and/or cooling. The optimal temperature for the SBR is 75°F with a 
Page 5 

maximum temperature of 95°F. The SBR’s also receive a carbon source addition 

with each batch cycle. 

 In the SBR influent equalization tank, Brandon Shores adds sodium bisulfite. A 

defoaming agent can also be added if the plant starts noticing foaming in the SBRs. 

 Sodium bisulfite eliminates free chlorine. The maximum chlorides concentration that 

can be handled by the SBR is 15,000 ppm. The TDS concentration is approximately 

45,000 to 50,000 ppm. 

 The system includes three SBRs, designed to operate two at a time each at 50% 

capacity in batch mode. The SBR tanks are not covered. 

 The first step in the SBR process is the fill, feed, and aerate step. The wastewater is 

fed into the tank along with a carbon source and the water is aerated. During this 

process, nitrification occurs, where the microorganisms convert ammonia present into 

nitrates. In the second step of the SBR process, the aeration is stopped and the tank 

becomes anaerobic. During this process, denitrification occurs, where the 

microorganisms convert the nitrates to nitrogen gas. 

 The SBR system is designed to handle a maximum of 290 ppm total nitrogen and get 

to 4 ppm (not including TKN). The permit limit requires and annual net zero nitrogen 

load. Monitoring is conducted every week using a 24-hour composite at the influent 

and the internal outfall. The expected influent nitrogen concentration is composed of 

60 to 70 ppm nitrates, less than 10 ppm TKN (primarily ammonia), and an 

insignificant concentration of nitrites. Phosphorus control is also required. 

 After the wastewater is denitrified, the wastewater is settled and decanted. The 

decanted water goes to the SBR effluent equalization tank, which is shared by all 

three SBRs. 

 Some of the sludge from the SBRs is wasted to the sludge holding tank (same one 

used for the solids contacting clarifiers in the physical/chemical portion of the 

treatment system). However, most of the sludge remains in the SBRs to retain the 

microorganisms in the system. 

 After the SBR effluent equalization tank, Brandon Shores adds ferric chloride and 

polyaluminum chloride to the wastewater as it is being transferred to the continuous 

backwash gravity filters, as a polishing step. The filtered water is collected in the 

treated effluent storage tank and is then either recycled back to the equalization tank 

or transferred to the outfall for discharge. 

 The effluent flow rate is not continuous. It depends on the purge, water source, 

limestone source, station load (varies seasonally), scrubber performance and 

turndown rate.

 
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Solids Handling 

 The sludge from the primary flocculation clarifier, physical/chemical solids 

contacting clarifier, and the SBR underflow are collected in the sludge holding tank. 

 The sludge is pumped through plate and frame filter presses operated in batch mode. 

 The filtrate is transferred back to the equalization tank via the filtrate sump. 

 The dewatered solids are hauled via dump trunk to an off-site landfill. 
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Table 1. Site Visit Attendees 

Name Organization (Representing) Telephone E-maTerry Murphy Constellation Energy Generation Group (410) 787-6971 terry.murphy@constDavid May Constellation Energy Generation Group (410) 787-6936 david.l.may@consteCatherine Stewart Constellation Energy Generation Group (410) 787-5782 catherine.stewart@cAmy Hetherington Constellation Energy Generation Group (410) 787-9093 amy.m.hetheringtonJim Balik Constellation Energy Generation Group (410) 787-6514 james.balik@constelGrace Counts-Smith Constellation Energy Generation Group (410) 787-5588 grace.a.counts-smithEd Much Constellation Energy Generation Group (410) 787-9073 edwin.much@consteJack Kusterer Constellation Energy Generation Group (410) 787-6928 john.n.kusterer@conMark De Vries Constellation Energy Generation Group (410) 787-5443 mark.a.devries@conHeather Lentz Constellation Energy Generation Group (410) 917-3209 heather.m.lentz@conBill Kennedy Orion Engineering/Constellation Energy Generation Group (980) 721-7626 b.kennedy@orionenDonna Hill Southern Company/UWAG (205) 587-4846 dbhill@southernco.Josh Hall EPA/Office of Water (202) 566-1002 hall.josh@epa.gov Ron Jordan EPA/Office of Water (202) 566-1003 jordan.ronald@epa.Deb Bartram ERG (Contractor to EPA) (703) 633-1669 deborah.bartram@eT.J. Finseth ERG (Contractor to EPA) (703) 633-1698 thomas.finseth@ergKavya Kasturi ERG (Contractor to EPA) (703) 633-1701 kavya.kasturi@erg.c